利用遥感与GIS对农田损失的监测及定量评价方法——以东莞市为例

INTEGRATION OF REMOTE SENSING AND GIS FOR MONITORING AND EVALUATING AGRICULTURAL LAND LOSS——A CASE STUDY OF DONGGUAN

珠江三角洲近年来经济呈现高速增长，但同时也存在着一系列环境问题。其中相当数量的农田被推平当成城市用地。本文以珠江三角洲发展最快的城市为例，利用多时相遥感图像分类方法，发现该市在１９８８年～１９９３年之间共损失２１２８５．７ｈｍ２（占总面积１０．４％）农田。利用ＧＩＳ方法，在土地资源评价的基础上，分析了该市农田损失对农业的影响。利用熵计算了土地开发的分散度，并提出了属性损失的定量指标。

This paper focuses on the monitoring and evaluation of agricultural land loss with the integration of remote sensing and GIS techniques. Firstly, the research provides a method for land use change detection to avoid the over estimation of land use change in the classification of multi date remote sensing images. Over estimation of land use change frequently happens in the classification of remote sensing images because of the inadequate creation of classification signatures. The method can clarify some untrue land use changes obtained from conventional detection methods. This presents a quantitative method to analyze land loss based on more an ‘objective’ approach. The dynamic of landscape can be vividly captured and stored using the detection technique. The results of the detection reveal a fast urban growth pattern of Dongguan since the economic reform. The evaluation of the impacts of agricultural land loss is necessary for urban planning and policy making to resolve the intense land use conflicts in recent China. An evaluation system is provided with the integration of remote sensing and GIS in assessing agricultural land loss. The evaluation is mainly based on the concept of suitability loss, which is developed for the measurement of the impacts of land loss. The evaluation system consists of land development monitoring, land evaluation and GIS overlay analysis. The approach demonstrates that the indicator AREA (the total amount of land loss) is inadequate to identify the complete influences of agricultural land loss. It is illustrated that the indicator I loss , which integrates the spatial integrity of land development and land quality, is more adequate than the indicator AREA to address the impacts of land loss. If used, the indicator AREA will lead to the false perception of agricultural land loss because of the negligence of land quality. This research shows that the proposed indicator I loss can be easily applied in the GIS environment.