Research Of Rainfall-rainoff In Wenzhou Area

In this paper, we selected 82 hydrologic stations and 8 weather stations inWenzhou that had 11 years daily precipitation data from 1991 to 2000, used daily runoff data from 1999 to 2000 of Feiyunjiang catchment basin in Wenzhou and a Wenzhou DEM map with a scale of 1:25000. With the aid of GIS, we made spatial extension research of 11 yeas' each month's climate mean precipitation from 1991-2000 in Wenzhou.We not only fully made use of hydrologic data and weather data but also drew the conclusion that 50 stations were enough to set up area precipitation rainfall interpolate net to Wenzhou. We also found different interpolate method had marked effect on the result. Through a great deal of work, we considered inverse distance weighted method was better to Wenzhou.So we took Feiyunjiang catchment basin as research object, set up rainfall-rainoff relation of this basin. We applied those rainfall-rainoff relation formulas to the whole Wenzhou area, and gained flat surface flow-off deepnees distributing map of 100m 100m grid in Wenzhou.With the aid of GIS, we computed spatial distributing of topographic index and grade in Wenzhou. After computing grade, through statistic, we found flow-off deepnees and grade had exponential relation. When precipitation rainfall is of the same quantity, the area there is steep grade is easier to give birth to runoff than where is flat grade. Appling this idea, we set up exponential relation between runoff deepness and grade. Finally we gained terrain surface flow-off deepnees distributing of 100m 100m grid in Wenzhou.