Demystifying the impacts of dredging on the physicochemical characteristics of wetland sediments in Kashmir Himalaya

Abstract

The potential impacts of dredging on the physicochemical characteristics of sediments are poorly understood in the Himalayas. The present study was conducted to examine the impacts of dredging activities on the sediment physicochemical characteristics of Brari Nambal wetland located in Kashmir Himalaya. A UWITEC gravity corer was employed to retrieve the sediment core from the wetland. The sediment core was subsampled at regular 2 cm intervals, air dried, powdered, and removed of any foreign materials. The sediment samples were examined for various physicochemical variables pH, salinity, organic matter (OM), organic carbon (OC), phosphorus (P), nitrogen (N), total dissolved solids (TDS), electrical conductivity (EC), and carbon/nitrogen (C/N) ratio following standard procedures. The vertical variations in the concentration of physicochemical parameters showed a strong heterogeneity throughout the length of the core. The C/N ratio revealed that the primary productivity and inflows of sewage and raw faecal matter from the catchment are the principal sources of nutrient enrichment to the wetland. Regression analysis displayed significant (p < 0.05) positive and negative associations among various physicochemical parameters highlighting the role of EC, OC, and depth in the differences and overall distribution of different physicochemical variables. Principal component analysis (PCA) lead to the formation of two principal components (PCs) with PC1 and PC2 accounting for 49% and 22% of variation respectively. One-way Analysis of variance (ANOVA) test was carried out between the sediment physicochemical characteristics of a dredged (Brari Nambal) and an un-dredged (Khushalsar) wetland. The results of the ANOVA test revealed that significant (p < 0.05) variations in various physicochemical parameters such as pH, N, and C/N exist between the dredged and un-dredged wetlands. The findings of the study demonstrate that dredging can be adopted as a viable method of wetland restoration for preventing eutrophication and increasing the water storage capacity of the wetland ecosystems. The study's findings can serve as benchmark data for wetland restoration for other urban wetlands across the Himalayas.