Purple soil is highly susceptible for overland flow and surface erosion, therefore understanding surface runoff and soil erosion processes in the purple soil region are important to mitigate flooding and erosion hazar...Purple soil is highly susceptible for overland flow and surface erosion, therefore understanding surface runoff and soil erosion processes in the purple soil region are important to mitigate flooding and erosion hazards. Slope angle is an important parameter that affects the magnitude of runoff and thus surface erosion in hilly landscapes or bare land area. However, the effect of slope on runoff generation remains unclear in many different soils including Chinese purple soil. The aim of this study was to investigate the relationship between different slope gradients and surface runoff for bare-fallow purple soil, using 5 m × 1.5 m experimental plots under natural rainfall conditions. Four experimental plots(10°, 16°, 20° and 26°) were established in theYanting Agro-ecological Experimental Station of Chinese Academy of Science in central Sichuan Basin. The plot was equipped with water storage tank to monitor water level change. Field monitoring from July 1 to October 31, 2012 observed 42 rainfall events which produced surface runoff from the experimental plots. These water level changes were converted to runoff. The representative eight rainfall events were selected for further analysis, the relationship between slope and runoff coefficient were determined using ANOVA, F-test, and z-score analysis. The results indicated a strong correlation between rainfall and runoff in cumulative amount basis. The mean value of the measured runoff coefficient for four experimental plots was around 0.1. However, no statistically significant relationship was found between slope and runoff coefficient. We reviewed the relationship between slope and runoff in many previous studiesand calculated z-score to compare with our experimental results. The results of z-score analysis indicated that both positive and negative effects of slope on runoff coefficient were obtained, however a moderate gradient(16°-20° in this study) could be a threshold of runoff generation for many different soils including the Chinese purple soil.展开更多
Large leisure activities usually use large sport facilities. There is often no serious problem with people gathering, but both incomplete facilities and negligence of people security manage may court injury or death. ...Large leisure activities usually use large sport facilities. There is often no serious problem with people gathering, but both incomplete facilities and negligence of people security manage may court injury or death. The purpose of this study is to analyze crowded nodes and to improve evacuation path use Simulex models. The fastest and safest way to achieve safe egress was then well planned. For turn locations, it was found that fixing the plane angle did not significantly raise the overall exiting efficiency. However, replacing the right angle or other angles with arc angle makes overall exiting moving line more fluent. For multito single-directional converging T-junction intersections, modification of turn angle increased the movement fluency, with the higher the modified angle, the higher in fluency. However, changing to round angle did not have as significant effect as expected while gate opening width must be increased to 1.0 m before more significant effects were produced. The results showed that modifying turn angles to 60° produces better improvements.展开更多
文摘Purple soil is highly susceptible for overland flow and surface erosion, therefore understanding surface runoff and soil erosion processes in the purple soil region are important to mitigate flooding and erosion hazards. Slope angle is an important parameter that affects the magnitude of runoff and thus surface erosion in hilly landscapes or bare land area. However, the effect of slope on runoff generation remains unclear in many different soils including Chinese purple soil. The aim of this study was to investigate the relationship between different slope gradients and surface runoff for bare-fallow purple soil, using 5 m × 1.5 m experimental plots under natural rainfall conditions. Four experimental plots(10°, 16°, 20° and 26°) were established in theYanting Agro-ecological Experimental Station of Chinese Academy of Science in central Sichuan Basin. The plot was equipped with water storage tank to monitor water level change. Field monitoring from July 1 to October 31, 2012 observed 42 rainfall events which produced surface runoff from the experimental plots. These water level changes were converted to runoff. The representative eight rainfall events were selected for further analysis, the relationship between slope and runoff coefficient were determined using ANOVA, F-test, and z-score analysis. The results indicated a strong correlation between rainfall and runoff in cumulative amount basis. The mean value of the measured runoff coefficient for four experimental plots was around 0.1. However, no statistically significant relationship was found between slope and runoff coefficient. We reviewed the relationship between slope and runoff in many previous studiesand calculated z-score to compare with our experimental results. The results of z-score analysis indicated that both positive and negative effects of slope on runoff coefficient were obtained, however a moderate gradient(16°-20° in this study) could be a threshold of runoff generation for many different soils including the Chinese purple soil.
文摘Large leisure activities usually use large sport facilities. There is often no serious problem with people gathering, but both incomplete facilities and negligence of people security manage may court injury or death. The purpose of this study is to analyze crowded nodes and to improve evacuation path use Simulex models. The fastest and safest way to achieve safe egress was then well planned. For turn locations, it was found that fixing the plane angle did not significantly raise the overall exiting efficiency. However, replacing the right angle or other angles with arc angle makes overall exiting moving line more fluent. For multito single-directional converging T-junction intersections, modification of turn angle increased the movement fluency, with the higher the modified angle, the higher in fluency. However, changing to round angle did not have as significant effect as expected while gate opening width must be increased to 1.0 m before more significant effects were produced. The results showed that modifying turn angles to 60° produces better improvements.
