Journal of Environmental Science and Water Resources ISSN 2315-7259 Vol. 2(8), pp. 290 - 301, September 2013 2013 Wudpecker Journals

Integration of hydrologic processes for zoning agricultural landscapes: perspectives for ecosystem

services maintenance

Ramon F. Bicudo da Silva1,*, Sílvio F. de Barros Ferraz2, Anderson A. da Conceição Sartori3, Célia R. Lopes Zimback3

1Center for Environmental Studies, University of Campinas; Rua dos Flamboyants, 155 - Cidade Universitária Zeferino

Vaz, Campinas, SP - Brasil - CEP 13083-867. 2Departament of Forest engineer, Laboratory of Forest Hydrology, University of Sao Paulo; Av. Pádua Dias, 11 –

Agronomia, Piracicaba, SP - Brasil – CEP 13418-900. 3Departament of Soil Sciences, State University of Sao Paulo; Rua José Barbosa de Barros, 1780, Faculdade de

Agronomia, Botucatu, SP – Brasil – CEP 18610-307.

*Corresponding author E-mail: ramonbicudo@gmail.com; Tel.: +55-19-3521-7690; Fax: +55-19-3521-7690.

Accepted 02 August 2013

Integration of hydrologic processes for zoning agricultural landscapes forms a better perspective for ecosystem services maintenance. The loss of hydric and natural potential of water resources and soils converts diverse landscapes and that leads to loss in agricultural productivity. The paper deals with the maintenance of ecosystem services for the management of agricultural landscapes in the Sao Paulo state, Brazil. Suggestions have been made on proper management of areas and watershed zoning at different levels of sensitivity so as to keep water cycle most suitable for crops and best management practices. Information also given on the spatial integration of tree hydrologic process in a GIS-based approach in order to zone agricultural landscapes in the perspective of ecosystem services maintenance. The paper proposes combined use of infiltration potential, erosion susceptibility and variable source area & their potential to transport contaminants to the surface drainage network, groundwater as well as their erosion susceptibility, based on the analytic hierarchy process and ordered weighted averaging methods. Recommendations have also been provided to deal with the situation. Key words: Water resources; hydrologic process, analytic hierarchy process, ordered weighted average, support decision.

INTRODUCTION Taking into account the current world population (Kollodge and Puchalik, 2011) and its prospective growth for the coming decades, it is evident that a great challenge is posed to humanity by hydric and nutritional security. Considering the potential of Brazil for agricultural and, more recently, biofuel production, the assurance of hydric resource availability and conservation and maintenance of ecosystem services in agricultural landscapes have become key to planning and decision-making in areas intended for the development of these activities (Margules and Pressey, 2000).

The need for studies on the watershed and the physical environment for modeling hydrologic processes, in order to conserve ecosystem services or landscape

management are identified by numerous studies (Arnold et al., 1998; Belmonte et al., 1999; Biswas, 2004; Brauman et al., 2007; Chowdary et al., 2003; Chowdary et al., 2004; Foley et al., 2005; Gonçalves et al., 2007; Yang et al., 2000; Scanlon et al., 2007; Silva et al., 2010). The loss of hydric and natural potential in many regions in response to land use and inappropriate use of water resources and soils, has led diverse landscapes toward a collapse in agricultural productive capacity of their systems (Christofidis, 2003; Foley et al., 2005; Lohmar and Wang, 2002; Ojeda-Bustamente et al., 2007; Paz et al., 2000; Silva et al., 2010).

According to Brauman et al. (2007), the ecosystem service, the benefits that people obtain from ecosystems,

291 J. Environ. Sci. Water Resourc. are a powerful lens through which to understand human relationships with the environment and to design environmental policy. The properly landscape management is a key factor to the maintenance of ecosystem services provided by the watershed as soil conservation, water production and conservation of the surface and groundwater quality (Balvanera et al., 2012; Brauman et al., 2007).

Considering the concept of ecosystem services (Brauman et al., 2007), three hydrologic processes (Variable source area (VSA), potential for water infiltration and erosion susceptibility), fundamental for the maintenance of agricultural production and for water supply were modeled in an integrative perspective, bringing new insights for the field of environmental management and ecosystem services. Many studies that use the hydrologic modeling to calculate the VSA were developed to meet several research goals, similarly to studies on the potential for water infiltration and soil erosion susceptibility (Agnew et al., 2006; Bertolani, 2003; Beven and Kirkby, 1979; Giesler et al., 1998; Gomes et al., 2002; Oliveira, 2004; Pellegrini, 2005; Quinn, 1991; Ridente, 1997; Soares et al., 2007; Sorensen et al., 2005; Walter et al., 2000; Xavier, 2007; Zinko et al., 2005). However, none of these prior studies presents an integrated approach for analyzing these processes simultaneously in the same water system.

