The choices of irrigation technologies and groundwater conservation in the Kansas High Plains: A dynamic analysis

The most important irrigation water source in Kansas is the High Plains aquifer, which recharges very slowly and has been steadily declining over the past three decades. A common policy prescription for conserving groundwater is to encourage the adoption of more efficient irrigation technologies, which have higher water application efficiencies. In Kansas, such a policy approach has already been implemented through cost-share programs.; Although conserving water is the stated justification for such a cost-share program, its effectiveness is questioned. There is substantial controversy and conflicting evidence in the empirical literature on the conservation effects of technology. The conflicting results have likely come about because the processes driving the observed changes are highly complex and dynamic in nature. The purpose of this study is to examine the interactive and dynamic relationship among groundwater levels, crop selections and irrigation technology investments, which has so far been addressed separately or statically. The main objective is to examine whether the cost-share program is effective at conserving groundwater. To achieve this goal, I have analyzed the factors that determine the choice of irrigation technologies and water use and compared the cost effectiveness of the cost-share program with other policy tools.; The model developed has a nested framework, in which three optimization problems are involved. First, the optimal quantities of irrigation water are selected for all combinations of crop choices and irrigation technologies; second, the crop choice is determined under a certain irrigation technology; finally, the choice of irrigation technology is made by comparing the sum of current and discounted future profits.; Starting from a certain groundwater level, the model predicts the representative irrigator's choices of water use, crop and irrigation technology over time as the water table declines. The results suggest that the more efficient technology is adopted mainly because of limited water quantity rather than increased pumping costs. The cost-share program is effective at increasing the adoption rate of more efficient technologies. However, it is only effective at conserving water for irrigators with relatively high well capacities. In addition, the cost-share program would be more effective if it is implemented together with commodity programs providing incentives to plant less water-intensive crops.