北京林业大学学报2017，Vol.39Issue(8)：77-86,10.DOI:10.13332/j.1000--1522.20170126
降雨和坡面流共同作用下的坡面薄层流水动力学特性
Hydrodynamics of overland flow under combined effects of precipitation and slope discharge
摘要
Abstract
To better understand the role of precipitation and slope discharge on hydrodynamic characteristics of overland flow, the simulated rainfall experiments were carried out at a steep slope ( slope gradient was 20o) flume in Jinyun Forest Ecological Station, Chongqing of southwestern China. Velocity v and flow depth h were measured under different conditions of 5 unit discharges q ( ranged from 0. 486 × 10 -3 to 1. 736 × 10 -3 m3/( s·m)), 4 typical rainfall intensities P (0, 30, 60, 100 mm/h) and 4 different surface roughness ks(0. 009, 0. 180, 0. 250, 0. 425 mm). Furtherly, the hydraulic parameters, i. e. , the mean velocity u, the velocity correction factor, flow-state indicator m, flow regime and overland flow resistance coefficient f were calculated. The results showed that: 1 ) mean velocity increased with increasing q in power function and v decreased with the increase of ks. The velocity correction factor ranged from 0. 04 to 0. 37 in rainfall condition while ranged from 0. 42 to 0. 98 without rainfall. The overland flow was disturbed by rainfall. 2) The flow-state indicator ranged from 0. 291 to 0. 538. Without rainfall, flow-state indicator was mainly affected by roughness which was negatively correlated with m. The reduction rate was 21％, 28％ and 39％, respectively. With medium-low rain intensity, no obvious variation pattern existed. When the rain intensity was 30 mm/h, the variation rate was 18％, -29％ and 12％, respectively. When the rain intensity was 60 mm/h, the variation rate was 12％, -17％ and-16％. With high rain intensity, the flow-state indicator significantly decreased with increasing roughness. The reduction rate was -6％, 1％ and -11％, respectively. 3) The Re ranged from 500 to 2000, therefore the flow regime of overland flow was mainly transition flow. In most cases, flow pattern was supercritical flow. Without rainfall, the roughness was obviously related with the flow regime, that the overland flow tended to be supercritical with smaller roughness value, but this trend was not detecte with rainfall because of its disturbance effect. 4) Darcy resistance coefficient was positively related to ks, while negatively correlated with unit discharge. Comparing the calculation formula of resistance coefficient with rainfall intensity to condition of without rainfall intensity, the correlation coefficient declined by 0. 01％, showing that rainfall had no significant influence on resistance coefficient.关键词
模拟降雨/坡面薄层流/水动力学特性/粗糙度Key words
simulated rainfall/overland flow/hydrodynamic characteristics/roughness分类
农业科技引用本文复制引用
蒋利斌,张会兰,杨坪坪,刘文剑..降雨和坡面流共同作用下的坡面薄层流水动力学特性[J].北京林业大学学报,2017,39(8):77-86,10.基金项目
国家自然科学基金项目(51309006)、北京林业大学"国家级大学生创新创业训练计划"(201610022016). （51309006）
