hydrology of mountanious areas

8/3/2019 Hydrology of Mountanious Areas

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HYDROLOGY OF MOUNTAINOUS AREAS


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TTTf FK R E C E N T L Y P U B L I S H E D B Y I A H SProceedings of the symposia held during the Second IAHSAssembly, Budapest, Ju ly 1986:

Modelling Snowmelt-Induced ProcessesPubl.no.155 (1986), price $40Conjunctive Water UsePubI.no.156(1986), price $48Monitoring to Detect Changes in Water QualityPubl.no.157(1986), price $40Integrated Design of Hydrological NetworksPubfno.158 (1986), price $40Drainage Basin Sediment Delivery. Proceedings of theAlbuquerque Symposium, August 1986Publ.no.159(1986), price $45

Hydrologie Applications of SpaceTechnology. Proceedingsof the Cocoa Beach Workshop, August 1985Publ.no.160(1986), price $45Karst Water Re sources. Proceedings of the AnkaraSymposium, July 1985Pubt.no.161(1986), price $45Avalanche Formation, Movement and Effects. Proceedingsof the Davos Symposium, September 1986PubI.no.162(1987), price $50Developments in the Analysis of Groundwater FlowSystems. Report prep ared by a Working Group of theIAHS International Commission on GroundwaterPubl.no.163(1986), price $35Water for the Futu re: Hydrology in PerspectiveProceedings of the Rome Symposium, April 1987Publ.no.164 (1987), price $50Erosion and Sedimentation in the Pacific Rim. Proceedingsof the Corvallis Symposium, August 1987PubI.no.165(1987), price $55

a held during the IU GG Assembly,roceedings of theVancouver, AugustLarge Scale Effects of Seasonal Snow CoverPubl.no.166 (1987), price $42

Forest Hydrology and W atershed ManagementPubl.no.167 (1987), price $55The Influence of Climate Change and ClimaticVariability on the H ydrologie Regime and WaterResourcesPubl.no.168(1987), price $55Irrigation and W ater AllocationPubl.no.169(1987), price $32The Physical Basis of Ice Sheet ModellingPubl.no.170 (1987), price $40

Hydrology 2000. Report of th e IAHS Hydrology 2000Working G roupPubl.no.171(1987), price $22Side Effects of Water Reso urces Management. ReportP repared by an IHP-HI Working Gro upubl.no.172(1988), price $40Groundwater M onitoring and M anagem ent Proceedings ofthe Dresden Symposium, March 1987Publ.no.173(1990), price $55Sediment Budgets. Proceedings of the Porto AlcgreSymposium, December 1988Publ.no.174(1988), price $60

Consequences of Spatial Variability in Aquifer Propertiesand Data Limitations for G roundwater M odelling Pra ctice.Report prepared by a Working Group of the InternationalCommission on GroundwaterPubl.no.175(1988), price $45Karst Hydrogcology and Karst Environment Protection.Proceedings of the IAH/IAHS Guilin Symposium, October1988Publ.no.176(1988), price S55Estimation of A rea! Evai don. Proceedings of aworkshop held during the IUGG Assembly, Vancouver,August 1987Pu61.no.177(1989), price S45Remote Data T ransmission. Proceedings of a w orkshopheld during the IUGG Assembly, Vancouver, August 1987Publ.no.178 (1989), price $30

s of symposia held during the Th ird IAHSembly, Baltimore, Maryland, May 1989:Atmospheric DepositionPubI.no.179(1989), price $45Systems Analysis for Wa ter Resources Management:Closing th e Gap Between Theory and PracticePubl.no.180 (1989), price $45Surface Water Modeling: New Directions forHydrologie P redictionPubUio.181 (1989), price $50Regional Characterization of W ater QualityPubl.no.182(1989), price $45Snow Cover and Glacier VariationsPubI.no.183(1989), price $30Sediment and the EnvironmentPubl.no.184(1989), price $40Groundwater ContaminationPubl.no.185(1989), price $40Remote Sensing and Largc-Scale Global Processe sPubl.no.l86(1989), price $40

FRIEND S in Hydrology. Proceedings of the BolkesjoSymposium, April 1989Publ.no.187 (1989), price $50Groundwater Management: Quantity an d QualityProceedings of the Benidorm Symposium, October 1989Publ.no.188(1989), price $60Erosion, Transport and Deposition Processes. Proceedingsof the Jerusalem Workshop, March-April 1987Publ.no.189(1990), price $40Hydrology of Mountainous Areas. Proceedings of theStrbske Pleso Workshop, Czechoslovakia, June 1988Publ.no.190 (1990), price $45Regionalization in Hydrology. Proceedings of the LjubljanaSymposium, April 1990Publno.191 (1990), price $4S

First of New S eries!Hydrological Phenomena in G eosphcre-BiosphereInteractions: Outlooks to Past, Present and Futureby Mtin FalkenmorkMonograph n o.l (1989), price $15Available only romIAHS Press, Wallingford

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Hydrology ofMountainous AreasE d i t e d b yL . M O L N RCzechoslovak Committee for Hydrology, Tmavsk 32 ,82651 Bratislava, Czechoslovakia

Proceedings of the international workshopheld at Strbsk Pleso, Vysok Tatry,Czechoslovakia, 7-10 June 1988. Theworkshop was a contribution to theInternational Hydrological Programme ofUNESCO, project no. 4.8, and it wasco-sponsored by UNESCO, the WorldMeteorological Organization, theInternational Association of HydrologicalSciences and the InternationalAssociation of Hydrogeologists

IAHS Publication No. 190


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Published by the International Association ofHydrological Sciences 1990.IAHS Press, Institute of Hydrology, Wallingford, OxfordshireOX10 8BB, UK.IAHS Publication No. 150.ISBN 0-947571-42-6.The designations employed and the presentation of material throughout thepublication do not imply the expression of any opinion whatsoever on the part ofIAHS concerning the legal status of any country, territory, city or area or of itsauthorities, or concerning the delimitation of its frontiers or boundaries.The use of trade, firm, or corporate names in the publication is for theinformation and convenience of the reader. Such use does not constitutean official endorsement or approval by IAHS of any product or serviceto the exclusion of others th at may be suitable.

The Ed itor would like to express his thanks to Dr P. Miklnek, DiptEng I. Msa ros and Mrs A. Meliskov for their efforts and theircontinuous assistance with the proceedings. Mrs Poulette Richardof the National Hydrology Reearch Institute, Saskatoon, and MissHeather Gulka, formerly with the same Institute, are also thankedfor retyping the papers in the final section.

The camera-ready copy for the papers was partly prepared at the Institute ofHydrology and Hydraulics, Slovak Academy of Sciences, Trnavsk 32, 826 51Bratislava, Czechoslovakia, and partly prepared at the National HydrologyResearch Institute, 11 Innovation Boulevard, Saskatoon, Saskatchewan, CanadaS7N 3H5.

Printed in The Nethe rlands by Krips Rep ro Meppel.


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PREFACEBeautiful but often hostile and harsh mountains contribute to formation of the nature of man living in harmonywith them, and teach him to live in the same harmonywith others. Therefore, it has been so easy to bringhydrologists studying mountainous hydrological processestogether into the Slovakian High Tatras.The International Hydrological Decade (IHD) and International Hydrological Programme (IHP) of UNESCO, togetherwith the International Association of Hydrological Sciences (IAHS), for more than 20 years provided strong incentives for world-wide studies of the hydrological processes in mountainous areas. They, as the sources of freshwater also become the sources of better understanding ofthe studied processes in complicated climatic, orographicand physico-geographic conditions. Moreover, if typicalfeature of mountains seems to be the elevation only, thehydrologists should also add features as the absence ofdata, their dominant spatial and temporal distributionsand lacking accuracy.The third phase of IHP within the project No.4.8 hascreated room to exchange the knowledge and experiencesalready gained in various mountainous regions, and toidentify the so far open problems of mutual interest ofthese countries leading to internationally coordinatedresearch.

