Designed ecologies_Portfolio

Studio Brief:

With increasing urbanisation, there have been pressures on the existing natural processes. Due to this phenomenon, there are conflicts areas that are often highly stressed pockets which require an in-depth and empathetic approach.

Such areas are causing ecological disruption and affecting social constructs. It is the need of the hour to propose paradigms of designed ecologies to rebuild, support, and recollect gradually fragmenting land mosaics.

These devised ecosystems take time to evolve and are often the outcome of multiple interactions that are dynamic in nature, operating over multiple scales across socio-economic and physiological processes. The resilience of a city - the degree to which change is acceptable before reorganization to create a new set of structures - is highly dependent on these interactions.

The studio allows for self-exploratory research which gives foundation to the proposal, as well as explores design strategies to implement the research outcomes.

CONTENTS

Introduction:

Larger context

1. Introduction to site, locating the site

2. Chronology of the extent of the marshland

3. Land ownership inside the Marsh

4. Climate, topography and watershed mapping

5.Original and modified conditions of the marsh

Site Documentation & Analysis: Site context

1. First impression of site - Eidetic photo montage

2. Ramsar criteria’s for the site

3. Site Plan and site photos documentation

4. Site edge conditions

5. Topography and hydrology

6.Vegetation map and typologies

7. Different faunal species on site

8. Food web and conflicts

9. Locating the birds and habitat study

10. Activity and sensory mapping

11. Issues mapping

12. Systemic thinking

13.Vision ideation & eidetic photo montage

Conceptual Exploration:

1. Site synthesis and identifying zones

2. Ideating through layers

3. Programming

4.Guidelines

5. Zoning - Hydrology & Habitat conditions

6. Zoning - Edge conditions

7. Zoning - Human interactions

Crafting the Landscape:

1. Master plan

2. Edge conditions

3. Transect plan 1 and views

4. Transect plan 2 and views

5. Transect plan 3 and views

6. Transect plan 4 and views

7. Conclusion

8. Project outcome

Annexure:

1.References

2.Plant list

3.Fauna & Avifauna list

4.Initial zoning and concept ideations

5.Planting recommendations

6.Readings and seminar

7.Case studies, site visits and workshops

Pallikaranai marshland is a freshwater and partly saline marsh located in Chennai, India, along the Coromandel coast. It is the city’s only remaining wetland ecosystem, and it performs a vital role in acting as a sponge, absorbing excess water and preventing flooding. It also recharges the groundwater table, serves as a carbon sink, and provides a habitat for 334 flora and fauna species. Pallikaranai Marsh drains over 250 km2 of south Chennai, containing 30 wetlands, via two outlets, Okkiyam Madavu and the Kovalam Creek and flows into the Bay of Bengal. This system of the watershed is disturbed by encroachments in the marshlands like road and infrastructure development, landfill dumping, sewage water intrusion and invasive species etc. Given that, it’s located on the fringes of the city, it has shrunk by more than 90% over the decades due to the urbanization pressure. It is currently a designated Ramsar site and is protected from further disturbances. The aim of the project is to revive the ecology of the marsh, restore the edge and habitat conditions of the marsh and help people reconnect with the marsh. The project’s vision was developed using systematic thinking, and its key phrases in the title “REVIVE|RESTORE|RECONNECT” served as the framework for the project as a whole. As project outcomes through implementation guidelines, design strategies and interventions were ideated as a proposal for the reviving of the marshland.

Photograph_View of sewage water entering into the marshland

Pallikaranai marshland is a freshwater and partly saline marsh located in Southern part of India along the Coromandel coast in Chennai. It is the only surviving wetland ecosystem present in the city as it plays as critical role in acting as sponge in absorbing excess water and thereby preventing flooding in the city. It also recharges the ground water table, acts as carbon sinks and habitat for 334 species of both flora and fauna.

On its eastern periphery, the marsh is flanked by the Buckingham Canal and the Old Mahabalipuram Road, which houses the Information Technology (IT) Corridor. The southern and western boundaries are typified by mixed residential and institutional land use. To the North of the marsh the public infrastructure such as the Mass Rapid Transit system and dense human habitations are present.

Locating the site

Larger context

Velacherry railway station

Pallikaranai Eco park

National Institute of Wind Energy

Perungudi landfill site

200 ft radial road (National Highway)

National Institute of Ocean Technology

Pallikaranai Marshland Okkiyam Madavu(canal)

Nanmangalam reserve forest

Aerial view of the State highway dividing the marsh into parts

View of the marsh from the highway

View of the dried up marsh near the settlement

Chronology of the extent of the marshland

• The original extent of the marshland where the marsh had direct link to the sea.

Change in marsh extent

• The Buckingham canal was constructed in 1804, to carry ferried salt from Andhra Pradesh to Tamil Nadu.

• This lead to the breakage in the link to the sea water. The marshlands interconnection of backwater from the sea was from Okkiyam madavu(canal).

• The marshland has reduced in size over the years through urbanization pressures. The extent of the marsh is 2450 hectares.

• The water spread area has decreased to about 70% of the original condition due to increase in land cover.

• The Site had maximum pressures through settlements along the edges and agriculture has also had a huge impact on the marshland shrinkage.

• The extent of the marsh is 1880 hectares.

• The water spread area has decreased to about 50% of the original condition due to increase in land cover.

• The Site had more residential and commercial development in the early 2000’s, where people migrated from urban areas to peri urban areas due to lack of housing facities and congestion issues.

• The extent of the marsh is 990 hectares.

• The water spread area has decreased to about 35% of the original condition due to increase in land cover.

• The Site was booming with the IT corridor along the OMR road. Thus lot of development in residential, mixed use, institutional and industrial sectors started.

• The extent of the marsh is 500 hectares.

• The water spread area has decreased to about 10 % of the original condition due to increase in land cover.

• The site surroundings developed rapidly with lot of encroachments around the site. These rapid developements had left the Pallikaranai marsh to degrade.

• The southern portion of the marsh consisting of 620 Ha which was part of the SEZ(Industrial zone) earlier was included within the Ramsar site boundary.

• Site extent as per Ramsar(2022) extends upto 1,247.5 Ha.

Change in water spread to land cover ratio Change in land use around the marsh

Change in water spread to land cover ratio Change in land use around the marsh

Land ownership inside the Marsh

Legends

Site boundary(As per Ramsar site in 2022)

Site extent as per TP scheme

Dumping yard

MRTS

Revenue land as per TNFA

Area taken from Chennai Corporation

Reserve land (317 ha)

NIOT

Drainage channel

ELCOT City

SEZ area

Residential area

Waterbody

Source: Forest department, Tamil Nadu (till 2022)

During the early 1900s, the marsh area covered 6000 hectares (60 km2), of which only 593 hectares remain (Care Earth, 2002). NIOT (National Institute of Ocean Technology) and CWET (Centre for Wind Energy Technology) have constructed institutes that have reduced and fragmented the marsh, and the Perungudi dumpyards and wastewater treatment plants have occupied a considerable portion of marsh land, while on the other hand, IT corridors, residential complexes have been constructed.

The dumping yard consists of 173.33 Ha, area taken from Chennai corporation is 170.405 Ha, drainage channel is 54.21 Ha, Elcot comprises of 85.43 Ha and revenue land as per TNFA is 131.55 Ha and the SEZ consists of 445 Ha.

Earlier, the Palikaranai marshland was considered uptil the Perumbakkam main road as the reserve boundary. Later the SEZ zone was also included when it was declared as the Ramsar site.

Climate Topography

Wind direction

Annual temperature

Rainfall data

Source: www.meteoblue.com

The wind direction is mostly towards south west direction. It receives an annual rainfall of 1,300 millimeters (51 in), mostly during the northeast monsoon (September–November), but also during the southwest monsoon (June–August). Temperature ranges from 35 to 42 °C (95 to 108 °F) during the summer, and from 25 to 34 °C (77 to 93 °F) in the winter.

Map source: Qgis

Legend:

Grid size: 2000 x 2000m

Ramsar site boundary

Watershed Map source: Qgis, Bhuvan

Legend:

Watershed boundary Stream line Water bodies

Pallikaranai Marsh and its wetland complexes are part of one watershed that is spread over an area of 231 km.

