pravaya vetka irrigation system: feasibility study · 2018. 12. 4. · i. pravaya vetka irrigation...

Climate Change and Disaster-Resilient Water Resources Sector Project (RRP KGZ 51081-001)

PRAVAYA VETKA IRRIGATION SYSTEM: FEASIBILITY STUDY

http://www.adb.org/Documents/RRPs/?id=51081-002-3

Table of Contents I. Pravaya Vetka Irrigation System .................................................................................... 1

II. Topographic Survey and Mapping ................................................................................. 1

III. Design Flood Hydrology ................................................................................................. 1

A. Present Stationary Climate at Sites 2 and 3 ............................................................... 1

B. Future 2050 Climate at Sites 2 and 3 ......................................................................... 2

C. Present Stationary Climate at Site 1 ........................................................................... 2

D. Future 2050 Climate at Site1 ...................................................................................... 3

IV. Site Investigations .......................................................................................................... 3

V. Hydraulic Design ............................................................................................................ 4

VI. Scope of Works.............................................................................................................. 4

VII. Cost Estimates ............................................................................................................... 5

A. Main Canal Protection ................................................................................................ 5

B. Canal Modernization................................................................................................... 6

Tables Table 1: Shaidon River peak flood discharge ........................................................................ 1

Table 2: Critical rainfall durations .......................................................................................... 2

Table 3: Precipitation intensities ............................................................................................ 2

Table 4: Precipitation depth estimates .................................................................................. 3

Table 5: Mudflow crossing structures – hydraulic design parameters .................................... 4

Table 6: Summary of estimated main canal protection costs ................................................. 5

Figures Figure 1 – Schematic Layout of PVIS .................................................................................... 7

Figure 2 – PVIS Main Canal and Protection Structures ......................................................... 8

Figure 3 – Plan - Mudflow crossing #1 .................................................................................. 9

Figure 4 – Plan - Mudflow crossing #2 ................................................................................ 10

Figure 5 – Plan - Mudflow crossing #3 ................................................................................ 11

I. Pravaya Vetka Irrigation System

1. The PVIS layout is in Figure 1. The main canal, third secondary canal and proposed protection works are in Figure 2. The core subproject will construct a new main canal mudflow crossing structure, at site 1 (Figure 3), replace two inadequate secondary canal mudflow crossing structures, at sites 2 (Figure 4) and 3 (Figure 5), and rehabilitate two lengths of canal lining at sites 4 and 5 (figures 1 and 2).

II. Topographic Survey and Mapping

2. Topographic levelling survey was carried out in accordance with the requirements of SNiP KR 11-01-98 "Engineering surveys for various types of construction". Contour maps were prepared at a scale of 1: 1000 (mudflow crossing structures) and 1: 2000 (main canal lining).

III. Design Flood Hydrology

3. In the Kyrgyz Republic, hydraulic structures, including mudflow crossings, are designed for the flood with a 5% probability of exceedance (Q 5%) and checked for the 1% flood (Q 1%).1

A. Present Stationary Climate at Sites 2 and 3 4. Peak Shaidan River flood flows occur mainly in May.2 The results of May flood flow frequency analysis, using a conventional log-normal frequency distribution, are in Table 1.

Table 1: Shaidon River peak flood discharge

Year Q Year Q Year Q Year Q

1980 15.08 1990 31.60 2000 9.56 2010 17.25

1981 12.43 1991 14.86 2001 4.15 2011 9.56

1982 7.20 1992 13.76 2002 40.97 2012 12.30

1983 14.54 1993 63.47 2003 25.00 2013 10.24

1984 10.15 1994 27.32 2004 31.87 2014 8.18

1985 14.25 1995 20.54 2005 14.51 2015 6.12

1986 8.97 1996 40.44 2006 17.25 M 2.757

1987 21.91 1997 18.21 2007 14.25 S 0.610

1988 31.87 1998 41.24 2008 6.43 Q 5% 43.0

1989 14.51 1999 21.67 2009 10.65 Q 1% 65.1

Legend: M = mean of natural logarithms of Q, Q = peak flood discharge (m3 sec-1), Q 5% = exp (M + 1.645S), Q 1% = exp (M + 2.326S) S = sample standard deviation.

1 Existing Shaidan River mudflow crossings were designed for 16.4 (Q 5%) and 25.0 m3 sec-1 (Q 1%) at sites 2 and 3. 2 The catchment area is 126 km2, at the gauging station, and 131 km2 at the downstream mudflow crossing site 3.

