Effects Of Urban Landscape Pattern And Configuration On Rainfall Runoff

With the rapid development of urbanization, the land surface features in built-up regions were directly changed, causing great changes of hydrological conditions, Knowledge of the relationship between surface runoff and urban landscape becomes extremely crucial in preventing city flooding and enhancing rainwater harvesting. In this paper, the author made full use of the artificial rainfall stimulator and the city underlying surface simulation technology to simulate the process of the rainfall-runoff under the various underlying surface and rainfall intensity, and then discussed and analyzed the process of rainfall-runoff in different kinds of experiment plot, the main conclusion of study cover several points:(1) Both the rainfall intensity and the underlying surface condition have significant impact on the rainfall- runoff process. The bigger the rain intensity, the shorter the runoff time, the greater the runoff, the smaller the runoff reduction rate; the better permeability of the underlying surface, the longer the runoff time.(2) Under the same rainfall intensity, the difference of rainfall runoff process between different underlying surface types was significant. Performance in the runoff producing time is impervious surface <bare land < permeable brick < grass; Runoff volume and the runoff producing time is different which is showed as impervious surface > bare land > grassland > water permeable brick. Different kinds of underlying surface in unit time of runoff with rainfall duration trend has obvious differences, after producing runoff, the rate of runoff on impervious surface is faster than bare land and grass. for the permeable brick, under the lower rainfall intensity, both the rate of runoff a nd the total runoff are lower than the other three types of underlying surface, It shows that it has a very good effect on reducing runoff, but the opposite is the case under higher rainfall intensity.(3) Under the condition of the same rainfall intensity, different impervious surface distribution patterns are different in the process of rainfall runoff. For Initial runoff time, Impervious surface in the lower < Impervious surface in the middle < Impervious surface in the upper. But for the stable time of runoff, which is showed that Impervious surface in the middle< Impervious surface in the lower < Impervious surface in the upper. In the initial production flow. The difference of the rate of runoff under impervious surface distribution patterns is bigger, the initial production flow for Impervious surface in the middle is more than that of Impervious surface in the lower and Impervious surface in the upper. But the three different kinds of impervious distribution pattern has no significant difference in stable runoff, but still showed Impervious surface in the middle< Impervious surface in the lower< Impervious surface in the upper.(4) Different distribution patterns of grassland have different effects on the reduction of rainfall. Runoff time for bare land is the shortest, but the yield is the highest. But for the surface covered with grass, the runoff time obviously lags and the runoff is less, which shows a better reduction effect than bare land. Different grassland distribution patterns under the same coverage conditions has different reduction effect. When the surface is covered by the bare grass aggregated distribution, the runoff time is longer than that of the uniform distribution of bare land and grassland, and in the small and short duratio n rainfall events, the bare grass aggregated distribution’s outlet has no runoff which shows that it has a better effect of reducing.