In this regard, studies supported in the multi-criteria analysis were developed to integrate the largest number of biophysical and anthropic factors on the landscape (Al-Adamat et al., 2010; Eastman, 1995; Ferraz and Vettorazzi, 2003; Malczewski, 2004; Valente, 2005; Vettorazzi, 2006), but without proposing the integration of the three aforementioned hydrologic processes.

Decisions concerning allocations for land use are often in competition and typically involve the assessment of a number of criteria according to several objectives that are often in conflict (Eastman, 1995). The decision-making process, by which land is leased for a particular activity or particular interest, is one of the most important activities in the development and use of resources (Eastman, 2001).

The hierarchical analytical process - ordered weighted average (AHP_OWA) is a multicriteria combination operator, developed to facilitate exploratory multicriteria analyses including qualitative information, and its nature depends on parameters that are expressed by fuzzy linguistic quantifiers (Boroushaki and Malczewski, 2007). The procedures of modeling and integration of field data and secondary data in the Geographic Information System (GIS) environment aim to model the possible environmental responses to the different types of natural and anthropic stimuli. In this sense, with the intention of spatializing several biophysical parameters and possible responses to anthropogenic stimuli, especially those related to decisions on land use cover and forms of

management to which a specific system, led to the development of research adopting a definition of critical management areas (Siefert and Santos, 2010; Walter et al., 2000).

The present study aimed to zone areas with high importance to the maintenance of ecosystem services related to water and soil conservation, , taking into account different hydrologic processes modeled in a integrative perspective. METHODOLOGY Study area The Araquá watershed is located in the Midwestern region of Sao Paulo state - Brazil, at the geographic coordinates 220 38 'and 220 54' South latitude and 480 34 'and 480 23' West longitude, comprising an area 27,400 hectares (ha) or 274 km ², part of the tributary watershed of the Tietê River (Figure 1).

The climate, identified as Cwa according to classification of Koppen, is mesothermal, with drier season in the winter with annual average temperatures of around 20 º C and rainfall between 1,100 and 1,700 mm per year (Carvalho, 1983), and, as described by Leopoldo et al. (1998), may reach values higher than 1,800 mm annually. The months with the highest total precipitation are between September to March (Silva et al., 2011).

This region is situated on two geological groups: Bauru and São Bento, referring to the Cretaceous and Jurassic-Cretaceous geologic period, respectively. The Bauru group consists of four sandstone formations and form the Reverse of Cuesta (altitude elevations ranging from 700 to 920 meters above sea level). The São Bento Group consists of three formations: the Serra Geral, Botucatu and Pirambóia (Zimback, 2008).

The Serra Geral formation is composed of basalt and sandstone lenses that form the geomorphological feature called the Cuesta Front (IPT, 1981), characterized by shallow soils and land with slopes steeper than 30%. The formations Botucatu, composed of eolian sandstones, and Pirambóia, formed by water deposition, have combined to produce the geomorphological feature called the Cuesta Depression (IPT, 1981). Dataset For the gathering of information on the characteristics of the soils in the watershed, 60 samples were collected at two depths (0-20 and 20-40 cm), using the borehole method followed by the recording of the GPS coordinate of each point sampled (Figure 1). Soil was collected at random points and analyzed in the laboratory for determination of physical and chemical attributes.

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Figure 1. The Araquá Watershed: its location and distribution of geomorphological features and soil samples.

Based on the laboratory data and soil classification techniques (CNPS – Embrapa, 2006; Lemos and Santos, 2006), a soil map for the watershed was generated according to the Brazilian soil classification. A textural map (% clay) and a map of hydrological groups adapted from Sartori et al. (2005) were obtained by utilizing the classification of the Soil Conservation Service (SCS); a third additional map depicting erodibility was generated from the natural erodibility index classifications for soils of Sao Paulo state (Bertoni and Lombardi, 1985).

