工程科学与技术   2018, Vol. 50 Issue (3): 185-192

Experimental Study on the Flow Concentration Influenced by Vegetation
PENG Qing’e, LIU Xingnian, HUANG Er, YANG Kejun, ZHAO Minghui
State Key Lab. of Hydraulics and Mountain River Eng., Chengdu 610065, China
Abstract: Due to the steep slope of mountainous watersheds and large changes in vegetation,flood responses to rainstorms are complicated.At present,the most widely used formula is the constant index of slope length,effective roughness,effective rainfall intensity and slope.However,the effect of vegetation on the confluence time is implicit in the effective roughness,which makes impossible to directly use the high-precision remote sensing data of vegetation in calculation.In this study,a series of heavy rainfall induced confluence tests under different slopes and vegetation coverage were carried out.By introducing the vegetation coverage factor C and employing the statistical analysis method,the relationship between the flow confluence time on a slope and the vegetation coverage is established.The results showed that the influence of vegetation coverage on the flow confluence time was significant.The flow confluence time increased with the increase of vegetation coverage,and decreases with the increase of rainfall intensity and slope.The flow confluence time under turf vegetation was slightly larger than that under shrubs vegetation.In this study,the vegetation factor was separated from the effective roughness to facilitate the more effective use of vegetation remote sensing data.The calculation accuracy of the flow confluence time on the slope is improved.
Key words: vegetation type    vegetation coverage index    slope flow concentration time    artificial rainfall

1 试验概况 1.1 模型设计

 图1 降雨试验模型布置 Fig. 1 The model layout of rainfall experiment

1.2 试验设备简介 1.2.1 室内人工降雨系统

1.2.2 LH-1自动水位仪

1.3 试验方案设计

 图2 试验下垫面设计简况 Fig. 2 Experiment arrangement of the underlying surface

2 坡面汇流试验结果分析

2.1 坡面汇流时间试验结果及初步分析

2.1.1 同一坡面雨强对汇流时间的影响

2.1.2 同一坡面植被对汇流时间的影响

2.1.3 不同坡面坡度对汇流时间的影响

2.2 植被对坡面汇流时间的影响指数

 $T = {L^{0.6}}{n^{0.6}}/{i^{0.4}}{S^{0.3}}$ (1)

3 结　论

1）植被的种类（草或灌木）对坡面汇流时间影响存在一定差异，其它条件相同情况下，草植被下的坡面汇流时间大于灌木植被下的坡面汇流时间。

2）植被覆盖度（草或灌木）对坡面汇流时间存在显著影响，其它条件相同情况下，坡面汇流时间随植被覆盖度的增大出现明显的增加。

3）降雨强度、坡度对坡面汇流时间的影响也较为显著。其它条件相同情况下，坡面汇流时间随雨强的增大出现明显的减小；随坡度的增大出现明显的减小。

4）草及灌木植被覆盖度指数随坡度及雨强变化规律基本相似，总体上草植被覆盖度指数略大于灌木植被覆盖度指数。植被覆盖度指数 ${a_0}$ 随着雨强增大减小趋势较为明显；随坡度变缓而有所增大。