However, no adjustment is necessary as the sites are close together and there is no appreciable inflow between them.

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B. Future 2050 Climate at Sites 2 and 3 5. From the separate Climate Risk and Vulnerability Assessment (CRVA), the mean

maximum annual (mainly in May) one day (24 hour) rainfall will increase by 21% from the present stationary climate to 2050 (with climate change). Therefore, to estimate flood discharge, the above results were used to calibrate a simple flood rainfall – runoff water balance model:

Precipitation (P) = Runoff (Q) + Infiltration (I)

6. The critical duration T (min) is a function of catchment length L (m) and slope S (m/m).3

Table 2: Critical rainfall durations

Site A (km2) L (m) S (m/m) T (hrs)

2 and 3 131 30,000 0.032 3.4

1 7.74 7,000 0.056 0.9

7. Peak discharges were converted to runoff depths using a simple conventional triangular flood hydrograph (base = 2T and height = Q). Therefore, 43.0 m3 sec-1 (cumec) is equivalent to a runoff volume of 43.0 x 3.4 x 3,600 = 526,320 m3 and a runoff depth of 1,000 x 526,320 / (131 x 106) = 4.02 mm. Similarly, 65.1 cumec = 796,824 m3 or 6.08 mm. 8. Separate Sector Assessment presents frequency estimates of mean monthly precipitation for May. These are 208 mm (P 5%) and 302 mm (P 1%). Assuming: (i) for the critical rainfall duration (3.4 hours), P 1% / P 5% = 302 / 208 = 1.45 and (ii) the soil is saturated, and infiltration is constant for both the 5% and 1% floods, gives P5% = 4.02 + I, 1.45P 5% = 6.08 + I, and I = 0.56 mm. Table 3: Precipitation intensities

Prob P Q I

5 4.58 4.02 0.56

1 6.64 6.08 0.56

9. Assuming critical duration precipitation will also increase, by a factor of 1.21 in 2050, gives the following estimates of the 2050 design floods: Q 5% = 1.21 x (4.02 + 0.56) – 0.56 = 4.98 mm = 53.3 cumec; Q 1% = 1.21 x (6.08 + 0.56) – 0.56 = 7.47 mm = 80.0 cumec.

C. Present Stationary Climate at Site 1 10. Application of a common soil infiltration equation 4 indicates that, if cumulative infiltration is 0.56 mm after 3.4 hours (as estimated above), it is 0.33 mm (59%) after 0.9 hours. Precipitation depths (P), estimated above, are in Table 4, for the May (744 hour) and 3.4-hour durations (T), together with 0.9-hour precipitation depth estimates based on the equation lnP = a + blnT.

3 T = 0.0195L0.770S-0.385 (http://onlinemanuals.txdot.gov/txdotmanuals/hyd/time_of_concentration.htm). 4 https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/WR013i002p00395.

http://onlinemanuals.txdot.gov/txdotmanuals/hyd/time_of_concentration.htm

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/WR013i002p00395

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Table 4: Precipitation depth estimates

Prob Duration

May 3.4 hrs 0.9 hrs

5% 208 4.58 1.79

1% 302 6.64 2.59

11. Therefore, runoff depths = 1.79 - 0.33 = 1.46 mm (5%) and 2.26 mm (1%) and peak flood discharges, over the 7.74 km2 site 1 catchment, are 3.49 cumec and 5.40 cumec. 12. Alternatively, the rational formula is Q = CiA/360, where A = catchment area (ha) C = runoff coefficient, i = rainfall intensity (mm hr-1) and Q = peak flood discharge (cumec). 5 Using it relatively gives Q 5% = 43.0 (7.74 x 1.79/0.9)/(131 x 4.58/3.4) = 3.75 cumec and Q 1% = 65.1 (7.74 x 2.59/0.9)/(131 x 6.64/3.4) = 5.67 cumec. Therefore, the two results are consistent.

D. Future 2050 Climate at Site1 13. Using the method in Section 3.2:

Q 5% = 1.21 x (1.79 + 0.33) – 0.33 = 2.24 mm = 5.35 cumec; Q 1% = 1.21 x (2.59 + 0.33) – 0.33 = 3.20 mm = 7.65 cumec. 14. Using a Kyrgyz empirical formula, KECI estimated Q 5% = 6.31 and Q 1% = 8.30 cumec. These are all small design floods that result in small mudflow crossing structures. For example, if the design flood increases from 7.65 cumec to 8.30 cumec the width of an 0.6 m high mudflow crossing waterway only increases by 8% from about 4.3 m to say 5m. 2050 design floods are:

Q 5% = 6.31 cumec; Q 1% = 8.30 cumec.

