Purbasthali Wetland Study Notes
Chapter 1: Literature Review, Significance of Study, Objectives, Methodology
Introduction
Wetlands are vital ecosystems providing essential services like water quality improvement, habitat for wildlife, flood control, and carbon storage. Purbasthali Wetland, an oxbow lake of the Bhagirathi-Hooghly River in West Bengal, is threatened by human-induced pressures like agricultural runoff, encroachment, unregulated tourism, and waste dumping, leading to water quality decline and biodiversity loss.
Formation of the Ox-Bow Lake
Purbasthali Wetland originated from the meandering Bhagirathi-Hooghly River. Its formation timeline includes:
Pre-17th Century: Active Ganges river system with the Jalangi River shaping meanders.
17th–18th Century: Cutoff of a Jalangi River meander forming an oxbow lake.
19th Century: Stabilization of the oxbow lake, ecological growth, local community use.
Early 20th Century (1900–1950): Increased biodiversity, agricultural use.
Late 20th Century (1950–2000): Rising human pressure, beginning of ecotourism.
21st Century (2000–Present): Conservation awareness, bird watching hub, increased ecological threats.
Significance of the Study
The study of Purbasthali Wetland is crucial for understanding wetland degradation processes due to climate and land use change in eastern India. The wetland faces ecological degradation from man-made and natural impacts, including unregulated agriculture, overfishing, and increased tourism. Climate change further complicates these threats, disrupting ecological hydrology, making it an important case study for understanding ecosystem degradation and its socio-economic impacts.
Objectives
The objectives of the study include:
Studying physical aspects, ecology, and uses of the wetland.
Analyzing causes of wetland degradation and loss.
Analyzing degradation impacts on living and non-living environments.
Measuring effective conservation and restoration approaches.
Recommending sustainable management practices.
Summarizing current wetland status.
Literature Reviews
The literature review covers studies on:
Wetlands providing ecosystem services, including carbon sequestration.
Household use of wetlands and influencing factors.
Instrumental forces responsible for ecosystem deterioration.
Wetland habitat for avian species and cultural ecosystem services.
Water bird conservation and public knowledge.
Arsenic contamination problems in the Purbasthali Region.
Avian fauna and human intervention.
Pre and post monsoon diversity and ecology of avi-faunal species.
Methodology
The methodology involves three phases:
Pre-Field Phase (Desk Study): Literature review, remote sensing analysis, stakeholder engagement, and development of a preliminary assessment framework.
Field Phase (Data Collection): Field observations (vegetation, wildlife, water quality, soil), water quality monitoring, socio-economic surveys, and geospatial data collection.
Post-Field Phase (Data Analysis and Reporting): Data analysis, integration of results, and assessment of degradation.
Chapter 2: Physical Features of the Study Area, the Ecology of the Wetland and Flora Fauna
Physical Features of Purbasthali Wetland
Geography: Located within the Ganga-Brahmaputra deltaic plain with alluvial material.
Topography: Low-lying area with an average elevation of 10-15 meters above mean sea level.
Relative Relief: Low relief, highest elevation recorded at 20 meters above mean sea level.
Drainage Density: High drainage density with a close-knit network of rivers and streams.
Drainage Pattern: Dendritic drainage arrangement with meandering rivers and streams.
Climatic Condition: Humid subtropical climate with high temperatures and precipitation (1500 mm annually).
Soil Condition: Alluvial soil with high water holding capacity.
Vegetation: Diverse vegetation, dominated by aquatic plants like Hyacinth and Water Lily.
Water Quality: Freshwater wetland with a pH range of 6.5-8.5, nutrient-rich in nitrogen and phosphorus.
Land-Use Pattern: Dominated by agriculture (rice, wheat, jute) and wetland vegetation. The wetland's geology is also shaped by several faults and fractures, affecting the area's topography and hydrology
Ecology of the Purbasthali Wetland
Purbasthali Wetland is a popular bird-watching spot known for its rich biodiversity and migratory birds. It supports over 70 species of local and migratory birds. The wetland offers 37 ecosystem services, including provisioning, regulating, cultural, and supporting services. However, the ecosystem faces increasing threats from human activities, with 24.32% of bird species considered rare and 36% experiencing population declines globally.
