Land Use Features In Qiantang River Watershed, Zhejiang Province

Land use is the integrative reflection of human activities on land. To some extent, theland use types and intensity reflects the process of human activities on nature ecosystem.Limited by the total supply amount of regional land resources, terrain factor determinesthe basic distribution pattern of land use. However, soil is an important resource whichguarantees the human beings could access to material wealth.The land use development is largely influenced by the natural factors, such aslandform, soil types, and so on. With the global environment of deteriorating ecosystemand increasing the contradictions between human being and land resources, it isimportant to understand the suitability of regional terrain conditions and the characteristicsof soil types correctly, as well as study the spatial distribution of different land use typeson the terrain grads and soil types.In this paper, Qiantang River Watershed (QRW) was chosen as the study area toextract the relative elevation, slope gradient and slope aspect from Digital Elevation Model(DEM) for calculating the distribution indexes of different land use types. The distributionmap, soil map and land use map are overlapped for spatial analyze the mutual relationships. After finding the problems existed in land use of QRW, some land usemeasures are proposed to optimize allocation of soil resources and offer usefulinformation for intensive use of land.The leading conclusions of this dissertation can be seen as follows:1. Regional land use/cover classification in QRW with a stratified andregionalized approachIn land use/land cover classification, it is usually difficult to obtain satisfied resultsusing routine approaches in large-scale and diversed areas. A stratified and regionalizedsupervised classification (the Maximum Likelihood Classification) approach wasintroduced. With this approach, water and mountain areas were first stratified andextracted through a set of equations that were used to compute parameters from LandsatTM bands. Subsequently, by using mask method, we obtained plains and foothills, whichwere subdivided into six sub-regions according to the geomorphic features and landuse/cover characters. Additionally, the plains and foothills should be classified separatelyin the case the images were acquired at different seasons. The supervised classificationcould be carried out after respective signatures in every region were identified. Theclassification accuracy reached 90.7% with a Kappa coefficient of 0.881, which was muchhigher than that obtained from routine classification approach, which had a classificationaccuracy of 51.6% and a Kappa coefficient of 0.411. This study showed that the stratifiedand regionalized approach was very efficient in land use/cover classification in a broadregion, such as watershed level in southern China.2. Relationship between landform and land use/coverTerrain has great influence on Land use pattern, which is determined by naturalconditions, such as light, temperature, water, nutrients and so on. Human activities onland use are largely affected by elevation, slope gradient and slope aspect. Therefore,basic elevations of every landform are confirmed by analyzing QRW topography. With thehelp of remote sensing and GIS, relative elevation, slope gradient and slope aspect areobtained from DEM. The distribution indexes of different land use types in QRW are calculated in order to find the relationship with land use/cover.2. Relationship between soil types and land use/coverLimited by the total supply amount of regional land resources, soil is an importantresource which guarantees the human beings could access to material wealth. As the soilis greatly affected by natural conditions and human activities, QRW has great regionaldistributions. The natural conditions include terrain, climate, soil parent materials, andhydrogeology. However, human activities on land are determined by soil texture andphysical-chemical properties. The land use distribution on different soil types can beobtained by overlapping soil map and land use map. The relationship between soil typesand land use/cover in QRW can provide a scientific basis for better using of regional land,maintaining soil fertility and preventing land degradation.4. Reasonable distribution of land useBased on analyzing the problems of land use distribution in QRW, it is important tounderstand the suitability of regional terrain conditions and the characteristics of soil typescorrectly, as well as study the spatial distribution of different land use types on the terraingrads and soil types. With different landform in watershed, human activities on landresources should comply with elevation, slope gradient and slope aspect. As for thedifferences of soil parent material, soil texture and physical-chemical properties, it isimportant to optimizing soil and increasing fertilities as well as using soil resources. It canoptimize land use distribution and fully extract the potential of land resources with cyclereunification of "soil utilization, soil conservation and soil fertilization". With thedevelopment of precision agriculture in plains, it can reduce build-up land on Paddy soil.In foothills, it can be developed into a complex ecosystem of woodland and orchard toachieve best ecological, economic and environmental effects.