| According to the rating standard of meteorological drought (GB/T20481-2006), through statistical analysis for the yearly average drought frequency from 1971 to 2010 of nine meteorological stations in Longnan City as covering 8 counties and 1 district, have obtained the conclusions as follows: The average drought occured yearly frequency was 60.3% in the last 40 years. Among them, the spring drought was 39.3%, the early summer drought was 20.5% and late summer drought was 38.5%, the autumn drought was 35.3%. By using the longitude, latitude, altitude and the yearly mean drought frequency of the nine stations, has established the multivariate linear regression equation, to calculated the average annual drought frequency of each region in Longnan City, then combined with the information such as population, GDP and the cultivated land ratio and so on, using the ARCGIS software to obtain the drought disaster danger map layer. Then added and combined the evaluation of disaster easy damage, the background of disasters and compartmentalizing the grade. In the last, has obtained the risk evaluation for the drought disaster. The results showed that: The dangerous grade of drought was highest in the dry-hot valley with lower altitude areas of Bailong River and Baishui River in Longnan City and the Huicheng Basin, and southeast of Wen County, the yearly drought frequency was higher than 60%. From here to the north, the high dangerous grade of drought declined, the lowest risk grade of drought were at the Chiba Town of Wudu, the higher altitude region in Maying Town, the northwest of Tanchang County and the northwest part with high altitude in Wen County, where the average annual drought frequency was lower than 50%. The risk of drought was high in Hui County, Cheng County, the central and northwest of Liangdang County, the Bailong River and Baishui River Basin in Wudu and Wen County; the risk of drought was low in Tanchang County, Chiba Town and Maying Town in Wudu, and the northwest of Wen County. |