�ƺ����ε������й����ػ�Į����������֮һ�����й���Į���������������ص����򡣱��IJ��� MSS��TM��ETM��CBE��S �������ݣ����� ��S �� GIS ��������Ҫ�����˹�Ŀ�ӽ��뷽��������Ұ�������֤���õ����ڽ������ݡ��������׶ε����ݽ��пռ�������о� 1975 �굽 2007 ��ƺ����λ�Į����ʱ�շֲ�������̽���ݱ���򣬲���ϸ��������ºͽ�ˮ���ݣ����ط����������Į���ݱ���̵Ĺ�ϵ���������: 1975—2007 �꣬������仯���ƿ����ƺ����ε������ػ�Į������������� 3 499. 76 km2������ɳ�ʻ�Į���������3 407. 62 km2���μ��ʻ�Į�����������92. 14 km2���������׶εı仯���ƿ������������Ӻ���ٵķ�չ���ƣ�2000 ��֮ǰ�ǻ�Į��������ʱ�ڣ�2000 ��֮���ǻ�Į���ļ���ʱ�ڡ�������ºͽ�ˮ�����ݵ��ӷ����ó�������仯�ǻƺ����λ�Į����չ����Ҫԭ��; ���ʱ���������������߻����á�

Upper reaches of Yellow ��iver have been one of the worst-hit areas of land desertification and of the key areas of desertification monitoring and handing operation in China�� Based on ��S and GIS technologies��the authors used artificial visual interpretation method and the field survey to obtain interpreting data for 4 periods by MSS-��TM-��ETM-and CBE��S images�� The authors studied the situation and distribution of desertification and the space-time evolutionary process in the upper reaches of the Yellow ��iver from 1975 to 2007�� Then��with the regional air temperature and precipitation data��the authors analyzed their relationship with the evolutionary process of desertification�� The results showed that the desertification of the upper reaches of Yellow ��iver increased 3 499. 76 km2totally from 1975 to 2007��thereinto��sandy desertification area increased 3 407. 62 km2and the saline desertification area increased 92. 14 km2�� The development trend of the desertification firstly increased and then de- creased from the three stages�� The desertification increased before 2000 and decreased after 2000�� Combined with the analysis of temperature and precipitation data��it was considered that the climatic change was one for the impor- tant reasons for the development of land desertification of the upper reaches of Yellow ��iver��and its geological background was the internal cause and human activity was the catalytic role��