Assessing the hydromorphological condition of the Sub-Himalayan Mahananda-Balason system using the hydromorphological quality Index

• Published in: Advances in space research 2023-02, Vol.71 (3), p.1397-1417
• Main Authors: Mitra, Suman, Chatterjee, Ankana, Kumar De, Sunil, Datta, Debajit, Tamang, Lakpa
• Format: Article
• Language: English
• Subjects: Anthropogenic alterations; Hydromorphology; Least altered condition; Multiple Correspondence Analysis; REFORM; Sub-Himalayan foothills
• ISSN: 0273-1177
• DOI: 10.1016/j.asr.2022.09.037

•Hydromorphological quality was assessed with modified MQI of Rinaldi et al. 2013.•Confined reaches showed better hydromorphological quality than unconfined reaches.•Unconfined reaches degraded by sediment extraction, embanking, and urbanization.•In response, the width of unconfined reaches was narrowed by > 50 % during 1968–2020.•This protocol can be useful in hydromorphological assessment of data scarce regions. An evaluation of the hydromorphological condition of the Mahananda-Balason River system of the sub-Himalayan foothills, West Bengal, India was attempted using a multiparameter-based Hydromorphological Quality Index (HQI). After segmenting these rivers based on continuity, bed material and channel planform, a total of 18 indicators, divided into 3 subgroups Continuity (C), Planform (P), and Floodplain Morphology (FM), were quantified reach-wise and scaled upon the level of alteration (1 for highly altered and 5 for no alteration). The derived overall HQI (3.6) exhibited a moderate hydromorphological quality of the system, however, significant differences between the HQIs of confined and unconfined reaches were witnessed. Students ‘t-test and Multiple Correspondence Analysis both portrayed vast dissimilarities among the confined and unconfined reaches and the clustering was depending on their confinement. The deviations measured from the system’s mean and least altered conditions portrayed that the confined reaches with lesser human interventions were in comparatively more pristine hydromorphological conditions. Conversely, unconfined reaches showed moderate to very poor hydromorphological conditions chiefly due to intense human-induced alterations regarding urbanization, embanking and sediment extraction. Restorations on these aspects should initiate with immediate effect to avoid a shortage of riverine resources such as fluvial sediment, fish and groundwater. Overall, this methodology was found suitable for continuous monitoring of the river systems along with the precise identification of areas and aspects to be restored for upgrading the hydromorphological quality. More testing of this methodology would eventually help in validating the hydromorphological quality assessment protocol for Indian rivers.