A laboratory study on rill network development and morphological characteristics on loessial hillslope
- 146 Downloads
Rills are basic pathways for runoff, sediment, and pollutant transport at hillslopes within agricultural watershed. The objectives of this study were to investigate the development processes of rill network and morphological characteristics and to examine their affecting factors.
Materials and methods
A soil box (10 m long, 1.5 m wide, and 0.5 m deep) was subjected to four successive simulated rains under rainfall intensity of 90 mm h−1 with slope gradients of 15° and 25°. Digital elevation models (5 mm resolution) were created from the terrestrial laser scanning measurements.
Results and discussion
Total soil loss was 46.3 and 61.0 kg m−2 at the 15° and 25° slope gradients, and rill erosion occupied over 75% of the total soil loss. Soil loss and rill erosion were expressed as power equations to the product of slope gradient and accumulated rainfall. Rill networks evolved in a converging way and reached maturity in the fourth rain. Main rill length and rill width, depth, and degree of contour line departure increased with increased rains, while rill width/depth ratio showed the opposite trend. Secondary rill length and rill density increased in the first two rains, and then both decreased in the latter two rains. Scour effect of lateral interfluve flow and meander cutoffs of rill flow were two sub-processes of rill piracy. Rill length and density decreased due to rill piracy specific in merging of secondary rills into main rills. Plow pan and secondary headcuts played key roles in main rill bed incision and sidewall expansion processes, while both had little impact on secondary rills.
Results of this study can improve the understanding of how plow pan, rill piracy, and secondary headcut affect rill network and morphologies and provide fundamental knowledge for designing rill prevention practices.
KeywordsPlow pan Rill morphology Secondary headcut Soil erosion TLS
The authors would like to thank Dr. Glenn V. Wilson’s help in revising the English grammar, as well as Dr. Robert R. Wells, the editors, and anonymous reviewers for their valuable comments and suggestions.
This study was supported by the National Natural Science Foundation of China (Grant no. 41271299 and 4171101192), Opening Funds of MWR Key Laboratory of Soil and Water Loss Process and Control in the Loess Plateau (No. 2017001), Special-Funds of Scientific Research Programs of State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau (A314021403-C2), and China Scholarship Council.
- Brunton DA, Bryan RB (2000) Rill network development and sediment budgets. Earth Surf Proc Land 25(7):783–800. https://doi.org/10.1002/1096-9837(200007)25:7<783::AID-ESP106>3.0.CO;2-W CrossRefGoogle Scholar
- Favis-Mortlock DT, Boardman J, Parsons AJ, Lascelles B (2000) Emergence and erosion: a model for rill initiation and development. Hydrol Process 14(11-12):2173–2205. https://doi.org/10.1002/1099-1085(20000815/30)14:11/12<2173::AID-HYP61>3.0.CO;2-6 CrossRefGoogle Scholar
- Foster GR, Lane LJ, Mildner WF (1983) Seasonally ephemeral cropland gully erosion. Proceedings of Natural Resources Modeling Symposium. Pingree Park, CO., USA, 16–21:463–365Google Scholar
- Gómez JA, Darboux F, Nearing MA (2003) Development and evolution of rill networks under simulated rainfall. Water Resour Res 39(6):1148Google Scholar
- Gravelius H (1914) Flusskunde. Goschen’sche Verlagshandlung, Berlin, p 176Google Scholar
- Horton RE (1945) Erosional development of streams and their drainage basins. Hydrophysical approach to quantitative morphology. Bull Geol Soc Am 56(3):275–370. https://doi.org/10.1130/0016-7606(1945)56[275:EDOSAT]2.0.CO;2 CrossRefGoogle Scholar
- Lal R (2002) Gully erosion. Encyclopedia of soil science. Marcel Dekker, New York, pp 630–632Google Scholar
- Li G, Abrahams AD, Atkinson JF (1996) Correction factors in the determination of mean velocity of overland flow. Earth Surf Proc Land 21(6):509–515. https://doi.org/10.1002/(SICI)1096-9837(199606)21:6<509::AID-ESP613>3.0.CO;2-Z CrossRefGoogle Scholar
- Momm HG, Wells RR, Bennett SJ, Gilley A (2016) Image analysis for quantifying spatiotemporal evolution of rill networks in laboratory experiments. In: Garcia and Hanes (eds) Proceedings of the River-Flow 2016—Eighth International Conference on Fluvial Hydraulics; Constantinescu. Taylor & Francis Group, St. Louis, MO, U.S.A., July 12–15, 2016Google Scholar
- USDA NRCS (1999) Soil taxonomy: a basic system of soil classification for making and interpreting soil surveys. Agric. Handbook 436, 2nd edn. U.S. Government Printing Office, Washington, DCGoogle Scholar
- Wu Q, Wang L, Wu F (2014) Tillage—impact on infiltration of the loess plateau of China. Acta Agri Scandi, Section B—Soil Plant Sci 64(4):341–349Google Scholar
- Zhang HX (1983) The characteristics of hard rain and its distribution over the loess plateau. Acta Geograph Sin 38(4):416–425 (in Chinese with English Abstract)Google Scholar
- Zheng FL, Tang KL (1997) Rill erosion process on steep slope land of the loess plateau. J Sediment Res 12(1):52–59Google Scholar
- Zhou PH, Wang ZL (1987) Soil erosion rainfall standard in the loess plateau. Bull Soil Water Conserv 7(1):38–44 (in Chinese with English Abstract)Google Scholar
- Zhou PH, Zhang XD, Tang KL (2000) Rainfall installation of simulated soil erosion experiment hall of the State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau. Bull Soil Water Conserv 20(4):27–30 45 (in Chinese with English Abstract)Google Scholar
- Zhu XM (1956) Soil erosion classification at the loessial region. Acta Pedol Sin 4(2):99–116 (in Chinese)Google Scholar