Land Use Conversion And Migration Of Economy Gravity Center In The Bosten Lake Basin

Changes in land use and land cover are among the most important key issues in global change research. Land use/cover change and its effects on ecological hydrology are the important part of the environmental change research. Under the effects of global warming and human activities, the land use/cover change affecting the spatial distribution of water resources and changing the water cycle and water quality condition, moreover, it has significant impacts on the development of social economy and ecological environment. Therefore, the sustainable use and protection of water resources is prerequisite for the sustainable society development.Bosten Lake, featuring the nation’s largest freshwater lake, is where the Kaidu River ends and the Kongqi River begins. Both of them called Bosten Lake Basin. Based on land use/cover classification data derived from the Landsat TM imageries in 1990, 2000, and 2010, as well as governmental socioeconomic statistics, we investigate land use/cover change(LUCC) in the Bosten Lake Basin from 1990 to 2010.Using the technologies of remote sensing, GIS, and land use dynamic change model to reveal the spatial and temporal evolution characteristics of LUCC, discuss its driving force, and explore the migration of gravity centers of LUCC and economy. And then analyze its effects on water resources, water quality, and ecological environment. The results are as follows:(1) In the period 1990-2010, land area devoted to cultivation, residential and industry area increased, while forestland and grassland decreased. In particular, cultivated land saw significant growth as high as 67.6%.Over the designated 20-year time-span, integrated index, information entropy and balanced degree all increased in the study area. This reflects an increasing instability in the land use system as well as instability of the oasis.(2) Land use and land cover change is resulted from the interaction of natural environmental changes and human activities. The changing runoff affected by climate change plays a basic role of land use conversion, while human factors are the main driving forces of land use change. Human activity intensity index rises from 0.75 in 1990-2000 to 0.88 in 2000-2010.With the rapid increase of population density and development of economy and society, the degree of land use change will also increase. Population growth is indirectly promoting the increase of the cultivated land. With the continuous growth of population, large areas of wasteland or natural grassland are reclaimed for cultivated land. Firstly, the growth of population increases the demand of agricultural products and the per capita land in general, which results in the continuous expansion of the scale and intensity of land resources development and utilization. From the analysis of land use and land cover change, it can be drawn that the cultivated land increased continuously. Secondly, population growth also increases the demand of residential land, which leads some cultivated land into residential land.(3) The gravity center of population, GDP and the main three industries in Bosten Lake Basin show the trends of migration to southwest from northeast in the past 30 years. There is still imbalance of GDP, the second industry and population distribution, while there is little imbalance of the first industry, the third industry and population distribution. The results also show that when the gravity center of population show the trend of migration to southwest, the gravity center of economy show the trend of migration to northeast, where is the direction of the Bosten Lake Basin. It is indicated that the imbalance of economy and population is increasing.(4) The oasis agriculture has profound impact on the development of rivers, lakes and water environment in the basin. The results indicated that the drainage of water and salt in the agricultural irrigation process directly influenced the water quality in the Bosten Lake, then affected the water quality in the downstream of Kongqi River. Total phosphorus and total nitrogen is also concentrated in the agricultural areas around the river. Therefore, the development of oasis agriculture greatly promoted the agricultural chemicals. A large number of irrigation water in the upstream of Kaidu River will not only lead to the reduction of water resources, and the rapid decline in the water level of the Bosten lake, but the agricultural drainage of polluted water and salt make the freshwater lake to brackish lake.