Tracing Morphological Transformations and Braiding Dynamics in the Himalayan Rivers of Nepal

IF 4.5 Q2 ENVIRONMENTAL SCIENCES

Remote Sensing Applications-Society and Environment Pub Date : 2025-08-01 DOI:10.1016/j.rsase.2025.101705

Bishwas Bhatta , Umesh Singh , Basanta Raj Adhikari , Saroj Karki , Astha Bhatta

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引用次数: 0

Abstract

This study quantifies multi-decadal (1990–2022) planform change and braiding behavior in three Himalayan rivers of Nepal: The Koshi, Narayani, and Karnali using a unified geospatial workflow. Multi-temporal Landsat and Sentinel-2 imagery were processed with water-detection indices (MNDWI, NDWI) to extract channel boundaries and map erosion, accretion, and persistence. High-frequency gauge records were used to derive discharge and examine functional relations between wetted-area ratio and flow, and 180 Sentinel-2 scenes (2017–2022) supported braiding-intensity (BI_T3) estimation and bar-scale assessment at sub-reach level. Results show strong river-specific contrasts: the Koshi exhibits the greatest adjustment, with only 32.5 % channel persistence and a pronounced westward lateral migration, whereas the Narayani and Karnali are comparatively stable, with 64.8 % and 54.5 % unchanged areas, respectively. Functional analyses indicate distinct sensitivities of wetted-area ratio to daily maximum discharge, and braiding intensity peaks at intermediate flows before attenuating at higher discharges. Focused sandbar analysis (2017–2022) in the Koshi reach reveals persistent bifurcation asymmetry and directional bar migration, consistent with post-monsoon redistribution of flow and sediment. By linking satellite-derived morphology to real-time discharge within a consistent, transferable framework, the study provides robust, repeatable indicators for monitoring Himalayan braided rivers and establishes a basis for comparative evaluation of planform stability and braiding across data-sparse systems.

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追踪尼泊尔喜马拉雅河流的形态转变和编织动力学

本研究使用统一的地理空间工作流量化了尼泊尔三条喜马拉雅河流：Koshi、Narayani和Karnali的多年代际（1990-2022）平台变化和编织行为。利用水探测指数（MNDWI、NDWI）对多时相Landsat和Sentinel-2图像进行处理，提取河道边界，绘制侵蚀、增生和持续性图。利用高频测量记录推导流量，并检验湿面积比与流量之间的函数关系，180个Sentinel-2场景（2017-2022）支持河段编织强度（BIT3）估算和条形尺度评估。结果显示出强烈的河流特异性对比：Koshi表现出最大的调整，只有32.5%的河道持续存在，并有明显的向西横向迁移，而Narayani和Karnali则相对稳定，分别有64.8%和54.5%的区域未改变。功能分析表明，湿面积比对日最大流量有明显的敏感性，编织强度在中等流量时达到峰值，在高流量时减弱。重点沙洲分析（2017-2022）表明，Koshi河段持续的分岔不对称和定向沙洲迁移与季风后的流沙再分布一致。通过在一致的、可转移的框架内将卫星衍生的形态与实时流量联系起来，该研究为监测喜马拉雅辫状河提供了可靠的、可重复的指标，并为跨数据稀疏系统的平台稳定性和辫状河的比较评估奠定了基础。

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来源期刊

Remote Sensing Applications-Society and Environment Multiple-

CiteScore

8.00

自引率

8.50%

发文量

204

审稿时长

65 days

期刊介绍： The journal ''Remote Sensing Applications: Society and Environment'' (RSASE) focuses on remote sensing studies that address specific topics with an emphasis on environmental and societal issues - regional / local studies with global significance. Subjects are encouraged to have an interdisciplinary approach and include, but are not limited by: " -Global and climate change studies addressing the impact of increasing concentrations of greenhouse gases, CO2 emission, carbon balance and carbon mitigation, energy system on social and environmental systems -Ecological and environmental issues including biodiversity, ecosystem dynamics, land degradation, atmospheric and water pollution, urban footprint, ecosystem management and natural hazards (e.g. earthquakes, typhoons, floods, landslides) -Natural resource studies including land-use in general, biomass estimation, forests, agricultural land, plantation, soils, coral reefs, wetland and water resources -Agriculture, food production systems and food security outcomes -Socio-economic issues including urban systems, urban growth, public health, epidemics, land-use transition and land use conflicts -Oceanography and coastal zone studies, including sea level rise projections, coastlines changes and the ocean-land interface -Regional challenges for remote sensing application techniques, monitoring and analysis, such as cloud screening and atmospheric correction for tropical regions -Interdisciplinary studies combining remote sensing, household survey data, field measurements and models to address environmental, societal and sustainability issues -Quantitative and qualitative analysis that documents the impact of using remote sensing studies in social, political, environmental or economic systems