Original condition of the marsh

Pre monsoon

Before the encroachments started within the marshland, steady connectivity with the surrounding water bodies was efficiently draining the water into the marshland.

Taking into account, the original spread of marshland to be around 5000 Ha and an average depth of 1m, during the peak monsoons (when flooding is also widespread) the water-holding capacity of the marshland may be estimated as 50 million cubic meters.

Post monsoon

The marshland is connected to 31 different water bodies all of which release surplus water into the marsh during the monsoons. There is backflow of water from sea via Buckingham canal during high tide which brings in the influence of brackish water into the marsh.

The mixing of freshwater and brackish water is brought about by the huge volume of surface runoff that the marshland receives year after year during the monsoons.

Right mix of freshwater and brackish water is important in maintaining the ecological integrity of the marshland.

Modified condition of the marsh

After encroachments

State Revenue records the marshland was classified as wasteland and so the Government of Tamil Nadu fragmented the marsh and large parts were reclaimed to be developed as residential and rehabilitation areas.

This system of the watershed is disturbed due to the pertubations all along the catchment area of the marsh.

Encroachments in the marshland like road and infrastructure development, landfill dumping, sewage water intrusion and invasive species etc. have also contributed to the lesser water retention quality of the marsh.

It has made the system of watershed not work due to the urbanization impacts.

Adapted Source: Care Earth trust

Encroachments Marshland

Buckingham canal

Change in topography and land use

Site section upto the sea - YY’

development Residential development

Buckingham canal

Due to residential, mixed-use and institutional development along the marsh’s catchment area, this system of the watershed has been disturbed.

Marshland

Okkiyam madavu(creek) Okkiyam madavu (creek)

Corridor Mixed use development

Buckingham canal

ECR road

ECR road

CRZ-II zone CRZ-II zone

Bay of Bengal Bay of Bengal Freshwater Brackish water

Mixed use development Mixed use development Mixed use development Mixed use development

In site documentation analysis section, site importance is established through Ramsar’s criteria. Later through site plan, photo documentation, topography, hydrology, vegetation typologies, habitat conditions and fauna documentation, food web and its conflicts and activity analysis and issues are mapped to understand the site layers. Later, the systemic thinking is arrived through synthesis. Then the vision is developed.

Figure_Section of deep water habitats

First impression of site - Eidetic photomontage Site photos

Distress / Destruction / Forgotten / Hope

Increasing urbanization has encroached on the Pallikaranai marshland rapidly, resulting in its current plight. It is the only remaining wetland in the city, and it has been pushed to the brink of extinction due to anthropogenic pressure. The birds depend on this wetland as its their only hope for respite on their way home.

The State highway dividing the marsh into parts

Landfill inside the marsh

Smaller puddles of waterbody inside the marsh

Prosopis juliflora invasion inside the marsh

Scrublands with Prosopis juiflora invaded marsh

Grazing pressure inside the marsh

Construction debris dumped along the edges

Entering of sewage water into the marsh

Photo credits: Author

Photo credits: Author

Ramsar criteria’s Site importance:

Criterion 1: Representative, rare or unique natural or near-natural wetland types

Pallikaranai Marsh acts as a sponge absorbing excess stormwater runoff from surrounding areas in the city of Chennai. The adjoining wetlands discharge water into it either as an overflow or through a drainage network.

Criterion 4 : Support during critical life cycle stage or in adverse conditions

Pallikaranai Marsh has a diverse habitat including large and deep reservoirs with several inlets and surrounding irrigated agricultural fields, which provide good nesting and foraging habitats for birds.

Criterion 6 : >1% waterbird population

The site regularly supports over 1% threshhold population of Calidris subminuta, Charadrius alexandrines, Dendrocygna bicolor, Limicola falcinellus, Himantopus Himantopus, Limosa limosa, Mycteria leucocephala, and Tringa erythropus.

Spot billied Pelican in the intermediate waters

Criterion 2 : Rare species and threatened ecological communities

It is the natural habitat to some of the most endangered reptiles like the Russell’s viper and birds such as the glossy Ibis, pheasant tailed Jacana, etc.

Criterion 3 : Biological diversity

Pallikaranai Marsh supports an estimated 381 species of flora and fauna.165 species of birds, 10 species of mammals, 21 species of reptiles, 10 species of amphibians, 50 species of fishes, 9 species of molluscans (snails and clams), 5 species of crustaceans, and 7 species of butterflies have been reported from the area.

Criterion 7 : Significant and representative fish

Significant and representative fish species include Anguilla bengalensis, Anguilla bicolor, Trichogaster chuna, and Channa orientalis. The above-mentioned fish species are known to use the site for feeding, breeding, and migration purposes from adjoining tributaries and vice versa.

Criterion 8 : Fish spawning grounds, etc.

Pallikaranai Marsh serves as feeding and spawning grounds for several fish species, such as Anguilla bengalensis, Anguilla bicolor, Trichogaster chuna, and Channa orientalis. These species periodically use (disperse/migrate) the site throughout the year to complete their life-cycle.

Flamingos in the shallow water

Photo credits: Dinesh

Photo credits: Dinesh

Lesser whisting duck in the wet meadows

Wood sandpiper in the wet meadows

Photo credits: Dinesh

Photo credits: Dinesh

Site pictures

Pallikaranai marshland Park

National Institute of Wind Energy

National Institute of Ocean technology

Forest department watch tower Thangavelu Engineering College

Pallikaranai marshland conservatory

Okkiyam madavu(canal)

Site edge conditions

Okkiyam madavu(canal) with Pontederia crassipes cover

200 ft Road with embankment

Grazing pressure edge Road

Section BB Section CC

Marshland edge with garbage dump

Marshland edge with construction debris

Marshland edge

Prosopis juliflora spread

Proposis juliflora edge Slum settlement

Section DD

Section EE

Section FF

Marshland edge with Prosopis juliflora

Road edge with dumping

Marsh with Pontederia crassipes cover

cover

Topography and hydrology

The maximum elevation is at 20 m and minimum elevation is at 0.5 m within the marshland.

Legends

Brackish water inflow during high tide

Deep waters (1-2m)

Intermediate waters (0.3-1m)

Shallow waters (0-0.3 m)

Waterbody Green cover

Built Structures inside Ramsar site boundary

Ramsar site boundary with compound wall Road Buildings

Ramsar site boundary with free edge

The southern parts remain dry while the northern and the central portion retain water. The water movement is from north to south draining in the Okkiyam madavu(canal). And movement of water is from south to north from the channel connecting from higher grounds in the south connecting the canal. There is a mix of brackish and freshwater at the high tide time and when the excess water enters the marsh through the Okkiyam madavu.

Adapted Source: Care earth trust

The vegetation exisiting now is highly altered state due to urbanization pressures on the marsh and its in relictual state with 10% of habitats intact.

Different habitat types

1.Deep open water

3.Mudflats

Adapted Source: Care earth trust

Grid size: 500x500 m

Shallow water Grassy banks

Deep open water

Grassy banks

Deep water attracts diving waterbirds like darters, cormorants, grebes, and some ducks that dive for bottom-dwelling invertebrates or aquatic vegetation.

Mudflats with sedges and grassy banks

Shallow water

Grassy banks & emergent reeds

Shallow waters and mudflats are rich feeding areas for a range of migratory waders who probe the water and flats for tiny animals. Larger waterbirds with long legs and bills such as the egret, pelican, heron, flamingo etc. can be found in the shallows probing, spearing, sieving and scooping for food.

2.Emergent sedges, rushes and grassy bank areas

4.Islands

Legends

Brackish water inflow during high tide

Deep waters (1-2m)

Intermediate waters (0.3-1m) Shallow waters (0-0.3 m)

Waterbody Green cover Ramsar site boundary with free edge

Built Structures inside Ramsar site boundary

Ramsar site boundary with compound wall Road Buildings

Swampy grassland

Marshland Afforested area

Scrublands

0 750 1500 3000 m

Emergent reeds & grassy bank

Shallow water Intermediate water

Emergent reeds & grassy bank

Grassy bank

Many wading birds are attracted to emergent sedges, reeds, and grassy bank areas. This sort of vegetation provides cover for waterbirds. Ducks, moorhens, and coots forage in emergent plants and grassy bank areas near open water. Ibis, herons, and swamp hens are drawn to bordering sedges as feeding places as well.

