Wetlands, critical ecosystems that provide immense ecological and socioeconomic benefits, are facing severe degradation worldwide due to anthropogenic activities such as urbanisation, agriculture, and pollution. Among these threatened wetlands, Kabartal wetland in Bihar, India, holds special significance as Asia's largest freshwater ox-bow lake and the first Ramsar-designated wetland of the state.
Spanning an area of 2620 hectares, it serves as a vital bird sanctuary supporting 166 bird species, including migratory species like the Siberian Crane and the Black-necked Stork. However, increasing encroachment, land-use changes, and declining water quality and quantity have raised concerns about its sustainability.
This paper ‘Geospatial approach to identify the indicators of wetland change: A study for Kabartal (Ramsar Wetland), India’ explores the findings of a comprehensive geospatial and physicochemical analysis of Kabartal wetland conducted over a timeline from 1989 to 2023 and highlights the key indicators of wetland change, driving forces of degradation, and necessary conservation measures.
Methodology
The study employed an integrated approach, utilising LANDSAT data, statistical tools, and field analyses to examine the changes in land use and land cover (LULC), vegetation indices, soil and water quality, and the correlation between core and buffer zones of the wetland.
Key geospatial indices such as the Normalised Difference Vegetation Index (NDVI) and Modified Normalised Difference Water Index (MNDWI) were calculated to monitor vegetation and water bodies. Water and soil samples from seven locations were analysed for physicochemical parameters, including pH, electrical conductivity (EC), total dissolved solids (TDS), and nutrient concentrations. The study delineated the core wetland zone (26.02 km²) and an extended buffer zone (623.08 km²) to assess changes systematically.
Key Findings
Land Use and Vegetation Trends
NDVI Analysis: NDVI trends from 1989 to 2023 revealed a consistent decline in dense vegetation and an increase in sparse vegetation in both the core and buffer zones. In the core zone, vegetation decreased from 106 km² in 1989 to 78.6 km² in 2023, while water areas declined significantly, from 16.10 km² in 1989 to 5.08 km² in 2023. Similar trends were observed in the buffer zone, where vegetation reduced by over 70% during the same period.
MNDWI Analysis: Water bodies in the buffer zone also exhibited a steep decline, with water-covered areas shrinking from 55.83 km² in 1989 to 14.56 km² in 2023. The maps highlighted transitions from water bodies to agricultural and built-up areas due to urbanisation and encroachment.
LULC Classification: The LULC maps indicated significant increases in agricultural land and built-up areas in both zones. Agriculture in the core zone expanded from 5.08 km² in 1989 to 9.13 km² in 2023, while built-up areas increased moderately.
Water Quality Assessment
Water quality remained within permissible limits according to CPCB guidelines, but the high electrical conductivity and increased levels of nitrate and phosphate during both pre- and post-monsoon seasons indicated agricultural runoff as a major contaminant source. Correlation analyses showed strong positive relationships between nitrate and phosphate levels.
Seasonal variations in parameters such as pH, TDS, and alkalinity reflected the influence of agricultural practices and precipitation patterns. Pre-monsoon data indicated higher nutrient concentrations due to evaporation and reduced water flow, while post-monsoon data showed dilution effects.
Soil Analysis
The soil samples revealed significant concentrations of macro and micronutrients, including calcium (Ca), magnesium (Mg), and potassium (K), primarily sourced from agricultural runoff and fertilisers. Heavy metals such as lead (Pb) and cadmium (Cd) were also detected, indicating potential contamination from both point and non-point sources.
The elemental analysis through EDS highlighted the abundance of silicon (Si), oxygen (O), and aluminum (Al), which can influence nutrient cycling and wetland productivity. However, excessive silicon was linked to diatom blooms, potentially depleting oxygen levels in water bodies.
Hydrological and Climatic Insights
The Kabartal wetland, fed by tributaries of the Ganga River, benefits from seasonal flooding, which deposits nutrient-rich sediments. However, this natural hydrological process is increasingly disrupted by groundwater extraction and agricultural water diversion.
