Water management in arranged-demand canal

Irrigation water-management characteristics within the command area of an arranged-demand irrigation canal were examined, including on-farm scheduling practices. Supply/demand ratios were used as the key indicators for the conceptual framework; however, spill ratio and the farmers' satisfaction with the system were also considered. To minimize the cost the methodology considered existing data sets and used secondary data where appropriate. Data sources included direct measurement, existing data sets, farmer questionnaires, and simulation of hypothetical demand. Total water use was not sufficient to meet the hypothetical demand of the crops, although some form of scheduling technique was used by more than half of the respondents. The farmers were satisfied with the level of service, although land loss due to seepage was a major concern. There were similarities between the hypothetical demand and actual supply hydrograph, although significant deviations over short time periods suggested that forecasting of actual demand at the canal level using evapotranspiration data would not be practical in this arranged demand canal.