Submitted to: Model and Computer Program Software Documentation
Publication Type: Government Publication
Publication Acceptance Date: July 23, 1993
Publication Date: N/A
Interpretive Summary: Irrigated agriculture diverts a large percentage of water in the Western United States. Water applied to farm fields in excess of crop consumptive use is returned to the water supply, but typically with degraded quality. Most of this excess water results from poor irrigation system design and management, leading to poor application efficiency. Level-basin irrigation nhas been touted as a more efficient irrigation method; however, this has not always been borne out in practice. This report describes an interactive computer program for analyzing and designing level-basin irrigation systems. The program includes design procedures that explicitly take operation and management into account, which should help to improve the potential performance of these systems. This program will benefit farmers, agricultural consultants, agricultural research and support organizations, and ultimately the public in improved water quality.
Level-basin irrigation systems, in some situations, provide an efficient and cost effective method of irrigation. There are a number of limitations to the adoption of level basins, some physical and some economic. The BASIN computer program assists the user with the hydraulic design of level- basin irrigation systems (i.e., it does not include economic considerations). The program is menu driven for easy user interaction. I includes three design modes and one mode for evaluation of a particular design. The first design mode is used to establish the limits of design conditions, for example maximum length for a given design efficiency or maximum design efficiency for a given length. The second design modes uses the design concept developed by the Soil Conservation Service. It assumes that flow rates are measured and cutoff is determined by application time. The third design mode provides design based on the advance distance at cutoff. This is a common mode of level basin operation, since it does not require precise measurement of flow rate or volume. This design mode, with cutoff at the end of advance, has been recommended by Wattenburger and Clyma for developing countries. The operation evaluation mode allows the user to test the results of individual irrigation events, for example to determine how the basin will perform under the range of possible field conditions. Design solutions are obtained quickly since they are simply interpolated between tabled values. The program currently includes the influence of advance and recession on uniformity and efficiency, but not such factors as soil infiltration spatial variability and variations in soil surface elevations.