Effect Of Land Use/Cover Change Research On The Formation Of Sanchuanhe River Basin Flood In Gedong

Shanxi province is located in North West of the Loess Plateau,complex terrain conditions,the uneven distribution of rainfall,and human activities have led to dramatic changes in land use / cover,resulting in fragile ecological environment and flood disasters have occurred,seriously restricting the sustainable development of social economy.Therefore,according to the characteristics of Shanxi Province,the effects of land use / cover change form in all aspects of the flood,carried out in the context of flood forecasting,it is of great significance to assess its impact on flood forecasting.This paper takes Shanxi province Lvliang City West Sanchuanhe River a tributary of the Beichuan river basin above Gedong hydrological station as the research object,using the remote sensing data of 1987-2016 years Gedong watershed land use / cover change characteristics;using linear regression analysis,accumulative anomaly analysis and Mann-Kendall test method of rainstorm and flood data of Gedong basin 1965-2011 years of trend analysis;using the HECHMS distributed hydrological model of Gedong basin during 1965-2011 years the biggest rainstorm flood simulation and sensitivity analysis of parameters;discusses the land use / cover change effects on the parameters of runoff yield and flow concentration basins.Show that the remote sensing interpretation of 1987,1990,2003,Gedong in 2007,2011 and 2016,the land use / cover change data:(1)the study area 1987-2016 land use types had different degree of change,increase the land area of cultivated land,woodland,grassland,construction,water area and unused land area reduced terrace area,basically unchanged;(2)2003-2007 years of comprehensive land use change rate to a maximum of 4% years 2007-2016 years,the transformation of land use quickly,but because of all kinds of land transfer area changed little,causing all kinds of land net variation is relatively small;(3)the normalized difference vegetation index during 1987-2016,decreased the rise,the overall upward trend,and the average and the changes of land use type was positively correlated.Through the Gedong valley from 1965 to 2011 years of storm flood data analysis shows that:(1)the period of rainfall and rainfall intensity of Gedong basin showed a trend of first increasing then decreasing,the change trend is not significant,the distribution of rainstorm is transferred to the upper end of the trend in the space,the rainstorm occurred in 1999,the mutation point in 2001 and 2004 the rainstorm intensity,point mutation occurred in 2002,2004 and 2010;(2)the period Gedong watershed peak flow and runoff depth decreased,the change trend of significant flood,uneven distribution of the flood occurred in 60 s,seventy to 90 s to flood,flood peak discharge point mutation occurred in 2000 the runoff mutation occurred in 1992;(3)similar to rainfall and similar rainfall intensity peak flow and runoff in the cover increased after decreased rainfall From 30 to 40 mm,the rainfall intensity is from 5 to 6mm/h.The change of the underlying surface condition is the biggest to the flood peak discharge and the runoff depth attenuation.The use of HEC-HMS hydrological model(runoff loss by Green-Ampt method,using the SCS unit of the overland flow line,base flow calculated by the regression method of base flow,channel flow by Muskingum method for calculation of Gedong basin,1965-2011)over the years the biggest storm flood data were simulated,the qualified rate is 75.68%,indicated that the hydrological flood disasters forecast the model is suitable for GE Dong basin,prediction can be applied to guide the flood disaster.Linear regression method was used to investigate the relationship between land use / cover change and runoff parameters,establishes a linear relationship between the amount of canopy interception I and leaf area index,surface interception W,soil infiltration rate and the linear relationship between the type of land use is the linear relationship between the lag time of watershed Lag and Time the roughness and slope are given,at the significance level a =0.05 condition,the regression equation was significant.The results of the study will be effective use of the strategy of ecological construction flood warning,arid and semi-arid areas in North China and the reasonable adjustment of water resources and reasonable regulation,has important significance to realize the harmonious development of regional social economy and nature.