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Rachel Fernandes is a student of Architecture; as an architect she repeatedly visits the Nanda Lake and the site of a proposed research and observation centre. Through her research she maps and examines this wetland site and proposes architectural intervention. This project is based on her thesis “Wetland Research and Observation Centre” submitted to the Goa College of Architecture in collaboration with artists from the SAIL program at Sunaparanta Goa Centre for the Art and artists from workshops conducted by Goa Water Stories.
Nanda Lake in Goa, designated as a Ramsar site in 2022, has sparked differing opinions between the local village community and government environmental agencies. While the designation highlights the ecological significance of the lake, many locals feel they were left out of the decision-making process. They believe that, as residents who depend on and interact with the lake daily, they should have been consulted and actively involved in planning. The proposal to build an on-site research and observation centre has further intensified this debate. Local villagers argue that they have a deep connection with the lake, using its resources for farming, fishing and other livelihoods. They worry that the development of such a centre could disrupt their traditional practices, particularly if tourism increases. While the observation centre aims to promote ecological research and attract eco-tourism, the community fears that their role as custodians of the lake could be overlooked.
Location
Nanda Lake is located in the village of Cacora, in Quepem Taluka, South Goa. It is one of Goa’s largest wetlands, covering an area of 42 hectares. The lake consists of intermittent freshwater marshes, situated near a major tributary of the Zuari River. A sluice gate connects the marshes to the river, and when closed, it allows the marshes to flood.
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This wetland is rich in biodiversity, providing a habitat for a variety of migratory waterbirds, including the Common Kingfisher, Black-headed Ibis, Wire-tailed Swallow, Red-wattled Lapwing, Intermediate Egret, Little Cormorant, Lesser Whistling Duck, Brahminy Kite, and Bronze-winged Jacana. Beyond birds, the wetland supports diverse plant and animal species crucial for the ecosystem.
Nanda Lake plays a vital role in the local community’s water management. It stores water during the dry season, supports rice paddy cultivation downstream, and enables fishing and recreational activities. Moreover, it serves as a natural buffer, protecting downstream areas from flooding during the monsoon. This multifunctional wetland demonstrates its importance both as a biodiversity hotspot and as an essential resource for local livelihoods.
LAND USE and 50m BUFFER
LAND USE and COVER
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CURCHOREM-CACORA
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LAND USES
Nanda Lake and the Ramsar Convention
The Ramsar Convention provides a "wise use" framework, encouraging the inclusion of wetlands in global sustainable development efforts. This approach ensures that these crucial ecosystems are managed effectively, benefiting both nature and humans. The Convention provides a mechanism for ensuring that wetlands are incorporated into the global agenda for sustainable development, supporting initiatives relating to biodiversity, climate change, disaster risk reduction and land degradation.
Wetlands
The Nanda Lake is a distinct wetland ecosystem, where the ground is either permanently or seasonally flooded, creating waterlogged conditions. These conditions lead to low oxygen levels (anoxia), especially in the soil, which influences the type of vegetation that grows here. The plants in Nanda Lake have roots adapted to survive in oxygen-poor, waterlogged soils, distinguishing the wetland from typical terrestrial or aquatic ecosystems.
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Wetlands like Nanda Lake serve as transitional zones between water bodies and dry lands, and are some of the most biologically diverse ecosystems. They support a wide variety of aquatic and semi-aquatic plants and animals. The wetland vegetation helps to improve water quality by removing excess nutrients such as nitrates and phosphates, making Nanda Lake an essential component of local water purification processes.
Nanda Lake provides crucial ecosystem services to the surrounding communities. It helps purify water, stabilise shorelines, and protect against storms and floods. Additionally, wetlands play a significant role in carbon sequestration, trapping carbon and other pollutants. When functioning as a carbon sink, Nanda Lake can contribute to climate change mitigation by absorbing carbon from the atmosphere. However, like many wetlands, it may also release methane due to the anaerobic decomposition of organic material in the water, and sometimes nitrous oxide, both of which are potent greenhouse gases.
