Application of GIS-based SWAT framework for water management of irrigation project under rotational water supply S.D. Gorantiwar Head, Dept. of Irrigation and Drainage Engineering Dr. A. S. College of Agril Engg., Mahatma Phule Krishi Vidyapeeth, Rahuri, Dist. Ahmednagar, Maharashtra State, INDIA sdgorantiwar@rediffmail.com R.T.Thokal Head, Dept. of Irrigation and Drainage Engineering College of Agril Engg. And Tech., Dr.BSKKV, Dapoli Maharashtra State, INDIA
Importance of Irrigation Water Management in Water Scarce Regions Development of framework using SWAT for irrigation water management of command area Case study Application
Irrigation agriculture is a primary user of diverted water Irrigated agriculture is caught between two perceptions that are contradictory agriculture is highly insufficient by growing waterguzzling crops irrigation is essential for production of sufficient food in the future, given the anticipated increases in food demand due to world population growth and changes in diets Globally, food production from irrigation represents more than 40% of the total and uses only about 17% of the land area devoted to food production Irrigated agriculture practiced with complete disregard to resource conservation and sustainability Most efficient irrigation water management Water saving and maximizing its productivity
Failure in water saving strategy insufficient water supply for irrigation will be the norm irrigation management will shift towards maximizing the production per unit water consumed, the water productivity. Deficit irrigation strategy - application of water below full crop-water requirements Deficit irrigation can lead to greater economic gain in case of drought and water scarce condition
Objective To evaluate the crop yield for deficit irrigation, and to select the most suitable and sustainable irrigation planning strategy under rotational irrigation system in the irrigation command
Components of Framework Watershed- Total command area, Subbasin- Outlet command area; Stream-Canal, HRU- Allocation unit Tool framework mainly comprises three modules: Allocation rules module SWAT modules economic module Framework also has a facility to use crop growth module externally Water allocation rules can be given as input according to water availability in reservoir Soil water balance is done through SWAT module External crop growth model uses output of ETp and ETa from SWAT Economic module computes cost of cultivation of crops, gross and net benefits of individual crop as well as project net benefit for respective allocation rule Tool framework is able to estimate daily updates of reservoir storage
1 Development of Conceptual Framework Input Data: Allocation Units (AUs), crop, soil, weather related data, reservoir storage data Allocation Rules Provide various combinations of Water Allocation Rules Initialize Reservoir Storage Day = 1 (Max. 365 days) SWAT AU = 1 Soil = 1 3 Crop = 1 6 Initialize soil moisture 5 4 Estimate root zone depth, ET o and effective rainfall
2 1 Update soil moisture in root zone 5 Continued SWAT Estimate ETa Estimate depth of irrigation according to Allocation Rule Yes Is the event day of irrigation? 4 No 6 All Crops over? Yes No Crop = Crop + 1 All Soils over? No Soil = Soil + 1 AU = AU + 1 No Yes All AUs over? Yes Calculate Canal Water Release Canal Network Model
2 Update Reservoir Storage SWAT Continued Terminate Yes Is reservoir storage less than or equal to dead storage or predefined stage? 3 No All days over? No Yes Obtain crop growth stage- wise ET o, ET a for each crop, soil and in AU Plant Growth Model Estimate Crop Yield Economics Model Estimate Net Benefit Estimate carry over storage Output: Canal Water Storage, Net Benefit, Crop Yield for each Crop, Soil and AU, Carry over Storage
External Crop Growth Model Stewart water production function (or any other suitable model) Y Y a m = 1 K s ns y ET s = 1 os o s ET ET a s
Location of Study Area Location of Sina Irrigation Project Sina Medium Irrigation Project Tributary of river Bhima in Krishna basin Location: Nimgaon Gangarda village, Tal. Karjat, Dist. Ahmednagar Location: Latitude 18o49 0 N Longitude 74o57 0 E Topo-sheets No.: 47 J/13, 47 J/14, 47 N/1 and 47 N/2
Features of Study Area Annual rainfall: 503.80 mm Reservoir gross capacity: 67.98 M cum Live storage: 52.33 M cum Dead storage: 15.65 M cum Observed percentage of live storage in reservoir over a period of 25 years is 69.92 (36.57 M m 3 ) Culturable Command Area (CCA): 9677 ha Irrigable Command Area (ICA): 8445 ha ICA under Right Bank Canal: 7655 ha
Stream network and area commanded by different units RBC length: 73 km Total 71 units (RBC): 36 Direct Outlets, 31 Minors and 4 Distributaries
Cropping pattern in study area Kharif season (June to October) crops: Sunflower (4154 ha) Pearl millet (3320 ha) Mung bean (89 ha) Kharif sorghum (14 ha) Rabi Season (November to March) crops: Wheat (4154 ha) Groundnut (3320 ha) Rabi sorghum (89 ha) Onion (14 ha) Annual crops: Sugarcane (78 ha)
Soils of study area Mirajgaon series (Clay): 1566 ha Ratanjan series (Silt clay): 1820 ha Ghumari series (clay loam): 3084 ha Nagalwadi series (Silt loam): 1185 ha
Soil Slope in study area 0-0.5% slope: 75 ha 0.5-1% slope: 1276 ha 1-3% slope: 6265 ha 3-5% slope: 38 ha Above 5% slope: 2 ha
Water Allocation Rules Percentage of area to be irrigated 100% ICA 80% ICA 60% ICA 40% ICA 20% ICA Release rate from reservoir 5 m 3 /sec 4 m 3 /sec 3 m 3 /sec 2 m 3 /sec 1.5 m 3 /sec Irrigation depth 90 mm 70 mm 50 mm
Irrigation Rotation Kharif season (June to October): 28 days Rabi season (November to February): 21 days Summer season (March to May): 14 days
Parameters for SWAT Calibration For reservoir storage, calibration parameter was considered as saturated hydraulic conductivity of reservoir bed, which was varied from 0.2 mm/hr to 2.0 mm/hr NSE approaching to 1, lowest RMSE and RSR approaching to 0 was found at saturated hydraulic conductivity of 0.54 mm/hr For canal conveyance efficiency, saturated hydraulic conductivity of canal material, which was varied from 0.3 to 3.5 mm/hr and Manning s coefficient (n) varied from 0.025 to 0.060, were considered as calibration parameters NSE approaching to 1, lowest RMSE and RSR approaching to zero was found at saturated hydraulic conductivity of canal as 0.68 mm/hr and Manning s coefficient as 0.037.
Calibration of SWAT for Reservoir Storage Simulated reservoir gross storage (M m 3 ) 80 70 60 50 40 30 20 10 y = 0.9913x - 0.0096 R 2 = 0.9931 Reservoir gross storage calibration using slope and y-intercept method 0 0 10 20 30 40 50 60 70 Observed reservoir gross storage (M m 3 ) Reservoir gross storage calibration using quantitative statistical methods Gross reservoir storage (M m 3 ) 80 70 60 50 40 30 20 Observed Simulated NSE = 0.993 RMSE = 27.86 RSR = 0.084 10 0 Jan-90 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08
Calibration of SWAT for Canal Conveyance Losses Simulated canal conveyance losses (M m 3 ) 35 30 25 20 15 10 5 y = 0.9895x + 0.2545 R 2 = 0.9905 0 0 5 10 15 20 25 30 35 Observed canal conveyance losses (M m 3 ) Conveyance losses from canal network calibration using slope and y-intercept method Conveyance losses from canal network calibration using quantitative statistical methods Canal conveyance losses (M m3) 40 35 30 25 20 15 10 5 0 Observed Simulated NSE = 0.991 RMSE = 4.30 RSR = 0.098 1990-91 1991-92 1992-93 1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-2000 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08
Assessment of Operational Rules Scenario was developed for the year 1998 and 1999 Assessment was done for Longevity of Live storage in reservoir Water distribution uniformity in irrigated area Conveyance efficiency in canal network Project net benefit