The Czechoslovak Committee for Hydrology (CSVH) hasresponded by organizing the International workshop onhydrology of mountainous areas (7-10 June, 1988, StrbskPleso, Czechoslovakia) together with:- Institute of Hydrology and Hydraulics- Slovak Hydrometeorological Institute- Water Research Institute- D.Str Geological Institute,under the international sponsorship of:- UNESCO, WMO, IAHS, IAH and cooperation of FAO,and the national sponsorship of:- Czechoslovak and Slovak Academies of Sciences- Czechoslovak Commission for UNESCO- Ministries of Forest and Water Management of the Czechand Slovak Socialist Republics- Czech and Slovak Geological Offices.The Workshop has covered the following topics:1. Integral data networks, hydrometeorological data collection and processing in mountainous areas.Conveyed by WMO and CSVH, convenor Dr.Georg Gietl

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Preface VI2. Hydrological balance as a basis for water resourcesassessment and water management in mountainous regions.Conveyed by UNESCO and CSVH, convenor Dr.Lev S.Kuchment.3. Surface water and groundwater interactions in mountainous areas.Conveyed by IAH, IAHS and CSVH, convenor Dr.Jan Silar4. Modelling of hydrological processes and of man's

activity impacts in mountainous areas.Conveyed by IAHS, UNESCO and CSVH, convenorDr.Vit Klemes.The presented volume within IAHS publications shouldbe viewed as a more or less partial result of the Workshop. The papers selected by convenors, the members ofeditorial board, do not cover all results presented at thewell attended Workshop (the participants are listed inAppendix 3 ) . Naturally, with limited space, the volumecannot be fully comprehensive, and therefore, further pre

sentations of achieved results in other journals orpublications are welcomed, and the continuation of worksin the field of mountainous hydrology is very muchappreciated.Finally, let us express our thanks to all the membersof editorial board Dr.Gietl, Dr.Kuchment, Dr.Silar andespecially Dr.V.Klemes, who generously invested a lotof time to fulfil the editorial decision to make to theoriginal texts as few changes as possible, in order topreserve the authors' points of view, but to improvethem according standards of IAHS publications. Also, letus thank all the members of the team from the Instituteof Hydrology and Hydraulics of the Slovak Academy ofSciences, Bratislava, and the National Hydrology ResearchInstitute, Saskatoon, reponsible for the camera-readycopy of this publication.

Dr. Ludovt Molnr Prof.Dr. Jan BenetinEditor Chairman of the CSVH


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FOREWORDHydrology of mountainous areas is lagging behind manyother areas of hydrological inquiry, in proportion to itsgreater difficulty. In hydrology research, as elsewhere,more attention has been paid to things which are easythan to those which are difficult. Man is the GreatOpportunist and hydrologists are, after all, people.This is why we have, for example, so many computer models,sensitivity analyses, simulation studies, etc., and sofew good hydrological data on mountainous basins: it ismuch easier to play with a computer in a cosy office (andcheaper, too) than to cope with blizzards, avalanches andrough and roadless terrain while making hydrologicalmeasurements in the mountains. But access is not theonly difficulty. It is the very nature of the mountainenvironment that complicates matters seriously the highvariability of topography, soils and vegetation, of thetemperature distribution, radiation and albedo, of thedeposition and melting of snow and ice; the turbulentcharacter of mountain streams, the rapidity of changes inatmospheric conditions and a host of other factors thatcomplicate the life of the mountain hydrologist.

But hhe importance of mountain hydrology can hardly beoverestimated. While the tropical regions are the mainsource of atmospheric moisture, the mountainous regionscontrol much of its distribution over the continents.Mountain ranges are the source areas of all the largeriver systems of the world and their temperature regimeis a key factor for the seasonal distribution of theirstreamflow.It is a disquieting thought that, inspite of theirhydrological importance, mountainous areas represent,practically speaking, some of the blackest black boxes inthe hydrological cycle: not only their internal structureis "black", but often even their water input howeverwhite it may appear on the ground! Only about theiroutput the streamflow of mountain-fed rivers do we haveany accurate and systematic information.Therefore it is with great satisfaction that Iwelcomed the initiative of our Slovak colleagues toorganize this international workshop, from which aselection of contributions is presented here, and with agreat pleasure that I had an opportunity to participatein it.

Vit KlemesPresidentInternational Association of Hydrological SciencesVll


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CONTENTSPreface Ludovit Molnr & Jn Benetin vForeword Vt Klemes vii

1 Keynote PapersCollection and processing of hydrometeorological and hydrological data inmountainous areas G. Gietl 3Water balance as a basis for water resources estimation and management inmountainous areas L. S. Kuchmeni 13Surface water and groundwater interactions in mountainous areas/. Silar 21The modelling of mountain hydrology: the ultimate challenge V. KlemeS 29

2 Integral Data Networks, Hydrom eteorological DataCollection and Processing in Mountainous AreasMeasurement and processing of atmospheric precipitation in mountainousareas of Slovakia M. Lapin AlInfluence of topography on spatial distribution of rain C. Givone &X. Meignien 57A French hydrometeorological experiment to evaluate weather radarcapabilities for medium elevation mountain hydrology H. Andrieu,J. D. Creutin, J. Leoussoff & Y. Pointin 67Hydrometric stations on the rivers of mountainous catchmentsL Pobeha & P. DobeS 87Tests of three discharge gauging techniques in mountain rivers/. C. Bathurst 93Correlation analysis of distribution characteristics of mean daily dischargesand morpho logical watershed characteristics L. KaSprek 101Hydrologie and hydraulic research in mountain rivers R. D. Jarrett 107Roughness and resistance of flow in cross sections of gauging stations onmo untainou s rivers in south Bohem ia /. Mareov & K. MareS 119

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Contents xEvaluating the "characteristic" discharge based on the equilibrium slope ofmountainous streams G. Crescimanno, V. Ferro & G. Giordano 129Hydrology research in the upper Indus basin, Karakoram Himalaya,Pakistan G. /. Young & K. Hewitt 139Results of the regime observation of climatic and hydrological phenomenain the Tatras region /. Drako, M. Kupco, J. Turbek & P. Stastny 153

3 Hydrological Balance as a Basis for W ater ResourcesAssessment and Water Management in MountainousRegionsProblems of the water balance components determination in a mountainouswatershed L. Molnr, P. Miklnek & I. M szrof 167Water budget of forest ecosystems in the Small CarpathiansL. Tuzinsky & S. Gavenciak 179Monthly water balance with account of physico-geographical and climaticcharacteristics in the catchment O. Mendel & W. Golf 189An analysis of the water balance in a cold region of a high mountainousarea Z. Xuecheng, Y. Zhenniang, C. Zhentang & W. Qiang 213Cloud and fog water deposition as a process affecting water balance andchemistry V. Elias, M. Tesaf & B. Moldan 111Evap otranspiration from a forested basin in the Jizera Mountains /. Krecek 229Evaluation of vapotranspiration for a mountainous river basin P. Sastny 239

4 Surface W ater and Groundw ater Interactions in MountainousRegionsUtilization of factor analysis by the study of runoff characteristics inmountainous areas B. A. Shmagin & M. Fendekov 247Interpretation of wadi hydrograph for wadi water resources management/. Mucha 253Estimation of the surface, subsurface and groundwater runoff components inmountainous areas /. Gurtz, R. Schwarze, G. Peschke & U. Griinewald 263Time and its meaning in groundwater studies /. Silar 281Hydrological behaviour of glacial deposits in mountainous areasA. Partiaux & G. F. Nicoud 291


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Groundwater runoff in the mountainous areas of Slovakia and itsrelations to precipitation and hydrogeological conditions F. M ihlik &J. Kajan 313Groundwater balance and flow pattern in overdeepened sections ofvalleys in the Bavarian Alps K, P. Setter 329

5 Modelling of Hydrological Processes and of Man'sActivity Impacts in Mountainous AreasRunoff modelling in mo untaino us basins /. Turcan 341On the information content of air temperature in the context of snowmelt estimation H. Lang & L. Braun 347Modelling the runoff from a glaciated drainage basin (Vernagtferner,Oetztal Alps) H. Oerter & O. Reinwarth 355Quantitative geomorphology, stream networks and instantaneous unithydrograph G. Pristachov 369Unit hydrograph revisited: the first differenced transfer function (FDTF)approach D. Duband, I. Nalbantis, Ch. Obled, J. Y. Rodriguez &P. Tourasse 311Application of adapted curve number model on the Sputka basinPavel Kovr 391Some aspects of hydrodynamic models used in mountainous areasE. Zeman & R. Zizka 403Hydrological impact of deforestation in the central Himalaya M. J. Haigh,J. S. Rawat & H. S. Bisht 419Results of international co-operation within a regional project on hydrologyof mountain ous areas of the countries of central and eastern EuropeA. Svoboda 4356 A p p e n d i c e s1. Chairmen and Key-Speakers of the Workshop 4452. Recom men dations of the Workshop 4473. List of Particip ants 449


