Modeling Irrigation Systems in Semi-Arid Regions: Current Status & Emerging Needs for SWAT

Transcription

1 Modeling Systems in Semi-Arid Regions: Current Status & Emerging Needs for SWAT Ryan T. Bailey Timothy K. Gates Miles Daly SWAT Conference, Oct. 15

2 Irrigated Stream-Aquifer Systems Salts, N, P Salts, N, P Soil Table FeS 2 Seepage NO 3 SO 4 Pumps

3 Motivation Simulate water flow and solute transport in irrigated watersheds, under varying management scenarios. - Effect of high water tables on crop yield (waterlogging; soil salinity) - Effect of high water tables on municipal infrastructure - rights: Effect of groundwater pumping on nearby streams - groundwater return flows to streams - Nutrient leaching: effect on groundwater quality, loadings to streams - Groundwater salinity: effect on groundwater quality, loading to streams Quantity Quality

4 Outline (Soil, Groundwater, Loading to Streams) 3. ( heds ) 4. : Groundwater vs. Surface

5 Lower Arkansas River Basin : Canals (earthen) : Groundwater Pumping Canal seepage

6 Lower Arkansas River Basin : Canals (earthen) : Groundwater Pumping Canal seepage Salts, N, P Salts, N, P

7 Semi-arid agricultural areas: Excessive irrigation Seepage from earthen canals Inefficient drainage systems Evaporative concentration USDA Laboratory High soil salinity High groundwater salinity Reduction in crop yield

8 South Platte River Basin

9 Lower Arkansas River Basin

10 Lower Arkansas River Basin

11 Lower Arkansas River Basin

12 Lower Arkansas River Basin Groundwater

13 River ~ 900 mg/l Freshwater Limit (WHO) Estimated Maximum to Prevent Crop Loss

14 Assess Impact of BMPs on Soil Groundwater Salt loads to River Modeling: Groundwater Flow and Transport Model MODFLOW + RT3D 1. Sulfur Cycling 2. Major Ion Chemistry 3. Precipitation-Dissolution

15 Assess Impact of BMPs on Soil Groundwater Salt loads to River Modeling: Groundwater Flow and Transport Model SO 4 Groundwater concentration

16 Assess Impact of BMPs on Soil Groundwater Salt loads to River Modeling: Groundwater Flow and Transport Model SWAT (SWAT-MODFLOW) Module

17 August 2015 Loading of: Salt Nutrients (N,P) Trace Metals (Se, U)

18 Modeling MODFLOW Conduit Flow Package + MT3D CFP (Solute Transport) SWAT capabilities for Drain Flow

19 The use of water in many of the states in the western U.S. is governed by the doctrine of Prior Appropriation. (also known as the "Colorado Doctrine" of water law) Allocation of = First in Time, First in Right South Platte River Basin

20 - By 1965: 10,000 wells drilled in South Platte Basin (drought): 3,000 not allowed to pump - May 7, 2006: 440 wells shutdown

21 Augmentation Plans Pump Groundwater Estimate Stream Depletion Add recharge water to mimic return flows to stream

22 South Platte River Stream Depletion

23 Recharge Ponds

24 Pump Groundwater Augmentation Plans MODELING Estimate Stream Depletion Glover Model (1D Analytical) MODFLOW Add recharge water to mimic return flows to stream SWAT (SWAT-MODFLOW)

25 Summary To use SWAT in Irrigated Stream-Aquifer Systems: (Soil, Groundwater, Loading to Streams) 3. ( heds ) 4. : Groundwater vs. Surface - SWAT+ (object connections) - SWAT-MODFLOW-RT3D

26 Questions