Sustainable development through River Restoration

Submitted by-Shraddha Bahirat

Before

After

Urban development and climate change

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IntroductionOne of the most pre-dominant factors for selection of site for establishing permanent settlements since ages

It has been a source of

Water

Food

Transport

To dispose wasteHydropower

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• It has acted as major part of people’s social and cultural life, thus making it an integral part of their lifestyle.

• And habitat sustaining green corridors in the city, thus maintaining the ecology and temperatures around it.

• However the river channels have been harnessed and modified to suit the requirements of the growing settlements.

• Rivers have been straightened and culverted to provide flood protection and to make maximum use of land for housing, industry and agricultural use.

“Disturbed the ecological balance and disrupted the riverine systems and their functions ”

Aim and Objective

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Aim:

The study endeavours to analyse through case studies and examples of river restoration the impact of restoration on the social, economic and ecological life in the city and how the restoration of rivers has impacted the improvement in climate of the city.

Understanding Rivers, Water shed and stream orders

• A watershed is the land area drained by a particular stream or river.

• Small streams join to form larger streams in a branching pattern that forms a drainage network.

• Therefore, larger watersheds are made up of a joining of smaller watersheds.

• The different channels draining these watersheds can be designated by how many tributaries they have or by order.

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A cross section of a river corridor

• First order stream channel has no tributaries, when two first order streams join; they create a second-order stream.

• When two second order streams join they create a third order stream and so on.

• One can designate a stream by its order to get the concept of the size of the drainage area concerned.

• Stream drainages follow the lowest topography and form valleys and become separated from each other by ridges or divides.

Two types of floodplains: • Hydrologic floodplain, the land adjacent to the baseflow channel residing below

bankfull elevation. It is inundated about two years out of three. Not every stream corridor has a hydrologic floodplain.

• Topographic floodplain, the land adjacent to the channel including the hydrologic floodplain and other lands up to an elevation based on the elevation reached by a flood peak of a given frequency (for example, the 100-year floodplain).

• 100- year and 500-year floodplains are commonly used in the development of planning and regulation standards.

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The need for River Restoration

• Urbanisation has affected The physical process of river growth Modified stream structure Influenced the function of the river systems

• More than 60% of the rivers in the world have experienced high level of human modification

• Urbanization causes river degradation due to the amount of impervious surface area which causes Increased erosion, Channel destabilization and Widening of stream

• Leading to loss of Habitat from channelizationExcessive sedimentation Increases in temperature and Reduction in large woody debris causing more

homogeneous in stream habitats.

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• Urbanization of watersheds is almost invariably accompanied by loss and alteration of aquatic habitats, two of the most frequently mentioned causes for losses of aquatic biota.

• Rapid urbanisation has resulted in a clear decline of drainage density and an obvious ecological degradation in river ecosystem.

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• Geographically, there is a shifting of urban land, and the extent of drainage density decreases from the core of towns to the outskirts.

• Outward expansion of the urban land and the decrease/ disappearance of the wetland and water bodies are found to be among the most important driving forces explaining the ecological degradation in river ecosystems.

• The impact of urbanisation on the water body/ river can be studied under four categories: Hydrology Geomorphology Water Quality Habitat

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Hydrology• The impact of urbanisation on hydrology is evident from the following facts:

1. Disruption of natural water balance2. Increased flood peaks3. Increased stromwater runoff4. More frequent flooding5. Increased bankfull flows6. Lower dry weather flow

• The bankfull flooding (or the condition of the flow that fills up the channel) occurs much more frequently in highly urbanized areas and has the potential to be extremely erosive and damaging to the natural morphology of the stream.

The Stream and its floodplain before and after development

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Geomorphology

• The impact of urbanisation on geomorphology of the river is as follows:1. Stream widening & erosion2. Reduced fish passage3. Degradation of habitat structure4. Decreased channel stability5. Loss of pool-riffle structure6. Fragmentation of riparian tree canopy7. Decreased substrate quality

• In watershed with less than 5% impervious cover stream are:1. Stable and persitine,2. Maintaining good pool and riffle structure3. A large wetted perimeter during low flow with

a good riparian canopy coverage.

• 8- 10 % impervious cover the stream is:1. Relatively stable however erosion are more

apparent and include loss of the wetted perimeter

2. More eroded material in the bank and debris.

• 10% impervious cover the stream is:• Tree roots are exposed and the pool riffle

structure seen in sensitive streams is lost. • 20% impervious cover with decreased

substrate quality due to more material flushing through the system. Active erosion becomes much more evident

• The stream having a surrounding area of approximately 30% impervious cover. The large amount of impervious cover increases the size of the stream by a factor of five to ten.

• In many highly urbanised areas, natural streams have been channelized to speed runoff along, but these fail to provide any habitat value.

Impervious Cover and Surface runoff relationship

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Water Quality• The impact of urbanisation on the stream

water quality is evident through the following:1. Increased stream temperature2. Increased pollutants3. Increased risk of shellfish bed/ beach clouser

• Once urban development moved into the floodplain, rivers were heavily modified to allow maximum land take and to provide the subsequent flood protection that these new developments required.

• Hence there is a urgent need to check the situation for the overall sustainable development of city.

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What is Restoration? Types of restoration• River restoration describes a set of activities that help improve the environmental health of

a river or stream. • On a larger scale, a restoration project might include the entire floodplain, removing past

structures and restoring more natural processes and channel forms to the watercourse. • On a smaller scale, restoration might be simply removing the hard banks and replacing

these with more natural features. • Even using systems such as green roofs can contribute to restoration by enhancing

sustainable drainage and biodiversity.

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Relation between river restoration and sustainable development

The major benefits of river restoration can be classified under three major heads:• Environmental benefits• Social benefits• Economic benefits

Environmental Social

Economic Environmental benefits

Restoring the river’s original form allows the natural processes of erosion and deposition which can sustain a rich variety of aquatic life.• Improving the river corridor• Improving flood storage capacity• Addressing water quality by:

1. Promoting sustainable urban drainage systems in new developments.

2. Creating green river corridors and buffer zones through urban centres.

3. Promoting less-intensive agricultural practices.4. Prosecuting polluters.5. Improving sewage treatment works.

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Social benefits1.Re-establishing natural channel processes2.Improving wellbeing3.Balancing community access and the needs of wildlife4.Providing sustainable transport5.Educating the community

Economic benefits1.Generating sustainable development and attracting business

Thus the major benefits of river restoration in Urban areas includes:1.Improved quality of housing and landscape2.Improved sustainable transport - footpaths and cycleway, jogging tracks3.Climate change adaptation and reduction in flood risk4.Improving the river corridor and green space networks5.Improving biodiversity6.Addressing water quality and land drainage

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Case Study: 1

Cheonggyecheon Restoration, Seoul, South Korea

• Flows through the heart of the city passing through the CBD and connects the Han river in south

• Cuts the city in two distinct parts

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Early 20th Century

The stream was an integral part of the life of the citizens

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• Development of Slums• City faced problems of sanitation• The stream started getting polluted

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• The solution was to cover the stream in 1958-77

• Further with rapid urbanization and need for transportation Cheonggyecheon highway was constructed on the stream .

• Followed by construction of flyovers in the area over the stream in 1999.

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• Building: over 6,000• over 100,000 small shops• Nation’s biggest commercial area• CBD redevelopment stopped where the• Cheonggye Expressway started• Population and employment reduced Population:

40,000Employment: 80,000 in 10 years• Business headquarters moved to Gangnam (new

sub-center)• Industries in CBD lost competitiveness• