Research Of Land Use Change And Its Impact On Surface Runoff Of Songhua River Of The Harbin Section

With the rapid development of social economy of Songhua River basin, water environmental problems are becoming more and more serious. The study of land use change and its impacts on the surface runoff is of great significance to the sustainable development of social economy, the sustainable use of water and soil resources, the optimal allocation of water and land resources, and the protection of ecological environment. Firstly, through interpretating remote sensing images of the study area of Songhua River in Harbin in 2006, 2010, 2014, concluding the land use data, to analyse land use change and driving factors;Then, using the SCS-CN hydrological model to simulate the annual runoff, to analyse the influence of land use change on surface runoff; And analysing the correlation between the land use type percentage of different scales buffer area and water quality, to analyse the influence of land use change on surface runoff water quality.The results of land use change and driving factors analysis showed that:(1) The land use degree of the study area was in the period of development during 2006 to 2014.(2)During 2006 to 2014, the area percentage change of land use types were: the dry farmland area percentage decreased 10.69%; the building area percentage increased 5.77%; the forest area percentage increased 2.73%; the grassland area percentage increased by 0.69%; the unused area percentage decreased 0.43%. However, the paddy field area showed a trend of increase during 2006 to 2010, and showed a trend of decrease during 2010 to 2014.(3)The amount of cultivated land was mainly transferred to the land, the building land and forest land were mainly transferred to the quantity, and the other land use types were more complex.(4) The change of land use in the study area were mainly affected by natural factors, population factors, economic factors.The results of the impacts of land use change on surface runoff showed that:(1) The study area land use types annual flow capacity, from the time, 2010 >2006 >2014; from the space, the northern area > the southern area> the central area.(2) During 2006 to 2014, the contribution of annual flow rate on land use types in descending order: farmland, building land, forest, water, unused land, grassland.(3) The contribution rate of land use types in the study area was closely related to the proportion of the area.The results of the impacts of land use change on water quality showed that:(1) Overall, in 2010 and 2014, there was a positively correlated relationship between water ? grass and DO, and there was a negative correlation relationship between other land use types and DO;(2) There was a negative correlation relationship between water? forest?grassland and CODMn?BOD5?CODCr?NH3-N?TP?TN, indicating that the forest, grassland had the effect to improve the water quality;(3) There was a positively correlated relationship between farmland and CODmn?BOD5?CODcr?NH3-N?TP?TN, indicating that the surface runoff water quality in the study area mainly for non-point source pollution, and pollution influence coefficient decreases with the increase of buffer distance.(4) From the regression coefficient, farmland impacted on water quality:the frozen season > the wet season > the dry season.