IV. Site Investigations

15. Site investigations determined the engineering-geological and hydro-geological conditions of the sites and construction material quarries. According to AUSS 20522-75, AUSS 25100-95 and p.p. 3.37-3.43 "Benefits for the design of the buildings and structures foundations (to CRaR 2.02.01-83), based on the results of engineering and geological surveys and vertical electrical sounding (VES), 2 engineering geological elements (EGE) were selected on the studied territory:

EGE-1. Clay loams are light, silty, solid consistency, with inclusions of pebbles up to 10%.

Designed resistance is recommended: R0=2,0 kgs/sm2 Manual development group -2(35B) Soil category by seismic properties –III.

EGE-2. Pebble ground with sand filler.

Manual development group – 3(6В) according to (CRaR 4.02-91) Designed resistance is recommended: R0=4,0 kgs/sm2 Soil category by seismic properties – II.

5 http://onlinemanuals.txdot.gov/txdotmanuals/hyd/rational_method.htm.

http://onlinemanuals.txdot.gov/txdotmanuals/hyd/rational_method.htm

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According to the results of chemical analyzes of water extracts, the soils on the studied area are non-saline, non-aggressive in relation to concrete.

Groundwater traversed workings to 3.0 m are not opened. Type of terrain by nature and degree of moistening I

Seismicity of the work area – magnitude 9 Soil category by seismic properties – II и III.

V. Hydraulic Design 16. Mudflow crossing structures were designed as class IV hydraulic structures according to national standards MSN 3.04-01-2005 and SNiP 2.06.01-86. Design parameters are in Table 5.

Table 5: Mudflow crossing structures – hydraulic design parameters

MFC

#

Q5%

(m3 s-1)

i

(%)

W

(m)

H

(m)

h

(m)

v

(m s-1)

1 6.31 0.0200 3.0 1.2 0.73 2.88

2 53.3 0.0086 18.0 1.6 1.04 2.85

3 53.3 0.0140 24.0 1.6 0.74 3.00

Legend: H= height of structure, h = height of water for Q5%, i = slope of mudflow channel, MFC = mudflow crossing, Q5% = 5% design flood, v = water velocity and W = width of structure.

VI. Scope of Works

17. The scope of work, of the three mudflow crossing structures, is summarized below and their bills of quantities, are in Annex A. 18. Mudflow crossing structure 1 (Figure 3):

i. Upstream: Lined rubble concrete channel with trapezoidal cross-section with width = 3.0

m, height 1.2 m side slopes = 1.5 horizontal to vertical.

ii. New rectangular reinforced concrete mudflow crossing structure with width 3.0 m, height

= 1.2 m and length = 23 m. This is supported by three off 11 m long 2.0 m x 2.0 m concrete

culverts to cross Pravaya Vetka main canal under the new mudflow crossing structure;

iii. Road bridge to provide access across item (iv) below;

iv. Downstream: 162.3 m of open cut trapezoidal rubble concrete mudflow channel.

19. Mudflow crossing structure 2 (Figure 4):

i. The broadening of the inlet canal upstream pounder of mudflow structure;

ii. The widening of mudflow structure #2 parameters b=15 m, m=0, H=1.5 m. (for 2050 b=18

m, m=0, H=1.5 m);

iii. Lower pounder of mudflow structure is provided in a rectangular cross section b=15 m,

m=0, H=1.5 m (for 2050 b=18 m, m=0, H=1.5 m) with the construction of three weirs;

20. Mudflow crossing structure 3 (Figure 5): i. Mechanical cleaning Shaidan Say riverbed to the average slope i=0.015;

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ii. Construction of a regulated canal in the upper pounder with a length of 400 m. Parameters

B=14.5 m, m=1.5, H=1.5 m (for 2050 b=18 m, m=0, H=1.5 m), the width of the dam on top

of 4 m.;

iii. Lining of the right bank of the regulated riverbed with a length of 400 m a ragged stone in

two layers. The diameter of the stone is 0.45 m.

iv. Lining approach to the construction of a ragged stone. The length of 100 m.

v. The construction of mudflow structure rectangular cross section. Parameters b=14.5 m,

m=0, H=1.5 m. (for 2050 b=18 m, m=0, H=1.5 m);

vi. The construction of a regulated canal in the lower pounder with a length of 800 m.