Intermediate water

Islands with grassy banks

Shallow water

Grassy banks

Several types of ground-nesting species use islands and mounds as breeding grounds. Grasses have been planted to offer habitat for ducks such as teals and pintails. The elevated mounds were made to improve survival rates during prolonged inundation periods.

Swampy grassland

Marshland

Scrubland Afforested area

Different faunal species on site

349 species of flora and fauna are found on the site.

Birds (135 species in total)

Fishes (50 species in total)

Spot-billed Pelican

Legend

Diadromous fish

Freshwater fish

Amphibians (10 species in total)

Potamodromous fish

Legend

Swimming birds

Non diving birds

Predator birds

Arboreal birds

Shore/wading birds

Ground birds

Leaf walking birds

Indian Pond Frog Mudskipper Jerdon’s Bull Frog Indian toad

Images source: https://animalia.bio/collections

Glossy Ibis

Grey Francolin

Darter

Greater Flamingo

Pheasant-tailed Jacana

Eurasian Thick-knee

Marsh Harrier Rose-ringed Parakeet

Black-bellied Tern Small Bee-eater

Lesser Whistling Duck Garganey

Black Kite

Purple Heron Painted Stork

Long-fin Eel

Half beak

Panchax

Peninsular Olive Barb Common Tilapia

Climbing Perch

Mullet

Mosquito fish

Giant African Catfish

Armored Catfish

Reptiles(21 species in total)

Molluscans (9 species in total)

Mammals (10 species in total)

Indian

Butterflies (7 species in total)

Three-striped Palm Squirrel

Crustaceans

Freshwater Semiaquatic Terrestrial Both brackish/freshwater

Pallikaranai Marshland is an ecologically rich with the mix of enormous Bay of Bengal Large Marine Ecosystem. It is home to about 130 bird species and over 50 fish species. Wetland ecosystems are defined by the presence of fish and fish-eating birds. Pallikaranai Marsh is also a feeding area for a variety of visitors. Migrants such as sandpipers and teals are abundant, while Black-winged Stilts can normally be found in small numbers near the water’s edge.

The population and diversity of waders and shorebirds in the marsh begin to increase during the northeast monsoon and peak between December and March, when the water recedes and becomes shallower.

Pipistrelle

Garden Lizard

Flapshell turtle

Spotted Gecko

Rat Snake

Russell’s Viper

Striped Keelback

Pond Turtle Common Skink House Rat Leaf-nosed Bat

Mottled Emigrant Common Crow Plain Tiger Peacock Pansy

(5 species in total)

Apple Snail

Freshwater Shrimp

Freshwater Mussel

Fresh water prawn Pond Crab Mud Crab

Freshwater Snail Ram’s Horn Snail

Legend

Images source: https://animalia.bio/collections

Food web and conflicts

Predator bird

Food web - Brackish water marshland

Carnivorous bird

Insectivorous bird

Omnivorous bird

Foodweb complex of the freshwater organisms is important more maintaining the balance and healthy functioning of the ecosystem. The different bird varieties found on the marsh are dependent on the microhabitat conditions and the adequate food resources on the marshland. The underwater food web also plays an important role as it governs the food chain for the shore/wading and piscivorous birds.

Food chain

Conflicts in food web- Freshwater marshland

• Giant african catfish is affecting the underwater food web by competiting with the Piscivorous and Omnivorous bird species and feeding on other native species of fish found in the marsh.

• The bony skeleton of the catfish may cause chocking in smaller shore/wading birds.

• The presence of Lemnaceae in the surface at continous stretches can cause oxygen depletion in the water affecting the underwater web.

• The presence of Prosopis juliflora at the edges causes hindrance to nesting birds which visits the marsh causing the birds to migrate to some other locations.

Predator bird

Insectivorous bird

Carnivorous bird

Omnivorous bird

Grass/floating plants

Amphibian

Crustacean Soil Phytoplanktons

Piscivorous bird

Reptile

Foodweb complex of the brackish water is important for maintaining the right balance in the ecosystem. The presence of diadromous fish varieties indicates the connectedness to the sea and helps in feeding the piscivorous birds dependent on the coastal marsh conditions.

The underwater foodchain is in conflict due to the debris floating and the excessive growth of Pontederia crassipes in the marsh causing lesser oxygen levels in the underwater.

Grass

Fish

Reptile

Piscivorous bird

Crustacean Soil Phytoplanktons

Debris

Pontederia crassipes

Giant african catfish

Lemnaceae

Prosopis Juliflora

Conflicts in food web - Brackish water marshland

Prosopis Juliflora

Food chain

Habitat study

Species: Black-bellied

Type of bird: Wading shore-birds

Habitat: Open water

Type of visitor: Resident

Breeding period: February to April

Food requirement: Insects, and plunging obliquely into the water to feed on crustaceans, tadpoles and fish.

Basic habitat requirements: Lowland rivers and marshes, and sometimes ditches and pools, at altitudes of up to about 730 m.

Nesting sites: It nests on the ground, usually in depressions or scrapes in sand, gravel, or coral. They also use bare rocks or vegetated substrates, such as mats of dead leaves or grasses.

Species: Indian skimmer

Type of bird: Wading shore-birds

Habitat: Open water swamps and coastal estuaries

Type of visitor: Resident and winter migrant

Breeding period: February to May

Breeding habitat: Mudflats

Food requirement: Fish but also take small crustaceans and insect larvae.

Basic habitat requirements: Swamps and coastal wetlands such as estuaries. Nesting sites: It requires a specific habitat for nesting, which includes sandbars and islands within the waterbody. They prefer to nest on open sandbars that are free from vegetation and close to the water’s edge.

Species: Common pochard

Type of bird: Diving bird

Habitat: Marshes and lakes with a metre or more water depth.

Type of visitor: Non breeding winter resident

Migration period: November to February

Food requirement: Aquatic plants with some molluscs, aquatic insects and small fish.

Basic habitat requirements: Freshwater and brackish wetlands with abundant emergent fringing vegetation.

Nesting sites: For nesting, the common pochard prefers to use dense emergent vegetation such as reeds, rushes, and sedges. It will also nest among grasses and other aquatic vegetation.

Emergent sedges, rushes and grassy bank areas - Deep water

Tadpole Pond crab Insect Freshwater Shrimp

Emergent sedges, rushes and grassy bank areas - Shallow water

Worms Fish Pond crab Freshwater Shrimp

Fish Aquatic plants Pond crab Nesting sites Dragonfly

Emergent sedges, rushes and grassy bank areas - Deep water

Habitat study

Species: Great Knot

Type of bird: Wading shore-birds (brackish)

Habitat: Wet mudflats, Shallow puddles.

Type of visitor: Resident and winter migrant.

Migration period: October to March

Food requirement: Worms, larvae and other soil invertebrates.

Basic habitat requirements: Sheltered, coastal habitats containing large, intertidal mudflats, including inlets, bays, estuaries and lagoons.

Nesting sites: They rely on the surrounding vegetation for protection and camouflage. It prefers to nest in areas with low-lying vegetation, such as grasses, sedges, and small shrubs. The plants provide cover for the nest and chicks, which helps protect them from predators and harsh weather conditions.

During migration and wintering, the Great Knot uses a variety of habitats, including mudflats, sandy beaches, coastal wetlands, and intertidal zones.

Emergent sedges, rushes and grassy bank areas - Shallow water

Species: Great spotted eagle

Type of bird: Predator bird

Habitat: Bogs, wetlands, some sea coasts, and other waterways surrounded by woodland or forested land.

Type of visitor: Resident winter migrant

Migration period: November to February

Food requirement: Prey on ground or on the water

Basic habitat requirements: Freshwater wetlands, grasslands, scrublands, forest and urban niches.

