Land use spatiotemporal changes and its driving forces analysis in vulnerable ecological region of Yellow River Estuary

The Yellow River Delta is a typical eco-environmental fragile region where land use changed intensively due to the interaction of human activities and natural environment; hence, it is a hot spot area for land use and land cover change (LUCC) research. This study was conducted in Kenli county of the Yellow River Estuary using five temporal remote sensing images of 1989, 1995, 2000, 2005 and 2011 to extract land use information of different times. Land use temporal and spatial characteristics in more than 20 years of the study area were analyzed using land use dynamic degree model, land use degree composite index model and land use gravity center transfer model, and their driving factors were further explored. The results showed that the main characteristics of land use changes in the study area were that the dry land and forest-grassland were decreased, and the construction land, water area, salt wasteland and shoaly land were increased. The overall degree of land use changes before 2000 was 2-3 times higher than that of the later period, which indicated that the trend of changes was rapid before 2000 and slow after that. The single land use dynamic degree of river water surface, water area and construction land was comparatively distinct. The land use spatial pattern appeared obvious features in distribution with regular variation. Within the studied time period, the gravity center of dry land, salt wasteland, paddy fields and construction land all moved to the southwest, while the gravity center of forest-grassland, the river water surface and shoaly land moved to northwest, and that of water area turned to the southwest with little changes in distribution as a whole. Driving forces of land use changes in the study area included two aspects of natural and human related factors. The climatic and hydrological factors including high ratio of evaporation to rainfall, sandy soil texture, shallow ground water with high salinity, and cutoff of the Yellow River were the dominant natural driving forces for land use changes, and unreasonable farming exploitative activities of local people were the main artificial driving forces. This study provides a reference for the utilization and protection of resources and environment, and sustainable development of society and economy in the vulnerable ecological region of the Yellow River Estuary.