Prioritise conserving peri-urban wetlands

Wetlands are multi-functional landscapes between terrestrial and aquatic ecosystems that provide habitat for wildlife, support groundwater recharge, moderate climate, control flood and fulfill the livelihood of the communities. Covering nearly 12% of the global area, these contribute significantly to ecosystem services, sustaining human well-being.

Despite their vital role in curbing greenhouse gas emissions and promoting ecological stability, wetlands face threats from rapid urban expansion and anthropogenic activities. The decline in wetland area globally, particularly in developing nations like India, is a cause for concern. Urban and peri-urban wetlands, vital for sustainable development, are experiencing unprecedented loss due to unplanned land use changes. This loss poses challenges to urban living conditions, especially in fast-growing cities.

The concept of ecosystem health, introduced by Rapport et al. (1985), emphasises the stability and sustainability of ecosystems. Various models and methods, including remote sensing and GIS, have been employed to assess ecosystem health. This study assessed the ecosystem health of urban and peri-urban wetlands of Lucknow district in India and recommended a sustainable solution for their management.

Remote sensing data derived from the normalized difference vegetation index, modified normalized difference water index, and land use/land cover change were utilised for analysing the spatiotemporal change in areas under wetlands, from 1989 to 2018. Site-specific indicators on pressure, state and response were integrated in FRAGSTATS-based assessment to construct a Pressure-State-Response (PSR) model. A qualitative field survey has been conducted through focus group discussion and expert opinion to validate the result from the PSR model.

The study focuses on Lucknow district in central India, encompassing urban, peri-urban, and rural areas. Lucknow experiences a sub-tropical climate with distinct seasons. The district has witnessed a significant increase in urban areas and population due to migration and rapid growth. Natural wetland ecosystems, including lakes, ponds, rivers, and oxbow lakes, cover around 9670 ha, facing threats from anthropogenic pressures. The biodiversity of these wetlands is under threat, emphasising the need for effective conservation measures.

The study employed Landsat satellite imagery from 1998, 2008, and 2018 to construct land use/land cover (LULC) maps and extract wetlands during pre and post-monsoon seasons. To model urban, peri-urban, and rural areas, a classification scheme based on population density, built-up density, and road density was employed. Wetland degradation rates during pre and post-monsoon seasons from 1998 to 2018 were determined, and landscape metrics were derived for analysis.

The Pressure State Response (PSR) model was applied using site-specific indicators for ecosystem pressure, state, and response. Ecosystem Pressure Index (EPI), Ecosystem State Index (ESI), and Ecosystem Response Index (ERI) were calculated, leading to the computation of the Wetland Ecosystem Health Index (WEHI). A pragmatic approach normalised scores for each parameter of pressure, state, and response indices. Wetland health scores were categorised into six classes based on ecological characteristics.

To validate WEHI-based maps, field-based activities included community mapping, focus group discussions, expert interviews, and administrative recommendations. Community mapping engaged wetland communities in recognising historical changes, while focus group discussions provided insights into wetland degradation and community connections. A symposium of experts addressed livelihood regeneration, wetland conservation, and conflict resolution.

Results

• Land Use/Land Cover Change analysis: Understanding landscape degradation and anthropogenic pressure is crucial for environmental management. Analysis of land use/land cover change in Lucknow District from 1998 to 2018 revealed an increase in built-up areas and a decrease in water bodies, forests, agriculture, and barren/wasteland.
• Spatio-temporal change in area under wetlands: Wetlands in Lucknow face pressure from local development, leading to biodiversity richness loss. The area under wetlands decreased from 4.36 sq. km in 1998 to 1.31 sq. km in 2018. The scatter plots and trend analysis indicated a significant decline in wetland areas, particularly during the pre-monsoon season.
• Correlation among wetland health indicators: Correlation matrices revealed relationships among landscape indices and state parameters. Positive correlations were observed between road density, built-up, and population density. State indices showed negative correlations among various metrics in 2008 and 2018. Response indicators exhibited positive correlations in 2018.
• Wetland ecosystems health assessment: From 2008 to 2018, varying health conditions were observed across different regions. Urban high-density areas improved from healthy to very healthy conditions. Urban low-density areas deteriorated from degraded to sick conditions. Peri-urban high-density areas declined from unhealthy to degraded health, and peri-urban low-density areas worsened from stable to unhealthy conditions. Rural areas maintained healthy conditions.