Nesting sites: Great Spotted Eagles typically build their nests in the crowns of large trees, using sticks, twigs, and other materials. They may also use other tall vegetation, such as reed beds or rushes, for nesting if suitable trees are not available.

The nests are typically quite large, often measuring over a meter in diameter, and are built up over several years of use.

Worms Larvae

Fish Owl Pond crab Squirrel Freshwater Shrimp

Islands with shallow water

Issues map

Issues on the site due to urbanization pressures

Major encroachments inside the marshland have atlered the hydrology and the ecology of the marsh.

The encroachments are residential, It offices, Dumpyard site, Institutions, NIOT, National institute of Wind energy, CMSSWB STP, and more squatter settlements.

Landfill

Grid size: 500x500 m

Produced leachate contains high contents of Mercury, Cadmium and Lead.

It is apparent that the Pallikaranai marsh is largely affected by organic waste disposal and contamination as is indicated by the high levels of Chloride and Sulphate. It has lead to Enviromental, air and water pollution which is becoming hazardous to people and other fauna species living in water.

Water pollution

Untreated sewage water from STP and the drainage water flowing through the water channels is fed into the marshland, causing depletion in the water quality.

PH is acidic in nature near the dumpyard and the TDS level is higher in concentration than the permissible level 500mg/L, which is safe for drinking.

High levels of Chlorides and sulphates are present in the water leading to higher BOD levels near the dumpyard. Also leading to eutrophication near the water bodies.

Invasive species - fauna

Giant African Catfish, the Armored Catfish, Kerala Pomphret were introduced by fisheries department for fishing activities. These species can grow larger in size and create conflict between the other native fishes.

It is larger in size and has bony skeleton which can chock smaller fish eating shore birds.

Habitat degradation

The availability of deep water is very less in comparison to shallow depth waters leading to habitat fragmentation. The maritime ecology of the marshland is also be responsible for the diversity of certain species of migratory waders, which is getting affected now.

1.Fishing on the marshland

2.Dumping the waste in the marshland (converted dumpyard)

3. Grazing pressure on the marshland from the settlements

4. Dumping the construction debris into the road edges along the marshland

5. Gathering wooden logs from Prosopis juliflora for a living

Leisure walk in the marshland eco park

1694 MT OF MUNICIPAL WASTE DUMPED DAILY

Unprotected edge

Systemic thinking

URBANISATION

Unprotected edge along the marshland has altered vegetation patch density due to grazing pressure and dumping of construction and other debris on the edges.

The surface run off water from the surrounding residences are also causing pollution to the marshland and siltation along the eastern portions of the marsh. It is indirectly affecting the birds nesting and roosting habitats.

Lesser water retention

700-800 tankers extract water within 3 km of the Pallikaranai marshland either by directly pumping water from the wetlands or through bore-wells.

The shrinkage in water holding capacity is also due to alteration in marsh conditions due to encroachments and shrinkage in water spread.

Invasive species - flora

Invasion of Prosopis juliflora has been rapid along the site boundaries has altered the vegetation mosaic. Other aquatic invasive species are water lettuce, duckweed and water hyacinth.

It can quickly spread over a whole waterway and may double its size every 5 days under ideal conditions. It lowers water levels and water quality, affects water temperature and pH, reduces oxygen levels, and limits the quantity of sunlight under the water. This affects the fishes and other aquatic species.

Conversion of marshland into scrublands

According to TP Scheme, the southern portion comes under Industrial zone, where people have built residential and institutions on the marshland.

These encroachments lead to change in landform and species diversity to become scrublands with less grounds for open waters.

ENGAGEMENT

FISHING ENCROACHMENTS

CLEAN

ECOLOGICAL VALUES

SILTATION

GRAZING PRESSURE

UNPROTECTED EDGE

POLLUTION

HISTORY

UNIQUENESS

FLOOD MITIGATION

WATER DEPTHS

DUMPYARD

ECOSYSTEM

FRAGILE

RAMSAR SITE

BUFFER REPLACED BY HARD EDGE

WATER RETENTION

STORMWATER DRAIN

CAMPING

SAFETY BRAKISH WATER

RECONNECT

DEBRIS

ECONOMIC VALUE

REVIVE

FAUNA

PALLIKARANAI

MARSHLAND

HABITAT FRAGMENTATION

WATERSHED

INCLUSIVE

FIBRE/FUEL

FOOD CHAIN

RESTORE

IMBALANCE

EDUCATION

SCRUBLANDS

NATIVE FLORA

HABITATS

NATURE INFLUENCE

LOST

WATER QUALITY

INVASIVE SPECIES

MIGRATORY BIRDS

FRESHWATER INTERACTIONS

BIRD HABITAT

HERITAGE VALUES

SEWAGE WATER

THERAPEUTIC

LESS TREE COVER

IT CORRIDORS

ECOTOURISM

POTENTIALS ON SITE RECONNECT REVIVE

Pallikaranai marshland in Chennai, India, is one of the city’s last remaining wetlands. Unfortunately, the marshland has been subjected to severe encroachment and pollution over the years, resulting in its degradation. In order to arrive at strategic solutions for the proposal, the concepts of revive, restore, and reconnect emerged from the systemic thinking diagram.

The objective of the project is to resolve the marsh’s current challenges with specific recommendations and measures that could revitalize the ecosystem’s ecology and hydrology.

The method of narrowing down the keywords entails transforming the crucial concepts and issues from systemic thinking into diagrams and listing them briefly to arrive at the vision.

HABITATS

WATER RETENTION

PALLIKARANAI MARSHLAND

Vision eidetic photomontage

WATER QUALITY

HYDROLOGIC & ECOLOGICAL VALUES

LANDFILL/DEBRIS DUMPING

PASSIVE RECREATION VALUE & COMMUNITY PARTICIPATION

GRAZING PRESSURE

SEWAGE INFLOW

NATIVE FLORA

ENCROACHMENTS

Protected / Sustainable / Activate / Co-existence

Vision statement:

The project aims to REVIVE the ecology of the marshland through interventions and guidelines, RESTORING with improved habitats for critical faunal and avifaunal species as well as RECONNECTING with the humanbeings.

In conceptual exploration section, the overall zones are identified through site synthesis. Moving forward, the conceptual zoning and programming are done based on case studies and inferences from projects. Then guidelines were framed, followed by zoning in different layers of the site through hydrology, edge and habitat conditions and interventions are formulated accordingly.

Figure_Illustration_View of the boardwalk ln the interpretation centre

Site synthesis

Site existing conditions

Existing structures

The existing structures included landfill and the infrasture developments inside the marsh.

Identifying the zones

ENVIRONMENTAL CRITICAL ZONE

This zone has undergone lot of changes due to landfill, which is now recovered by Bio mining.

Water levels- Pre monsoon

Deep waters (1-2m)

Intermediate waters (0.3-1m)

Shallow waters (0-0.3 m)

Water levels- Post monsoon

Deep waters (1-2m)

Intermediate waters (0.3-1m)

Shallow waters (0-0.3 m)

Water salinity

Brackish water

Sewage water inflow

Sewage water inflow

Grazing pressure + Prosopis juilifora invasion

Grazing pressure Prosopis juliflora

Sensory mapping

Dumping of garbage/debris

Foul smell

Noise level

SENSITIVE ZONE

This zone has undergone changes due to grazing pressure, debris dumping and unprotected edges.

AFFORESTED ZONE

This zone is a protected zone where proper maintanence of islands/mounds and water bodies have been taken care by the Forest department.

UNPROTECTED ZONE FOR POTENTIAL

This zone is unprotected as it wasn’t considered as marshland site before Ramsar designation. It has the potential of becoming terrestrial grounds for both fauna and avifauna.

Guidelines

Based on Hydrology

Trenching, bund construction, and earthern mound construction are well-established procedures employed by the TN Forest Department for enhancing the marsh’s water retention capacity.

All areas identified as wetland / marsh areas needs to be protected and encroachments existing within the marsh should be relocated accordingly.

In order the network to operate properly, regions outside the scope of the marsh, particularly the 30 wetland complex specified under the catchment area, must be under the purview of the Pallikaranai Marshland Conservation Authority.