Ecologically, Nanda Lake is highly significant. It supports complex food chains and webs, regulates the local hydrological cycle, recharges groundwater, and traps solar energy. It shelters a rich diversity of flora and fauna, many of which have both ecological and economic importance to the village and surrounding areas. Wetlands like Nanda Lake are vital for human survival, providing food, water, shelter, biodiversity, and nutrients. This ecosystem's efficient and productive nature ensures numerous long-term benefits, making its conservation essential for both local communities and the environment.
Wetlands like Nanda Lake serve as transitional zones between water bodies and dry lands, and are some of the most biologically diverse ecosystems.
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Hydrology
Wetlands, such as Nanda Lake in Goa, are primarily shaped by hydrology, particularly flooding. The frequency and duration of flooding, or the saturation of soil by groundwater, determine the type of wetland that forms – whether it supports aquatic plants, marsh vegetation, or swamp ecosystems. Other factors influencing this wetland includes soil fertility, natural disturbances, competition between species, herbivory (grazing by animals), sediment burial and salinity levels. In some cases, the accumulation of peat from dead plants leads to the formation of bogs and fens.
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The hydrology of wetlands refers to the flow and distribution of surface and groundwater over time and space. Water enters wetlands like Nanda Lake mainly through rainfall, surface water freshwater and groundwater. Water exits through evapotranspiration, surface outflows, tides and underground drainage. The movement of water through a wetland, known as hydrodynamics, controls the hydro-period, which refers to changes in water levels over time. This process helps manage water balance and storage within the wetland.
The Nanda Lake provide critical functions such as flood protection and water storage. This wetlands in floodplains act as natural reservoirs by absorbing excess water and spreading it over a wide area to reduce its depth and flow speed. Similarly, wetlands near the headwaters of rivers and streams, like those connected to the Zuari River, slow down rainwater runoff and prevent it from rushing directly into watercourses. This natural process helps mitigate sudden, destructive floods downstream, protecting both the environment and local communities.
This lake plays an essential role in groundwater replenishment. Although the visible surface water is the most apparent aspect, it is only a small part of the broader water cycle, which also includes atmospheric water from rainfall and groundwater. The lake is directly linked to groundwater systems, making them vital in regulating both the quantity and quality of water beneath the surface. Wetlands with permeable substrates, like limestone, are particularly important for groundwater recharge. In areas where water tables fluctuate, wetlands allow water to seep through the porous soil and rock, replenishing aquifers, which are essential sources of drinking water. Nanda Lake, with its intermittent marshes and proximity to the Zuari River, likely has a similar role in recharging groundwater, especially during times when the surrounding water table is low. Additionally, wetlands can serve as discharge zones when water tables are high, releasing excess water back into the environment.
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Water Purification and Impact on Species Diversity
This lake plays a crucial role in water purification, similar to other wetland ecosystems like floodplains, freshwater marshes, and mangroves. Wetlands act as natural filters, recycling both sediments and nutrients, often serving as buffers between land and water. In the case of Nanda Lake, its vegetation absorbs and stores nutrients, including nitrates, from surface runoff. This helps prevent excess nutrients from entering nearby water bodies, improving water quality.
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When rainwater and surface runoff cause soil erosion, sediment is carried into the lake. This sediment can include clay, silt, sand and even heavy metals. Nanda Lake’s wetland vegetation acts as a barrier, slowing water flow and trapping these sediments. This process protects the surrounding ecosystem, but like all wetlands, Nanda Lake has a limit to how much sediment and nutrients it can process. Excessive nutrient input from agricultural runoff or sewage can lead to eutrophication, a process where the water becomes overly enriched, leading to reduced oxygen levels and harming biodiversity. Similarly, deforestation upstream can cause increased erosion, overwhelming the lake with sediment and threatening its delicate ecosystem.
