Flow velocity is not only an important hydraulic property of overland flow, but also an indispensable index to calculate other hydraulic parameters. The purpose of this paper is to investigate the spatial distribution of rill and interrill flow velocity along the hillslope. Simulated rainfall and 7 plots (5 degrees steepness) with the lengths of 1, 2.5, 4, 5.5, 7, 8.5 and 10 m, repectively, were employed. The tested soil was a silty loam, sampled from Yanqing County, Beijing. For each slope length, the experiment consisted of two identical rainfall events (dry run and wet run), timed apart about 24 hours. Each rainfall lasted 2 hours with varied rainfall intensity (27-142 mm/h) and a total rainfall of 121 mm. Flow velocities in rill and interrill area were measured with dying tracing at different slope positions between 60 and 70 min of each rainfall. The results showed that the interrill flow velocity, on plots of all slope lengths and for both dry and wet runs, varied from 0.03 to 0.1 m/s, whereas the rill flow velocity ranged between 0.15 and 0.45 m/s. The latter was 2 to 4 times of the former. Both rill and interrill flow velocity were power functions of L, the distance downward from the upper end of the plot, and the exponents of L for rill were larger than those for interrill, being 0.409-0.420 and 0.175-0.218, respectively, which was due to the concentration of flow into rills along the slope. Additionally, the rill velocity in wet run was higher and accelerated faster than that in dry run, whereas it was opposite for interrill flow velocity, which may be attributed to the fact that more water was delivered into rills and the rills were stabler and smoother in wet run. The results are helpful in understanding the processes and mechanism of rill and interrill erosion.
LIU He-ping, WANG Xiu-ying, LIU Bao-yuan
. Study on rill and interrill flow velocity along hillslopes with simulated rainfall[J]. GEOGRAPHICAL RESEARCH, 2011
, 30(9)
: 1660
-1668
.
DOI: 10.11821/yj2011090010
[1] Morgan R P C.Soil Erosion and Conservation.Malden, MA, USA: Blackwell Publishing, 2006.11.
[2] 张科利, 秋吉康弘, 张兴奇.坡面径流冲刷及泥沙输移特征的试验研究.地理研究, 1998, 17 (2): 163~170.
[3] 雷廷武, Nearing M A. 侵蚀细沟水力学特性及细沟侵蚀与形态特征的试验研究. 水利学报, 2000, 31(11): 49~54.
[4] 夏卫生, 雷廷武, 赵军.坡面侵蚀动力学及其相关参数的探讨.中国水土保持科学, 2003, 1 (4): 16~19.
[5] 胡世雄, 靳长兴. 坡面流与坡面侵蚀动力过程研究的最新进展.地理研究, 1998, 17 (3): 326~335.
[6] 张光辉. 土壤水蚀预报模型研究进展. 地理研究, 2001, 20 (3): 274~281.
[7] Foster G R, Huggins L F, Meyer L D. A laboratory study of rill hydraulics: I. Velocity relationships.Transactions of the American Society of Agricultural Engineers, 1984, 27 (3): 790~796.
[8] Guy B T, Dickinson W T, Rudra R P. The roles of rainfall and runoff in the sediment transport capacity of interrill flow. Transactions of the American Society of Agricultural Engineers, 1987, 30 (5): 1378~1387.
[9] 江忠善, 宋经文. 坡面流速的试验研究. 西北水土保持研究所集刊, 1988, (7): 46~52.
[10] 张科利, 唐克丽.黄土坡面细沟侵蚀能力的水动力学试验研究.土壤学报, 2000, 37 (1): 9~15.
[11] Govers G.Relations between discharge, velocity, and flow area for rill eroding loss, non-layered material.Earth Surface Processes and Landforms, 1992, 17:515~528.
[12] Nearing M A, Simanton J R, Nortion L D, et al.Soil erosion by surface water flow on a stony, semiarid hillslope. Earth Surface Processes and Landforms, 1999, 24: 677~686.
[13] 张光辉, 卫海燕, 刘宝元. 坡面流水动力学特性研究.水土保持学报, 2001, 15 (1): 58~61.
[14] 张光辉. 坡面薄层流水动力学特性的实验研究.水科学进展, 2002, 13 (2): 159~165.
[15] 陈国祥, 姚文艺. 坡面流水力学.河海科技进展, 1992, 12 (2): 7~13.
[16] 李凤英, 李琳, 何小武.坡面流水力学参数的估算.江西农业大学学报, 2006, 28 (3): 477~480.
[17] 李鹏, 李占斌, 郑良勇.黄土坡面径流侵蚀产沙动力过程模拟与研究.水科学进展, 2006, 17 (4): 444~449.
[18] Chaplot V, Bissonnais Y L.Field measurement of interrill erosion under different slopes and plot sizes.Earth Surface Processes and Landforms, 2000, 25: 145~153.
[19] 丁文峰, 李占斌, 鲁克新.黄土坡面细沟侵蚀发生的临界条件.山地学报, 2001, 19 (6): 551~555.
[20] 夏卫生, 雷廷武, 刘春平, 等.降雨条件下坡面薄层水流速度特征.水利学报, 2004, (11): 119~123.
[21] 李勉, 姚文艺, 陈江南, 等.草被覆盖对坡面流流速影响的人工模拟试验研究.农业工程学报, 2005, 21 (12): 43~47.
[22] 范昊明, 王铁良, 周丽丽, 等.不同坡形坡面径流流速时空分异特征研究.水土保持学报, 2007, 21 (6): 35~38.
[23] Wischmeier W H, Smith D D.Predicting Rainfall Erosion Losses-A Guide to Conservation Planning. USDA, Agriculture Handbook No 537. Washington DC, USA: USDA, 1978.4.
[24] 郑粉莉, 唐克丽, 周佩华. 坡耕地细沟侵蚀的发生、发展和防治途径的探讨. 水土保持学报, 1987, 1 (1): 36~44.
[25] 夏卫生, 刘贤赵. 土壤侵蚀中细沟流的初步分析. 水土保持通报, 2002, 22 (2): 13~15.
[26] 夏卫生, 雷廷武, 张晴雯, 等. 冲刷条件下坡面水流速度与产沙关系研究. 土壤学报, 2004, 41 (6): 876~880.
[27] Giménez R, Planchon O, Silvera N, et al. Longitudinal velocity patterns and bed morphology interaction in a rill. Earth Surface Processes and Landforms, 2004, 29: 105~114.
[28] Schiettecatte W, Verbist K, Gabriels D. Assessment of detachment and sediment transport capacity of runoff by field experiments on a silt loam soil. Earth Surface Processes and Landforms, 2008, 33: 1302~1314.
[29] Abrahams A D, Li G. Rill hydraulics on a semiarid hillslope, Southern Arizona. Earth Surface Processes and Landforms, 1996, 21: 35~47.