The guidelines for real estate developers around the marsh landscape must be unique, emphasising the dos and don’ts. For example, low-water-use gardens, rather than huge lawns, could become a possible norm.

All three Tilapia species imported into the country for fishing are presently flourishing in Pallikaranai marshland. These invasive species can be eliminated by continuously monitoring and harvesting the overabundance of these fishes.

Involving local community stakeholders in the restoration process will help them understand the ecology of the marshland and to stop extracting water in the adjoining, non-protected habitats through digging wells or drilling borewells.

Based on Ecology

Existing structures, particularly national institutions such as the National Institute of Ocean Technology and the Centre for Wind Energy Technology, have evolved to become refuges and nesting sites for some of the large wetland birds due to their location within the marsh.

The landfill site after ex situ approach of bio-mining can be reclaimed by phytoremediation and through this approach the polluted marshland could be reclaimed.

Underwater stacking of water-washed rocks to offer habitat for small creatures and fish that are prey for birds. Waterbirds can roost on logs and rocks that protrude from the water.

The institutions should abandon their intentions to extend or improve the current infrastructure on the basis of the benefit sharing mechanism with the landscape, as well as valuing the ecosystem services that the institutions could give.

Placing branches and dead logs at varied heights around the border of the marsh to provide roosting and nesting areas. Providing a diversity of water depths offers habitat for waders, connect shallow mudflats to an island rather than the shoreline.

Promoting an increase in the wetland’s overall species diversity and thus ensuring ecological processes are in place and functional. The intent is to help avifauna and other faunal groups with their nesting, breeding, and feeding routines and preferences.

Using natural margins with slopes instead of steep banks. The addition of vegetated banks in bare areas will allow birds to traverse across the wetland and also allowing them to spot predators.

Based on Interventions

Removal of the alien species(flora) through methods like mechanical, Mechanical with application of systemic herbicide and Herbicide alone. Physical method can be used to remove water hyacinth from the infested water bodies. For large infestations, machines, like aquatic weed harvesters and crusher boats need to be employed.

Bio fencing can be used to restrict cattle access, hence reducing bank erosion and disruption to fringe vegetation. Natural regeneration is also possible in disturbed regions as a result of this.

Keeping mature trees around the marsh to provide habitat for birds and small animals. A variety of aquatic birds build their nests in tree hollows or forks.

Responsive eco tourism activities can be allowed such as nature trails, interpretative centre and wetland study centres to create awareness among the public regarding the marshland ecology and its unique species diversity.

Creation of more terrestrial islands and mounds through the similar trench method utilised by the forest department can increase the perching and resting habitats for the avifauna in the southern portion of the marsh.

*Reference taken from the site management plan proposed by Care earth trust

Methods

Excavation through digging trenches

Zoning - Hydrology & Habitat conditions

Trenches are dug out to deepen pits and increase the water retention capacity along the areas where water depths are less and siltation is a major concern.

Conceptual sections

Section A

Design strategies

1. Increasing the percolation capacity and connecting water bodies along the catchment area to the wetland.

Road edge along compound wall

Section B

Buffer vegetation

Shallow water along the grassy banks

Creating islands/mounds

Mounds are created thereby excavating trenches all around the mound and also the excavated sand is used to create grassy mounds along edges.

Mounds around waterbody

These mounds help birds to perch and nest while the excavated trenches will help fishes to migrate during lesser water availabillity period.

Increased water depths

Legend

Swimming birds

Predator birds

Leaf walking birds

Non diving birds

Shore/wading birds

Arboreal birds

Ground birds

The proposed water depths will allow the marshland to retain more water capacity during pre monsoon months.

Freshwater

Brackish water

Mix of both fresh and brackish water

Proposed Stormwater connection

Water bodies

Proposed water bodies

Road edge along compound wall

Section C

Bio-retention pond Grassy mounds acting as a natural edge

2. Creating Bio-retention ponds and raingardens along the buffer edges which filters the runoff water and eventually released to the wetland.

Shallow water along the grassy banks

3. Increasing the water depths of deepwaters of the marsh to support more water holding capacity and also increasing the biodiversity of species living in the water.

Buffer vegetation

Increased depth in the deep water

Section D

Section E

Road edge along compound wall Dead

4. Introducing perching barks along the banks will increase lot of shore and terrestrial birds to rest on them.

Buffer vegetation along the edge

Perching barks

5. Introducing dead logs along the grassy banks will increase the population of Swimming, shore wading, ground and arboreal birds to nest and perch on them.

Grassy

Methods

Zoning - Edge conditions

Conceptual sections

Section A

Section B

Design strategies

Buffer vegetation

The buffer vegetation is proposed along edges for edge protection and increased terrestrail habitats for the avifauna. It also blocks the noise from the surrounding.

Edge stablisation

Creation of gentle slopes surrounding the marsh with a height to length ratio of 2:1 or 3:1, as well as for irregular shorelines for the wetland can be ensured along the edges.

Type of edge

The edge conditions vary widely accordingly to the varied conditions all along marsh with varied treatment.

1. The strategy is to include more trees and shrubs along the compound wall and providing buffer vegetation along the banks.

The strategy of providing biofencing along the unprotected edges is used in section B as a protective edge

With the proposed edge condition the human conflict with the marsh can be avoided and the waterbody can be protected.

Legend

Freshwater

Brackish water

Mix of both fresh and brackish water

Water bodies

Compound wall edge with buffer vegetation

Biofence with thick vegetation

Buffer along the road

Grazing area with biofence

Mangrove species buffer

Mound acting as the edge

Thick vegetation cover with gradual slope

Road edge along compound wall

Section C

Buffer vegetation

Shallow water along the grassy banks

Road edge along compound wall

Buffer vegetation Biofence

2. Along the unprotected edges, the strategy is to provide biofencing with Euphorbia spp. as a protective layer preventing humans or animals to enter the waterbody.

Inspired from “Haha wall” providing controlled grazing areas will prevent people from entering the wetland.

Road edge along compound wall

Section D

Grazing area

Biofence

Shallow water along the grassy banks

3. Introducing undulating mounds with fencing along the edge as a protective barrier for the wetland. It also acts as microhabitats for birds to feed and perch within the mounds.

Road edge along compound wall

Section E

Grassy mounds acting as a natural edge

4. Introducing mangrove species along the buffer edges of the brackish water to act as protective edges for the faunal species dependent on them and also as a support to the whole ecosystem.

Road edge along compound wall

Section F

Mangrove edge Shallow water along the grassy banks

5. Along the road edges thick buffer vegetation is created with stepped embankment for allowing more buffer against noise pollution and breaking the steeper slope which is existing.

Gradual slope with buffer vegetation

Shallow water along the grassy banks

User group

Birdwatchers, nature enthusiasts, Scientists, researchers, hikers, outdoor enthusiasts, local residents and community members visit the marsh for varied interests accordingly.

Conceptual sections

Section A

Design strategies

1. Introducing watch towers which replicates a tree as a strategy to add minimal distraction to the birds and also creating spaces where people can view the different bird species visiting there.

Watchtower along the grassy mounds

Section B

Monitoring and assessment

This facility can be helpful to tracking marsh health and determining the effects of human impact on these ecosystems. This may involve performing regular assessments of water quality, vegetation, and biodiversity surveys.

Educational outreach

A wetland monitoring study and interpretative center can be employed to teach people about the importance of wetlands. For students and members of the community, the center may offer guided tours, workshops, and educational programmes.

Legend

Floating bridge Grassy banks with perching barks

Section C

2. Introducing viewing decks along the interpretation centre where we can view the birds from a distance without disturbing them. It also has a informatory section to guide the user to check upon the different species they might spot.

Boardwalks are a valuable methods for integrating accessibility to the public and protecting the environment in flooded regions. Likewise programs are designated to allow public only in restricted

Freshwater

Brackish water

Mix of both fresh and brackish water

Water bodies

Compound wall edge with buffer vegetation

Biofence with thick vegetation

Buffer along the road

Grazing area with biofence

Mangrove species buffer

Mound acting as the edge

Dense vegetation cover with gradual slope

Intrepretation centre

Wetland study centre

Wildlife healthcare centre Interaction zones Viewpoints

Terrestrial grounds

Road edge along compound wall

Section D

3. Introducing Hideout viewpoints where people can come see from hidden points though private trails where people can use the space with paid entry.

