Comprehensive evaluation of agricultural water-saving potential in the middle reaches of Hei River using genetic projection pursuit model

A comprehensive evaluation of agricultural water-saving potential is the basis for agricultural water planning. Currently, however, insufficiencies of quantitative research have precluded the comprehensive evaluation of regional agricultural water-saving potential. This study therefore focused on agricultural water-saving potential in the middle reaches of Hei River, which is located in the northwest inland of China. Based on the principle of analytical hierarchy, a comprehensive evaluation index system of the regional agricultural water-saving potential was established, which combined a series of statistical data and participatory rural appraisal which took into account the impacts of socio-economic development, hydrology and water resources, agricultural water resources development and utilization, agricultural water-saving level and ecology on regional water-saving potential. Given that the evaluation indexes were incompatible, the projection pursuit model (based on genetic algorithm) was used to evaluate agricultural water-saving potential. The model used the optimum projection vector to evaluate the directional contribution of each index in the comprehensive evaluation system. Projection index value was used to evaluate future achievable agricultural water-saving potential of the district and counties in the study area. The districts/countries included Ganzhou District, Minle County, Linze County, Gaotai County and Shandan County. Results indicated that the index ratios of water conservancy investment to GDP, impermeable channel area and pipeline irrigation area had significant influence on regional agricultural water-saving potential. Then per capita grain yield index, per capita water resources index and water supply modulus index had little influence on regional agricultural water-saving potential. The projected values Z(i) for Ganzhou District, Minle County, Linze County, Gaotai County and Shandan County in 2005 were 1.366 5, 1.170 4, 1.239 1, 1.259 6 and 1.158 6, respectively. This showed that agricultural water-saving levels of Ganzhou District, Gaotai and Linze Counties were higher than other counties/districts. These other counties/districts were at a lower level and had large agricultural water-saving potential. This study provided scientific basis and decision-making support for developing regional agricultural water-saving technology.