Rill Hydraulics - An Experimental Study on Gully Basin in Lateritic Upland of Paschim Medinipur, West Bengal, India

Abstract

This paper reports the results of field investigations aimed to establish relationship between morphologic and hydraulic characteristics of rills. A rill network within a small Rangamati Gully Basin, on the bank of Kansai at Paschim Medinipur, in West Bengal, India of 256 m 2 was mapped. Experimental basin is exposed to natural rainfall of varying intensity and characterised with an average of 25-35% slope gradient. The depth, length, gradient, width, runoff contributing areas of all the 33 rills within the basin were recorded and thoroughly mapped. Present study incorporates close monitoring of runoff and velocity along the channels during a storm on 31.08.2010 at 15 minutes interval using dye tracer technique. The velocity along each rill was linked with gradient, width-depth ratio and Manning's roughness coefficient. Analysis shows that flow velocity is not directly controlled by rill gradient (R 2 =0.15), but is influenced by hydraulic roughness coefficient (R 2 =0.53). Finally, the relationship between Reynolds number and Froude number reveals that sub-critical turbulent flow is responsible for rilling process. No significant relationship between W/D ratio and channel roughness (n) can be established (R 2 =0.083) by the present study.

Assessment of Factors Affecting Ephemeral Gully Development in Badland Topography: A Case Study at Garbheta Badland (Pashchim Medinipur,

“…We also observed that the overall retreat of gully head had very strong and positive relationship with the RCA (r = 0.89, p < 0.001). The result is also corroborated with the previous study [34][35][36]. It may be due to the effect of huge volume of soil loss from these gully slopes be prejudiced by the upslope contribution of runoff and sediment.…”

Modeling of potential gully erosion hazard using geo-spatial technology at Garbheta block, West Bengal in India

“…However, the present result is corroborated with previous study carried out by Bandyopadhyay (1998) in other regions of West Bengal. Site-specific factors such as gully bank height, soil properties, and the length of the drying period affect crack development (Oostwoud Wijdenes and Bryan, 1994;Shit and Maiti 2012b). Results illustrated in our study identified the slope with [20°h aving the maximum influence on gully occurrence.…”

Estimation of Forest Canopy Cover and Forest Fragmentation Mapping Using Landsat Satellite Data of Silabati River Basin (India)

“…2). The upper course of the basin is characterized by very undulating surface whereas lower course is composed by plain topography with isolated lateritic soil pockets (Shit and Maiti 2012). The upper and middle courses of the river basin have high lateritic concentration and hydro-geologically, these areas are also characterized by high-iron (Fe) content, high leaching capacity and also low water-holding capacity (Ghosh and Guchhait 2015).…”

“…Subsequently, the middle and lower reaches are more vulnerable with respect to the upper reach (Mahala 2019). The extensive rill and gully erosion are one more significant hydro-geomorphic characteristic in the middle and upper reaches whereas gully is being accelerated towards the head (Shit and Maiti 2012). Ghatal and Khirpai Township areas are the high flood susceptible zones because almost every year, people are experiencing devastating flood hazard due to strategic geographical locations and unscientific human intervention within the river valley.…”