Streambank Erosion Susceptibility Index and Flood-prone Area Mapping along the Karra River, Hetauda, Central Nepal Sub-Himalaya
Keywords:Streambank Erosion Susceptibility Index (SESI), Near Bank Stress Index (NBSI), Entrenchment Ratio (ER), Floor-prone area, Siwalik
The Karra River, one of the major tributaries of the Rapati River, is the 5th order stream that extends for about 21.91 km length in 92 sq. km. of watershed area. It is situated in the southern region of the Hetauda City, which is under the rapid development as a settlement and industrial area. The Karra River area is frequently impacted by streambank erosion and flooding during the heavy rainfall in monsoon due to loosely consolidated sedimentary terrain of the Upper Siwalik Subgroup and the unconsolidated Late Quaternary Deposits, which are vulnerable to erosion. Morpho-hydraulic parameters and stream cross-sectional characteristics and parameters of streambank erosion susceptibility index (SESI) rating system were assessed along the Karra River at 19 transects. The rating of the SESI are based on bank angle, bank height ratio, root depth ratio, root density, surface protection, bank materials and characteristics of stratification. The flood-prone area map was prepared based on the morpho-hydraulic parameters of the stream based on the maximum bankfull depth. The ER and W/D ratio were estimated to determine the affinity of flooding and lateral instability of the stream. Near Bank Stress Index and SESI dealt with streambank erosion potential were assessed to estimate the streambank erosion rate.
(2) Jacobson, R.B., and A.T. Primm, et al., Historical land-use changes and potential effects on stream disturbance in the Ozark Plateaus, Missouri, 1997. USGS Water-Supply Paper 2484. Denver, Colorado, U.S. Geological Survey, 1997.
(3) Lane, E. W., et al., The importance of fluvial geomorphology in hydraulic engineering. Proc ASCE 81(745): p. 1-17.
(4) Thorne, C.R., et al., Processes and Mechanisms of River Bank Erosion, in Gravel-Bed Rivers: Fluvial Process, Engineering and Management, R.D. Hey, J.C. and C.R. Thorne edited by Wileyand and Sons, Chichester, England, 1982, p. 227-221.
(5) Tamrakar, N. K. and Karki, B., et al., Geomorphometric properties and varaibility of sediment delivery ratio and specific sediment yield among sub-basins of the Karra River, Hetauda, central Nepal Sub-Himalaya, Journal of Nepal Geological Society, 2019. v. 59, p. 19-37.
(6) Tokuoka, T., Takayasu, M. Yoshida and K. Hisatomi, et al., The Churia (Siwalik) Group of the Arung Khola area, West Central Nepal. Mem. Fac. Sci., Shimane Univ., 20: 135-210. West, R.M., and Munthe, J. 1981 Cenozoic vertebrate palaeontology and stratigraphy of Nepal. Himalaya Geology. 1986. v. 11., p. 18-27
(7) Gautam, P. and Rösler, W., et al., Depositional chronology and fabric of Siwalik Group sediments in Central Nepal from magentostratigraphy and magnetic anisotropy. Journal of Asian Earth Sciences. 1999. v. 17, issue 5-6, p. 659-682.
(8) Rosgen, D. L., et al., A stream Channel Stability Assessment Methodology. Federal Interagency Sediment Conference. 2001, March 25-29, Reno, Nevada, p. 18-26.
(9) Rosgen, D. L., et al., Applied River Morphology. Wildland Hydrology Books, edited by Pagosa springs, Colorado. 1996. P. 6-42.
(10) Rosgen, D.L., et al., Stream Classification using the Rosgen System. Stream Classification using the Rosgen System. Companion Document, EFH Notice 210-WI-119 February 2009.
(11) Rosgen, D. L., et al., A Practical Method of Computing Streambank Erosion Rate. Proceedings of Seventh Federal Interagency Sediment Conference 2001 March 24-29, Reno, Nevada, p. 9-17.
(12) Shields, A., et al., Application of similarity priciples and turbulent research to bed-load movement. In: W.P. Ottand J.C. Uchelen (translators), Mitt. Preuss, Verschsanst, Berlin. Wasserbau Schifbau, California Institute of Technology, Pasadena, 1936. CA, Report No. 167, p. 143.
(13) Leopold, L.B., Wolman G.M., and Miller J.P., et al., Fluvial Process in Geomorphology. W.H. Freeman and Co. San Fracisco, 1964, p. 522.
(14) Doll, B.A., G.L. Grabow, K.R., J. Halley, W.A. Harman, G.D. Jennings and D.E. Wise, et al., Stream Restoration: A Natural Channel Desighn Handbook. North Carolina Stream Restoration Institute, North Carolina State University and North Carolina Sea Grant. 2003. 128p.