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1 Keynote Papers


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Hydrology of M ountainousylreas/Proceedings of the trbsk Pleso Workshop, Czechoslovakia, June 1988).IAH S Pub l. no. 190, 1990.Collection and processing of hydrometeorological and hydrological datain mountainous areasG. GIETLBayerische Forstliche Versuchs- und Forschungsanstalt,MunchenINTRODUCTIONWater is the basic precondition of all life on earth.Irrespective of extension and geographic situation,mountainous are - as a rule - areas with the most extensive exchange of water and energy within a region. Because of the constantly rising number of people populatingthis world and wishing to improve their standard of living, the need of settlement space and cultivation areasis growing, thus the consumption of water for individualneeds, and for production of energy is increasing over-proportionally.Reserve of water and energy exist primarily in themountainous regions of the world causing the pressure onutilization of the mountainous resources increase permanently. Therefore, the hydrology is forced to studyintensively the watercycle - the water yield and itstemporal distribution - in order to secure the existenceof mankind and to improve our conditions of living. Soit is necessary to collect data and provide informationson how the resources of water (and energy) can be developed, and how the water causing dangers to the settlements and cultivated areas, could be diminished or avoided.In order to solve these problems, hydrologists canuse methods and experiences aquired in the lowlands andadapt them to the mountainous regions if possible. Butbecause of specific climatic, morphological and energyconditions, which control and influence the water cyclein the mountains, there have to be found new conceptsand methods as well.GOAL OF DATA COLLECTING AND PROCESSINGHow the data should be collected and how exactly theobserved values have to be measured and processed it dependsin each case on what they are to be used for.The general aim should be a hydrological networkproviding data, that could be used to determine thecharacteristic hydrological and hydrometeorologicalparameters everywhere in a region or a country by interpolation of the measured values of different networkstations. Of course, this applies also to the mountainous

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G. Gietl 4areas. Since the great mountain ranges of the earth areon a large scale undeveloped, it is often impossible toinstall in a short time a network of this sort. Therefore,it is necessary to develope an integral network from theminimum to the optimum required size.A minimum network should at least dispose data aboutthe water yield and its temporal distribution, and aboutthe potential dangers of floods and droughts. These dataare required for planning. Primarily, the evaluation ofthe data is done retrospectively - statistically andprognostically by means of theory of probabilities.An optimum network should meet the requirements ofthe operational hydrology and allow the process orientedprognoses of runoff. In this case, the data processingwill also include the simulation of water cycle by hydro-logical models.Considering all the differences in specific requirements and natural conditions, it will not be possible todesign a standardized hydrological network. Only thegeneral principles regarding its establishment and development are feasible. It should be mentioned, that hydro-logical stations will be in operation for decades orlonger and that new requirements and tasks will be arisingduring that time. Therefore, the stations should be sufficiently equipped for new tasks and possible extensionright from the beginning and should fit into the otherintegrated networks.HYDROLOGICAL NETWORKSNetworks for planning purposesHydrological networks serve to inform about a country'swater resources with the aim to secure the regional andnational socioeconomic development. They should supplyquantitative data and verified characteristic valuesabout the natural water resources and their temporal andspatial distribution.Parameters. Unless specific regional hydrological modelsare available the discharge is the most important hydrological value. The runoff is the integral expression of allhydrological processes in the upstream catchment areaand a key factor for the hydrological regime in the downstream areas.To achieve a better understanding of the hydrologicalprocesses, some more hydrological parameters should bemeasured parallelly to the discharge. In the first placethis means the observation of the quantity of precipitation in form of rain or snow as the basic input parameter.Where liquid or solid forms of precipitation are notspecified they can be estimated in the first approximation by taking into consideration the air temperature.


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5 Collection and processing of dataFinally, the surface water storages in form of lakes,reservoirs,snow cover and glaciers should also be observed, since they control the runoff from the area.Density of network. The optimal network density is determined by the aim to describe the hydrological parametersover the area of interest. It primarily depends on themorphological and climatic conditions and the structureof a region, in the mountains especially on the respective elevations. An orientation regarding the minimaldensity of network is given by the WMO for mountainousareas of the temperate, mediterranean and tropical zonesin Table 1 (values in brackets are given for the smallmountainous islands with very irregular precipitationsand very dense stream network).Table 1 Minimal density of networks for mountainousareas by WMOType of Range of norms Range of provisionalstation. for minimum norms tolerated innetwork difficult conditions

Area per station (km2)Stream gauging 300 - 1000 1000 - 5000 (*)station (140 - 300)Precipitation 100 - 250 250 - 1000 (*)gauge (* *) (25)Note:(*) Last figure of the range should be tolerated onlyfor exceptionally difficult conditions.(** ) A t least two precipitation stations should be located in each catchment area, one near the streamgauging station and the other one in the upper parto f the basin. Observation of snowfall, water equivalent and depth of snow on the ground should bemade at all precipitation stations.

To assess the influence on the water balance, thechange of storage of the glaciers should be determinedat least once a year before the winter season.Hierarchy of the stations. Hydrological observationshave t o be carried out over a long period of time, oneof the reasons being the medium-term fluctuation of theclimate, so that statistically secured statements aboutthe probability of extreme situations can be made. Foreconomic reasons, the number of stations with observations .for an indefinite time should not be too high. Onthis account it is above all advisable to split thestream gauging stations - except stations for special


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G. Gietl 6research - into two categories:

- principal or permanent stationswith continuous and undefinite observation- secondary stationswith limited number of years of observation.The permanent stations offer the basis for the statistical analyses and for the analysis of time series, whilethe secondary stations provide data for the spatialextrapolation of these results. After a number of years,when a correlation of runoff data between permanent andsecondary stations has been found, the later could betransfered into other areas, so that the informationsabout all areas can be secured in a long run. Of courseserious changes in the land use during the operation ofsecondary stations could make it necessary to prolongthe time of the observation. The correlation between bothtypes of stations could be improved, if the comparisonincludes precipitation and physical characteristics ofthe basins.In mountainous regions with their typically distinctspatial and temporal variations of precipitation, theprecipitation networks should therefore still be retained,when the second order stream gauging stations get transfered.Time resolution. The time resolution of the observationsdepends on the response time of the runoff which reflectsthe size of the catchment its morphology and the surfacecover. It influences the accuracy of the discharge measurements, and therefore, recording instruments should beinstalled, since they offer the most temporal informations. If continuous recording is not possible, dailyobservations are advisable. In remote region the waterlevel can be observed depending on the situation andhydrological regime.Under low water conditions a few observations aresufficient, whereas during the flood or flash floods andsnow melt in small catchments, sometimes hourly measuringwill be necessary. Can this not be done either, at leastthe water level at the peak runoff should be measured.In the mountains and after flood event it is furthermore important to measure out new cross section of thestream channel because of the transport of sediments andbed-load, and possible river bed erossion. Under unstableconditions it is also necessary to determine new ratingcurve.The precipitation should be measured daily, since thedensity of precipitation measurements has great influenceon the hydrological analyses. In remote regions themeasuring by totalizers is still useful, as long as thetime resolution is able to show the required seasonaldistribution of precipitation.


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7 Collection and processing of dataThe water equivalent of the snow cover should at leastbe determined at the time of its probable maximum, because this serves as a datum for the determination and separation of snow melt runoff. Here, the periodical measuring of snow depth and of snow cover percentage is alsorecommended.

Network for the operational hydrologyThe operational hydrology deals with the hydrologicalforecasting, e.g. of floods or droughts, and the management of reservoirs and streamflows. Because of theshort response time in the mountains, the collection ofdata is inevitably process oriented. The input parametersand water storage in the hydrological cycle are in theoperational network of higher importance than in a network for planning purposes. The forecasting or regulationof the runoff by means of mathematical or physical modelsare widely used.Parameters. Measured values of precipitation and meltingrates of ice and snow, as well as data on water storagesin the snow cover and the lakes, and in larger areasalso informations about the upstream discharge, are usually needed. Furthermore, there have to be determinedthe water loss by evaporation from the water surfacesand the vapotranspiration, since they can considerablydecrease the long-term water yield.

For special purposes the transport of sediment is alsoof importance, as well as the water quality in reservoirs for drinking water and irrigation purposes.According to the models used, the meteorological parameters have to be determined, especially radiation,windspeed, air temperature and humidity.Density of network. As a rule, the network especiallyused for operational projects is of a greater densitythan the general network, since the data have to be moreaccurate. Its features are similar to an optimal networkwhich gives informations covering the entire area ofinterest.For example, in the mountains of the Switzerland thedensity of the precipitation network for water resourcesresearch is 6 sq.km per station and for general hydrological purposes less than 10 sq.km per station is requested. The selected basis station for operationalhydrological projects should at the same time be integrated in the network of the permanent stations, since fromthese stations reliable data can be expected over a longperiod of time.Time resolution. The time resolution is dependent on thesize of the catchment and the hydrological task. Since


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G. Gietl 8these areas are well developed and observation personnelis usually available, the recording instruments for themeasuring of precipitation and discharge should be used.This is important especially in areas with the highintensities of precipitation or with a higher percentageof snow melt runoff. The time resolution of the measuring,of course, depends also on the use of hydrological modelsfor the prognoses and the time step of these models. Forforecasting purposes the time resolution should be afraction of the time between the main events the precipitation and runoff. In small mountainous watersheds thetime step is about 1 - 2 hours.Special networksIn the most cases the network density of hydrologicalstations is not sufficient to parameterize the specificregional hydrological process and develop or adapt hydro-logical models with the necessary accuracy. Therefore,for this purpose the special research has to be done.Representative basins. In every mountainous region withtypical hydrological characteristics a representativebasin should be established. Here, the hydrological andhydraulic conditions, which depend on climate and geology, on relief and vegetation, can be studied in detail.Thereby, the regionally specific regularities of thehydrological cycle can be much better understood and beextrapolated to the regions with similar structures.Reference basins. In order to estimate the influence ofhuman activities on the hydrological cycle in the labilesystems of the mountains and to separate it from naturalinfluences, e.g. fluctuation of climate, it is necessaryto establish reference basins. In the first place, theyserve to observe and scientifically analyse the naturalhydrological cycle. Their importance is based on the fact,that they serve a measure for the stress on nature incomparison with man affected, catchment areas.

