Abstract
Abstract The Lower Indus reaches – Guddu and Sukkur – are among the most complicated areas in terms of reach migration. Both climate change and human activities in recent periods along with pond system operation accelerated riverine channel morphology. A GIS-based approach using multi-temporal Landsat images (1986–2020) was employed to characterize the morphometric parameters. Results showed that width of the study reaches varied from 2.1 to 12 km. The braiding index (BI) value for Guddu reach varied from 3.47 to 7.18, and BI value for Sukkur reach varied from 2.11 to 4.92. It is observed that no erosive activity of banks occurred for peak runoff value of <5,880 m3s−1. The sediment load during low flow (LF) period was estimated to be 0.715 million tons/day which comprised 77% fine sediment and 23% sand. The sediment load during high flood (HF) period was about 1.296 million tons/day. The median size (D50) of bed material during the HF period was 0.101–0.206 mm and during LF period was <0.0625 mm. The rough set theory (RST) showed that velocity, shear stress, slope, runoff, and sediment load factors are major contributors to the river shape changes. This study is a standpoint of planning flood recovery, riverine regulations, and navigation safety.
Highlights
River morphology is highly related to environmental conditions (Eaton et al 2010; Rozo et al 2014), and geometry of the alluvial channel changes due to variable rates of water and sediment inputs, climate variability, and human activities such as flow diversion, construction of dams, and deforestation (Dewan et al 2017)
The centerline of the Indus River regime at Guddu reach represents the steady state with a few typical reaches such as at Ghotki, Khanpur, Pano Aqal, and Rohari tending to a meandering form (Figure 3(a))
6.721 million tons (MT) of sediment was diverted into tail channel (TC), 0.489 MT (7% of sediment inflow) was deposited in TC
Summary
River morphology is highly related to environmental conditions (Eaton et al 2010; Rozo et al 2014), and geometry of the alluvial channel changes due to variable rates of water and sediment inputs, climate variability, and human activities such as flow diversion, construction of dams, and deforestation (Dewan et al 2017). A change of river geometry will result in an imbalance dynamic equilibrium (Petts & Gurnell 2005), perturbing the channel form and pattern. These activities cause deterioration of the river conditions, such as hydro-geomorphology, bank erosion, and bank failure (Yang et al 2015), and adversely affect the ecosystem and biodiversity ( Jain 2012). Based on a literature review, understanding the channel form and pattern due to unstable river conditions is essential to develop modeling and management schemes for such rivers
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