汾西县坝地防洪能力分析和防洪保收经验调查

坝地土肥水足,适宜于发展高产优质高效农业。晋西水土流失严重的汾西县打坝淤地历史悠久,经过多年配套建设,目前共有坝地3344hm~2,农业人均0.03hm~2。统计资料表明:坝地仅占全县耕地面积的9.26％～10.04％,而粮食产量却占总产量的27.2％～51.7％;坝地平均每公顷淤积泥沙26595m~3,全县坝地共拦泥8527万m~3,折合11511万t,相当于治理前年均向黄河输沙量593.6万t的19倍。坝地防洪保收在很大程度上取决于降雨的时间分布及雨量大小,其允许淹水深度依坝地作物株高而定。经典型小流域分析,汾西坝地具有较高防洪保收能力。其主要经验是,合理布设坝系工程,修建坝地排洪渠和加强管护。

Analysis of the Ability of Flood Prevention of the Farmland Behind Silt-arrester in Fenxi County and Investigation of the Experience of Securing Harvest

The farmland behind silt-arrester with sufficient soil and water is suitable for developing high-yield fine-quality high-benefit agriculature. After many years of construction, at present there are 3344 hm2 of this kind of farmland in Fenxi County, the agriculture population has an average of 0. 03 hm2 per capita. Statistics show that although the land behind silt-arrester only constitutes 9. 26%~10. 04% of the total farmland of this county, its grain output comprises 27. 2% ~51. 7% of the total output. In average, 26595 m3 of sediment were deposited per hectare of the land behind the silt-arrester, so a total of 8. 5 million m3 of sediment have been arrested in the whole county, which amounts to about 19 times of the average annual rate of 5. 94 million tons entering the Yellow River before the harnessment. Whether or not the land behind-silt arrester can prevent flood and secure a good harvest depends on rainfall and it's temporal distribution. The permitted depth of flooding is decided by the height of stem of plant.