Author(s): Resmi S R; P. L. Patel; P. V. Timbadiya
Linked Author(s): Prem Lal Patel, Prafulkumar V Timbadiya
Keywords: Geomorphic effectiveness; Gumbel’s distribution; Hydraulic geometry equations; Miller-Magilligan threshold
Abstract: Present study aims to evaluate the geomorphic effectiveness of daily annual peak flows in Upper and Middle Tapi Rivers, India. As part of analyzing the effectiveness of peak flows in shaping the channel morphology, at-site flood frequency relationships have been developed using Gumbel’s Distribution for two stream gauging stations, Dedtalai, and Burhanpur, which fall on Upper Tapi River and Gidhade and Sarangkheda, that fall on Middle Tapi River, using the daily annual peak flows. Hydraulic geometry equations have been developed for aforesaid stations, using the daily annual peak flows and prevailing cross-sectional details, on a decadal basis, i.e., 1980-1989, 1990-1999 and 2000-2010. The peak flows are categorized into low flows, medium flows, floods and large floods, based on their return periods. The results indicate that the width-depth ratios remain high at low flows (Qr) which occur on an average of more than once every year and takes minimum values during floods of return period more than 8.32 years. The unit stream power values were observed to vary between 3.45 - 151.34 W/m² during 1980-1989, 26.08 - 306.87 W/m² during 1990-1999 and 16.07 - 216.14 W/m² during 2000-2010 at various stations in Tapi Basin. However, the Miller-Magilligan threshold for major modification of channel or fluvial landscape (300 W/m²) was exceeded only once within the gauge period, at Burhanpur stream gauging station during the flood year of 1998. The channel morphology of Tapi River has been observed to get adjusted to the flood events, without any significant modifications in the channel form.
Year: 2018