关中平原近200年来洪涝灾害研究

在对关中平原近200年来历史资料的搜集、统计和分析的基础上,研究了该时期关中平原洪涝灾害的等级序列、年际变化、季节变化、空间变化及灾害成因。结果表明:关中平原这一时期共发生洪涝灾害81次,平均每2.53年发生1次,从民国中期开始该地区洪涝灾害发生频率有明显增加的趋势。该地区洪涝灾害以第二级(中度偏涝)为主,共发生47次,占洪涝灾害总数的58%;第三级(大涝)共发生24次,占洪涝灾害总数的29.6%;第一级(轻度偏涝)和第四级(特大涝)分别发生7次和3次,各占洪涝灾害总数的8.6%和3.8%。关中平原近200年来洪涝灾害的发生具有明显的时间和空间差异。洪涝灾害主要集中于渭河中下游的西安、蓝田、周至、渭南、华县、大荔、华阴以及洛河下游的铜川、千河下游的宝鸡等县市。关中平原近200年来洪涝灾害的发生具有明显的季节差异,多集中在夏秋季的7~9月。此外,关中平原地势平坦、土质疏松、地表植被较稀少,所以同样的降水量在该平原较易造成洪涝灾害的发生。

Study on Flood and Waterlog Disasters in the Guanzhong Plain since Recent 200 Years

On the basis of collecting and analyzing the historical materials and their statistical results,this paper researches the grade series,annual and seasonal change,spatial distribution and causes of flood and waterlog disasters in the Guanzhong Plain since recent 200 years.The results show that the Guanzhong Plain has suffered from 81 flood and waterlog disasters since recent 200 years,once every 2.53 years in average.Since the middle period of the Republic of China,the occurring frequency of flood and waterlog disasters has been increased.According to the grade series of flood and waterlog disasters,flood and waterlog disasters in the plain are dominated by the ones at the second grade,47 disasters have occurred and occupied 58% of the total;24 disasters at the third grade have occurred and occupied 29.6%;7 disasters at the first grade have occurred and occupied 8.6%;3 disasters at the forth grade have occurred and occupied 3.8% of the total.Spatiotemporal difference of flood and waterlog disasters in the Guanzhong Plain since recent 200 years is significant,and flood and waterlog disasters occur mainly in Xi'an,Lantian,Zhouzhi,Weinan,Huaxian,Dali and Huayin in the middle and lower reaches of the Weihe mainstream,Tongchuan in the lower reaches of the Luohe River,and Baoji,etc.in the lower reaches of the Qianhe River.Temporally,flood and waterlog disasters in the plain occur mainly in July,August and September.Moreover,it is easy to occur flood and waterlog disasters because of the subdued uplift,loose soil and sparse natural vegetation.