渭河干流生态环境需水量的动态计算

Dynamic calculation of ecological water demand by the Wei river

将生态环境需水量分为输沙、河流稀释自净和基本生态环境需水三个组成部分,提出了综合考虑年际、年内及河道空间变化分区的生态需水计算模型以满足渭河干流水资源开发利用特征。研究表明,渭河河道生态环境需水量与输沙及稀释自净需水量关系密切,汛期以输沙需水为主,非汛期以稀释自净需水为主;输沙需水量年内变化明显,汛期占到了全年的67%;受沿程流量、排污和泥沙冲淤形势的影响,渭河干流自上而下生态环境需水量逐渐增大,中水年分区最大需水量达35.1亿m3。该方法适用于水量年内分配不均,自然条件及河流沿程开发利用变化程度较大的河流。计算出的生态需水量具有动态可操作性,可用于指导渭河干流水量分配与水资源管理。

This paper puts forward a dynamic ecological water demand method for a river system of great variations in its main channel under hydrological conditions of annual and seasonal variations, including three calculations, i.e. sediment transport, diluting and self-cleaning, and fundamental ecological water demand. This method adopts corresponding algorithms developed for three calculations, and it has been applied to the Wei River in Shaanxi province. The results indicate that the ecological water demand by this river much depends on runoff, discharge capacity, and sediment erosion and deposition, and it is dominated by the demand by sediment transport in flood season and the demand by diluting and self-cleaning in the other seasons. Our analysis reveals a general tendency of water demand increasing from the upper to the lower reaches, with the maximum demand of 3.5 × 10^9m3 over the reach studied. The proposed method is useful for water allocation and management of a river system.