Spatial structure and fractal model of land use in Qingjian river basin of middle Yellow River

In order to reveal the spatial differences and the change course of land use in the middle reaches of the Yellow River, taking the Qingjian River area in the middle reaches of the Yellow River as the case, the spatial evolution of the land use was analyzed through the land use gravity center migration theory and fractal theory, and the fractal structure model of sorted land spatial distribution pattern was built based on RS and GIS technology. The results showed that land-use focus migrated significantly from 1990 to 2009 in Qingjian River area. The gravity center of farm land and water migrated towards the southwest, and migration of water gravity towards the direction reached 7205.85 meters. Forest, construction land and unused land gravitated towards the southeast, and the focus of construction land migrated in the direction most, reaching 7421.89 meters. The focus of grassland moved 3546.38 meters to the northwest. During 1990-2009, the land fractal dimension of land use types decreased except water area, which indicated that the complexity of landscape types reduced in the region and the stability increased. Natural factors played a promoting role in the land use spatial variation; however it is human disturbance that played the main driving role. The article provides a scientific basis for reasonable land use plan and intensive land use in ecological restoration areas.