Study on Variation Law of Backwater Length in Reservoir Area by Numerical Model

Based on theoretical analysis of backwater length in reservoir area,a 2-D numerical model is developed to simulate the phenomena of backwater length′s fluctuation of a simple example to demonstrate the validity of analytic theory of backwater length,and perform comparative studies on influential factors of backwater length as well.The results indicate that in general there is an extreme value in the range of backwater length variation.Criterion for the terminal of backwater may have effect not only on backwater length,but also on the rule of backwater length′s fluctuation with discharge.More accurate criterion for the terminal of backwater will get a greater extreme value of backwater length;while rough criterion for the terminal backwater may lead extreme value in the range of backwater length variation to vanish.Traditional knowledge about the rule of backwater length variation is reasonable,which is a special case of analytic solution to backwater length.