DETERMINATION OF CANAL LEAKAGE POTENTIAL USING CONTINUOUS RESISTIVITY PROFILING TECHNIQUES IN WESTERN NEBRASKA AND EASTERN WYOMING

In the North Platte River Basin, a ground-water model is being developed to evaluate the effectiveness of using leakage of water from selected irrigation canals to enhance ground-water<br>recharge. The U.S. Geological Survey, in cooperation with the North Platte Natural Resources District, used land-based capacitively coupled and water-borne direct-current continuous resistivity profiling techniques to map the lithology of the upper 8 meters and interpret the relative canal leakage potential of 110 kilometers of the Interstate and Tri-State Canals in western Nebraska and eastern Wyoming. Lithologic descriptions from 25 test holes were used to evaluate the effectiveness of both techniques for indicating relative grain size. An interpretive color scale was developed that symbolizes contrasting resistivity features indicative of different grain-size categories. The color scale was applied to the vertically averaged resistivity and used to classify areas of the canal as having either high, moderate, or low canal leakage potential. When results were compared with the lithologic descriptions, both land-based and water-borne<br>continuous resistivity profiling techniques were determined to be effective at differentiating coarsegrained from fine-grained sediments. Both techniques were useful for producing independent, similar interpretations of canal leakage potential.