Process of Land Use/ Land Cover Change in the Oasis of Arid Region
干旱区绿洲土地利用与覆被变化过程

Using remote sensing imagery data of 1978, 1987 and 1998, and tak in g the typical oasis in alluvial-diluvial fan/alluvial-plain type in Sango ng River basin as the study area, the process and trend of oasis LU CC are analyzed by applying the methods of remote sensing (RS), geograp hic information system (GIS) and statistics. The main results of oasis LUCC in Sangong River basin are as follows. (1) RS and GIS are powerful techniques and m ethods in capturing oasis LUCC data and analyzing its spatial change. ( 2) Establishing mathematical models in the range, speed, regional diffe rences and trend index of LUCC, especially the model of LUCC trend and s tate, the process and trend of oasis LUCC can be deeply studied, including bi-direction process, single-direction process, positive and negative proces s, rising and falling trend, etc. These models are applied to oasis of Sangong River basin and satisfactory effects have been obtained. (3) The LUCC in oasis has had a slow tendency since 1978 and obviously shows tempor al and spatial differences. In the period of 1978-1987, the index of oasis LUCC trend and state was 0.58, which indicates that oasis LUCC presented non-equilibrium state with the transitional process in single direction and evident regional differences: the state of LUCC was qua si-balanced in the upper part of oasis, but non-balanced in the middle a nd lower parts of oasis. In the period of 1987-1998, the index of oasis LUCC trend and state was 0.3, which indicates that the state of oasis LUCC was quasi-balanced with the transitional process in bi-direction and showed the different regional changes compared with the period during 1987-1 998: the state of LUCC was non-balanced in the upper and middle parts of oasis, but balanced in the lower part of oasis. (4) No matter how qua ntitative change or spatial change, the speed of LUCC in the middle pa rt of oasis is the biggest among its parts and more than that of LUCC of ent ire oasis; the next is the lower part and the smallest is the upper part, whose speeds are all less than that of LUCC of entire oasis.