Representative and reference basin are nowadays useful,if they become integrated in the network of the permanentstations. The small number of these special networksallows an overproportional technical effort providingfor more accurate results. If an integrated network isbuilt, the individual stations will have different tasksand the collected data have to meet different requirements. Van derMade has comprised them in the Table 2.MEASUREMENT METHODS AND DATA PROCESSINGMethods and instruments in the field of mountainoushydrology vary as much as its objectives, parametersand temporal conditions. They depend on infrastructure


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9 Collection and processing of dataTable 2 Network objectives and requirements (afterVan der Made)

Objective RequirementHydrological forecasting 1 (2)Operation and water management 1 2 (3)Water balance compilation 2 3 (4)Study of long-term changes (2) 3 41 - immediate availability2 - representativity3 - high accuracy4 - availability of long time series

accessibility, supply of energy and availability of observers. They have to withstand often rough conditions withtemperatures far below the freezing-point, as well asdifficult hydraulic conditions and impact of the kineticenergy. For this reason, only a general view of measurements of the most important parameters - precipitation,snow cover and runoff - can be presented.PrecipitationFor hydrological analyses and considerations, the arealprecipitation is the primary value. As far as this ispossible, it should be recorded by remote sensing techniques or be determined traditionally from direct observations by the precipitation network. Usually, the different methods do not compete but complement each other.Rain gauges and totalizers. The instruments mostly usedto measure precipitation are rain gauges. They haveproved to be successful in the low lands in spite of theinstrument related systematic errors. As a result of thegrowing wind influence at the exposed mountainous sites,these errors become more important, and even with thewindshield, a considerable systematic error will remain.Underestimations of precipitation occur especially duringthe winter, when falls the snow. These errors can be corrected to a certain degree depending on instrumental andlocal conditions by the special detailed research.The ar ea! precipitation can be determined from point-measurements by the isohyete or Thiessen-Polygon methods.Generally it applies: the larger the area, the more stations are operating, the longer the period of integration, the lesser the errors at the end. This means ,especially for mountains with the high spatial and temporal variation of precipitation, that a great numberof stations is necessary. For this reason, a timely limited overinstrumentation is recommendable, which may be


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G. Gietl 10reduced after sufficient statistical analysis is accomplished.The operation of rain gauges network requires enoughobservation personnel in the upper parts of the mountains,and sufficient energy to heat at least the recordinginstruments, unless weighting instruments are used. Whereboth of them are not available, the totalizers have tobe used. Generally, it is possible to obtain comparatively accurate data of the areal precipitation over longperiods of integration with the simple rain gauges.Radars. By using the radar, remarkable improvements inmeasuring the rainfall rate could be achieved. It ispossible, to register short term rainfall rates in aradius up to 100 km, and locate it with a diameter of1 km times 1 degree. For short-term observation theresolution of rainfall distribution is better than withthe point measuring. Still, the quantitative determination of precipitation is very inaccurate. The data haveto be calibrated with values obtained by recording raingauges, problems arise especially in determining mixedprecipitation and snowfall rates, and in the bright bandat freezing level. Thus, in large parts of the mountainsthe use of radar is limited; it is also limited due tothe problems with the anomalous ground echo.Satellites. Satellites do not determine the precipitationdirectly. The precipitation are estimated from passivemeasurings in the micro wave range by measuring of thewater vapour. A quantitative estimation of the rain fallrate is possible untill now only for heavy rains. Withthe cloud cover, snowfall can only be assumed. Remotesensing by satellites is less exact than radar measurements regarding the spatial resolution and quantification. Therefore, it is helpful for estimating the precipitation only in extensive mountainous areas withoutsufficient conventional instrumentation. In such regionthe remote sensing is a basis for flood forecastingthrough determination of the area of precipitation andestimation of the precipitation rate.Micro wave attenuation. The method of determining rainfall rate by means of micro wave attenuation is still inthe state of development. This method is comparativelyindependent of the drop size and could become a goodway to determine the average rainfall rate along thepath from the transmitter to the reflector. By measuringseveral paths it should be possible to determine thespatial distribution of the rainfall rate with the helpof tomographic inverse techniques. Path lengths rangingfrom 1 to 10 km are visualised.


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11 Collection and processing of dataS n o w c o v e rData acquisition related to snow cover, like snow depth,snow density, snow cover percentage, temperature andwater equivalent of snow pack is traditionally carriedout by observers. The data are collected either nearrain gauge stations or at special snow surveys. Only veryfew parameters, like temperature of snow pack or snowdepth, are suited for automatic measurement. Accordingly,the meteorological parameters, like degree days or energybalance components are mainly used to forecast the snowmelts. Another possibility of forecasting the runoff isthe observation of the temporal development of snowcovered areas. In the Switzerland the satellite picturesof NOAA - AVHRR and of the Landsat - TM are used forthis purpose. NOAA has a temporal resolution of six hoursand a spatial resolution of 1.1 times 1.1 sq.km, Landsat16 days and 30.0 times 30.0 sq.km respectively. The pictures have been interpreted under three categories (fullsnow cover, 50%, and snow free), from which the transitional zone and the snow line can be determined by meansof integration. A good temporal resolution with a repeating period from 3 up to 8 days is more important for thesubject procedure than a high spatial resolution. In forested areas, however, the use of satellite picturesremains problematic.DischargeIn hydrological networks the runoff is usually not measured directly, but by the water stage-discharge relationship. The rating curve itself is developed specificallyfor each station from short-term measurements of thedischarge under different water levels. With stableriverbeds and well selected cross-sections the ratingcurves could be valid for a long time. The dischargemeasurements 'l'themselves can be carried out by differentmethods. Apart from direct measuring of volume and timein small brooks, the direct or indirect hydraulic parameters are measured and the runoff is finally calculated.The equations on this score were usually developed inthe lowlands under conditions of laminary flow and horizontal homogeneity. However, such conditions are hard tofind in the mountains. Bedrock outcrops cause tur.bulentflow, under low water conditions the water covers onlyparts of the riverbed, and bed load transport at floodchanges the river's cross-section and the zero point forthe water stage measurements. This means that the rightchoice of stream reaches requires exceptional experienceand that the hydraulic parameters and the rating curvehave to be determined over and over again. It also meansthat the methods of discharge determination have to bemodified for mountains and that the hydraulic equations


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G.Gietl 12have to be specifically parametrized.A further problem with direct discharge measurementsin the mountains is the danger observers and instrumentsare exposed to, especially at high water levels becauseof the high kinetic energy in steep rivers and floatingdebris. That is also true for the water stage gaugingstations. The importance of an accurate discharge measurement in the mountains and the respective efforts beingmade in scientific research today are reflected in thepapers for topic 1.REFERENCESJoss, J., Millier, G. (1985) Instrumente. In: Per Nieder-schlag in der Schweiz (ed. Sevruk B.) GeographischerVerlag Kttmmerly + Frey, Bern, pp.31 - 47Raschke, E. (1983) Strahlungshaushalt, Niederschlag und

Schnee. In: Neuere Ergebnisse der Satellitenmeteoro-logie. Promet 3/4 1983. Schon und Wetzel, Frankfurt.pp.13 - 22Riedl, J. (1986) Radar - Flachenniederschlagsmessung.In: Hydrometeorologie. Promet 2/3 1986. Schon undWetzel, Frankfurt, pp. 20 - 23Sevruk, B., Martinec, J. (1985) Fehlerquellen, Genauig-keit, Korrekturmoglichkeit. In: Der Niederschlag inder Schweiz (ed. Sevruk B.) Geographischer VerlagRummerly + Frey, Bern. pp. 65 - 8 6Van der Made, J.W. (1988) Analysis of some criteria fordesign and operation of surface water gauging networks.Rijkswaterstaat communications nr. 47, The Haag,440 pp.Van der Made, J.W. (19 88) Integrated networks for variouscomponents and objectives. In: Design aspects of hydro-logical networks (ed. van der Made). TNO Committee onhydrological research nr.35, The Haag, pp. 125 - 143WMO, (1974) Guide to hydrological practices. 3rd ed. WMO-No.168WMO, (1988) Rainfall measurement technology. In:Validation of satellite precipitation measurements for theglobal- precipitation climatology project. WMO/TD-No.203, pp. 5.1 - 5.10


