Comparative Study on LUCC and CLID of Zhangjiagang, Hanoi and Dehradun in the developing countries of Asia-Pacific region: A real challenge to food security

Three cities with different degrees of urbanization in developing countries of Asia-Pacific region are selected as the study areas, They are Zhangjiagang city in China, Dehradun in India and Hanoi in Vietnam. In this paper, data was collected concluding nearly a decade of remote sensing data, population, economic data and other relevant information. We studied land-use and land-cover change (LUCC) and cultivated land instability degree (CLID) of three cities by the means of spatial analysis and CA model analysis supported by the 3S technology. The results show that: All three cities have significant land use/land cover (LULC) changes under the background of urbanization over the past decade, mainly in the increase of urban land and reduction of agricultural land. The changes of Dehradun is the greatest, Hanoi second, and Zhangjiagang city is the smallest; The CLID value shows the pressure size of transformation for the cultivated land in Zhangjiagang, Dehradun and Hanoi. Among three cities, the pressure of cultivated land in Dehradun is the greatest. Hanoi is the second, the minimum is Zhangjiagang. Facing the changes, rapid urbanization is increasing the risk of food security. Local government should make positive policy to the challenge of decreasing availability of cultivated land and offer unremitting efforts towards the goal of food security.