Environmental Effects Of Land Use/Cover Change In The Middle Reaches Of Heihe Basin

Land use and land cover change is an important research field in global change research. Nowadays the environment problems which we faced is concerning with LUCC. Middle reaches of Heihe basin is located at the inner drought area in north-west of China which is environment sensitivity and ecological fragility. Working at LUCC-related issues at study area is important for the ecological balance and sustainable development of the Heihe basin.Based on the reviewing works both domestic and abroad, that is concerning with the interaction between LUCC and environmental impacts, its mechanism, patterns, and characteristics. On the basis of the spatial analysis module of GIS and mathematics models of land use chang, study the LUCC of the middle reaches of Heihe basin both at time and space. Through qualitative and quantitative analysis, study the natural and human factors that affect LUCC, which can provide a reference for optimal allocation of land use. Quantitative study of land use/cover changes in the eco-environmental effects including on hydrological systems, soil systems, ecosystems, etc. Evaluated the ecological sustainability of the whole region and put forward the feasibility recommendations.Characteristics of land-use change: during the 25 years from 1981 to 2006, Agricultural land, grassland, water area has decreased, construction land, forest land and unused land increased. Changes in spatial is that: centre of agricultural land, forest land, grassland, water area, construction land, unused land moved at varying degrees. Change of LUCC in south of study area is higher than north part.Driving force of land-use change: in a short period of time, the main factors of the impact of LUCC is social-economic factors, contribution of Socio-economic factors for LUCC is 74.6579%。The non-parametric Mann-kendall trend test and Mann-kendall abrupt change test were used to identify trend and change points in the annual runoff. Evaluated the impacts of climate variability and human activities on mean annual runoff based on precipitation and evaporation, the result showed that, in the recent 20 years human activities are the main factors that affected the runoff of middle reaches of Heihe river。Desertification of agricultural oasis in the middle reaches is strong, land desertification of oasis edge is 5.6×10~4hm~2 , strongly land desertification is 227.2hm~2,seriously land desertification is 182.4hm~2。The value of ecosystem services had decreased from529614.5×10~4yuan to 511822.5×10~4yuan。As a whole, the value of ecosystem services had decreased during the past 20 years, and the eco-environment deteriorated furtherly.