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Hydrology of Mou ntainous Areas Praceedines of the Strbsk Pleso Workshop, Chechoslovakia, JuneIAH S Publ. n o. 190, 1990.Water balance as a basis for water resources estimation andmanagement in mountainous areasL . S. KUCHMENTWater Problems Institute, USSR Academy of Sciences13/3 Sadovo-Charnogriazskaya, Moscow, USSRINTRODUCTIONIn many regions mountains are the basic areas of runoffformation. The increasing human activity does not layapart of those places, on matter how enthusiastically weadmire them and how hard can we try to leave them intact.Our understanding of runoff formation mechanisms in mountains results in the decrease of damages caused to the water resources and natural environment. In some cases itincreases the efficiency of water resources use in thenational economy.Hydrological cycle of mountainous river basin is acomplex interaction of processes influenced both byregional peculiarities of climatic, soil, geologicalconditions and vertical zonal variability together withslope exposition. Limited hydrometeorological data inmountainous watersheds is an important characteristicfeature of the research and forecasting of the hydrological processes in the mountains. The analysis of theseprocesses and methods of their forecasting should besupplemented by methods of observation and vertical extrapolation of data, or by methods of remote sensing dataacquisition and processing. Unfortunately, these methodsare developed too slowly.At the same time, increased human impacts on mountainous watersheds and the interests of environmental protection necessitate not only to obtain the informationon mountainous water resources (as it was earlier), butalso the information of possible changes in the waterbalance components, resulting from man-induced impacton watersheds and from expected climatic changes. In connection with the increased environmental pollution, thegreater attention is now being paid to water qualityformation. It expands our knowledge and our requirementsto the detailization of the concept of the hydrologicalcycle and the account of soil and geological peculiarities in the river basin.For many mountainous basins especially for the oneslocated in densely populated regions the problem ofland-use planning, taking into account possible controlof hydrometeorological conditions (artificial increasingof precipitation, changes in the intensity of snow andglacier melting and other man-induced changes) is aquiring

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L. S. Kuchment 14ever greater prominence. Physically based models of themountainous basins hydrological cycle should become abasis for such planning and for the prediction of changesin its components including water quality.WATER BALANCE COMPONENTSThe water balance method allowing us to improve ourknowledge of hydrological processes is one of its obligatory stages in developing the physically based models.At the same time, the method remains the basis for theestimation of our possibilities to control the hydrological cycle and water resources. Experimental measurements or determination of water balance components, theestablishment of relations between these components, andthe estimation of their possible changes under variousconditions, provide sufficient information on the character of hydrological processes, their temporal and spatialvariability, interaction with the environment and possibleresponse to man-induced changes. Frequently, due to theabsence of observed data at mountainous basins, the waterbalance method is often reduced to the determination andcomparison of annual precipitation, runoff and vapotranspiration. Due to this fact, the method is sometimesregarded as inadequate to the tasks of modern hydrology.However, its possibilities have not been exhausted yet.Increasing the number of water balance components, theirtemporal and spatial detailization, increasing the accuracy of the relations between different components,revealing "contrlable" ones - all these are the maintrends in mountainous basin investigations, that cancontribute to the analysis of the hydrological cycle andthe development of physically based models. At the sametime, it is important not to overestimate the possibilities of the method as a tool of water resources controland estimation of human effects on the hydrological cycle.

The papers submitted to the Workshop reflected boththe possibilities of using this method in the researchof the hydrological cycle and also its drawbacks. Thebigger part of papers is devoted to the methods of determining the main water balance components and their temporal and spatial variability in various geographicalzones and different mountainous watersheds.In most cases the analysis of mountainous catchmentwater balance for long time intervals is reduced to thecomparison of runoff and precipitation data. The runoffis usually measured accurately, the precipitation (especially during winter season) are measured mainly at lowaltitudes. Its simple altitudinal extrapolation oftenresults in low accuracy. Complete account of the watershed topography and direction of air mass movement isessential.Data on changes of the watershed areas coveredwith snow, obtained from space satellites gives good


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15 Water balance as a basis for water resources estimationbasis for determination of the water equivalent of snowand correction coefficient necessary for the elevationextrapolation of solid precipitation.In some papers classification of mountainous basinsbasis with the account of canopy peculiarities is carried out with the aim to increase to accuracy of elevation precipitation extrapolation. For different geographical zones the runoff-precipitation and runoff-altituderelations were then obtained.In many cases, the hydrographs can be divided intosurface and groundwater components. Based on this, Lvo-vich suggested to use six components of the water balancestructure (precipitation, total runoff, surface runoff,groundwater runoff, total vapotranspiration, differencebetween precipitation and groundwater runoff). Carriedout research allowed to obtain zonal regularities of.variations between difference components for the greatCaucasus, Tien-Shan, South American Ands and WesternHimalayas.ltwas also proved that differences in thestructure of water balance of similar zones in differentmountainous systems can be explained by man-inducedimpact on the landscape. Obtained regularities can beuseful in the spatial interpolation of water balance data.In mountainous regions with considerable snow coveragethe estimation of precipitation can be carried out onthe basis of snow-line movement and air temperatureobservations. These observations can serve a basis forthe determination of the subject component in the riverrunoff necessary for more justified estimates of waterresources.Evaporation is a component of water balance which isthe most difficult to determine in mountainous watersheds. In addition to the vertical changes in air masscharacteristics, cloudness and canopy, the effect ofchanges in solar radiation depending on slope orientation is important here. The main perspectives in improving the methods of determining this component are connected with the development of remote sensing methods.Measurements of the soil surface and canopy temperaturewith the help of radiometers, coupled with models ofsoil surface dynamics, can ensure the calculation ofevaporation in different areas of the mountainous watershed. Coefficients, required for these calculations, canbe precised on the basis of the vapotranspiration valuesfor a long-term period, determined by differences betweenthe precipitation and runoff.In order to understand mountainous watershed processesand to estimate runoff characteristics, necessary forwater resource systems management and control (temporalvariability, seasonal dynamics, extreme value of certainchemical substances concentration) a more detailed determination of water balance components (distinguishingsubsurface and groundwater runoff, seepage,interception
http://himalayas.lt/http://himalayas.lt/http://himalayas.lt/


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L. S. Kuchment 16of precipitation by plants, surface retention) are required. Direct measurement of these components is ratherdifficult. Therefore, various direct and indirect evaluations of the subject components are used and testifiedabout their considerable variations depending on thewatershed structure and types of vegetation. Differentvegetation species and their coverage of the watershedarea have a considerable effect on the ratio betweenstudied components. Forest soils increase appreciablythe subsurface flow and seepage, decreasing the surfaceretention.Unfortunately, most of water balance studies formountainous watersheds deal with only three or four components of the water balance for a year or a season, andthey are insufficient for the precision of our ideason runoff formation mechanisms, to say nothing of waterquality formation. Attention paid to the study of possiblechanges in water balance components caused by humaneffect on climate and watershed conditions, is insufficient either.MAN INDUCED EFFECTSChanges in the mountainous watershed conditions manifestthemselves mainly in deforestation. However, short-termexperimental observations at the watershed before andafter deforestation do not allow us to obtain convincingconclusions on the role of forests and changing of hydro-logical characteristics. The study by Valtyni can begiven as an example. This paper presents the analysis oflong-term water balance observations at a watershed withan area of 685 km 2, which was re-afforested in the60-ies - 70-ies so that the forested area increased by5.7%. Data of 55 year observation series reveals thetendency to diminish the total annual precipitation,however, re-afforestation did not entail any changes inthe mean annual runoff or maximum discharge variations.These results do not contradict to modern concepts of thehydrological role of forests. At the same time theydemonstrate problems arising in its experimental investigations because even 2-3 decades of experimental observations may not provide a sufficient information to determine the effect of afforestation on water balancecomponents under various hydrometeorological conditions.Nevertheless, the conclusions on the forest impact onwater quality are more definite. A comparison of thechemical composition of water flowing from forested andunforested watersheds is showing the increase in nitrate^chloride and sulphate contents in the both watersheds.The concentration of NO 3 - and Cl~ ions is a little higherat the agriculturally utilised watershed, which is resultof fertilizers application. The increase in SO4" contentcan be explained by the effect of acid rains.


