Multi-levels Long-Narrow Lake Flood Routing Modeling

Abstract

Nansi Lake,as a long-narrow lake,has the same features as those of rivers during flood routing.According to topographical and hydrological conditions of Nansi Lake,aided by DEM and remote sensing images of the study areas,combining field investigation and survey,several factors are generalized including boundaries of lake region,river centerlines,river trunk lines,flow pathway lines,no-effective flow regions and river cross section lines.The regions with fish ponds and densely covered by water plants are considered as no-effective flow regions.A coupled method to divide computed unit is adopted by topological generalization method under the multi-levels topological conditions.Flood routing models are built separately for the upper lake and the lower lake divided by the second-level dam constructed at the middle part of Nansi Lake,with individual topological relations,applying the method of comprehensive roughness.The models are tested and simulated by three actual floods in the past,the results manifest that it is feasible and effective to consider Nansi Lake as a river to build 1-D flood routing models.