Precipitation data showed a positive correlation with vegetation health in the buffer zone but limited direct influence on the core wetland. Monsoon rains contributed to temporary improvements in water levels, while pre- and post-monsoon seasons exhibited declining trends in water availability.
Driving Forces of Degradation
The study identified agriculture and urbanisation as the primary drivers of wetland degradation. Agricultural expansion, particularly into wetland areas, has led to increased runoff of fertilisers and pesticides, introducing high concentrations of nitrate and phosphate into the ecosystem. This nutrient loading promotes eutrophication, resulting in oxygen depletion and affecting aquatic life.
Encroachment by built-up areas has altered natural hydrological patterns and reduced water retention capacity. Urban sprawl and infrastructural development have contributed to habitat fragmentation, reducing biodiversity and ecological balance. Groundwater extraction for irrigation purposes further exacerbates the water deficit in the wetland, particularly during the pre-monsoon season.
Additionally, population growth in the Begusarai district has placed increasing pressure on the wetland to meet water and agricultural needs. The district’s population grew by 26.44% between 2001 and 2011, with further increases projected. The lack of effective waste management has led to the discharge of untreated wastewater into the wetland, compounding pollution levels.
Field interactions revealed that local livelihoods are heavily dependent on the wetland for agriculture, fishing, and other activities, driving unsustainable exploitation. The absence of adequate conservation policies and poor enforcement of existing regulations have further accelerated degradation.
Conservation Strategies and Recommendations
To ensure the sustainable management of Kabartal wetland, the following conservation strategies are recommended:
Policy and Regulation
Implement stringent laws to curb illegal encroachment and regulate groundwater extraction.
Introduce specific guidelines for nutrient and pesticide use in agriculture to prevent excessive runoff into the wetland.
Strengthen enforcement mechanisms to monitor industrial and domestic wastewater discharge, ensuring compliance with environmental standards.
Community Engagement
Organise awareness programmes targeting farmers and local residents to promote sustainable practices, such as using biofertilisers and adopting water-efficient irrigation techniques.
Establish community-led wetland conservation committees to ensure local participation in decision-making and management.
Monitoring and Research
Develop a centralised database to monitor changes in LULC, water quality, and biodiversity using remote sensing and GIS technologies.
Conduct periodic assessments of hydrological connectivity and the impacts of climate variability to inform adaptive management strategies.
Encourage academic partnerships to study the long-term impacts of pollutants and propose innovative restoration techniques.
Restoration Initiatives
Rehabilitate degraded areas by planting native vegetation and creating artificial water channels to improve hydrological flow.
Introduce floating treatment wetlands (FTWs) to naturally filter pollutants and enhance water quality.
Promote the reintroduction of native fish and bird species to restore ecological balance.
Resource Allocation
Allocate sufficient financial resources to implement large-scale restoration projects and enforce conservation measures.
Build capacity among local stakeholders by providing training on wetland management and sustainable livelihood practices.
Collaborate with national and international organisations to access technical expertise and funding support.
Incentivise Sustainable Practices
Provide subsidies or incentives for adopting eco-friendly farming practices near the wetland.
Promote ecotourism initiatives to generate alternative income sources while raising awareness about the importance of wetland conservation.
Kabartal Wetland, a unique and vital ecosystem, faces significant challenges due to anthropogenic pressures and climate variability. The study underscores the urgency of adopting targeted conservation strategies to mitigate the driving forces of degradation and restore the wetland's ecological balance.
By integrating scientific research with community participation and policy interventions, Kabartal Wetland can be preserved as a thriving habitat for biodiversity and a source of livelihood for local communities. Sustainable management of this Ramsar site will also contribute to broader regional and global wetland conservation efforts, reinforcing the critical role of wetlands in climate resilience and ecological stability.
The full paper can be accessed here