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17 Water balance as a basis for water resources estimationThe obtained results allow us to .regard afforestation as afavourable condition for water quality formation.The increase of snow and glacier melting intensity isan investigated way to increase the runoff from mountainous basins by diminishing the Central Asian glaciersalbedo. However, so far the solution acceptable from theview point of the ecology and economy was not find.The attempts to increase river runoff from mountainsby means of artificial effect on precipitation turnedout to be more successful. Large-scale experiments onartificial increase of precipitation in the Caucasuswere carried out by Svanidze. The evaluation of theeffect was carried out by comparing runoff values fromthe experimental and contrled watersheds. The comparisonshowed that during the period of active influence on theprecipitation, runoff could be augmented by 20%, andseasonal precipitation values at a watershed in the Eastern Georgia increased by 15% for 8 years. The total precipitation at the experimental area near the Lake Sevanincreased by 110 mm for the same period. Similar large-scale investigations of the possibility to increaseartificially the precipitation area also carried out inthe mountains of the Soviet Central Asia. The obtainedresults should be regarded as preliminary, however, theartificial increase of rainfalls is expected to be loreeffective in mountainous regions with high air humidityand unstable atmospheric stratification, than in aridzones.

Man-induced climate changes considerably affect thespatial and temporal distribution of precipitation andtemperature-- in mountainous areas. Undoubtedly, thiswould create and impact on other water balance components.However, the sensitivity of mountainous hydrologicalsystems to possible man-induced climate variationsturns out to be less than that of flat-lowland areas. Asan example the Table 1 is presenting the results ofestimating possible variations in snowmelt runoff frommountainous basin located in the Tien-Shan. These evaluations were carried out according to the model describedby Muzilev (1987)Table 1 Runoff changes of the Kassansai River for thesummer of 1980 under various scenarios (in %of runoff volume)

p ( % )T(%)+ 3+ 2+ 10-1

-2 -3

-20%-42.7-35.7-28.1-21.3-14.9- 8.4- 2.9

-10%-34.5-26.8-18.3-10.6- 3.53.69.9

0%-26.7-17.8- 8.3

08.015.822.8

10%-18.8- 8.81.610.819.627.835.7

20%-10.60.211.621.631.040.448.4


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L. S. Kuchmen 18The Table 1 shows that changes in precipitation (AP)entail nearly the same responses in the runoff volume(in lowland regions these changes are considerably greater) . The effect of temperature (AT) variations is perceived even stronger then precipitation.Calculations of possible fluctuations of rainfall floodvolumes were also carried out for two mountainous rivers.The Soliatinka in the Carpathians and the Rakovka in theSoviet Far East. Our studies show that the relative increase of the rwnof is higher than that of precipitation.Thus, a 5% increase of precipitation entails 7% growth ofthe runoff, 10% increase in precipitation, 13% growth ofthe runoff, and more precipitation causes 20% more ofrunoff. In spite of the fact that runoff variations arein mountainous areas not so high as it is in arid zones,they should not be neglected in the long-term planningof water resources management.MATHEMATICAL MODELLINGFinally, some results already presented show that particular problems inmountainous basins cannot be solved with thehelp of water balance method and have to be realised bymathematical modelling without additional input data. Forsome years our team (Kuchment, Demidov, Milukova, Motovi-lov and Smakhtin, 1983,1986) have been developing a physically based rainfall-runoff model. The Golyatinka catchment of the Rika river basin was chosen as an experimental one, where model verification and the estimation ofparameters sensitivity were carried out. The catchmentlocated in the territory of the Trans-Carpathian, withthe area up to Maidan of 86 km 2. One of the model'sversion was based on the basin presentation in the formof a one-dimensional slope of variable width. The following processes were taken into account:- surface flow (kinetic wave equations were used),- vertical moisture transfer in the zone of aeration(described by the equation of soil moisture diffusion) ,- soil moisture evaporation (modification of the Penman method was used, allowing us to account theinfluence of vegetation and the moisture contentin the upper soil layer),- groundwater recharge and groundwater flow (theBoussinesq equation was used),- subsurface flow (the convolution integral was used).Rainfall flood values of the five years observationperiod were used for the parameters calibration. Testingruns were carried out on the basis of 15 years observation period. The calculations showed that described version of the physically-based model satisfactorily reproduces the temporal variability of evaporation, the soilmoisture content, groundwater levels and the runoff


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19 Water balance as a basis for water resources estimationhydrograph at the outlet gauge. All this allows us touse the model for the separation of subsurface flowwhich in other experimental studies is connected withconsiderable difficulties. It turns out that the shareof subsurface flow in the Golyatinka river runoff constitutes 26-58% of the total rainfall flood volume. Lag timeof subsurface flow is 3 times longer than the corresponding time for the surface flow. The model also allows tostudy a mechanism of extreme discharge formation.Another version of a physically-based model of rainfall flood formation presents the watershed in the forma two-dimensional grid, where the channel network isschematized by straight lines, parallel to the coordinated axes. This version of the model is primarily designedto account the interaction of surface and groundwaterflows, both in the basin (through the zone of aeration)and in the channel network. The equations of the two-dimensional kinetic wave are used to describe subsurfaceflow, the equations of one-dimensional kinetic wavedescribe water movement in the channel network. Equations of soil moisture diffusion and empiric relationsfor the calculation of vapotranspiration allow us tocalculate vertical moisture transfer. Two-dimensionalBoussinesq equations were used to describe groundwaterand subsurface flow. (The coefficient of seepage in thegroundwater was adopted 0.6 m/day - by means of calibration - and the coefficient of seepage in the upper 30 cmlayer, where subsurface flow occurs, was assigned 200m/day). After the calibration and verification the modelwas used in numerical experiments on the estimation ofthe effect of deforestation and afforestation in thebasin. The model was also used to estimate the influenceof groundwater development on the runoff hydrograph. Theexperiments show that the deforestation in the Golyatinkariver basin can reduce the volume of subsurface flow 2times, and the ratio between surface and subsurface flowslargely depends on forest management in the watershed.The Figure 1 presents the results of experiments on theestimation of groundwater on the spatial distributionof subsurface flow depth and on runoff hydrograph. Theinitial position of the groundwater level before therainfall flood can considerably affect the active areaof mountainous watershed and the runff formation even if theratio between the main components of the water balance(precipitation, vapotranspiration, total runoff) remainsunchanged.CONCLUSIONSThe papers, submitted to the Workshop, are appreciablecontributions into the investigation of water balancecomponents of mountainous basins and their interactions.At the same time they have rather fragmentary character.


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L. S. Kuchment 20It clearly shows the importance to continue in the studies of hydrological cycle in mountainous areas. Theknowledge and experiences in mountains are usually verydifficult to achieve.

Q t n r P s 1 )

Fig.l Measured and calculated discharges under variousinitial value of groundwater levels in the near-channel zone (Z) of the basin (September 6, 1966)1 - Measured2 - Calculated Z = 0.4 m3 - Calculated Z = 0.5 m4 - Calculated Z = 0.6 mREFERENCESKuchment, L.S., Demidov, V.N., Motovilov, J.S. (19 83)Formirovanie rechnogo stoka. Fiziko-matematicheskiemodeli (River runoff formation. Physically basedmodels). Nauka. Moscow, p. 216Muzilev, E.L. (1987) Modelirovanie stoka gornych reki sputnikovaya informacia (Modelling mountainousriver runoff and remote sensing information). Nauka.

Moscow, p.136


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Hydrology ofMountainous Areas (Proceedings of the Strbsk Pleso Workshop, Czechoslovakia, June 1988).IAHS Publ. no. 190,1990.