The digital elevation model (DEM) was obtained by the interpolation method denominated Topo to Raster, using the digitalized information provided by the topographic maps at the scale of 1:10,000 with vertical equidistance of 5 meters in contours, provided by the Institute of Cartography and Geography of the State of Sao Paulo (IGC). The topography directly influences soil moisture and is the first-order control on the spatial variation of hydrologic conditions (Sorensen and Zinko, 2005).

Geological data provide important information in surveys about potential water infiltration, particularly in

studies assessing the risk of groundwater contamination, especially in aquifer recharge areas. Thus, the geological map produced by the Institute for Technological Research (IPT, 1981) was used at the scale of 1:50,000. Methodological approach Three hydrologic processes were mapped in the watershed. Each process in the proposed methodology represents criterion maps (objectives), that when analyzed together, presented a solution, while taking into consideration the purpose of zoning important areas for the ecosystem services within the possible limits inherent to the integration process between antagonistic but complementary phenomena, in the hydrologic cycle.

The hydrologic process are (a) VSA: a term adopted for saturated areas that expand and contract seasonally, as well as during individual storms, important source areas of surface runoff in humid areas (Agnew et al., 2006; Frankenberger et al., 1999; Hewlett and Nutter, 1970); (b)

293 J. Environ. Sci. Water Resourc. infiltration potential: the water absorption into the soil through the process of infiltration is responsible for maintaining the watershed as a reservoir of the dynamic hydrologic system, which allows the storage and transfer this resource through its underground movement toward drainage networks during periods of drought (Soares et al., 2007); (c) erosion susceptibility: soil loss through erosion process promote serious damage to the environment and to the agricultural systems, including siltation of water bodies, loss of soil fertility and water contamination by surface drift of pesticides and fertilizers used in agriculture (Oliveira Júnior and Dias, 2004; Valente, 2005).

After the application of AHP_OWA, the top 25% of the area was selected and represented by pixels with the highest values in an increasing scale.

To achieve a broader understanding, the best parcels in this article refer to the areas where the greatest potential for the processes of infiltration, erosion susceptibility and VSA hydrology intersect in the watershed, defined herein as priority areas for the maintenance of ecosystem services. Modeling and integration of GIS data Several authors have already conducted similar studies with the purpose of conserving soil and water resources (Brito et al., 2006; Meals et al., 2008; Soares et al., 2007) by defining special areas of management according to the physical, chemical and hydrologic properties of the land. In the present study, the method comprises the integration of the three separately determined processes, for subsequently joint analysis. In many studies, each process that will be detailed below was developed for the sole purpose of research. Potential for water infiltration To the assessment of the potential for water infiltration into the soil (Figure 2.A), the methodology proposed by Brito et al. (2006) was utilized with adaptations. The adopted parameters for mapping infiltration are presented in Table 1. These parameters received the same relative weights of importance because all attributes are considered equally crucial to the modeling purpose.

The factor buffer zone for “flooding areas” was delimited using the DEM and an information plan of stream network. The slope information plan for access runoff production was produced by DEM. Erosion susceptibility The erosion susceptibility was assessed according to the methodology proposed by Ridente (1997), combining the

individual factors: soil erodibility and slope. Table 2 shows the weights produced by the overlay (weighted overlay) between the classes of erodibility (row) and slope (column), resulting in the map of erosion susceptibility (Figure 2B). Variable source area To modeling the potential areas for the variable source area (VSA), the Terrain Analysis Using Digital Elevation (TauDEM) was utilized with the specific watershed DEM (Tarboton, 1997).

The VSA is an important factor for modeling areas that present formation of runoff by the soil saturation after rain events (Hewlett and Hibbert, 1967; Pereira, 2007). The contribution area is variable because the factors that determine the runoff formation are represented by the surface topography and by an exponential law that relates transmissivity to the surface depth of soil saturation (Beven and Kirkby, 1979).

The topographic wetness index represents the index of hydrologic similarity in a watershed (Xavier, 2007) by the formula (1): [TI = ln (a/tangβ)] (1) Where; ln is a natural logarithm, a is the specific contributing area and β the slope of the surface. The specialized variable source areas for the Araquá watershed are presented in Figure 2C. Analytical hierarchy process using ordered weighted averaging The information plans were aggregated according to the method proposed by Boroushaki and Malczewski (2007) where the analytical hierarchy process and the ordered weighted averaging are integrated in the same process. The AHP_OWA procedure permits the AHP to include a quantifier-guided instead of a simple weighted average in the process by which the values of the criteria are aggregated, which gives rise to a natural language of quantification for the analysis in the spatiality of decision. In a GIS environment, the information plans (criterion maps) were inserted to represent one goal each. For the present case, the aims presented in maps were standardized on a scale of values in increasing order of importance. This set of procedures resulted in the Figure 2.D that shows the combined criteria according to their importance levels in a spatial solution.

