Research on Variable Eco-Environmental Water Demand and Its Application to the Weihe River

摘要

Ecological water was stolen by industrial and domestic water consumption in the Weihe River, which led to a disquieting decline in riverine ecologic functioning. Based on river regionalization and typical years of hydrologic frequency analysis, a variable eco-environmental water demand (EEWD) calculation method was put forward with a monthly runoff process against its traditional fixed volume. The main stream of the Weihe River in Shaanxi Province was regionalized into seven zones in accordance with the location of gauging stations, boundary of administrative districts, and desirable target of water qualities by water function regionalization; typical years with hydrologic frequencies of 25, 50, 75, and 95% were introduced to take annual variation into account, so as to meet the hydrologic characteristics of the river. In addition, the monthly process was suggested to reflect the seasonal change of EEWD. In this study, EEWD was divided into three parts: water demand for sediment transport, diluting and self-cleaning, and basic ecological water demand according to the major problems with the Weihe River. The results showed that EEWD had obvious annual and seasonal variation at time scale, while it tended to increase from upstream to downstream, with the maximum value being 4,570 M㎥/a. The EEWD showed a strong relationship with runoff, sewage discharge, and sediment erosion and deposition status. The method used herein provided a credible scientific basis for estimating EEWD on the river with serious annual and seasonal hydrologic variation and with great changes along the river, which proposed a significant reference to rivers with similar situations to the Weihe.