梯级水库水温影响的极限

The limit of water temperature influence of cascade reservoir

水库的修建给防洪、发电、灌溉、供水等带来巨大经济效益的同时,也对环境产生一定的影响,尤其是水库泄流对下游河道水温的改变,扰乱下游动、植物繁殖与生长的自然节律,而梯级水库无疑将这一影响进行了放大。为研究水库梯级修建对水温的极限影响,构建了虚拟水库Alpha,并使Alpha水库首尾相连无限叠加,采用宽度平均的立面二维数学模型CE-QUAL-W2对梯级水库水温进行模拟。结果表明:河流梯级开发带来的水温累积影响存在极限,梯级开发使水温分层现象极大地弱化,但库区分层结构不会消失;经过22个梯级调节,水库下泄水温相对来流水温不再变化,在同一时刻、同一位置无论是表层水温还是库底水温均与上游梯级相同,库区流场也与上游流场相同;水库水温累积影响达到极限表明入流热量、出流热量完全达到平衡。

The construction of reservoirs has a certain impact on the environment while bringing great economic benefits to flood control,power generation,irrigation and water supply. In particular,the water temperature of the downstream river is changed by the discharge of reservoirs,which disturbs the natural rhythm of swimming,plant reproduction and growth,while the cascade reservoir undoubtedly magnified this effect. In order to study the limited effect of reservoir cascade construction on water temperature,the virtual reservoir Alpha was constructed,and the Alpha reservoir was connected infinitely with the first and last ends,and then the water temperature of the cascade reservoir was simulated by the two-dimensional mathematical model CE-QUAL-W2 with the average width. The results show that the cumulative impact of water temperature brought by the cascade development of river is limited,and the cascade temperature has greatly weakened the water temperature stratification phenomenon,but the hierarchical structure of the reservoir will not disappear;after the adjustment of 22 cascades,the discharge temperature of the reservoir does not change relative to the temperature of incoming water,both the water temperature on the surface and bottom of the reservoir are the same as those of the upstream cascade,and the flow field of the reservoir area is also the same as the upstream flow field;when the cumulative impact of water temperature in the reservoir reaches the limit,it indicates that the heat of the inflow and outflow reaches the equilibrium completely.