水库下游河道水温沿程分布的解析解及与其他方法的比较

在考虑沿流向的温度梯度、假设河流水面热交换通量沿程恒定的基础上,根据河道一维水温控制方程推导出解析解,并与国内常用的一种河道水温计算解析解的简化解法作了较详细的对比。结果表明,基于热交换通量沿程恒定的解析解具有较高的精度,能较好地模拟水库下游河道水温复温过程。以安徽白莲崖水库为例,在预测白莲崖水库水温结构的基础上,利用推导的解析解对白莲崖水库下游河道水温沿程分布进行了预测,并分析了水库下游河道水温对周围环境的影响:白莲崖水库下游河道长期处于低温环境,河水不适于浇灌两岸的农作物,对鱼类生长、繁殖也产生一定的不利影响,需将其他温度适宜的水源输至农田进行灌溉,适合鱼类生长、产卵的场所将向下游推移。

Analytical solution of water temperature distribution in river downstream of reservoir and comparison with another method

With consideration of the temperature gradient in the flow direction, an analytical solution was deduced using a one-dimensional water temperature control equation, based on the assumption that the heat exchange over a unit surface area is constant along the river. This method was compared in detail with a simplified model for computing river temperature, which is commonly used in China. The results show that the deduced analytical solution had high accuracy, and could well simulate the temperature recovery process in the river downstream of the reservoir. A case study was conducted in the Bailianya Reservoir. Based on prediction of the water temperature structure of the Bailianya Reservoir, the deduced analytical solution was used to predict the water temperature distribution in the lower reach of the Bailianya Reservoir, and the influences of the water temperature distribution on the reservoir＇ s surrounding environment were analyzed. There has been a low temperature in the lower reach of the Bailianya Reservoir, where the water is unsuitable for irrigation of crops on both banks and for growth and propagation of fish. It is necessary to transfer suitable water to the croplands for irrigation. The region that is suitable for growth and propagation of fish needs to be moved downstream.