Land Use Changes And Effects On Soil And Water Resources Of The Yellow River Delta

Land use/cover change is the frontier and hot spot in global change research,environmental effects on soil and water resources of that is one of the important content inenvironmental effect of land use changes. Soil and water resources are essential for humansurvival and development as the most basic and the most important natural resources, andthey are the bottleneck factors of land use for the regional farming, forestry, animal husbandry,etc, in the one side, soil and water resources decide the direction and pattern of land usechange, and the other side, land use changes result the distribution of spatiotemporal variation,on the basis of the unreasonable development and utilization, the deterioration of ecologicalenvironment and decline of economic effect are caused.This study was conducted in Kenli County of the Yellow River Delta using five temporalremote sensing images of1989,1995,2000,2005and2011to extract land use information ofdifferent times with object-oriented method, the different levels of salinization were studiedby building up extracting model in soil salinization, on this basis, soil quality were evaluatedusing geostatistical statistics method, soil quality comprehensive index (SQ), andsurface water were studied by constructing Modified-Combined Index for Water BodyIdentification (MCIWI), by using spatial analysis function of GIS, the influence of soilsalinization, soil quality, surface water were analysis. Main conclusions were as follows:(1) Spatiotemporal variation of main land use typesThe results showed that dry land, forest-grassland, salt wasteland and shoaly land werethe main land use types in study area, and the main characteristics of land use changes in thestudy area were the decrease of dry land and forest-grassland, and the increase of water area,salt wasteland and shoaly land. The land use changes were faster from the land use dynamicdegree at the beginning of the study, with the single land use dynamic degree, river watersurface, and water area and construction land changed more bigly comparatively. The overalldegree of land use change before2000was2-3times higher than that of the later period,which was highest in1995-2000, showing the trend of land use changes from developmentperiod to plateau. During the entire study period, the land use changed large in amplitude and more in types, there were reciprocal transformation phenomenon between various land types.(2) The salinity effect of land use changethe distribution of the different salinity levels were extracted by constructing salinityextraction index model, and the study showed the overall salinity changes were reduce the firstand increase in the later with salinity composite index. Natural and human driving factors ofsalinization were researched by using the gravity model, and found natural driving factors playedthe main function in the later, and natural driving factors were the main cause of salinity soil inthe area. The salt of land use types from low to high were: dry land, paddy field, grassland, saltwasteland.(3) The effect of soil qualityThe nutrient levels of N, P, K, organic matter in1987,2007years were achieved usinggeostatistical statistics of ARCGIS, and showed the average content of available potassiumreduced, and other nutrients increased with different degrees. From the kind of nutrientsaround the country, the content of available phosphorus and available potassium changedlargely, and showed a trend of increase and decline respectively, other nutrient contents wereincreased, but the growth were slower. The nutrient contents of forest-grassland were bothhigher; especially in total nitrogen and organic matter content, Quick-acting nutrient contentswere higher in dry land, paddy field, and content of each nutrient were lowest in saltwasteland.Soil quality comprehensive index were used in comprehensive evaluation by GIS, andfound soil quality improved obviously, rendering the trend from intermediate to advancedconvergence. The quality of land use types were increased, the area of middle and end landdecreased and the area of high quality land increased, In terms of soil quality in land use types,dry land was higher than paddy field and salt wasteland, and forest-grassland was higher thanthe dry land in1987, but lower the dry land and paddy field in2007, salt wasteland was thepoorest quality, relative to the dry land and paddy field, the quality of forest-grasslandimproved less.(4) The effect of surface waterThe density of surface water in overall or regional were calculated using the informationof surface water according to image interpretation, which showed the water density of wholeresearch area was increasing year by year, the north and coastal regions had been reduced after the increase, and opposite In central and southwestern. Modified-Combined Index forWater Body Identification (MCIWI) was accepted to analyze the condition of surface water; itshowed that the area owing general moisture occupied absolute advantage, which accountedfor between40%and44%, and the lower area was getting less and less, the artificialconstruction of reservoir and increasing breeding pits were the main cause of the change onsurface water in combination with hydrological data.The land use information extracting and space-time change were studied using thetechnology such as GIS, RS according to remote sensing images, and based on the spatialpattern of land use, the influence of land use/cover change on soil quality, salinization,surface water were researched, which provided the basis for Rational planning and utilizationto the land and water resources in Yellow River delta.