The integrated analysis of land use/land cover change, wetland dynamics, correlation matrices, and health assessments provides a comprehensive understanding of the Lucknow district ecosystem. Urban areas saw improvements, but peri-urban and rural areas faced challenges. Effective conservation strategies should consider these diverse trends and prioritise areas undergoing degradation for targeted interventions.

Discussion and policy recommendations

• Landscape indices and wetland degradation: Landscape indices like patch density, LPI, total edge, edge density, mean patch size, NDVI, and diversity index were instrumental in gauging wetland fragmentation and degradation. Particularly in urban high-density areas, the wetland degradation rate surged due to population growth and escalating residential demands. The construction of roads around wetlands, lacking proper culverts, disrupted surface hydrology, exacerbating degradation. Proper culvert construction is essential to allow rainwater inflow, preventing summer-season dry-ups and instability.
• Impact of land use changes: Large-scale land use changes, notably the expansion of built-up and agricultural areas, posed significant threats to wetland water quality and ecology. Urban high-density areas, marked by high population and road density, experienced notable degradation. Peri-urban high-density zones exhibited the most degraded wetland ecosystem health, demanding wetland-sensitive land-use planning.
• Challenges and opportunities in rural wetlands: While rural high and low-density areas maintained relatively better wetland conditions, the rapidly changing land use patterns could pose future threats. Effective land use planning and conservation awareness programs are pivotal for safeguarding these rural wetlands.
• Commercial use impact on wetlands: Commercial use of wetlands for activities like water chestnut production and non-native fishing inflicted severe damage on wetland ecology and water quality. Excessive use of insecticides and pesticides for water chestnut cultivation posed threats to plant and animal species, necessitating sustainable practices and conservation efforts.
• Vulnerability in peri-urban areas: Peri-urban areas emerged as the most vulnerable, undergoing large-scale developmental alterations that adversely impacted wetlands. Climate regulatory roles of wetlands, especially in urban areas, emphasise the need for community engagement, awareness, and capacity-building for effective conservation.

Urban sustainability (SDGs) and wetland ecosystem health

• Ramsar Convention Goals and SDG Alignment: The Ramsar Convention's strategic plan (2016–2024) offers a framework aligning with Sustainable Development Goals (SDGs). Prioritising indicators like road density, built-up density, and population density under SDG 11 can contribute to sustainable urban and regional development.
• Wetlands supporting multiple SDGs: Conserving wetlands aligns with various SDGs, such as SDG 2 for ecosystem stability and sustainable agriculture, linked to wetland ecosystem state indicators like NDVI. Wetlands' role in providing irrigation aligns with SDG 6, emphasising water and sanitation management.
• Linking tourism and conservation: Wetlands, supporting sustainable tourism and job creation, connect with SDG 8. Utilising tourism income for wetland management establishes a link between long-term conservation and economic activities.
• Policy implications for urban wetlands: Urban wetland conservation necessitates pollution reduction, improved wastewater treatment, and creating recreational opportunities. Peri-urban wetlands demand sustainable land use practices, community involvement, and engineering for both recreation and livelihood.
• Rural wetland conservation strategies: Controlling pollution from agriculture and encouraging sustainable practices are crucial for rural wetland protection. Involving communities in invasive species removal and native vegetation planting supports biodiversity and ecosystem services.
• Expert recommendations: Experts across domains emphasise key priorities like improving drainage systems, wetland restoration, integrated planning, and community involvement. Attention to factors such as wise wetland use, pollution control, and education can fortify wetland health.

The full paper can be accessed here