Surface water and groundwater interactions in mountainous areasJ. SILARCharles University, Prague, CzechoslovakiaINTRODUCTIONTill now, hydrology of mountainous areas has not beenemphasized much among other special hydrological problems.Headlines as Arid Zone Hydrology, Hydrology of DeltaicAreas, Hydrology of Lakes, Urban Hydrology and even Airport Hydrology can be found among the names of symposiaand in contents of textbooks but few hydrologists seemto have felt the necessity to emphasize mountainous areasas a specific type of hydrological systems and even lessthe relationships between surface and groundwater as aspecial problem. Perhaps we have been underestimating thesignificance of groundwater in the mountainous areas aswe are used to develop it in large basins with extendingaquifers in lowlands. But hydrology of mountainous areasis specific in regard of space(due to the morphologicalconfiguration of surface and geological setting of thebedrock), of time (due to the course of the hydrologicalevents), and of the quality of the environment (especially due to particular climate, soil cover and vegetation).The terms mountain and mountainous have a very widemeaning but in geomorphology, they are specified. Inaccordance with the current definitions (Glossary ofGeology, 19 80) , we should consider mountainous areas asthose which are characterised by their morphology, i.e.by their sloping and dissected surface, with peaks projecting at least about 300 m above the surroudings. Having a considerably simple definition of the mountainsand mountainous areas we could be tempted to simplifyalso the hydrological phenomena relating them to the altitude and to the morphology. We know, however, thathydrological phenomena including the relationship betweensurface and groundwater depend, besides the altitude andmorphology, also on numerous other factors as e.g. climatic conditions, geological composition and structureof the bedrock, soil cover, vegetation, human activitiesand other. Some of the aspects and conclusions are quitecontraversial. Some hydrologists emphasize that forestedareas slow down the direct surface runoff and that forests promote infiltration and groundwater recharge,while others conclude that they increase vapotranspiration thus preventing groundwater recharge.However, our observations so far are often superficialand we still lack exact data to come to some unambiguous

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/. Silar 22quantitative conclusions. Moreover, the Earth's surfaceand the structure of the Earth's crust are too muchvariegated to allow to make some generally valid conclusions. From the history of groundwater hydrology is wellknown that an inadequate approach and generalization ofresults of scientific observations may lead to absurdand contradicting conclusions if local natural conditionsare not considered.MAIN PROBLEMSModern hydrology elaborated efficient methods to analysethe major part of hydrological processes and, with someexceptions, to provide very accurate data and to processthem in a statistical way. Modelling has been introducedfor analysing hydrological processes influenced by multiple natural factors as well as for studying the effect ofthe combined factors on the hydrologie phenomena resultingfrom a process. The computer techniques have made a considerable progress and complex processes, systems andwhole physical fields can be modelled using sophisticatedcomputers and programs. No model, however, can work if itdoes not represent the natural conditions of the subjecthydrological process. A week point seems to be the lackof understanding the substance of the natural processesand of the mutual relations between natural phenomena.The computation and modelling methods seem to have outrunthe knowledge of natural processes and the working methods of obtaining reliable input data necessary for themodels. In groundwater hydrology, we still have difficulties in inserting right values of vapotranspiration intothe hydrological balance equation, in estimating the infiltration and determining the actual extent of the drainage basin. On the other hand, efficient geophysical andtracer methods have been introduced to follow the groundwater flow direction and speed. Geochemical methods areused for studying the interactions of water and rocks,the transport of pollutants, the quality of groundwater,and equilibria of the chemical constituents. Environmental isotopes provide effective means for studying thehydrological cycle and identify the relations between itscomponents. The proportion of the stable isotopes ofoxygen and hydrogen helps to study the climatic circumstances under which groundwater originated and to separate stream hydrographs, the altitude gradient of theoxygen 180 to determine the altitude of the groundwaterrecharge area, and to study other problems. The radio-nucles tritium and radiocarbon introduce the dimensionof time into groundwater hydrology. We have varioushydrometric, analytical, data processing and modellingmethods at hand, but we often do not use them (apartof economic reasons) because we do not know the natureof the hydrological process or have no reliable input


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23 Surface water and groundwater interactionsdata to model it. But when regarding literature dealingwith the interactions of surface water and groundwater,it seems that we often limit our attention to the physical analysis of the hydrological processes and pay verylittle attention to the composition and structure of thenatural environment where the processes occur, in detailas well as in large dimensions. Perhaps, it is the resultof the effort to switch from the descriptive methods ofnatural sciences of the past to the modern quantitativemethods which have at hand the effective computer techniques. In view of this, we should pay more attentionto understanding of the environment where the hydrological processes and interactions of surface and groundwateroccur.In hydrology of mountainous areas, the geomorphologyshould be named at the first place as it defines themountainous areas, and as it is the most significantfactor influencing the hydrological processes. The quantitative expression of geomorphological features ofdrainage basins and channel networks is thoroughly analysed by Strahler (1964). Geomorphological features of amountainous area can be expressed quantitatively and sorelated to the quantitative values expressing hydrological processes. In this way, the influence of the surfaceconfiguration upon the runoff and other processes can beanalysed quite objectively. Areal aspects of drainagebasins are often used for studying runoff but analysingsurface gradients, hydrometric relations and dynamics ofevolution of drainage basins is not yet common in hydrology. It is not only the surface morphology which issignificant. In numerous mountainous areas, karst systemsrepresent the most expressive form of the surface waterand groundwater interaction which is controled by themorphology of the underground. The necessity to study thepecularities of karst hydrology should be emphasized asthere has not been presented any paper on this subjectat the Workshop. In numerous regions of the world, extensive karst system control the runoff as well as otherhydrological processes and affect water management andhydraulic engineering. Classic karst areas are in theBalkan peninsula, 600 000 km 2 of continuous karst regionsexist in southern China and other ones all around theworld. They are specific by their fast evolution, bytheir underground drainage systems which concentratedoutflow and by underground hydrographie connections forconsiderable distances disregarding the surface morphology.

The evolution of a hydrogeological structure in karststarts with the evolution of the groundwater circulationpathways. The secondary permeability along karst cavitieswhich developed due to preferential groundwater circulation in some fissures becomes more significant and increases progressively in comparison with the rest of


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J. Silar 24fissures and of the primary interstices of the rock. Sothe permeability of the karstified environment becomesvery heterogeneous. The distribution of the zones ofincreased permeability is controlled by lithological,structural, morphological, hydrological, and geochemicalcircumstance (Bogli, 1980).The karstification is an exogenetic process whichcontinues as long as a hydraulic gradient exists whichbrings into motion calcium-carbonate undersaturatedwater in fissures of carbonate rocks. Hence, this evolution depends on the geomorphological processes whichare linked with the stages of geological history. Thestages of karst evolution can be dated according tosediments covering its surface or filling the cavities,and related to other geological events. Due to this, theevolution of hydrogeological structures in karst can berelated to other geological phenomena and their extentand arrangement in the rock environment can be estimatedto a certain degree.The groundwater circulation in karstified rocks iseither limited to the rock masses above the drainage-baselevel or it may reach, according to the geological setting deep below it or even below the sea level. Thehydrogeological structure according to the degree ofkarstification, may form independent groundwater conduitsor, on the other hand, groundwater reservoirs which maybe able to accumulate large volumes of water and equalizeits discharge.

All the facts resulting from the fast dynamic evolution of the hydrogeological structures in karst are ofcrucial importance for groundwater research and management in karst regions, including prospection, evaluationof water resources, modelling, development, protection,saline water encroachment, leakage of reservoirs andother problems of practical significance. Karst is anenvironment which does not match our traditional ideason groundwater hydraulics and hydrology. It is peculiarby its great diversity of phenomena, by the heterogeneityof its groundwater flow systems and by its change intime. Thus, it is difficult to express the groundwaterflow in karst in a quantitative way using classic groundwater hydraulics. Even the course of hydrological processes is often different as demonstrated by Kullman(1986) on hydrographs of karst springs in the WestCarpathians. Under such circumstances, the analysing ofhydrological systems of karst by modelling becomes auseful method in the quantitative evaluation of thegroundwater flow. Besides the hydrological input values,which can be obtained with a fair degree or reliability,a general idea on the spatial arrangement of the groundwater flow system is needed which can be obtained bygeological and morphological analysis of the past evolution and of the present-day state of the karst.


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25 Surface water and groundwater interactionsIn hydrology of mountainous areas, we should also paymore attention to the quality and structure of the environment below the surface, which is a significant factorof the surface and groundwater interactions, i.e. weshould emphasize the geological aspects of the problems.A "pure hydrologist" is usually tempted to limit hisconsiderations to the orographic drainage basin which heassumes to be a sort of black box model. A look at ageological section of mountainous system, however, showsthe complexity of the groundwater flow in the bedrock,as well as in the covering formations. Very often, italso explains the irregularities and anomalies observedin hydrological processes. Even in non-karstified rocksexist streams recharging neighboured drainage basins.The dissected surface of mountainous areas with complexand faulted geological structures in the bedrock and withhigh hydraulic gradients between valleys presents suchexamples almost anywhere in the world. It is evident thatit is difficult to compile hydrological balance undersuch circumstances without investigating the hydrogeolo-gical conditions of the bedrock.Regarding the surface water and groundwater interactions, we should also consider the specific time-related aspect of hydrological processes. In general, inmountainous areas the course of various hydrological phenomena is faster than in lowlands, mainly because ofhigher hydraulic gradients, higher flow velocities andfaster transmitting of hydraulic impulses. This results

in a higher range of fluctuation of discharge of streamsand springs. This phenomenon relates mainly to processeslinked with a shallow groundwater circulation. But inmountainous regions, we also have evidence of a deepgroundwater circulation, as indicated by warm springswhich mainly occur in mountainous and hilly regions affected by tectonics. Due to the dissection of surface anddue to the resulting high hydraulic gradients, a deeppenetration of water from the surface to the depth andan ascent along tectonic faults are frequent. The deepgroundwater circulation often involves large hydrogeolo-gical structures and usually is very slow which is alsoreflected in a very high residence time of groundwater,sometimes reaching back to the geological past. In suchcases we should take up the right attitude towards themeaning of time in hydrology and towards the hydrologicalcycle.

