1938-1952年间黄泛区的农村经济演变趋势——以扶沟、西华县为个案研究

1938—1952年间的黄泛区农村经济在经历十余年的变迁后,仍然处于凋敝破败的境地:农业劳动人口、农具、耕地面积、人均耕地及产量等增长缓慢;农村集市商业尽管也出现过个别地方的“畸形”繁荣,但在整体上仍显萧条。当地固有的生态环境是影响黄泛区农村经济长期低迷的客观因素,因泛黄而遭变异的生态环境与动荡的社会、政治背景、混乱的社会秩序又是严重阻碍着农村经济发展的社会原因。     

Assessment of dam impacts on river flow regimes and water quality: a case study of the Huai River Basin in P. R. China

The Huai River Basin is a unique area in P. R. China with the highest densities of population and water projects. It is also subject to the most serious water pollution. We proposed a distributional SWAT （Soil and Water Assessment Tool） model coupled with a water quality-quantity balance model to evaluate dam impacts on river flow regimes and water quality in the middle and upper reaches of the Huai River Basin. We calibrated and validated the SWAT model with data from 29 selected cross-sections in four typical years （1971, 1981, 1991 and 1999） and used scenario analysis to compensate for the unavailability of historical data regarding uninterrupted river flows before dam and floodgate construction, a problem of prediction for ungauged basins. The results indicate that dam and floodgate operations tended to reduce runoff, decrease peak value and shift peaking time. The contribution of water projects to river water quality deterioration in the concerned river system was between 0 to 40%, while pollutant discharge contributed to 60% to 100% of the water pollution. Pollution control should therefore be the key to the water quality rehabilitation in the Huai River Basin.