The wetland’s biodiversity extends to a variety of aquatic plants, fish communities, and invertebrates that form the base of complex food webs. The seasonal changes in biodiversity at Purbasthali reflect the wetland's role along major migratory routes, with species composition changing dramatically between breeding and non-breeding seasons
Chapter 3: Wetland Loss and Surrounding Impacts on Degradation of Wetland and it's Catchment Area
Wetland Loss: A Major Problem of Purbasthali Wetland Degradation
Purbasthali Wetland faces rapid wetland loss due to human activities. These include building embankments, converting wetland into farmland, and construction. This leads to shrinkage, biodiversity reduction, and reduced ecosystem services. The decline poses serious risks for local communities relying on the wetland for their livelihoods.
Problems
The Purbasthali wetland faces serious challenges like agricultural expansion, brick kilns, and illegal hunting. The conversion of wetland banks into agricultural fields harms the biological resources of the lake, directly reducing habitat availability and fragmenting the ecosystem.The intensification of agriculture runoff leads to eutrophication. Industrial activities, especially brick kilns nearby, contribute to air and water pollution. These industries release toxic substances that accumulate in the wetland ecosystem and gather in the food chain.
Causes
Degradation stems from natural and human-made factors, including altered water cycles due to infrastructure, pollution from waste, conversion to agriculture, and climate change. The absence of solid management hampered protection & conservation.
Consequences
Consequences include the loss of biodiversity, pollution in water, soil erosion, socio-economic impacts, and climate change affect drastically. This needs a holistic approach to conserve the waterbody.
Uses of Purbasthali Wetland
Uses include fish and aquaculture, agriculture, ecotourism, and water supply, all crucial for local livelihoods and ecosystem services.
Prospects of Purbasthali Wetland
Despite tremendous degradation due to human activities, This include livelihood of the stakeholders, tourism development, cultural heritage of the local residents and the growth of the tourism sector.
Change Detection Analysis of Purbasthali Wetland Showing Degradation Scenario Between 2010-2024
From 2010 to 2024 water bodies, vegetation, settlements, agricultural land and waste land significantly changed.
Water bodies saw a marked decrease from about 12% to 9%.
Settlement areas grew dramatically, more than doubling from around 18% to 42%.
Vegetation experienced a severe decline, falling from about 38% to 16%.
Agricultural Land showed the opposite trend, increasing from about 16% to 32%.
Waste Land decreased from about 28% to 16%.
Chapter 4: Field Study, Analysis of the Secondary and Primary Data
Field Study
The field study involved a desk study gathering secondary data (Burdhaman Handbook, websites) on the wetland's physical, ecological, and socio-economic aspects. The wetland spans approximately 3.5 square kilometers in Bardhaman and extends into Nadia, part of the Ganga-Brahmaputra delta.
Secondary Field Survey: Agriculture vs. Fisheries
Paired t-Test Analysis
Agriculture greatly outperforms fisheries.
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Regression Analysis: Annual Rainfall vs. Annual Fish Production
Weak negative association between rainfall and annual fish production.
Multiple R = 0.316.
R Square = 0.10
Adjusted R Square = -0.080
Time Series: Fish Production and Rainfall Trends
From 2013 to 2016, fish production stayed relatively steady at around 21,000 to 22,000 quintals, despite significant rainfall changes. However, starting in 2017, fish production began to rise sharply, reaching nearly 30,000 quintals by 2019.
Scatter Plot: Rainfall vs. Fish Production
The scatter plot reveals a clear clustering pattern instead of aligning with the downward-sloping regression line, explaining the low R-squared value of 0.10.
Primary Field Survey
The primary survey interviewed 237 respondents. This included 112 agricultural workers, 50 households, and 75 fishermen.
Gender Distribution Among Farmers: Farmers are majorly male.
Religious Composition of Farmers: Muslim Farmers are the dominant religious group.