The steps presented in items modeling and integration of GIS data section was conducted to generated maps of

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Table 1. Potential for water infiltration in the Araquá watershed. Parameter Weight Description Infiltration capacity Class code Geology 0.25 Argillaceous sediments, sand sediments and

gravel (Depression and Reverse of the Cuesta) High 2

Volcanic basalt formation (Front of the Cuesta) Low 1 Soils Hydrologic soil group A High 3 0.25 Hydrologic soil group B Medium 2 Hydrologic soil group C Low 1 Hydrologic soil group D Very Low 1 Slope 0 - 2% High 3 0.25 2 - 5% Medium 2 > 5% Low 1 Flooding areas 0.25 Buffer zone Low 1 Outside buffer zone High 2

Table 2. Classes of erosion susceptibility in the Araquá watershed.

Soil Slope Class V (weight 1) Class IV (weight 2) Class III(weight 3) Class I (weight 5) < 6% (weight 1) 1 2 3 5 6 – 12% (weight 2) 2 4 6 10 12 – 20% (weight 3) 3 6 9 15 20 – 30% (weight 4) 4 8 12 20 > 30% (weight 5) 5 10 15 25

factors infiltration, erosion and VSA which were used as inputs for the multicriteria analysis process proposed by Boroushaki and Malczewski (2007). Thus, the process of the AHP method AHP_OWA was important in organizing the factors into a guided hierarchical structure to run the OWA.

The Ordered Weighted Average (OWA) method was used to combine these factors due to its flexibility in resolving a spatial decision anywhere in the area of interest between the AND and OR extremes in the spatial decision strategy.

To perform the AHP_OWA approach, the objectives received the same relative weights in order to assume the same relative importance for achieving the overall goal. The linguistic operators were "all" for the infiltration, erosion and VSA and "many" for the overall goal. Thus, the use of the linguistic quantifier "all" for infiltration, erosion and VSA, implied their importance in the decision-making process, where each must be addressed in an acceptable solution.

Applying the quantifier "many" to the overall goal means that many of the goals must be met within an acceptable solution, namely a solution capable of combining spatially the areas most sensitive to the formation of VSA, infiltration and erosion in the same decision space. RESULTS AND DISCUSSION The infiltration potential and erosion susceptibility are two

natural processes that present relative antagonism, since in areas where the potential for erosion is more influenced by steep slopes (a slope of at least 20%), the potential for water infiltration is correspondingly smaller in the same area, and vice versa. However, these processes are modeled with a combination of more factors such as hydraulic conductivity and erodibility index, which are directly related to the physical and chemical properties of soils (Sartori et al., 2005). The results show that, although the relative antagonism between these two processes varies according to the slope factor, both were covered in medium to high levels of importance in proportions above 60% in the important areas for the ecosystem services maintenance zoned by AHP_OWA (Figure 2).

The spatial representation of the sensitivity levels for the processes presented in Figures 2.A and B, shows the relative antagonism that exists, especially among the very high, low and very low levels in both process. The high and medium levels present better spatial overlap. When Figure 2.C (VSA) is analyzed together with A (erosion) and B (infiltration), what is observed is the increased occurrence of VSA between levels of middle and high sensitivity in both processes, erosion and infiltration.

Thus, Figure 2.D clarifies the result of AHP_OWA that assigned the values of highest importance in an ascending scale, where there were spatial overlaps for the high levels of erosion and infiltration exceeding the overlap with VSA. In addition to the ascending order of values in AHP_OWA, the greater values are represented

295 J. Environ. Sci. Water Resourc.

Figure 2. (A) erosion susceptibility, (B) infiltration potential, (C) VSA, (D) AHP_OWA result.

by the overlap of high levels of at least one of the processes, erosion or infiltration, with medium levels of the other, together with the overlap of VSA.

The 25% of pixels with higher values in AHP_OWA are shown in Figure 3. In these areas, the class indicating high potential for the erosion process is represented by 65.5% of the area versus 29.2% for the class of medium potential, whereas the infiltration potential follows the same trend in the classes of medium and high importance, covering 74.2% of the prioritized area.