Jogging track along the periphery

Section E

Buffer vegetation Shallow water along the grassy banks

Hideout spot

Grassy mounds acting as a natural edge

4. Introducing jogging tracks along the buffer spaces along the periphery of the wetland as passive recreation spaces for the community engagement.

5. Introducing pocket parks where people can sit and relax as a part of the community engagement which happens along the peripheral zones.

Road edge along compound wall Pocket park Bio-fence

Gradual slope with grassy bank edges

The overall strategy for the proposal is detailed in this stage using master plans along with transects details. The visualization of the spaces and the implementation measures are further detailed. The project outcomes are envisioned using visual narratives and as an end result of the proposal, the hydrological and ecological sustainability of the marsh is restored.

Figure_Illustration_View of the interpretation walk along the bridge

Master plan

Legend

1.Intrepretation centre

2.Marshland eco park(exisiting)

3.Wetland study centre

4.Grazing area

5.Pocket park

6.Bridge walk

7.Afforested area with nature trails

8.Wildlife healthcare centre

Road

Buildings

Watch tower

Bridges

Rope walk

Parking

Edge conditions

Compound wall edge with buffer vegetation

Biofence with buffer vegetation

Mound edge

Mangrove species buffer

Dense vegetation cover with gradual slope

Habitats

Island vegetation

Mixed vegetation

Swampy grasslands

Terrestrial grounds

Vegetated mounds

Open waters (3-4m)

Deep waters (2-3m)

Intermediate waters (1-2m)

Shallow waters (0.5-1m)

Very shallow waters (0-0.5m)

Avifauna species

Swimming birds

Arboreal birds

The master planning is planned based on the previously discussed design strategies and guidelines which are implemented on site to revive the lost habitats and water bodies, restore the edge conditions and reconnect with the humans.

The site is about 1247.5 Ha and there are interventions made abiding to the Ramsar convention guidelines which doesnot impact the ecology of the marsh.

Edge conditions

Type a : Compound wall with buffer vegetation

Non diving birds

Shore/wading birds

Ground birds

Predator birds

Leaf walking birds

Type

b

: Biofence with buffer vegetation

Buffer vegetation of 25-30 m wide native vegetation is provided along the compound wall.

Perching barks and floating vegetation are introduced within the marsh for the improved habitat conditions and increase in the habitat diversity within the marsh.

Biofence is provided with 3 m deep and 5 m wide planting with Euphorbia species along with buffer vegetation along the waterbody.

Mangrove species are planted along the edges of the brackish water condition with barbed wire fencing. It stabilises the shore line and also acts as habitats for the aquatic species.

Dense buffer vegetation of trees for about 50100m wide are planted along the terrestrial ground as noise barrier and also for edge protection.

Type c : Buffer vegetation along road

Mound edge with heights ranging from 5 m to 7m within the undulations with 5% slope ratio. This mound is built with the excavated soil and native grass covering is given on the mound.

Type d : Mound edge with fencing

Buffer vegetation of 25-30m wide belt of trees with tall shrubs are planted along the highway as a strategy for noise buffer.

Type e : Mangrove edge with fencing

Type f : Dense buffer vegetation

Transect plan 1

Transect 1

Visual composition of the transect 1

Habitats

Mixed vegetation

Swampy grasslands

Terrestrial grounds

Open waters (3-4m)

Deep waters (2-3m)

Intermediate waters (1-2m)

Shallow waters (0.5-1m)

Very shallow waters (0-0.5m)

Compound wall with buffer vegetation

Shallow waters

Wetmeadows

Type of users & programme

Deep waters

Intermediate waters

Shallow waters

Intermediate waters

Visitors include birdwatchers, nature lovers, academicians, and researchers interested in learning more about the marsh’s avifauna and ecological state. They can learn about, observe, and take photographs of the species that visit the marsh with the aid of the nature trails, boardwalks, and watchtowers.

Locals and tourists visit the marsh because its located within the city limits, this could raise public awareness and produce revenue for the marsh’s protection and management.

Deep waters

Dense vegetated zone

Interpretation centre

Reclamation of the landfill site

After 2 years

Bio mining in the landfill site

Sesbania aculeata L is planted in the soil and harvested during the flowering season and its crushed and added back to the soil as a green manure to improve the soil condition.

Buffer vegetation

Shallow - deep waters

Biofence with buffer vegetation

After 6 months

Phytoremediation helps additional toxins from the soil are removed by growing trees and bushes that don’t contribute to biodiversity and aren’t edible. The species which is useful for firewood and timber can be grown.

After10-15 years

The intrepretation centre can be built with guided walks which can be part of the dense vegetated zone.

Swimming birds Shore/wading birds Ground birds Amphibians Arboreal birds Predator birds Leaf walking birds Non diving birds

Crustaceans Fishes Amphibians Human interaction Landfill reclaimed site

Grid size: 500x500 m

The marshland interpretation centre can help the local community, visitors and children to be educated and experience the marsh holistically.

During the nature trails, the resting site is incorporated with the theme of emphasizing a particular bird community, its characteristics and its contribution to the ecosystem.

The ropewalk bridge allows the users to view the densely vegetated zone from an elevated view without causing much disturbance to the system.

The watch towers are situated at closer perimeters to water bodies ranging from intermediate to deep waters. The watch tower is designed mimicking a tree trunk which doesnt disturb the bird habitat conditions and also allow resting spaces for the birds.

The floating bridge is situated at the site entry level, where users can the view the birds from a distance by viewing them from elevated platforms. Binoculars and information boards are placed on the bridge for educative purposes.

Camping tents are provided near the water body with dense vegetation to provide shade and to experience the natural setting of the space. Education camps and tours can be held here.

Grid size: 500x500 m

1.Intrepretation centre

3.Floating bridge

2.Resting site

4.Watch tower

5.Rope walk bridge

6.Camping site

Visual composition of the transect 2

Habitats

Mixed vegetation

Swampy grasslands

Terrestrial grounds

Open waters (3-4m)

Deep waters (2-3m)

Intermediate waters (1-2m)

Shallow waters (0.5-1m)

Very shallow waters (0-0.5m)

Mound edge

Type of users & programme

Very shallow waters

Watch tower

Intermediate waters

Shallow waters

Deep waters

Visitors include birdwatchers, nature lovers, researchers, locals and tourists can take the trail along the periphery of the marsh along the edges and can access the watch towers and viewpoints to watch birds. The cycle trail also includes viewing points at every 2km interval along the entire stretch.

Intermediate to Shallow waters

Mound edge Institution

Very shallow waters

Dense vegetated zone

Reclaimed edge 1

Intermediate waters

Bridge walk

Mangrove edge Deep waters

Buffer vegetation

Reclaimed edge 2

Interlinked water bodies

The grassy mounds acts as protective barrier along the free edge of the marsh. As the elevation of the ground is very low the use of the mounds will act as natural barriers to prevent flooding and also creating habitats for the avifaunal species.

The Okkiyam madavu (creek) connecting to the Buckingham canal is the critical zone where exchange of freshwater and brackish water happens. The protective edge of planting mangrove species will help stabilise the bank and also provide habitats for fauna and avifaunal species.

The interlinking water bodies in the monsoon season helps in the mixing of fresh and brackish water sustaining the uniqueness of the ecosystem. It supports more biodiversity and also recharges ground water and also increasing the water retention capacity of the marsh during the pre monsoon months.

Swimming birds

Shore/wading birds Ground birds Amphibians Crustaceans Arboreal birds

Predator birds Leaf walking birds Non diving birds

Transect 2

Fishes Amphibians Human interaction

Grid size: 500x500 m

Island vegetation

Visualising the site - transect 2

The mangrove edge is proposed along the areas where there is an influence of brackish water and planting strategy would allow to select species of mangrove according to the buffer width and land availabily along the marsh.

