Numerical Simulation of the Influence of Design Rainstorm Pattern on Mountain Torrent Disaster in High Vegetation Coverage Basin.

In order to analyze the impact of rainstorm design on mountain torrent disasters in small watersheds in mountainous areas this paper uses a spatio-temporal variable source mixed runoff generation model, taking Guankou, and Hanwangchang in Sichuan Province as the research area, the response rules of descending water in high vegetation cover basins to different reproduction periods and rainstorm type conditions of different designs are analyzed, and the peak flow, peak present time and peak lag time of the river basin under different rain types and recurrence period conditions are compared and analyzed. The research findings show that the spatio-temporal variable source mixed runoff generation model is suitable for the simulation of hydrological processes with good simulation accuracy in mountainous areas with high vegetation coverage. The latter rain patterns in the Guankou and Hanwangchang basins have more flood peaks than those formed under the front and middle conditions under the same recurrent period, but the front rain patterns produce more floods than middle and rear rain patterns. Under the conditions of different rainfall patterns, with the increase in return period, the peak discharge of the Guankou and Hanwangchang drainage basins shows an increasing trend. The forest and grass vegetation coverage rate is Hangwangchang>Guankou watershed, and the peak emergence time of the Guankou is earlier than that of the Hangwangchang watershed under the design rainstorm conditions of different return periods, the vegetation coverage of forest and grass can regulate the runoff process of flood to a certain extent. The lag time between the occurrence time of the flood peak and the occurrence time of rainstorm peak in the Guankou watershed and the Hanwangchang watershed is forward type>middle type>rear type. Revealing the quantitative law of the high vegetation covered watershed in the southwest mountain area for the design of rainstorm patterns in different return periods has a guiding significance in analyzing the formation process of rainstorm and flood in the high vegetation coverage basin of the southwest mountain area, and improving the flood forecasting accuracy and flood control and disaster reduction capability of the basin. [ABSTRACT FROM AUTHOR]