四川省云阳县自然灾害概述

GENERAL REVIEW OF NATURAL DISASTERS IN YUNYANG COUNTY, SICHUAN PROVINCE

为改善本县生态环境、发展县内贫困山区经济,论述了全县的自然灾害类型及其成因和危害,并提出了防灾减灾措施。

Yunyang County is situated in east of Sichuan Basin (108°24′-109°15′E, 30°35′-31°27′N). The land area of whole county is 3,649km2. The population is 118×10~4(1990). In middle part of the county, the Changjiang River passes through from west to east, flowing 57km and the altitude is 107-95m. In the county, landfrom is hill (200-1,000m) and low mountain (1,000-1,500m). The county belongs to subtropical monsoon area. The annual mean temperature is 18. 7℃, and the annual precipitation is 1,145mm. The rainfall mainly is during June-August, occupying 42% of whole year. The forest coverage of the county is 7. 5%.The natural disasters in the county are flood, drought, landslide, hail, insect pest, plant disease and Microtus fortis, among them flood is the main natural disaster of this county, Druing 1949-1990,flood frequency is 52%. For example, a flood on July, 1982. Rainfall duration was for 14d. The flood destroyed building of 1. 4M(m)2, farm field 7733ha, and lost grain 3250t, rapeseed 560t, as well as killed persons 97,the severely wounded persons 802 and killed animal 10~4. At the same time, 106 landslides (>3. 3ha) occurred. A catastrophic landslide of0.77km2 had 15M(m)3 of earth and stone, and caused direct economic loss of 6Myuan (1982).1.8M(m)3 of earth and stone slipped into the Changjiang River Fairway.The disaster causest 1. rainfall is concentrated (mainly is rainstorm or extraordinary rainstorm), and lithology is alternating soft with hard, and the vegetation is sparse; 2. population increases 50×10~4from 1950 to 1990, unreasonable exploitation to the mountainous region worsened the ecologic environment ; 3. plant disease and the natural enemies (such as Rana nigro-maculata, Serpentes, and Mustela sibirca) of Microtus fortis have lessened.The measures for prevention and reduction disasters, 1. to strengthen birth control, coordinate the relation between human and land; 2. to afforest, green waste mountain and close hillside to facilitate afforestation, and improve the environment; 3. to carry out the integrate control of the small basin; 4. to set up the monitoring and forecasting system of natural disasters; 5. to heighten the consciousness of prevention and reduction disasters and protection environment.