Evaluation of Irrigation Efficiency Strategies for Far West Texas: Feasibility, Water Savings And Cost Considerations
A. Michelsen, M. Chavez, R. Lacewell, J. Gilley, Z. Sheng
Texas recently completed its second round of nationally recognized water planning. The Water Plan for the state addresses how each of 16 regions will supply projected water demands for the next 50 years. Water availability in these plans is based on supply conditions experienced during the drought of record, that is, the severe drought conditions in the 1950's. In arid Far West Texas, Region E in the State Plan, agriculture is projected to have the largest unmet demand for water during drought. This situation is similar to many other irrigated agricultural production regions in the U.S. and world that rely upon limited and variable water supplies. In the Far West Texas (Region E) 50-year Water Plan, the primary strategy proposed to mitigate the impact of insufficient water supplies for agriculture is implementation of water conservation best management practices. However, the conservation practices identified were generic and gave a wide range of potential water savings compiled from many other sources and for other locations and conditions. The feasibility and amount of water saved by any given conservation practice varies substantially across regions, specific location, type and quality of water supplies, delivery systems and operational considerations, crops produced, irrigation technologies in use, and location specific costs and returns of implementation. The applicability to and actual water savings of the proposed practices in Far West Texas were generally unknown.
This report evaluates the applicability, water savings potential, implementation feasibility and cost effectiveness of seventeen irrigated agriculture water conservation practices in Far West Texas during both drought and full water supply conditions. Agricultural, hydrologic, engineering, economic, and institutional conditions are identified and examined for the three largest irrigated agricultural areas which account for over 90% of total irrigated agricultural acreage in Far West Texas. Factors considered in evaluating conservation strategies included water sources, use, water quality, cropping patterns, current irrigation practices, delivery systems, technological alternatives, market conditions and operational constraints.
The overall conclusion is that very limited opportunities exist for significant additional water conservation in Far West Texas irrigated agriculture. The primary reasons can be summarized by: the most effective conservation practices have already been implemented and associated water savings realized throughout the region; reduced water quality and the physical nature of gravity flow delivery limit or prohibit implementation of higher efficiency pressurized irrigation systems; increased water use efficiency upstream has the net effect of reducing water supplies and production of downstream irrigators; and, water conservation implementation costs for a number of practices exceed the agricultural value and benefits of any water saved.
Those practices that suggest economic efficient additional water conservation included lining or pipelining district canals and the very small potential for additional irrigation scheduling and tail water recovery systems. In nearly all cases, these practices have been adopted to a large extent if applicable, further emphasizing the very limited opportunities for additional conservation. If all of these strategies were implemented, the water conserved would satisfy less than 25% of the projected unmet agricultural water demand in 2060 during drought-of-record conditions.
Overall, there are no silver bullets for agricultural water conservation in Far West Texas short of taking irrigated land out of production when water supplies are limited.