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绪言黄河冲积平原(河南地区)位于华北平原的中部(图1)。面积约46000平方公里,耕地约4600万亩。西邻太行山前冲洪积平原。研究区为地势平缓、微有起伏开阔的冲积平原,地表、地下径流滞缓,坡降1/2000～1/6000,海拔标高40～85米,微向东北、东南倾。具暖温带季风气候特征。年平均气温12℃～15℃。多年平均降水量自南向北由900毫米递减为600毫米,水面蒸发量则自南向北由1100毫米递增为1700毫米。区内降水时空分布不均,年内及年际
Introduction The Yellow River alluvial plain (Henan area) is located in the central part of the North China Plain (Figure 1). An area of about 46000 square kilometers, about 4600 acres of arable land. Taihang Mountains west of the former flood alluvial plain. The study area is gentle and slightly undulating alluvial plain. The surface and underground runoff are stagnant. The slope falls from 1/2000 to 1/6000 and the elevation elevation is 40 to 85 meters, slightly to the northeast and southeast. A warm temperate monsoon climate characteristics. The average annual temperature of 12 ℃ ~ 15 ℃. The average annual precipitation has been reduced from 900 millimeters to 600 millimeters from south to north. The water surface evaporation has increased from 1100 millimeters to 1,700 millimeters from south to north. Temporal and spatial distribution of precipitation in the region is uneven, year and year