Influence of Beach Between Yi River and Luo River on the Two River Floods into the Yellow River

Flood storage effect in the beach between Yi river and Luo river is different from natural condition because of the dykes of the two rivers. It has not only the effect of deducting flood peak and retenting flood but also a little decrease of the volume of floods into the Yellow River. The efficiency of flood storage by the beach area are various according to the dyke construction standard and river condition in different periods. Based on the analysis of flood data of 1935, 1937, 1954, 1958 and 1982, the flood storage effect is related to flood volume, flood process, intensity of dyke break and others. Under the current situation of river dykes, the beach area is estimated to reach 20%～25% of flood peak deduction rate for the same flood pattern of 1954 and 1958 if the beach area and southern flood retention area is effectively planed and used, but there will be little flood storage effect for total flood amount since there is limited storage for flood in the beach area.