Supplemental Material: Influence of hydrostratigraphy on the distribution of groundwater arsenic in the transboundary Ganges River aquifer system, India and Bangladesh

Details of methodologies and data used for the study along with ancillary figures.

Supplemental Material: Influence of hydrostratigraphy on the distribution of groundwater arsenic in the transboundary Ganges River aquifer system, India and Bangladesh

Details of methodologies and data used for the study along with ancillary figures.

Impacts of Land Use Change on Water Quality Index in the Upper Ganges River Near Haridwar, Uttarakhand: A GIS-Based Analysis

The water quality of rivers is deteriorating due to human interference. It is essential to understand the relationship between human activities and land use types to assess the water quality of a region. GIS is the latest tool for analyzing this spatial correlation. Land use land cover, and change detection are the best illustration for showing the human interactions with land features. This study assessed water quality index of the upper Ganges River near Haridwar, Uttarakhand, and spatially correlated it with changing land use to reach a logical conclusion. In the upper course of Ganges, along a 78-km stretch from Kaudiyala to Bhogpur, water samples were collected from five stations. For water quality index, physicochemical parameters like pH, EC, DO, TDS, CaCO3−, CaCO3, Cl−, Ca2+, Mg2+, Na+, K+, F−, Fe2+ were considered. The results of the spatial analysis were evaluated through error estimation and spatial correlation. The root mean square error between spatial land use and water quality index at the selected sampling sites was estimated to be 0.1443. The spatial correlation between land use change and site-wise differences in water quality index also showed a high positive correlation, with R2 = 0.8455. The degree of positive correlation and root mean square error strongly indicated that the water quality of the river in the upper course of the Ganges is highly impacted by human activities.

Spatial distribution of trace elements in surface sediments of Hooghly (Ganges) river estuary in West Bengal, India

The spatial distribution of trace elements in surface sediments of the Hooghly estuary was studied over the monsoons in 2014–2017. As, Cd, Ni, Pb and U were two- to sixteen-fold the crust means with increasing levels toward the estuary, with Ni peak during the post-monsoon. Pearson’s correlation matrix, cluster analysis, enrichment factors and pollution index revealed the anthropic source and association of trace elements with Fe, Mn and Al and of Pb with U. Geoaccumulation index revealed for Ni an extremely contaminated situation at the estuary water during monsoon and for Cd a heavily contaminated situation at freshwater location. The potential contamination index was >6; thus, sediments were very severely contaminated by As, Cd and Ni with worst situation for As and Cd at fresh and brackish water and during post-monsoon. The overall ecological risk was severe, 300≤RI<600 at all sites and seasons, especially after the monsoon, at fluvial and brackish locations.

Temporal variations of length, weight and condition of the Asian stinging catfish Heteropneustes fossilis (Bloch, 1794) in the Ganges river (NW Bangladesh)

The present study revealed on temporal variations of length, weight and condition of Heteropneustes fossilis (Bloch, 1794) in the Ganges River, Northwestern Bangladesh. Total 1161 individuals of H. fossilis were caught by various habitual fishing gears such as seine net, cast net and gill net during January to December 2019. For every specimen, body weight (BW) was taken by digital balance to the accuracy of 0.01 g and total length (TL) was taken using a measuring board. Relative condition factor (KR) was assessed by KR = W/(a×Lb), where W is the BW in g, L is the TL in cm and a and b are length-weight relationships parameters. The value of KR ~ 1 specifies good health, >1 specifies over bodyweight as compared to length, whereas <1 suggests a fish in poor condition. The TL varied from 8.5-28.7 cm whereas the BW was 37.17–2250 g. The overall KR for H. fossilis was 0.99-1.06 in the Ganges River. The highest KR was observed in May while the lowest was in January. The KR was significantly correlated with BW in the Ganges River. The outcomes of the study will be helpful for future management of this fish in the Ganges river ecosystem as well as adjacent water bodies. Res. Agric., Livest. Fish.8(2): 259-266, August 2021

Current Status of the Endangered Ganges River Dolphin (Platanista Gangetica), the Aquatic Megafauna in the Brahmaputra River System

The Ganges River Dolphin (Platanista gangetica) is the most charismatic aquatic species inhabiting rivers of India, Bangladesh, and Nepal. It is an endangered species that occurs both in the Brahmaputra and Barak river systems in Assam (India). In the Brahmaputra river system, the occurence of ‘hihu’ is primarily confirmed in the mainstream Brahmaputra, the Kulsi river of Kamrup district, and the Subansiri river of Lakhimpur district. The dolphins inhabit river confluences or tributary junctions followed by river meanderings with the prevalence of eddy counter-currents and prey-fish abundance. Of late, it has been observed that river dolphin population has declined at an alarming rate due to the potential threats including poaching for dolphin oil, by-catch, overfishing, net entanglements, sand mining, habitat destruction through aquatic pollution, construction of dams, and lack of awareness. The species is left only in certain pockets of the Brahmaputra River. Thus, there is an urgent need for the conservation of this endangered species in its natural habitats. Effective protection of this endangered aquatic megafauna requires elimination and management of the potential threats. This review provides an overview of the distribution and population status, ecology, and management strategies and recommendation to increase awareness for its long-term conservation.

Salinity and food security in southwest coastal Bangladesh: impacts on household food production and strategies for adaptation

The rising salinity of land and water is an important, but understudied, climate change-sensitive trend that can exert devastating impacts on food security. This mixed methods investigation combines salinity testing with qualitative research methods to explore these impacts in one of the most salinity-affected regions in the world—the Ganges River Delta. Data collection in 2015 and 2016 undertaken in Bangladesh’s southwest coastal region and Dhaka consisted of 83 in-depth household and stakeholder interviews, six community focus groups, and salinity testing of 27 soil and 45 surface and groundwater samples. Results show that household food production is a multifaceted cornerstone of rural livelihood in the southwest coastal region, and virtually every component of it—from rice plantation and homestead gardening to livestock cultivation and aquaculture—is being negatively affected by salinity. Although households have attempted multiple strategies for adapting food production, effective adaptation remains elusive. At the community level, improved irrigation and floodplain management, as well as restrictions on saltwater aquaculture to abate salinity, are viewed as promising interventions. However, the potential of such measures remains unrealized on a broad scale, as they require a level of external resources and regulation not yet provided by the NGO and government sectors. This study elucidates issues of accessibility, equity, and governance surrounding agricultural interventions for climate change-related salinity adaptation, and its findings can help inform the community of organizations that will increasingly need to grapple with salinity in order to guarantee food security in the context of environmental change.