武都山区干旱气候特征与灾害风险区划

根据气象干旱等级标准(GB/T20481-2006),统计分析陇南市8县1区9个气象站1971~2010年年平均各类干旱频率,并利用各站经度、纬度、海拔高度与各站年平均干旱频率建立多元线性回归方程,计算武都区各地年平均干旱频率,结合各地人口、GDP、耕地比等资料,利用ArcGIS软件,得到干旱灾害危险性图层,再同承灾体易损性评价、灾害的孕灾背景进行叠加、合并以及等级划分操作,最后得到干旱灾害的风险评估及其区划。结果表明,近40年武都区有30年均有干旱出现,共出现各类干旱49次,其中,发生频率春旱40.0%、春末夏初旱20.0%、伏旱35.0%、秋旱27.5%,年际出现干旱的频率为75.0%。武都区白龙江流域半山河谷和东南部低海拔区干旱危险性等级最高,年际干旱频率62.3%,由此向北向高干旱危险性等级递减,干旱灾害风险由白龙江干热河谷向四周递减。

Drought Climatic Characteristics and Disaster Risk Zoning in Wudu Mountain Area

Abstract According to the meteorological drought grade standard （GB/T20481 -2006）, statistical analysis was conducted on annual average of all kinds of drought frequency of nine meteorological stations in eight counties and one area during 1971-2010 in Longnan City. Multiple linear regression equation was established by using longitude, latitude, the altitude of sea level and average annual drought frequency of each station. Average annual drought frequency of Wudu all around area was calculated, combining with the material of local population, GDP, and farm land ratio. Using ArcGIS software, drought disaster risk layer was obtained, then hazard-affected body vulnerability assessment and disaster-pregnant background were overlapped, merged and classified operation. Finally drought disaster risk assessment and its regionalization were got. The re- suits showed that there has 30 years which have drought in Wudu district in recent 40 years. A total of 49 times in all kinds of drought, among them, the spring drought occurred frequency is 40.0%, late spring and early summer drought is 20.0%, late summer is 35%, autumn drought is 27.5%, and drought occurred frequency is 75.0% in a year. The dry-hot valleys of Bailongjiang and southeast low altitude area are highest risk level, the dry frequency of inter-annual is higher than 62.3%, and then drought risk level declines to the north to the high, drought disaster risk descends from the dry-hot valleys of Bailongjiang to all directions.