Constructed wetlands, which are artificial systems designed to mimic natural wetlands, are often used for wastewater treatment. They help treat sewage, greywater, and industrial wastewater by using vegetation, soil, and microorganisms to remove pollutants.
While Nanda Lake is a natural wetland, the principles of constructed wetlands demonstrate how effective wetland systems are in water purification. In Goa, constructed wetlands could support local agriculture and fish farming, providing sustainable ways to treat wastewater while maintaining ecosystem health.
The rich biodiversity of Nanda Lake is aligned with global efforts like the Ramsar Convention and initiatives by the World Wildlife Fund, which aim to protect wetland habitats. Wetlands like Nanda Lake create local employment, contribute to sustainable development, and support community productivity. Many species found in Nanda Lake are unique to this type of wetland ecosystem due to its isolation from other aquatic sources over time, emphasizing the need for continued conservation efforts.
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Threats
Nanda Lake in Goa faces several environmental threats, many of which are common to wetlands globally. One major issue is the presence of invasive non-native species, which can disrupt the delicate balance of the ecosystem. Additionally, garbage and solid waste pollution have become pressing concerns, as waste accumulates in the lake, impacting water quality and the health of aquatic species. Overfishing and unsustainable harvesting of aquatic resources further stress the lake’s biodiversity, threatening the survival of fish populations and other species.
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Another serious threat to wetlands like Nanda Lake is the conversion of these ecosystems into dry land for economic purposes. Wetlands are often drained using dykes and drains to make way for agriculture, reducing their natural capacity to support biodiversity and regulate water cycles. In Goa, where agriculture is a vital livelihood, the temptation to convert wetlands for farming is strong. However, these conversions often come with long-term environmental costs. The construction of dykes and dams can disrupt the entire watershed, leading to increased flooding risks. Once settlements are built near wetlands and protected by artificial barriers, they become more vulnerable to land subsidence and flooding as the wetland’s natural water management functions are lost.
The drainage of floodplains also poses a threat. Development activities that narrow floodplain corridors, such as building levees, reduce the ability of river systems to manage floods naturally. In the case of Nanda Lake, which is connected to the Zuari River, any alteration to the floodplain can lead to more severe flooding downstream. Historically, wetlands have been drained or altered for development and agriculture, leading to the loss of riparian vegetation, soil erosion, and a reduction in water storage capacity. In Goa, the loss of such wetlands could have catastrophic impacts on local agriculture and water security.
Overfishing is another challenge that Nanda Lake faces. Wetlands like Nanda are critical for local fisheries, providing food and income to communities. However, overexploitation of fish stocks can lead to population declines, disrupting the ecological balance. Aquaculture, particularly shrimp farming, has also been expanding across many regions, and while this practice provides economic benefits, it can devastate wetland ecosystems. In many parts of Asia, large-scale shrimp farming has led to the destruction of mangroves and wetlands, and similar risks exist in Goa if unsustainable practices are adopted.
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Bibliography & References
https://timesofindia.indiatimes.com/city/goa/nanda-lake-in-curchorem-is-states-first-ramsar-site/articleshow/93332412.cms
https://anujdaga.blogspot.com/2017/03/centre-for-environment-education.html
https://www.goa365.tv/localgovt/E/curchorem%E2%80%99s-nanda-lake-added-to-wetland-preservation-project-goa365/15069.html
https://en.wikipedia.org/wiki/Nanda_Lake
Acknowledgements
I would like to express my heartfelt gratitude to everyone who guided and supported me throughout this research. I am deeply thankful to Hyacintha Pinto for her valuable recommendations and insights, and to Pradip Sarmokadam for sharing his knowledge about Goa’s wetlands. I am especially grateful to my parents, grandparents and sister for their unwavering encouragement, support, and belief in my abilities, which sustained me during this journey. Finally, I express my profound gratitude for the divine grace that guided and strengthened me throughout my thesis journey and this work. I express my heartfelt gratitude to God.