In hydrology, we are still used to consider thehydrological cycle on the long-term as a steady processwhich results from the periodicity of hydrological phenomena and from equalizing their effects during the subsequent hydrological years. However, we know that theresidence time of groundwater is much longer than that ofatmospheric and surface water, and therefore, whenconsidering the groundwater circulation we correspondingly


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/. Silar 26should adopt a different time scale than a hydrologicalyear. Under such circumstances we have to calculate witha very long time lag between the groundwater rechargeand its discharge. If this time lag or residence timeexceeds the duration of the period of Holocene, i.e.about 10 000 years, then the conditions of the groundwater recharge have to be considered different than thoseof discharge due to the different climate. Then, consequently the groundwater flow has to be considered a nonstationary process.Regarding the surface and groundwater interactions, wealso should pay more attention to the environment wherethe interaction occurres, i.e. to the soil cover andvegetation. Soil as well as vegetation are generally pooror are missing in the arctic as well as in hot aridregions, whereas they are abundant in temperate zonesand are very specific in tropical, humid zones. Whenrealizing the differences between tropical lateriticsoils in Africa, the thick loess deposits in East Asiaand the multitude of soil types with very differentphysical properties in other continents, we cannot expectthat we will obtain unequivocal and generally validconclusions about the role of soil in the surface andgroundwater interactions. The same relates, too, to therole of vegetation cover. Thus, the role of soil andvegetation should be analysed and the problems concludedin relation to the peculiarities of the particular climatic and geographic zones. It follows, that even theimpact of agricultural activities, deforestation andgrazing,in regard to the runoff process and the surfaceand groundwater interactions can result under differentnatural conditions in quite different and even oppositeeffects. Thus, the recent efforts to control the environment by intentional activities influencing the soil cover and vegetation should be done very carefully takinginto account the pecularities of the natural conditionsand keeping in mind the possible consequences in therunoff process.

So far, hydrology has been analysing processes whichare repeating more or less regularly in short periodsand, unlike geology, has not felt the necessity to studythe history of the hydrosphere on a large scale and inthe early past, because usually the last hydrologicalyear or a few years provided enough hydrological datanecessary for calculating the hydrological balance andfor the statistical analyses used for predictions. Thereason is mainly in the fact that the hydrological cycle,at least in the case of atmospheric and surface water,is much shorter than the geological cycle of the lito-sphere. While the geological history of the lithosphreis one of the main subjects in the geological sciences,the study of the history of hydrosphere has not beenneeded among hydrologists since the hydrological cycle


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27 Surface water and groundwater interactionscould be observed, measured and studied very accuratelyduring short and regular periods of time percepted byhuman senses within the human time scale.Long-term changes in the hydrosphere and in the hydro-logical cycle have been rather a subject of study of thegeological history than of the hydrological research. Dueto the impact of human activities, however, long-termchanges of climate as well as of the hydrological cycleat an increasing rate have to be expected in future. Tobe able to predict such changes and to solve the resulting environmental problems, it seems necessary to adaptsomething of the geological way of thinking to analysethe past in order to predict the future not only in theshort periods of the hydrological year but also in thelong-term global history of the climate and of the hydrosphere. In this context, we should pay more attention topaleo-hydrological studies, even in the mountainousregions using a complementary system of working methods.For example the stable isotope concentration in groundwater and in glacier ice provides information about climate at the time of their origin, while the concentrationof radionuclides makes it possible to determine that time.In this way, isotope working methods provide valuabledata in studying the evolution of climate in the past.In mountainous areas, even the analyses of glaciologi-cal and geomorphological phenomena provide useful meansfor studying the evolution of climate and hydrologicalcycle in the past and making conclusions for the future.The advance and/or retreat of glaciers indicated by theposition of moraines is a sensitive indicator of theevolution of climate. The position of tufa deposits,river terraces and other geomorphological phenomena inrelation to large springs provides information on theevolution of the groundwater circulation and groundwater- surface water relation in the geological past andfuture.In view of the anticipated environmental changes, itseems necessary to extend our so far used marked witha hydrological year as a unit of time to longer intervals, even up to thousands of years, and to switch froma short-term time scale to a long-term one. As resultof this, we should also switch from steady state to non-steady state conditions in order to comprise the long-term and global changes of the hydrological cycle. Ifconsidering the rate of hydrological and geomorphologicalprocesses and the recent development of water resources,it follows that many of the environmental changes in thehydrological cycle will have to be accepted as irreversible. For example the change of runoff due to deforestation,acid rains or cutting woods influences on the groundwaterrecharge and base flow. Furthermore, the overpumping anddrainage of aquifers resulting in decline of groundwaterlevels and depleting groundwater resources as indicated


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/. Silar 28in numerous intermountainous basins and their alluvia inarid regions all over the world.CONCLUSIONSThe key note should be finished with concluding whichtopical problems have to be tackled in the research ofsurface water and groundwater interactions. Of course,such conclusion remains very subjective one. However, thepapers of the third topic allow to conclude, that weshould continue in analysing the runoff process, investigating the influence of the geomorphological and geological conditions, developing and applying up to date analytical methods, e.g. environmental isotopes, and modellinghydrological processes related to the surface and groundwater interaction. Moreover, we should intensify thestudy of vapotranspiration and of the quality of theenvironment which influences the interaction, i.e. of thesoil and vegetation cover. In the past, hydrology wasdeveloped under the views that water either was an elementwhich was necessary to be controlled to prevent destruction of human work, or it was a source of energy, or avaluable natural resource. In the temperate zones wehave only subsequently realised the full significance ofthe latter aspect. But recently, another role of waterarose, i.e. that of a transportation medium of pollutantsnot only on the surface but also within the soil androcks. Understanding the environment of groundwatercirculation will surely contribute to the solution of thevery actual problems of surface water and groundwaterinteractions and also problems of the groundwater pollution.REFERENCESBogli, A. (1980) Karst Hydrology and Physical Speleology.Springer - Verlag, Berlin, Heidelberg, New York, 284 p.Kullman, E (1986) Karst Groundwater in the Western Carpathians. Thesis, Comenius University, BratislavaStrahler, A.N. (1964) Geology, Part II, Quantitative Geo-morphology. In;Handbook of Applied Hydrology (ed. VenTe Chow), McGraw-Hill Book Co ., pp. 4-39 - 4-76


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Hydrology of Mountainous Areas (Proceedings of the Strbsk Pleso Workshop, Czechoslovakia, June 1988).IAHS Publ. no. 190, 1990.

The modelling of mountain hydrology: the ultimate challengeV. KLEMESPresident, International Association of HydrologicalSciences, National Hydrology Research Institute,11 Innovation Blvd. Saskatoon, Saskatchewan, CanadaINTRODUCTIONThere is little doubt that many will regard the title ofthis paper as an exaggeration and will tend to attributeits choice to the author's notorious predilection forirritating the fellow hydrologists. After all, why shouldthe modelling of mountain hydrology be signed out fromthe great variety of hydrological modelling problems whichall seem to be overwhelmingly difficult? If, as is oftenthe case, one views hydrological modelling merely as thefitting of some more or less plausible mathematical constructs to given sets of data so as to minimize the difference between the modelled and recorded time series ofrunoff, then there probably is no reason to single outmountain hydrology as the most challenging object ofhydrological modelling. This, however, is not what I meanby hydrological modelling. Rather, I regard it as a synthesis of observed empirical facts and their theoreticalunderstanding, expressed in terms of general (as opposedto ad hoc) and internally consistent quantitative relationships formulated in computationally feasible algorithms. Viewed in this way, the above title seems justified since observations of the states of nature in mountainous terrain are the most difficult to make and theprocesses governing mountain hydrology cover the widestrange thus posing the greatest demands. oh:\thoreticalida'der standing.Before coming to the problems of modelling, it maytherefore be proper to say a few words about each ofthese two prerequisites of it in order to be able to putthe modelling aspects into a proper perspective.The States of NatureMountains do not give up their secrets easily. This doesnot apply only to the proverbial yeti and sasquash butalso to such mundane things like precipitation, snowcoveror streamflow. The problem often is not what, from thescientific point of view, should be measured and observed,but what can be observed given the available logistics.The most formidable problem is accessibility on a continuous basis. In mountainous terrain, this is not assuredeven where roads and permanent settlements exist. Where

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hydrology of mountanious areas

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