Water Resources Research Act Program

Details for Project ID 2017OK338B

Economics of Groundwater Interaction and Competing Crops

Institute: Oklahoma
Year Established: 2017 Start Date: 2017-03-01 End Date: 2018-02-28
Total Federal Funds: $5,000 Total Non-Federal Funds: $10,000

Principal Investigators: Arthur Stoecker

Abstract: This study seeks to observe the benefits and costs due to interaction in groundwater when distinct groups of producers compete for a common supply of groundwater. Intensive use and low recharge means, producers in the Oklahoma Panhandle overlying Ogallala aquifer face continuous declines in groundwater levels. Recent study and field experiments have shown 145 bushels of grain sorghum can be produced with 10 acre-inches of irrigation while corn requires 22 acre-inches to produce 190 bushels. Research has shown producers can increase total discounted profits by choosing crops that use less water per acre but yield higher profits per unit of groundwater and by irrigating for a longer period of time. However, groundwater is a common pool resource. Part of the groundwater from a conserving producer may flow to a non-conserving neighbor thus reducing incentives for conservation. If several producers form their groundwater control groups, how large a contiguous land they must control to capture the benefits from an optimal long-term use? Two groups of producers are considered. Group one producer's chooses the crop (corn) and irrigation level to maximize annual profits until the aquifer is completed. The second group attempts to maximize the NPV of groundwater reserves. The second group may choose less intensively irrigated sorghum, which requires less water per acre but returns more profit per unit of water than corn. Group two may initially earn lower profits per acre than group one but may ultimately earn greater discounted profits by irrigating for more years. EPIC simulation was used for crops on 640-acre field irrigations for CP and SDI system with well capacities from 100 to 800 gallons per minute and plant water-stress factor from 0.30 to 0.90. The water use, net returns and irrigation investments (system replacement intervals) are then incorporated into a 60-year Mixed Integer Programming (CPLEX) model for a 640-acre field with four existing wells. In our model, the area controlled by producers in group two is surrounded by producers in group one, but two areas are linked by a groundwater model. The size to the area controlled by group two is taken as one, nine, twenty-five square miles. Based on USGS estimates of specific yield and hydraulic conductivity, possible drawdowns and well yields are estimated using the Cooper-Jacob approximation. Two levels of hydraulic conductivity will be considered. The results are expected to illustrate the effect on the size of the conserving district and hydraulic conductivity in the aquifer on the incentives for producers in group two.