水体交换周期模型的修正及其在黄河上游的应用

在考虑水体入流和出流不等的条件下,提出了水体交换周期的计算模型和相应的数值算法.并选取黄河上游兰州-下河沿、下河沿-石嘴山、石嘴山-头道拐三河段,在天然径流状态下和有水库调节作用下分汛期和非汛期分别计算了历年各河段水体的交换周期.结果表明:(1)在天然径流状态下,三河段非汛期历年的交换周期几乎均长于相应汛期的交换周期,而在水库调蓄作用下,则没有表现出这一特点;(2)无论汛期还是非汛期,在水库的径流调节作用下各河段水体的交换周期普遍长于天然径流状态下的交换周期,即水库的径流调节作用使得下游河段水体的交换周期普遍延长,从而减缓了该河段的水量循环速率,对相应河段的水资源的可再生量产生了制约作用.

Revised exchange period model of water bodies and its application in the upper stream of the Yellow River

The water renewal is the basic aspect of water cycle and water balance.On the condition that the water inflow velocity is not equal to the water outflow velocity,a revised exchange period model for water bodies and its numerical algorithm are set up.A case study of the three reaches of the upper reach of the Yellow River is made,including Lanzhou-Xiaheyan,Xiaheyan-Shizuishan and Shizuishan-Toudaoguai,to demonstrate the water exchange period in each reach in the natural flow situation and the reservoir regulation in the past years during the flood season and non-flood season.The results are as follows:(1) In the natural flow condition,the exchange period of three reaches during the non-flood season in the past years is longer than that in the flood season in the corresponding time.But it is not same in the condition of reservoir regulation.(2)The water exchange period of each reach in the condition of the reservoir regulation is longer than that in the natural flow condition in either the flood season or the non-flood season;it means the reservoir regulation prolongs the water exchange period in the lower reaches,slows down its cycle velocity of water quantity,and restricts the water renewal quantity of the correspond reaches.