Assessing ecological sustainability of the Narmada River using the macrophyte river index

Abstract

Narmada River, one of the largest waterways in India, plays a critical role in supporting aquatic ecosystems. This study examines the relationship between macrophyte diversity and nitrogen levels across fifteen sampling stations (A1-A15) in the central India (Anuppur, Dindori, Mandla, and Jabalpur) during the pre-monsoon seasons. Three macrophyte indices like RMNI (River Macrophyte Nutrient Index), MIR (Macrophyte Index for Rivers), and RMHI (River Macrophyte Hydraulic Index) were employed to assess ecological conditions and water quality. A total of 20 macrophyte species from 14 families were identified, with Lemna minor, Potamogeton pectinatus, Polygonum persicaria, Ceratophyllum demersum, Persicum hydropiper, and Potamogenton natans being the most prevalent in nutrient-rich environments. The principal component analysis is conducted to identify the similarities in the variables and to extract the key factors that exhibit strong internal correlations while remaining distinct from other factors. The analysis revealed significant spatial variability across monitoring stations, with A-5, A-6, A-10, A-11, A-12, A-13, A-14, and A-15 exhibiting elevated orthophosphates concentration. Notably, station A5 showed moderate level of DO, BOD and COD, whereas sulfate was comparatively low. These findings underscore the heterogeneity of water quality conditions along the Narmada River and highlight the influence of localized anthropogenic inputs. The clustering analysis grouped stations on their ecological status, highlights variations in macrophytes indices and water quality parameters. This study highlights the macrophytes' utility as ecological indicators for assessing riverine nutrient dynamics and overall environmental health, and further emphasizing the need for site-specific interventions to mitigate pollution and enhance ecological resilience.