The watch tower is situated along the grassy mound edges where users can access from the periphery of the marsh and watch birds through it.

10.Afforested zone with trails

The densely vegetated zone was previously left barren and unprotected niche within the marsh. Thus this zone has the potential to provide habitats for fauna and avifaunal species which depend on brackish water regimes.

The intrepretation walk provided along the bridge connecting to the Old Mahabalipuram road acts as a viewpoint and a stopover point where people can view and enjoy the sight of the birdwatching from a distance.

12.Cycle track

The afforested zone with trails are provided by the forest department with pathways and floating bridges for the tourists, locals and nature enthusiasts to enjoy the guided walks inside the marsh.

11.Intrepretation walk

The cycle track is provided along the roadways parallel to the periphery of the marsh where tourists and localites can take a ride enjoying the surrounding.

Grid size: 500x500 m

7.Watch tower

9.Dense vegetated zone

8.Mangrove edge

Transect plan 3

Compound wall with buffer vegetation

Deep Open Intermediate waters Very Shallow to shallow waters

Shallow waters Shallow waters Shallow

Type of users & programme

Reclaimed edge

Compound wall with

Waterbody with island vegetation

Nature trails

Habitats

Island vegetation

Mixed vegetation

Swampy grasslands

Terrestrial grounds

Vegetated mounds

Open waters (3-4m)

Deep waters (2-3m)

Intermediate waters (1-2m)

Shallow waters (0.5-1m)

Very shallow waters (00.5m)

Visitors include birdwatchers, nature lovers, researchers, locals and tourists can visit the southern portion of the marsh, which has nature trails, viewpoints and a wildlife healthcare centre for avi-faunal species. There a viewpoints situated along the outer periphery of the marsh .

The island vegetation which is proposed (replica of the islands created by the forest department) in the newly established waterbody gives more habitat space for the avifauna and also helps in the exchange of the freah and brackish water through the water channel leading from the northern portion.

The nature trails are proposed along the periphery where the users can experience the guided walk through the terrestrail grounds and also look at the birds and other fauna species from the floating decks and watch towers.

Swimming birds

Shore/wading birds Ground birds Amphibians Crustaceans Arboreal birds Predator birds Leaf walking birds Non diving birds

Visual composition of the transect 3

Transect 3

Fishes Amphibians Human interaction Grid size: 500x500 m

Visualising the site - transect 3

Key transect plan 3

The fishing spot is provided as a part of ecotourism and it is strictly restricted towards the area demarcated for it and timely allowance and charged entry is ensured for this activity.

The hideout cabins are secret bird watching spots placed along edges of waterbody which doesnot disturb the surroundings and the avaifaunal species in the marsh. There are peep holes and movable louver windows for birdwatching purpose.

The wildlife healthcare centre is present along the entry of the marsh where it allows injured fauna and avifauna species to be treated. This centre is present at 3 more points along the marsh.

Grid size: 500x500 m

13.Board walk

15.Floating bridge

14.Fishing spot

The experience of walking on the waterbody is provided with the guided walkways through the boardwalks which are proposed along the periphery of the shallow waters.

The floating bridge is provided along the periphery of the deep water body where users can watch the birds from the deck on their way through the trails.

16.Woodland Trail

17.Hideout cabin

18.Wildlife healthcare centre

The woodland trail allows the users to get the experience of the terrestrial grounds through the walk.

Visual

Type of users & programme

Visitors include birdwatchers, researchers, localites and tourists can visit the southern portion of the marsh, through the trails along the periphery of the marsh. There are parking spaces provided along the trails and the entry points for user convenience.

Waterbody with island vegetation

The water channel are connected to the proposed waterbody where the freshwater inflow is there. Similar approach towards the island vegetation is proposed inside the waterbody which allows more aquatic animals and birds to feed and perch on the mounds.

Terrestrial grounds

Habitats

Island vegetation

Mixed vegetation

Swampy grasslands

Terrestrial grounds

Vegetated mounds

Open waters (3-4m)

Deep waters (2-3m)

Intermediate waters (1-2m)

Shallow waters (0.5-1m)

Very shallow waters (0-0.5m)

The terrestrial ground comprises of densely vegetated grounds which are topographically placed at higher elevation to the norther portions. It has both terrestrial mounds and island mounds present in water bodies, which gives more perching space for birds.

Compound wall with buffer vegetation

Watch tower

Swimming birds

Shore/wading birds Ground birds Amphibians Crustaceans Arboreal birds Predator birds Leaf walking birds Non diving birds

composition of the transect 4

Transect 4

Compound wall with buffer vegetation

Grid size: 500x500 m Fishes Amphibians Human interaction

Visualising the site - transect 4

Key transect plan 4

22.Crossover bridge

19.Terrestrial

The terrestrial grounds are proposed along the southern portion where the land was dry scrublands earlier and had a potential of becoming a breeding and nesting grounds for lot of faunal and avifauna species.

20.Vegetated mounds

The egret trail is provided along the peripheral trails provided along the marsh boundary. Similarly there are many resting spots and views points provided for interaction and educational purposes along the trail.

24.Island vegetation

The crossover bridge is provided along the water channel which is part of the catchment area, which enters into the marsh through the peripheral buffer zone.

23.Egret trail

Island vegetation are proposed in the water body which acts as habitats and resting spaces for the birds and also for other semi-aquatic species residing in the marsh.

grounds

21.Watch tower along the periphery

Grid size: 500x500 m

The vegetated mounds are proposed inbetween the terrestrial grounds along the water body as perching and nesting grounds for birds.

Watch tower are provided along the periphery of the marsh as viewpoints from the outside of the marsh.

POLLUTED MARSHLAND

The Pallikaranai marshlands has been under a lot of pressure as the outcome of urbanisation. Construction debris has been dumped along the marsh edges, sewage water has been released into the marsh, and invasive species such as Prosopis juliflora and Pontederia crassipes are occupying the marsh and disrupting avifaunal habitats. There is air and soil pollution as a result of the dumping of waste and garbage. Pollution has severely impacted aquatic life, resulting in a loss of biodiversity in the region. The marsh’s water retention capacity has decreased due to siltation.

REVIVED HABITATS

With the design strategies the idea of reviving the marshland’s ecology is achieved through increased water depths which allow water bodies stay interconnected during monsoon and support more aquatic life and avifaunal species. Introducing perching barks and floating vegetation and woodland species along the reclaimed portion of the landfill site which supports the marshland to recover from the pollution. Due to the improved ecological condition there is increase in carbon sequestration, oxygen levels and micro climate of the region.

BEFORE

UNPROTECTED EDGE

The edges of the marsh are unprotected due to infrastructure development, Prosopis juliflora invasion, grazing pressure, garbage dumping, conversion of edges to scrubland, entry of sewage water into the marsh, people entering the marsh to collect firewood, and fishing, all of which have an impact on the marsh’s ecology and biodiversity value. There is a lack of understanding among local residents and authorities about the importance of the Pallikarnai Marshland, which has contributed to the marsh’s pollution and negative impacts to this day.

RESTORING THE EDGES AFTER

RESTORED EDGE CONDITION

Shoreline stabilisation, buffer vegetation along compound wall edges, providing mound edges, mangrove edge vegetation, and biofence along free edges are all used to restore edge conditions. The dense buffer vegetation is proposed at the boundaries of the marsh in the southern portion, where it works as a protective barrier for the terrestrial grounds. There are cycling routes, nature walks, and view points throughout the periphery of the marsh that allow users to engage with the marsh without interfering with it.

LANDFILL SITE

Pallikaranai marsh is largely affected by organic waste disposal and contamination as is indicated by the high levels of Chloride and Sulphate It has lead to Enviromental, air and water pollution which is becoming hazardous to people and other fauna species living in water. In addition, the landfill has also led to the emission of harmful gases such as methane, which contribute to air pollution and climate change.

RECONNECTING WITH NATURE AFTER

NATURE TRAILS

The woodland species are planted in the reclaimed landfill site where the interpretation centre and nature trails will allow visitors to engage with marsh and educate themselves about the biodiversity and the ecological value of the marsh. There are viewpoints, watchtowers, ropewalks, floating bridges, camping sites within the marsh where local community, nature enthusiasts, bird watchers, wildlife photographers, tourists and students can enjoy the marsh and document their learning and contribute towards the well being of the marsh.

