Driving Forces of Land Use Change/Cover in the Yellow River Delta
黄河三角洲土地利用/覆盖变化驱动力分析

The driving forces of land use and land cover change(LUCC) is one of the main issues for LUCC research.The land use and land cover changes are driven by natural and social-economical factors,but social-economical factors are determinative in the local and short time scale.In this paper,land use and land cover data of the Yellow River Delta derived from remote sensing data or GIS coverage in 1984,1986,1991,1996 and 2001 are used.As a whole,the area of land increased in the Yellow River Delta from 1984 to 2001.The largest area of land use types is dry land and wasteland.The dry land area is more than 30%,and waste land is more than 20%.The most frequent land use change types are changes between arable land and wasteland.The changes between wasteland and vegetation land and between vegetation land and arable land are also rapid.Based on the analysis of the characters of the LUCC of the Yellow River Delta,the determinative driving forces of LUCC were discussed.With its high sediment contents in the Yellow River,the coastal line in the present estuary extended to the ocean.In the old course estuary,because of ocean dynamic effect and the lack of sediment,the coastal line was eroded.When the extended area is larger than that of erosion,the land area of the delta increased,in which the main changes happened between tidal land and ocean.Due to the asymmetrical spatial and temporal distribution of freshwater,especially the break-off water discharge in the Yellow River channel,the area of inland water increased much from 1991.Land reclamation and extensive cultivation are the determinative factors for the frequent change between arable land and wasteland,which led to the large agriculture scale in one hand,and also led to land degradation in the other hand.Population increase,especially non-agricultural population increase,led to the residential area increased.Agriculture is the dominant industry in the Yellow River Delta.There was a negative correlation between arable land and farming output value,and a significant negative correlation between shrub-grass land and animal husbandry output value,while an extremely significant positive correlation existing between inland water area and fishery output value.So agricultural benefit has much effect on land use changes among arable land,vegetation land,inland water and wasteland.The Yellow River runoff and sand-transportation is the base for delta evolution.Because of the large irrigation works in the upriver of the Yellow River,the area of the whole Yellow River Delta will be in a dynamic balance and keep stable in the future.To keep sustainable development,the area ratio of water and land must be increased under the condition of natural factors,land reclamation and cultivation must be rationalized,and shrubbery and grassland must be greatly developed and protected.