Caste Distribution Among Farmers: OBC-A farmers make up the largest group, with approximately 55-60 farmers.
Motivation for Farming: Economic necessity is the main driver.
Learning Methods for Crop Cultivation: Family traditions dominate.
Farming Experience Duration: Farming is led by seasoned practitioners who have committed significant portions of their lives to agriculture
Fertilizer Usage Patterns: More farmers using chemical fertilizers than organic fertilizers.
Fishermen Survey data from 2025
Religion Distribution: Fishermen are majorly muslim
Caste Distribution: Scheduled Castes (SC) have the highest representation
Inspiration for fishing; To earn money
Learning method: Family Traditions
Fishing period: Throughout the year
Experience levels: Most of the fishermen has about 10-20 years of experience.
Chapter 5: Demographic Status in Human Response And Wetland Tourism
Demographic Status
The demographic situation in Purbasthali II and Idrakpur mirrors the socio-economic trends of rural West Bengal, with traditional farming meet new livelihood strategies. The closeness to the Bhagirathi River and the rich alluvial soil create ideal conditions for both farming and fish farming.
Gender Distribution of Household: The data indicates that males make up the vast majority of farmers
Religion Distribution of Household: Hindu households are more dominant in number
Caste Distribution of Household: General population are higher compared to other caste in residence.
Nature of Land Use Pattern Surrounding The Water Bodies: Agricultural lands are dominant around the survey area
Utilization Of Wetland; Irrigation is the main approach for wetland utilization throughout the year.
Recomend Visiting Time Period To Others: More recommendations for winter season to visit compared to summer.
Environmental Issues Facing The Wetland: Pollution has been the biggest threat for the area.
Rates of side conditions of Wetland: Condition of biodiversity and water quality is good at the moment.
Impacts of Human Activities on Wetland: Urbanization, agriculture and other factors contributed to wetland pollutions.
Sources of Pollution on Wetland: Factory wastes and plastic wastes were some of the source of pollution.
Human Response
The human responses to the pollution has been great. But over the past few decades, this wetland ecosystem has seen significant decline. Human activities have drastically changed its water flow, biodiversity, and functioning capacity.The building of embankments, roads, and other infrastructure has fragmented the wetland, upsetting natural water flow and creating isolated areas that struggle to maintain healthy ecological functions
Purbasthali Tourism
Purbasthali Wetland, quickly becoming a top spot for eco-tourism. guided boat safaris, bird watching tours, and nature walks offer immersive experiences. There are comfortable places to stay, from rustic village-style cottages to modern luxury resorts
Chapter 6: Finding, Suggestions, Remedial Measure and Concluding Remarks
Findings
The main findings were:
Habitat Loss and Degradation
Water Pollution.
Loss of Biodiversity
Climate Change
Inadequate Management and Conservation
Suggestions
Conservation and Restoration
Sustainable Land-Use Planning
Water Quality Management
Community Engagement and Education
Climate Change Mitigation and Adaptation
Eco-Tourism Development
Research and Monitoring
Policy and Legislative Support
Community-Based Conservation
International Cooperation
Remedial Measures
Here are the sector wise remedial measures-
Remedial measures for agricultural and fishing communities.
Sector-wise Remedial Measures for Wetland Conservation.
Trying To Evalute The Importance Of Purbasthasli Wetland As A Ramsar Site
Purbasthali Wetland has strong potential to meet several of these standards, especially those related to biodiversity conservation and bird habitat support.There are different criteras which this area satisfies and can be marked under Ramsar site.
Concluding Remarks
The investigation reveals a serious environmental crisis in Purbasthali, with the analysis highlighting various factors contributing to wetland degradation across India.
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1. The analysis of Purbasthali wetland's ecological decline highlights the various factors contributing to wetland degradation across India:
2 These include: Uncontrolled industrial pollution from many manufacturing units in both districts, intensive farming practices that use excessive pesticides and fertilizers, rampant encroachment for fish farming and human settlements, deforestation upstream that accelerates siltation, climate change effects that alter water cycles, and the overall impacts of urbanization and infrastructure development that have changed the wetland's natural water flow