An improved ET control method to determine the water-saving potential for farmland in Baiyangdian Watershed, China

Resource-based water-saving potential has been recognized as the reduction of evapotranspiration and water loss of inefficient irrigation systems. In this paper, an improved evapotranspiration control model is applied to calculate resource-based water-saving potential, considering the influences of effective rainfall (uncontrolled evapotranspiration) and irrigated water (controlled evapotranspiration). Farmland in Baiyangdian Watershed, a highly productive area in northern China, is analyzed to determine the water-saving potential of irrigation processes. The water-saving potential was zero, 163.90 x 10(6) m(3), and 318.24 x 10(6) m(3) in wet, normal, and dry years, respectively, and was greater in years with less rainfall. Under the combined effect of rainfall, crop water consumption, and crop water requirements, the water-saving potential showed obvious temporal and spatial variations. July and August comprised almost 98.6% of the annual potential. In the northeast and southwest corner of the study area, potential approached zero. The potential was 1.53 times greater in the north-central than in the south-central area. The model can furnish the appropriate timing and region to water managers for implementing water-saving strategies.