The analysis of the slope parameter, soil texture and hydrologic soil groups in the context of the zoned areas for ecosystem services maintenance revealed the predominance of hydrologic soil group B (79%), characterized by a moderate rate of infiltration potential and moderate resistance and tolerance to the erosion process. The slope classes, grouped into 10 groups on an ascending scale from 0 to 100%, showed a tendency to prioritize areas where the slope relief ranges from 0 to 20% (flat to undulating), indicating strong influence of soil

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Figure 3. Priority areas for ecosystem services maintenance in the Araquá watershed (25% of the watershed).

parameters on the characterization of the erosion process contemplated in the zoned areas (Figure 3) in relation to the slope factor.

This result was consistent with the research objective, because within the zoned areas the potential of the agricultural land areas are included (areas of flat and gently undulating terrain between 0 to 12%) (Lepsch et al., 1991). Thus, this approach is shown to be useful for studies to prioritize special zones for management in agricultural landscapes to maintain the ecosystem services provided by the watershed. According to Lepsch et al. (1991), areas with slopes up to 12% are areas with high potential for mechanized agriculture where erosion processes can be better controlled through the use of soil conservation techniques.

As observed in another study (Pereira, 2007), the VSA are hydrologically sensitive areas because they present increased formation of surface water flow and soil saturation after a rain event. This information represents an important element in assessing the environmental vulnerability of certain regions. As demonstrated by Meals et al. (2008) surface water quality can be optimized through proper management of these areas of higher runoff production while minimizing the loss of soil nutrients.

Fifty-one percent (51%) of VSA in the watershed occur in areas of slopes between 3-8% and 8-20%. This result can be explained, according to Meals et al. (2008), by the fact that the topographic index takes into account the relative contribution area of the watershed and slope.

297 J. Environ. Sci. Water Resourc. The VSA is represented in 40.5% of the areas zoned by the methodology. The present result demonstrates that VSAs was not prioritized solely by a slope gradient but also by the configuration of the landscape topography. This result also shows the spatial relationship between VSA hydrology and areas with potential for agricultural use, where the reliefs range from flat to gently undulating. Thus, the present study emphasizes the importance of VSA in the watershed system analysis, and demonstrates its correspondence with the processes of infiltration and erosion, which are spatially distributed in the same slope levels.

Thus, the VSA factor, to be determined solely by the topography, becomes an adequate parameter for increasing the importance levels of the other two processes (erosion and infiltration) when they do not present highly significant overlap in isolation. Thus, when the VSA overlaps with these factors, it raises the level of importance of the overlapped area, expressed in the pixels by higher values in the AHP_OWA.

The land use and land cover (LULC) map of the Araquá watershed classified the region as presenting coverage of sugarcane (38%), pastures (19%), and native vegetation remnants (18.6%). The LULC in the zoned areas (25% of the watershed) is represented by coverage of sugarcane (42.7%), pasture (21.3%), remnants of native vegetation (11%) and eucalyptus (9%).

LULC reinforces the agricultural suitability of the zoned priority regions for ecosystem services maintenance, thus demonstrating that the proposed methodology is an efficient tool for defining these areas and guiding the management of agricultural landscapes. The sugarcane cultivated in the region is considered intensive and mechanized, and requires continuous soil management, by application of fertilizers and pesticides during the crop cycle periods. Intensive agriculture increases erosion and sediment load, and leaches nutrients and agricultural chemicals to groundwater, streams, and rivers (Foley et al., 2005).

Management of the infiltration process requires field use of agrochemicals that present rapid degradation and high capacity to be retained in the soil. The application of vinasse, widely used as a fertilizer in sugarcane cultivation, can reach pollution levels one hundred times greater than that of domestic sewage (Silva et al., 2007).

When assessing the potential for erosion and runoff in these zoned areas, Cambuim (1983) found that the vinasse leaches the elements calcium, magnesium and potassium at almost the same proportion as the rates of vinasse application. In the VSA agrochemicals applied in these saturated regions tend to be carried directly to the watercourse (Agnew et al., 2006).

Therefore, the use of vinasse and other agrochemicals in agricultural landscapes exposes the surface and groundwater to contamination risks. One option for the management of fertilizers and pesticides in the priority regions for the ecosystem services maintenance would

be to restrict these products to the rainiest season. In rainy periods they may percolate into the soil and thereby affect the groundwater quality or be carried to the watercourses with sediments through runoff (Britto et al., 2011; Oliveira et al., 2009; Spadotto et al., 2004).

