The authors made a survey of the disaster caused by heavy rainstorm occured on July 23

1988(with a 300 year rainstorm frequency

precipitation in the center point was 210～240mm)in the hilly and gully regions in the east part of Gansu Province on the loess plateau. Based on the actual data

they analysed that this heavy rainstorm was formed by local geothermal convenction and initiated by the "人" -shaped shearing instability over 700 hpa. The heavy rainstorm only lasted from 2:05 to 2:35 in the morning

causing serious disaster. This paper analysed the natural and manmade causes of disasters caused by heavy rainstorm in the Yuan area. Also

it analysed the advantages and disadvantages of water and soil conservation engineering structures including stripe lands

gully head control works

reservoirs and dams as well as afforestation. Therefore

the idea of comprehensive control system of Yuan

slopes and gullies was presented

and it was suggested that the disaster resistant ability of water and soil conservation planning

design and construction should be improved since rainstorms characterized by heavey rainfall and great rain intensity are mostly caused by local geothermal convenction.