A SUCCESSFUL WATER CONSERVATION PROGRAM IN A SEMIARID REGION OF NEBRASKA¹

Abstract

Ground water irrigation pumpage of the High Plains Aquifer is controlled at the state level in Texas and Oklahoma but at the regional level in Kansas and Nebraska. Critical declines in the aquifer that threatened the reliability of local public water supply wells prompted Nebraska's Upper Republican Natural Resources District (URNRD) to mandate water restrictions in 1978. Under current regulations, irrigators may not extract more than 1,842 millimeters of water per certified hectare (ha) in any five‐year period. Meter monitoring ensures that irrigators comply with restrictions. Farmers now incorporate irrigation scheduling into their cropping practices in order to meet URNRD controls. This study examines whether irrigators are using ground water efficiently while complying with pumpage limits. Crop irrigation requirements (CIR) from 1986 to 1999 were derived from a water balance approach incorporating Penman‐Monteith evapotranspira‐tion (ET) calculations from weather data supplied by the High Plains Climate Center automated weather station network. A ratio of average water pumped per well to the CIR was developed to verify irrigation efficiency. Results indicate that irrigation applications were less than CIR during most irrigation seasons. Irrigation efficiency increases can be attributed to crop rotations, favorable growing season precipitation, use of ET estimates to schedule irrigation, and water allocations limited to less than all certified hectares.

Reply to comments provided by J. Szilagyi on “Evaluation of the impact of groundwater irrigation on streamflow in Nebraska” by Fujiang Wen and Xunhong Chen

“…Chen et al (1999) and Chen (2004) also investigated the hydraulic properties of the alluvial aquifer adjacent to the Republican River and its tributaries and the streambed hydraulic conductivity of this river, which are needed for the characterization of the hydrologic connection between the river and the adjacent aquifers. Adelman (2003) examined the efficiency of groundwater uses in the upper Republican River Basin of Nebraska. Because of a continued interest of numerous researchers to the hydrologic systems in the area, it is certain that more methods will be used to analyze the stream-aquifer systems in the Republican River Basin and new results will be reported.…”