Project outcome

Design strategies Categories Categories

Hydrology

Benefits

Increase in water retention capacity

Recharging aquifer

Increased water depths in the marshland

Improved water quality

Sustaining the ecology of the marsh through the exchange of fresh and brackish water

Improved functioning of the catchment area through proper stormwater drains

Improved micro climate and biodiversity hotspot found within the urban context

The interconnectedness of the water bodies during the monsoon allows for healthy functioning of the marsh and also allows more species diversity in the aquatic life. Through the implementation guidelines the entering of the water into the marsh is monitored and also this allows water to sustain within the marsh during summer months and also allowing the avifauna to visit the marsh from the different regions.

Benefits Design strategies

Improved habitats for avi faunal species

Increased biodiversity

Bringing back the endangered and vulnerable species back to the marsh

Increased oxygen production

Habitat conditions

Reclaimed landfill site which will become a habit for lot of avifaunal species

Terrestrial grounds enhances the barren scrublands nurturing into a terrestrial marshland

Increased habitats for aquatic species and help them in ease of migration

Through the trenches around the islands/ mounds developed there is free movement of aquatic species to migrate during summer months. Woodland species , terrestrial grounds along with island and mound vegetation helps improve biodiversity. Revegetated edges, reintroduced native vegetation and floating planting will allow more avifaunal species to breed and nest on marsh.

Protected edges which as a safety barrier around the marsh

Edge conditions

Acts as breathable and passive recreational spaces for public

Increased perching and nesting spaces for avifaunal species

Improved edge stabilisation for the marsh

Buffer vegetation along compound wall, biofence with buffer vegetation, grassy mounds, edge stabilisation with mangrove species and thick vegetation buffer along the terrestrial grounds help in stabilising the edges and act as protective barrier for the marsh. There are certain interventions which allow users to enjoy along the periphery of the marsh.

Increased passive recreation along the peripheral edges

Users can get educated and enjoy the marsh

Human interactions

Community strengthening through awareness on the marsh

Acts as noise barrier and increased carbon sequestration.

Provides habitats for faunal species

Revenue generation that will allow to protect the marsh

Research and monitoring of marsh regularly

Viewing avifaunal species within city extents will save lot on travel expenditure for tourists and visitors

Through boardwalks, guided tours, watch towers, interpretation centre, nature and avifauna viewing hideout trails, community pocket parks and cycle tracks along periphery, users can enjoy the marsh without interfering with the marsh’s ecology.

Photograph_View of the wetland in an urban setting

The project sources are detailed in this section, as well as the studio process, which includes readings from books, seminars for learning about the system, site visits, and workshops to further comprehend the site layers.

References for the study

1. Maheshwari, D. (2015). Defining urban and ecological interface when the citiy meets wetland : case of Pallikaranai Marsh, Chennai . http://hdl.handle.net/20.500.12725/8850

2. Surya, S. (2016). Landscape Ecological Urbanism for Restoration of Pallikaranai Marsh Land, Chennai, Tamil Nadu. Procedia Technology, 24, 1819–1826. https://doi.org/10.1016/j.protcy.2016.05.227

3. Milton, J., & Ganesh, J. (2016). CURRENT STATUS OF PALLIKARANAI WETLAND: A REVIEW. ResearchGate. https://www.researchgate.net/publication/324212327_CURRENT_STATUS_OF_ PALLIKARANAI_WETLAND_A_REVIEW/citations

4. Pallikaranai Marsh Reserve Forest | Ramsar Sites Information Service. (n.d.). https://rsis.ramsar.org/ris/2481

5. SWA Group. (2021, March 4). Optimizing Outdoors: 10 Pivotal Parks - SWA Group. https://www.swagroup.com/stories/optimizing-outdoors-10-pivotal-parks/

6. ASLA 2013 Professional Awards Ningbo Eco-Corridor - 3.3 km Living Filter. (n.d.). https://www.asla.org/2013awards/253.html

7. https://www.turenscape.com/en/project/detail/435.html

8. Slow Down: Liupanshui Minghu Wetland Park 2014 ASLA Professional Awards. (n.d.). https://www.asla.org/2014awards/002.html

9. The Siltcatcher: A Sediment-Capture System for Wetland Creation and Coastal Protection in Western Lake Pontchartrain | ASLA 2020 Student Awards. (n.d.). https://www.asla.org/2020studentawards/1267.html

10. Kranji Marshes, Singapore — Stephen Caffyn Landscape Design. (n.d.). Stephen Caffyn Landscape Design.

https://www.land-arch.net/kranji-marshes/774yz19k2d9lga1xompscfmkugl42w

11. Rani, S., Kumar, S., Ramulu, C., & Rao, J. (2020). Evaluation of Dhaincha (Sesbania aculeata L.) accessions for green manuring traits and soil fertility. ResearchGate. https://www.researchgate.net/publication/349677712_Evaluation_of_Dhaincha_Sesbania_aculeata_L_accessions_for_green_manuring_traits_and_soil_fertility_improvement

12. Jagdish. (2020, August 10). Bio Fencing Plants, Benefits in India - A Full Guide Agri Farming. Agri Farming.

https://www.agrifarming.in/bio-fencing-plants-benefits-in-india-a-full-guide

13. Forestry :: Mangroves. (n.d.). https://agritech.tnau.ac.in/forestry/forest_mangrove_index.html#:~:text=MANGROVES%20IN%20TAMIL%20NADU%20Top%20Mangroves%20in%20Tamil,decandra%20and%20Aegiceras%20corniculatum%20as%20the%20dominant%20flora.

14. Fletcher, J. A., Willby, N., Oliver, D., & Quilliam, R. S. (2019). Phytoremediation Using Aquatic Plants. In Concepts and strategies in plant sciences (pp. 205–260). Springer International Publishing. https://doi.org/10.1007/978-3-030-00099-8_7

15. Radhakrishnan, S., & Radhakrishnan, S. (2022). What do we do with Chennai’s legacy waste? Citizen Matters, Chennai. https://chennai.citizenmatters.in/chennai-legacy-waste-bioming-perungudi-kodungaiyur-fire-source-segregation-40678

16. Dt Next Bureau, & Dt Next Bureau. (2023). 7.5 MT CO2 emission prevented through biomining in Perungudi dump yard. DT Next. https://www.dtnext.in/city/2023/02/05/75-mt-co2-emission-prevented-through-biomining-in-perungudi-dump-yard

17. Freshkills Park NYC Parks. (n.d.). https://www.nycgovparks.org/park-features/freshkills-park/about-the-site

18. Bhagwat, R. V., Boralkar, D. B., & Chavhan, R. D. (2018). Remediation capabilities of pilot-scale wetlands planted with Typha aungstifolia and Acorus calamus to treat landfill leachate. Journal of Ecology and Environment, 42(1). https://doi.org/10.1186/s41610-018-0085-0

19. Martinez, S. L., Rivera, S. L., -González-Mondragón, E. G., & Velázquez-Martínez, J. R. (2019). PHYTOREMEDIATION OF LANDFILL LEACHATE USING VETIVER (CHRYSOPOGON ZIZANIOIDES) AND CATTAIL (TYPHA LATIFOLIA). ResearchGate. https://www.researchgate.net/publication/331563308_PHYTOREMEDIATION_OF_LANDFILL_LEACHATE_USING_VETIVER_CHRYSOPOGON_ZIZANIOIDES_AND_CATTAIL_TYPHA_LATIFOLIA

20. Tamil Nadu Treepedia. (n.d.). https://www.tntreepedia.com/trees/

21. Comprehensive Management Plan - for Pallikaranai Marsh (2014-2019), Conservation Authority for Pallikaranai Marsh - Care Earth Trust (2014)

Guided by : Prof. Dr. Deepa Maheshwari

Teaching associate: Anmol Tewari

LA4004 l Designed Ecologies

Master’s in Landscape Architecture

SPRING 2023 l CEPT UNIVERSITY