Feature Of Land Surface Changes And Statistical Analysis Of Its Effect On Floods In Haihe River Basin

As the development of economy and society and growth of population, the trend that mankind activities change the underlying surface becomes more and more obvious in many river basins. Land-use transformation activities not only change some nature of land-cover, but also have a significant impact on the production, conversion and space-time configuration of water resources, which affected the runoff generating and flood process. If these changes are ignored in hydrology calculation and construction of flood control projects, the results will have a certain bias. So analyzing the effects of land-use and land-cover change on flood in Haihe river basin could provide some reference to flood control and hydrological data consistency correction. Daqinghe river basin is selected as the study areas in this paper, the main contents and results are as follows:(1) Identify the factors that affect both flood peak and flood volume and collect the data.In the help of DEM and land-use remote sensing dates provided by Chinese Acedemy of Science, the land-use condition, area and average slope of five typical watersheds in 1970, 1980 and 1990 are extracted. Rainfall and runoff data is extracted from 1956 to 2005, including: total rainfall, antecedent precipitation index (API), maximum 1 hour rainfall, and maximum 3 hour rainfall and runoff depth. Flood level index system is established and flood is divided into greater than 10 years and less than 10 years.(2) Flood characteristics trend analysis and climate factors impact analysis. According to the historical data,moving average method and the Kendall rank correlation test method are used to analysis the trend of the flood peak and flood volume. Meanwhile, rainfall runoff correlation method and rainfall peak correlation are used to analysis the influence ratio which rainfall have on the peak, and lay basis for the further research on influence which underlying surface factors have on flood peak and flood volume.(3) Multivariate statistical analysis of flood characteristics and influence factor. According to the data of flood characteristics and influencing factors, multivariate equations are established between flood peak, flood volume and influencing factors. The model mainly adopts linear regression, principal component regression and nonlinear regression method. By analyzing the actual change situation of surface indicators, try to conclude influence ratio which the underlying surface changes have on flood.