| In the last several decades, the oasis agriculture and economy in inland basins have been rapidly developed together with its water resource exploitation. However, Some problems caused by the water resource development, especially the secondary salinization of soil in irrigation district and natural vegetation degeneration, become the important factors that restrict the social and economic sustainable development in the inland area. In view of these problems, taking the "harmonizing the water resource development with eco-environmental protection in order to realize sustainable development"as a guiding idea, the present thesis paid special attention to the discussion on the following problems. 1. Analysis of the catchment's compound system of hydrological cycle and ecology According to the pointview of system theory, the inland catchment is regarded as a united hydrological cycle and ecology system. Furthermore, the hydrological and ecological subsystems have been derived and the relation between the two subsystems has been discussed. Also, the relation among the change of hydrological cycle, the secondary salinization of soil in irrigation district, and the natural vegetation degeneration has been demonstrated. 2. Analysis and establishment of the groundwater eco-environmental index On the basis of previous studies, investigations and experiments, the discussion was focussed on analyzing the relations between the vegetation growth and some index such as soil moisture content, soil salinity, the burial depth of groundwater table and total dissolved solid of groundwater etc. Then the definition of "groundwater eco-environmental index"was given out and the index of groundwater eco-environment related to the secondary salinization of soil and natural vegetation degeneration have been established. 3. Analysis on the prevention of secondary salinization of the soil in irrigation district Started from analyzing the yearly characteristics of water and salt migration of soil in irrigation district and chosen the northern Xinjiang as a case area, the index was established so as the root zone soil salinity be controlled less than the anti-salt limitation value for crops, and the burial depth of groundwater table be less than the critical depth, and then a general idea to dynamically control groundwater and to irrigate in accordance with crop water demand has been put forward. 4. Analysis on ecological water demand for natural vegetation The method for ecological water demand assessment is chosen by analyzing the water source for plant growth in arid plain, and by analyzing the relation between the plant evapotranspiration and groundwater evaporation. Then taken the burial depth of groundwater table suitable for most plant community growth as index, the present ecological water demand for the main stream area of Tarim River has been evaluated and compared with its present inflow. Finally, some measures have been put forward for the purpose of increasing ecological water supply. 5. The formation mechanism of condensation water and its eco-environmental significance Taken the water-salt balance experimental station in Changji as a case study area, the formation condition and time of condensation water and the source of moisture have been analyzed. Also, the formation mechanism of condensation water in the frozen period with snow cover, and its main influencing factors have been discussed. Meanwhile, the eco-environmental protection significance of condensation water has been demonstrated. Finally, some rational recommendations have been given out for harmonizing the water resource development with eco-environmental protection in order to realize sustainable development.
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