中国地理科学 ›› 2020, Vol. 30 ›› Issue (5): 900-920.doi: 10.1007/s11769-020-1143-y

• 论文 • 上一篇    

Downstream Decreasing Channel Capacity of a Monsoon-dominated Bengal Basin River: A Case Study of Dwarkeswar River, Eastern India

MALIK Sadhan, PAL Subodh Chandra   

  1. Department of Geography, University of Burdwan, Burdwan 713104, West Bengal, India
  • 收稿日期:2019-08-14 修回日期:2019-11-29 发布日期:2020-06-23
  • 通讯作者: PAL Subodh Chandra.E-mail:geo.subodh@gmail.com E-mail:geo.subodh@gmail.com
  • 基金资助:
    under the auspices of the University Grants Commission (No. 21595/(NET-DEC.2013), F.15-6(DEC.2013))

Downstream Decreasing Channel Capacity of a Monsoon-dominated Bengal Basin River: A Case Study of Dwarkeswar River, Eastern India

MALIK Sadhan, PAL Subodh Chandra   

  1. Department of Geography, University of Burdwan, Burdwan 713104, West Bengal, India
  • Received:2019-08-14 Revised:2019-11-29 Published:2020-06-23
  • Contact: PAL Subodh Chandra.E-mail:geo.subodh@gmail.com E-mail:geo.subodh@gmail.com
  • Supported by:
    under the auspices of the University Grants Commission (No. 21595/(NET-DEC.2013), F.15-6(DEC.2013))

摘要: Downstream changes in channel morphology and flow over the ephemeral Dwarkeswar River in the western part of the Bengal Basin, eastren India were investigated. The river stretches from the Proterozoic Granite Gneiss Complex to the recent Holocene alluvium, forming three distinctive geomorphological regions across the river basin:the pediplane and upper and lower alluvial areas. Sixty cross-sections from throughout the main trunk stream were surveyed and the bankfull width, depth, cross-sectional area, and maximum depth were measured. Sediment samples from each location were studied and the flow velocity, stream power, Manning's roughness coefficient, and shear stress were estimated. The results show that the bankfull channel cross-section area, width, width-to-depth ratio, and channel capacity increased between the beginning and middle of the river. Thereafter, the size of the river started to decrease in the lower alluvial area. This was characterized by gentle gradients, cohesive bank materials with grass cover, and channel switching. Within the lower part of the river, the channel capacity was observed to diminish as the drainage area increased. This increased the bankfull flow frequency and accelerated large floodwater losses in the floodplain via overbank flows and floodways.

关键词: bankfull channel width, bankfull discharge, Dwarkeswar River, flat alluvial plain, channel degradation, overbank flow and flood

Abstract: Downstream changes in channel morphology and flow over the ephemeral Dwarkeswar River in the western part of the Bengal Basin, eastren India were investigated. The river stretches from the Proterozoic Granite Gneiss Complex to the recent Holocene alluvium, forming three distinctive geomorphological regions across the river basin:the pediplane and upper and lower alluvial areas. Sixty cross-sections from throughout the main trunk stream were surveyed and the bankfull width, depth, cross-sectional area, and maximum depth were measured. Sediment samples from each location were studied and the flow velocity, stream power, Manning's roughness coefficient, and shear stress were estimated. The results show that the bankfull channel cross-section area, width, width-to-depth ratio, and channel capacity increased between the beginning and middle of the river. Thereafter, the size of the river started to decrease in the lower alluvial area. This was characterized by gentle gradients, cohesive bank materials with grass cover, and channel switching. Within the lower part of the river, the channel capacity was observed to diminish as the drainage area increased. This increased the bankfull flow frequency and accelerated large floodwater losses in the floodplain via overbank flows and floodways.

Key words: bankfull channel width, bankfull discharge, Dwarkeswar River, flat alluvial plain, channel degradation, overbank flow and flood