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黄河中游的黄土高原是典型的干旱、半干旱地区。晋西28县即属这一类型。区内年降雨量300-500毫米,按国际通行标准,应归属于半干旱范畴。但因70-80％的降水集中于七、八月份,不能符合作物生育期的需水规律,更不能满足多年生牧草生长期和再生曲线分配特点的需要。加之山峦起伏,沟壑交错,地形复杂,土壤蓄水保水力差,径流
The Loess Plateau in the middle reaches of the Yellow River is a typical arid and semi-arid area. 28 counties that belong to this type. The annual rainfall of 300-500 mm in the area should be attributed to semi-arid areas according to the international standards. However, 70-80% of precipitation concentrated in July and August, can not meet the water requirements of crop growth period, but also can not meet the needs of perennial grazing period and regeneration curve distribution characteristics. Coupled with ups and downs, ravine staggered, complex terrain, poor soil water retention, runoff