Response of Ecological Base Flow to Water and Sediment Dispatching in Irrigation Areas along Water-Deficient and Sediment-Laden River

Ecological base flow is a basic requirement of water flow for a healthy river ecosystem. But in Weihe River the ecological flow is not guaranteed because of the water shortage, high sediment concentration and considerable agricultural water use along the river. In this study, Baojixia under-tableland irrigation area was selected as a representative area to which a mathematical model of one-dimensional steady water non-uniform sediment regulation was applied, to analyse the impact of channel desilting on guaranteeing the ecological base flow of Weihe River. The results indicated that scouring and silting of the channel was significantly correlated with the channel water capacity and sediment content in water flows. In addition, channel desilting contributed to 55.9×10⁴m³ and 79.2×10⁴m³ water saving in the irrigation area in January and December which belonged to the dry season. Their contribution rates to basic flow were 3.5% and 4.9%, respectively.