从’98洪灾看洞庭湖、鄱阳湖流域水土保持问题

分别代表洞庭湖流域和鄱阳湖流域的湖南、江西两省９０年代初已相继宣布消灭了宜林荒山，但９０年代以后“两湖”依然洪水频发，其主要原因是，两省水土流失总面积虽有所减少，而局部地区水土流失却进一步加剧，由于开发建设造成的人为水土流失与由于林种结构、林龄结构及造林方式不合理造成的林地水土流失均十分严重。５０年代以来，两省每年输入“两湖”的泥沙量基本稳定不变，主要是中上游塘、坝、库、堰等水利水保工程拦蓄的结果，为此付出的代价沉重，江西省平均每年损失库容１０４７万ｍ３，湖南省大中小型水库平均每年仅拦蓄悬移质泥沙６８６万ｔ。“两湖”流域中上游推移质泥沙数量巨大，不可忽视

Look at Soil and Water Conservation in Dongting Lake and Poyang Lake from 1998 Flood Disaster

Although the barren mountains in provinces of Hunan and Jiangxi, two representatives of Dongting lake and Poyang lake, have been declared recovered with afforestation one after another in 1990s, there have been frequent floods after 1990s in two lakes. The main reasons are that soil and water loss in local areas has been intensified with serious soil and water loss in forest owing to unreasonable forest variety structure, forest age structure and plantation methods and artificial soil and water loss by development and infrastruction, even though soil and water loss areas in the two provinces have decreased. Water tanks, ponds, reservoirs, dams and other hydraulic and soil and water conservation projects in the upper and middle reaches in the two provinces has result in stable amount of sediment delivery into the two lakes, for which such heavy cost has been paid with annual average storage loss of 10 47million m 3 in Jiangxi and average 6 86 million tons of suspended sediment detained annually by big, medium and small reservoirs in Hunan. Besides, there are quite a lot of bed load sediment in upper and middle reaches of the two lakes that should be paid much attention.