1939年海河流域洪涝灾害的气象—水文—灾害过程浅析*

1939年为海河流域20世纪特大洪涝灾害年之一。根据历史文献记载及观测资料,从降水过程、洪水过程及受灾情况等方面对1939年海河流域洪涝灾害过程作了梳理,得出以下结论: (1)1939年的洪涝灾害是7—8月份3次大范围集中暴雨导致的,集中降水出现于7月9—15日、7月23—29日和8月11—13日。3次暴雨中心均集中在昌平—紫荆关—中唐梅一带,其7、8两个月份总降雨量最高达到1000 mm以上,向东向西逐渐减小。(2)1939年海河流域诸河径流随着7—8月份集中降雨而出现涨落变化,稍滞后于降水变化1~2天,各河流最大流量和水位出现在7月23—29日集中降水后,并开始涨溢、决口,各河水位至8月底各河上游降雨中止而渐渐回落,9月中旬天津市区各河水位骤落,10月份以后洪水才迟缓退去,而洪水泛滥引发的涝灾一直延续到1940年。(3)1939年洪涝灾害在海河南系和北系都有发生,共造成150多个县市受灾,大部分受灾县市农业减产甚至绝收,被灾耕地面积成数超过8成的县市主要分布在大清河下游沿线、永定河下游沿线和南运河下游沿线靠近天津市的地区。

Analysis of heavy rain-flood-disaster process of the flood disaster in Hai-he River basin in 1939

The year 1939 was one of the extreme flood years in the Hai-he River basin in the 20th Century. Based on historical records and hydrological observation data,we analysed the process of rainfall,the route of flood and the damages of the flood disaster in 1939 in Hai-he River basin. Results are as follows: (1)The flood disaster that was caused by three large-scale concentrated torrential rain in July and August happened in July 9-15,July 23-29 and August 11-13 respectively. The centers of the three storm were in Changping-Zijingguan-Zhongtangmei area,where the rainfall reached over 1000 mm and gradually decreased from the center to eastward and westward. (2)The water levels of the rivers in Hai-he River basin rose and fell following with the change of the rainfall in July and August by lagged one to two days. All rivers reached their maximum flow and the highest water level,and began to overflow and burst,after the rainfall in July 23-29. The water levels began to fall lowly up to the end of August,when the rain season stopped in the upper reaches of the Hai-he Rivers. The water levels of rivers in Tianjin municipality dropped rapidly in mid-September,but the flood did not ended until October. However,the waterlog lasted to 1940. (3)The flood disaster in 1939 occurred both in the north part and the south part of the Hai-he River basin. More than 150 counties were in the flood area. In most of the counties,the harvest was reduced or even no harvest production. The counties with more than 80% damaged cropland were along the lower reaches of the Daqing River and Yongding River,and the area of the lower reaches of the South Canal near by Tianjin municipality.