Parameters B=14.5 m, m=1.5, H=1.5 m (for 2050 b=18 m, m=0, H=1.5 m), the width of

the dam on top of 4 m.;

vii. Fixing the discharge canal with a ragged stone. Length 50 m.

VII. Cost Estimates

A. Main Canal Protection

Table 6: Summary of estimated main canal protection costs for present and future climate conditions

Name Amount ($)

Present 2050 2050 with VAT

Upstream 61,750 61,750 69,160

Main crossing structure 50,538 50,538 56,602.56

Bridge 48,861 48,861 54,724.32

Downstream 52,723 52,723 59,049.76

Downstream stilling basin 7,181 7,181 8,042.72

Fencing 2,800 2,800 3,136

Mudflow crossing #1 223,853 223,853 250,715.36

Upstream embankments 8,716 10,757 12,047.84

Main crossing structure 26,370 32,070 35,918.4

Downstream stilling basin 124,891 146,713 164,318.6


Upstream embankments 211,508 213,901 239,569.1

Main crossing structure 102,817 131,350 147,112

Downstream embankments 71,639 73,573 82,401.76


Main canal lining (site 4) 450,653 450,653 504,731.36

Secondary canal lining (site 5) 703,285 703,285 787,679.2

Sub-total 1,923,732 1,986,155 2,224,493.6

Contingency +/- 10% 192,268 198,845 222,706.4

Total 2,116,000 2,185,000 2,447,200

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21. For mudflow crossing structure #1, TRTA Q5% estimates were about 3.6 cumec, without climate change, and 5.35 cumec with climate change in 2050. However, a Kyrgyz empirical formula indicated that Q5% = 6.31 cumec. Therefore, this small mudflow crossing structure was designed for 6.31 cumec and its cost is effectively the same with and without climate change. Table 6 presents cost estimates for the other two structures designed for the: (i) present stationary climate (Q5% = 43.0 cumec) and (ii) future climate with climate change in 2050 (Q5% = 53.3 cumec).

B. Canal Modernization 22. Main (1st and 2nd level) canal modernization works will be designed following a bottom-up participatory planning and design process 6 for lower-level (3rd and 4th) WUA canal modernization. Canal modernization works are expected to include but are not limited to:

i. Lower-level: (a) relocated and/or additional 3rd and 4th level canals, to improve irrigation efficiency and increase command (height) and the service area, (b) gated flow division boxes and measurement flumes or weirs and (c) limited canal lining with concrete;

ii. Main canals: depending on the results of (i) above, additional tertiary offtakes, including improved flow measurement flumes or weirs, new head regulators, across main canals, (cross-regulators) and possible main canal bank raising upstream of cross-regulators.

23. The following provisions are made to meet the expected additional cost of modernization works:

i. Main canal modernization works = $1.5 million excluding VAT ii. Lower-level canal modernization for roughly 600 ha = $1.2 million excluding VAT

6 Following the recommended technical irrigation system planning and design procedure from downstream to upstream.

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Figure 1 – Schematic Layout of PVIS

Feasibility stady (FS) of the pilot subproject "Pravaya-vetka" on irrigated agricalture

Schematic Layout

Bishkek 2018

Figure #

Sakaldy Suu WUA

Taimonku WUA

Aral Say WUA

Kenesh Suu WUA

Shaidan Kara Ungur WUA

Aikol Suu WUA

Murat Murap WUA

Nooken-K WUA

Vahum

Aral canal

Ko

ch

ko

r K

oz c

an

al

Koz Ja

man canal

Sakaldy canal

Taimonku canal

Nooken canal

Pra

vaya-V

etk

a c

anal

Masy canal

Shaidan-Vetka canal

Shaid

an S

ay r

.

Kara

-Unkur

Say r

.

