一、引言为了防洪及设置河滩貯灰场,在建设火力发电厂时,都需要修建防洪堤及貯灰场围堤。在河道上修筑这种堤防后,往往减小河道断面而引起上游水位的壅高。为了确切知道筑堤后对上游的壅水影响,可以通过河道水面曲线计算来了解壅水的情况。水面曲线计算亦称回水计算。我们在清河工程和高坎工程中,为了设计需要,先后进行了防洪堤和貯灰场围堤的回水计算。通过这两个工程在回水计算方面初步获得了一些经验,现把我们工作中应用的方法及体会加以总结,以供今后参考。二、现场踏勘与收集资料 1.现场踏勘在布置河道断面前,最好先进行现场踏勘,以便了解全河段上河槽和滩地的河床质情况、植物情况、河岸的弯曲和顺直情况、以及上下游河道有无束水建筑物和水工建筑物。同时调查历年洪水位,并了解滩 I. INTRODUCTION In order to prevent floods and set up floodplain farms, it is necessary to construct levees for flood control dike and ash yard when building thermal power plants. After the embankment is built on the river, it is often the case that the section of the river is reduced and the height of the upstream water level is raised. In order to know exactly the influence of embankment on the upper reaches of the sluice, we can understand the sluice situation by calculating the curve of the river surface. Surface curve calculation is also called backwater calculation. In the Qinghe Project and Gaokan Project, we designed the backwater calculation of embankments for flood control dike and ash yard in order to meet the design needs. Through these two projects, we have initially gained some experience in the calculation of backwater. Now we summarize the methods and experiences applied in our work for future reference. Site reconnaissance and data collection 1. Site reconnaissance It is advisable to carry out on-site reconnaissance before arranging river sections so as to understand the condition of the riverbed and beach on the whole riverbed, the condition of the plant, the bending and straightness of the riverbank, There is no water downstream of the river water structures and hydraulic structures. At the same time survey the flood level over the years, and understand the beach