Analysis of water resource variability over the irrigated area along the downstream reach of the Yellow River

Long-term changes in climate, river discharge, irrigation water and water-use efficiency were examined during a case study in the Weishan Irrigation District located to the northern side of the lower Yellow River. The relationship between actual evaporation and potential evaporation was examined on annual-regional scales. It was found that the annual precipitation fluctuated dramatically especially during the 1990s-2000s. High interannual water resource variability aggravates the water shortage, and irrigation from the Yellow River is required in order to secure agricultural production. Even though the water-use efficiency increased during the recent decade, there is a high potential for further water-saving by optimizing the irrigation schedule and irrigation methodology. In additional, a significant negative correlation between the actual and potential evaporation in the natural catchment, was found to be much weaker in the irrigated area which is located in the same region. This implies the local climate changed to some extent due to irrigation.