5）本研究将植被因子从综合糙率中剥离出来，便于融合植被遥感数据，从而提高坡面汇流时间的计算精度。

 [1] Liu Zhanzhou,Ao Tianqi,Wan Yu’an. Study on the effect of basin vegetation types on flood runoff[J]. Water Conservancy Science and Technology and Economy, 2014, 20(9): 1-4. [刘占洲,敖天其,万育安. 流域植被类型对洪水径流影响研究[J]. 水利科技与经济, 2014, 20(9): 1-4.] [2] Wang J,Sun G,Shi F,et al. Runoff and soil loss in a typical subtropical evergreen forest stricken by the Wenchuan earthquake:Their relationships with rainfall,slope inclination,and vegetation cover[J]. Journal of Soil and Water Conservation, 2014, 69(1): 65-74. DOI:10.2489/jswc.69.1.65 [3] Li X,Zhang X,Zhang L,et al. Rainfall and vegetation coupling index for soil erosion risk mapping[J]. Journal of Soil and Water Conservation, 2014, 69(3): 213-220. DOI:10.2489/jswc.69.3.213 [4] S Fusun,W Jinniu,L Tao,et al. Effects of different types of vegetation recovery on runoff and soil erosion on a Wenchuan earthquake-triggered landslide,China[J]. Journal of Soil and Water Conservation, 2013, 68(2): 138-145. DOI:10.2489/jswc.68.2.138 [5] Zheng Shaowei,Mu Changlong,Chen Zuming,et al. Simulations and analysis on the effects of forest on the hydrological processes in the upper reaches of Yangtze river[J]. Acta Ecologica Sinica, 2010, 30(11): 3046-3056. [郑绍伟,慕长龙,陈祖铭,等. 长江上游森林影响流域水文过程模拟分析[J]. 生态学报, 2010, 30(11): 3046-3056.] [6] Wang Qinghua,Li huaien,Lu Kefeng,et al. Analysis of affection of forest vegetation change on watershed runoff and flood[J]. Journal of Water Resources and Water Engineering, 2004, 15(2): 21-24. [王清华,李怀恩,卢科峰,等. 森林植被变化对径流及洪水的影响分析[J]. 水资源与水工程学报, 2004, 15(2): 21-24.] [7] Zhang Fahui,Chen Linwu,Wu Xuexian,et al. An analysis of influences of forest vegetation changes on the runoff in s mall watersheds in hilly areas in the upper reaches of the Yangtze river[J]. Journal of Sichuan Forestry Science and Technology, 2007, 28(2): 49-53. [张发会,陈林武,吴雪仙,等. 长江上游低山丘陵区小流域森林植被变化对径流影响分析[J]. 四川林业科技, 2007, 28(2): 49-53.] [8] Jimènez C C,Tejedor M,Morillas G,et al. Infiltration rate in andisols:Effect of changes in vegetation cover (Tenerife,Spain)[J]. Journal of Soil and Water Conservation, 2006, 61(3): 153-158. [9] Cui Yan,Liu Jinying. Study on the benefits of forest to prevent flash flood[J]. Heilongjiang Science and Technology of Water Conservancy, 2001, 29(1): 6-7. [崔岩,刘金英,杨文娟. 森林对预防山洪暴发效益的研究[J]. 黑龙江水利科技, 2001, 29(1): 6-7. DOI:10.3969/j.issn.1007-7596.2001.01.003] [10] He Jimzhi,Li Shuibao,Jiang Yongkui,et al. Analysis of the watershed runoff yield and concentration on the variation of the forest cover[J]. Journal of Hydroelectric Engineering, 2001, 2(2): 69-72. [何进知,李舒宝,蒋永奎,等. 森林植被对流域产汇流的影响分析[J]. 水力发电学报, 2001, 2(2): 69-72.] [11] Shen Hongbin,Xu Zongxue,Zhang Shuhan. Review on the simulation of overland flow in hydrological models[J]. Advances in Water Science, 2016, 27(3): 467-475. [申红彬,徐宗学,张书函. 流域坡面汇流研究现状述评[J]. 水科学进展, 2016, 27(3): 467-475.] [12] Li Ruilin. Some problems of flood prediction in Lianzhou City[J]. Guangxi Water Resources & Hydropower Engineering, 2010(4): 22-24. [李瑞林. 连州市洪水预报作业中几个问题的探讨[J]. 广西水利水电, 2010(4): 22-24.] [13] Melesse A M,Graham W D. Storm runoff prediction based on a spatially distributed travel time method utilizing remote sensing and GIS[J]. Journal of the American Water Resources Association, 2004, 40(4): 863-879. DOI:10.1111/jawr.2004.40.issue-4 [14] Lee Kwantun. Derivation of variable IUH corresponding to time-varying rainfall intensity during storms[J]. Hydrological Sciences, 2008, 53(2): 323-337. DOI:10.1623/hysj.53.2.323 [15] Chang C H,Lee K T. Analysis of geomorphologic and hydrological characteristics in watershed saturated areas using topographic-index threshold and geomorphology-based runoff model[J]. Hydrological Processes, 2008, 22(6): 802-812. DOI:10.1002/(ISSN)1099-1085