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华北地区的雨量,大部集中在雨季。根据河南省汲县16年的降雨资料统计,平均6—8月或7—9月,降雨量占全年总雨量的62%。由于雨水的过份集中,常使土壤水分过多,发生大量地面迳流,在排水不良的地区,甚至积涝成灾。1957年灌溉研究所在1,220亩的棉田上测定:在降雨77次中,有9次发生地面迳流,其中有暴雨也有小雨,总的迳流量为41.9公方/亩,占棉花生长期降雨总量的9%迳流系数为0.003—0.362。
Rainfall in North China, most concentrated in the rainy season. According to the rainfall data of 16 years in Jixian County, Henan Province, rainfall averaged 62% of the total rainfall in June-August or July-September. Due to excessive concentration of rainwater, soil moisture is often excessive, a large number of ground turbulence occurs, and in poor drainage areas, floods and even disaster. In 1957, the Irrigation Research Institute determined on 1,220 mu of cotton fields that ground turbulence occurred nine times during the 77 rainy seasons, with heavy rains and light rains, with a total discharge of 41.9 km 2 / mu, accounting for a total rainfall of cotton growing season The 9% of the flow rate was 0.003-0.362.