In these areas it is important to adopt management practices for soil conservation that minimize erosion processes, which are responsible for entraining pesticides retained in the soil and siltation of watercourses. This scenario highlights the advisability of utilizing terracing techniques, non-tillage and harvesting activities only during periods of less intense rainfall, to prevent soil exposure during rainy seasons, as good management practices to avoid soil and water degradation.

The pasture lands, covering an area of 21.3% of priority areas (25% of the watershed), are characterized by extensive ranching and low productivity, with pastures fields in different levels of degradation, onset of erosion and gully formation, siltation of watercourses and occupation on the riverbanks that should be occupied by riparian forests. Between the years 2000 and 2010, Silva et al. (2011) found a positive correlation between the decrease of pasture areas and the decrease of erosions.

This trend evidences that the livestock management practice currently used in the watershed, negatively impacts soil conservation and thereby increases susceptibility to erosion process. This trend can be explained by the replacement of pasture by sugar cane plantations and eucalyptus. The preparation of agricultural areas for these uses involves the recovery and stabilization of soils in areas undergoing an intensive erosion process. The cultivation of eucalyptus, used as the most important specie for commercial reforestation in the study region, is harvested on cycles that vary from 4 to 7 years according to the purpose of use. This semi-perennial crop type may represent an appropriate use of the land in the context of ecosystem services maintenance as soil conservation and water production, since it reduce the intensity of land management activity, in addition to offering a profitable option for farmers (SBS, 2005).

According to Baena (2005), the Internal Rate of Return for eucalyptus cultivation could reach 31.88% per year. It is important to emphasize that although this crop may be suitable for keep the ecosystem services, it should be conditioned by adoption of good management practices (Borges et al., 2004; Freitas et al., 2012; Lima, 2010; Lima, 1996).

The priority zones defined by research method approach are above all areas where the land should be subjected to the adoption of sustainable management practices. There are a variety of alternatives such as agro-systems that choose adequate perennial and semi-perennial crops, as well as crop varieties and plants that require little mechanization or agrochemicals, but rather utilize postharvest techniques, non-tillage and

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Table 3. Key combinations among criteria defined by the methodology of AHP_OWA. Potential for Infiltration

Erosion Susceptibility VSA Priority areas for the ecosystem services maintenance (%)

medium High No 11 high Medium No 9 high High No 38 medium High Yes 13 high medium Yes 12 high high Yes 8

agroforestry systems and organic cultivation. Considering the structure of AHP (Saaty, 1980) and the proposal presented here to generate maps of criteria as detailed in sections 2.4.1, 2.4.2, 2.4.3, the AHP Method of Boroushaki and Malczewski (2007) worked with a comparison matrix which made it possible to the OWA aggregate in the decision space, utilizing the linguistic quantifiers, a solution to achieve the objective of the present study. Thus, the complementation of AHP with OWA enabled the OWA to offer an alternative general framework for a series of local aggregations used in AHP that resulted in overlapping areas of high potential for erosion and infiltration process among themselves, using the VSA to raise the level of importance in regions where only one process, either erosion or infiltration, was dealt with in classes of high potential.

This approach was consistent with the zoning of priority areas for the ecosystem services maintenance, because six main combinations totalizing 91% of areas were prioritized in the same solution (Table 3). The result is expressed as a % of area in important areas for the ecosystem services maintenance. Conclusion The proposed aggregation method for integrating the processes of infiltration potential, erosion susceptibility and VSA to zone important areas for the ecosystem services maintenance in agricultural landscapes showed to be an interesting tool for access these priority areas. This approach is feasible because such areas have high aggregated levels of sensitivity in relation to the selected processes. The observation in these areas of intensive agricultural land use activities related to food and biofuel production, which has a high potential for degradation of the ecosystem services production capacity if poorly managed, constitutes further evidence of the effectiveness of this proposal.

In this context, the AHP_OWA is able to combine the optimum importance levels of each goal (hydrologic processes) in a feasible solution that met the overall goal within the decision-making process. This approach demonstrated that different processes as infiltration potential and erosion susceptibility, spatially distributed in

the watershed have high spatial correlation between high and medium potentials.

The hydrologic processes in a watershed are determined by many natural factors related to the biophysical environment. Modeling these processes requires an integrated scientific and methodological effort that must be achieved by collecting field data and modeling in a GIS environment.

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