Longevity of Live Storage in Reservoir Days to reservoir storage 300 250 200 150 100 50 5 m3/sec 4 m3/sec 3 m3/sec 2 m3/sec 1.5 m3/sec 0 100% ICA 80% ICA 60% ICA 40% ICA 20% ICA Longevity (days) of reservoir live storage from 1st October for different allocation rules (max days-243)
Water Distribution Uniformity 100% ICA Percentage of RR 120 100 80 60 40 20 0 Head Reach Middle Reach Tail Reach 5cum 4cum 3cum 2cum 1.5cum Water distribution for area to be irrigated 100% ICA (7656 ha) 80% ICA Water distribution for area to be irrigated 80% ICA (6195 ha) Percentage of RR 120 100 80 60 40 20 0 Head Reach Middle Reach Tail Reach 5cum 4cum 3cum 2cum 1.5cum
Water Distribution Uniformity 60% ICA Percentage of RR 120 100 80 60 40 20 0 Head Reach Middle Reach Tail Reach 5cum 4cum 3cum 2cum 1.5cum Water distribution for area to be irrigated 60% ICA (4621 ha) 40% ICA Water distribution for area to be irrigated 40% ICA (3011 ha) Percentage of RR 120 100 80 60 40 20 0 Head Reach Middle Reach Tail Reach 5cum 4cum 3cum 2cum 1.5cum
Percentage of RR 120 100 80 60 40 20 0 20% ICA Head Reach Middle Reach Tail Reach 5cum 4cum 3cum 2cum 1.5cum Water distribution for area to be irrigated 20% ICA (1511 ha) For areas to be irrigated more than 60% ICA and irrigation depth as, release rates reduced to zero in the tail reach Higher uniformity in all reaches due to reduced irrigation depths Higher uniformity with decrease in irrigated areas Operation rule with irrigation depth of 50 to and release rate below 3m 3 /sec achieved better uniformity in all reaches
Conveyance Efficiency in Canal Network 90 85 5 m3/sec 4 m3/sec 3 m3/sec 2 m3/sec 1.5 m3/sec Conveyance efficiency (%) 80 75 70 65 60 55 50 100% ICA 80% ICA 60% ICA 40% ICA 20% ICA
Project Net Benefit 200.00 Project net benefit (Rs.in Millions 180.00 160.00 140.00 120.00 100.00 80.00 60.00 40.00 20.00 90 mm 70 mm 50 mm 0.00 5 cumec 4 cumec 3 cumec 2 cumec 1.5 cumec 5 cumec 4 cumec 3 cumec 2 cumec 1.5 cumec 5 cumec 4 cumec 3 cumec 2 cumec 1.5 cumec 5 cumec 4 cumec 3 cumec 2 cumec 1.5 cumec 5 cumec 4 cumec 3 cumec 2 cumec 1.5 cumec 100% ICA 80% ICA 60% ICA 40% ICA 20% ICA Allocation rules
Required Monthly net irrigation water release from reservoir for highest benefited allocation rule 9.0 Irrigation water release (M m 3 ) 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 June July August September October November December January February March April May Month of water release
Net irrigation water demand for outlets for highest benefited allocation rule Net irrigation water demand (1000 m 3 ) 4000 3500 3000 2500 2000 1500 1000 500 Kharif season Rabi season ICA (ha) 700 600 500 400 300 200 100 ICA under outlet (ha) 0 Minor 1 DO 1 Minor 2 Minor 3 DO 2 Minor 4 DO 3 Minor 5 DO 4 DO 5 DO 6 DO 7 DO 8 Minor 6 DO 9 Minor 7 DO 10 DO 11 DO 12 DO 13 Minor 8 Minor 9 Minor 10 Minor 11 DO 14 DO 15 DY 1 DO 16 Minor 12 DO 17 Minor 12 A Minor 13 DO 18 DO 19 DO 20 DO 21 DO 22 Minor 14 Minor 15 Minor 16 Minor 17 DO 23 Minor 18 DO 24 DO 25 Minor 19 Minor 20 Minor 21 DY 2 DO 26 DO 27 DO 28 DO 29 DO 30 DO 31 Minor 22 DO 32 DO 33 Minor 23 Minor 24 Minor 25 Minor 26 DY 3 Minor 27 DY 4 Minor 28 Minor 29 Minor 30 DO 34 DO 35 DO 36 0 Outlets
Sensitivity Analysis for external parameter Project Net Profit (Rs. in Millions) 210.0 y = 200.59x + 184.16 R 2 = 0.9991 200.0 190.0 180.0 170.0 160.0-15% -10% -5% 0% 5% 10% 15% Percent change in prices Sensitivity of project net benefit for external parameter (change in prices)
Sensitivity Analysis for internal parameter 200 Project Net Benefit (Rs. Millions) 180 160 140 120 100 80 60 50 55 60 65 70 75 80 85 90 95 100 Irrigation Efficiency (%) Sensitivity analysis of project net benefit with internal parameter (irrigation efficiency)