Levaya-V

etk

a c

anal

2

1

2

3

4

5

8

Figure 2 – PVIS Main Canal and Protection Structures

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Figure 3 – Plan - Mudflow crossing #1

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Annex A: Draft Bills of Quantities

Table A1: Mudflow crossing structure #1

Item Description Unit Amount

Upstream

1 Excavation m³ 1293.5

2 Quality fill m³ 6493.5

3 Layout m² 858

4 monolithic rubble concrete m³ 309.4

Including concrete m³ 123.76

rubble stone m³ 185.64

5 Concrete preparation t=10 cm. m³ 114.4

6 Gravel preparation t=10 cm m³ 119.86

7 Metal pipe Ø = 1000mm m 30м

Main crossing structure

1 Excavation m³ 150

2 Quality fill m³ 1720

3 Layout m² 198

4 Prefabricated reinforced concrete pipes 2 * 2 Z.P.10.100.

pie/m³ 39/57.33

5 Monolithic reinforced concrete m³ 105.66

armature kg 3919.986

6 Monolithic concrete m³ 6.5



9 Waterproofing of concrete surfaces with bitumen in gasoline

m² 56.6

10 Painting with oil paint m² 50.24

Bridge

1 Monolithic reinforced concrete В22.5. t=30см.

m³ 39.36

2 Double mesh reinforcement kg 1460.256




m² 16.8


Downstream

1 Cutting of the topsoil t = 20cm m²/m³ 1700/340

2 Excavation m³ 4600

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3 Layout m² 1056

4 monolithic rubble concrete m³ 397.46

Including concrete m³ 158.984

rubble stone m³ 238.476



Downstream stilling basin

1 Monolithic reinforced concrete В22.5. t=30см.

m³ 35.24

2 Double mesh reinforcement kg 1307.404




m² 12.6


Fencing

1 Fencing m 562.7

14


Item Description Unit

Amount Q5% (cumec)

35.2 55.3

Upstream embankments

1 Dismantling of reinforced concrete m³ 11.25 11.25

2 Excavation m³ 532.00 574.80

3 Fill and backfill m³ 137.46 137.46

4 Monolithic reinforced concrete В22.5. t=40см. m³ 37.60 43.90

Double mesh reinforcement kg 1 046 1 222

armature AI 8mm kg 408 477

armature AIII 12mm kg 638 745

5 Concrete preparation t=10 cm. m³ 7.50 13.30

6 Layout m² 115.20 115.20

7 Gravel preparation t=10 cm m³ 8.40 17.60


m² 5 10



2 Excavation m³ 302.00 389.00


4 Monolithic reinforced concrete В22.5. t=40см. m³ 112.80 131.70


armature AI 8mm kg 1 225 1 431

armature AIII 12mm kg 1 913 2 234

5 Monolithic concrete m³ 4.08 4.08

6 Concrete preparation t=10 cm. m³ 22.5 38

7 Layout m² 302.40 302.40



m² 15 25



2 Excavation m³ 707.00 1 072.20


4 Monolithic reinforced concrete В22.5. t=40cm. m³ 584.71 679.40


armature AI 8mm kg 6 351 7 380

armature AIII 12mm kg 9 918 11 524

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Item Description Unit

Amount Q5% (cumec)

35.2 55.3

5 Concrete preparation t=10 cm. m³ 102 129.2

6 Layout m² 878.40 878.40



m² 40 65

16


Item Description Unit Amount

Q5% (cumec) 35.2 35.2

Upstream embankments

1 Excavation m³ 8860 10860

2 Cutting of the topsoil t = 20cm m³ 200 200

3 Mechanical cleaning m³ 5800 5800

4 Quality fill m³ 1820 2220

5 Layout m³ 515 515

6 Fastening with a torn stone d = 45 cm in 2 layers m³ 3845.5 3845.5


1 Dismantling of reinforced concrete m³ 190 190

2 Layout m² 570 570

3 Quality fill m³ 380 780

4 Prefabricated reinforced concrete pipes 2 * 2 З.П.10.100.

pie/m³ 62/91.14 76/111.72

5 Monolithic reinforced concrete t=40см. m³ 263.2 356

Double mesh reinforcement kg 7323.5 9905.7

armature AI 8mm kg 2859.0 3867.1

armature AIII 12mm kg 4464.5 6038.7

6 Monolithic concrete m³ 24.3 24.3

7 Concrete preparation t=10 cm. m³ 63.7 88.2


9 Painting with oil paint m² 92 92


m² 90 110


1 Excavation m³ 11140 13140

2 Mechanical cleaning m³ 17000 17000

3 Layout m² 515 515

4 Fastening with a torn stone d = 45 cm in 2 layers m³ 874 874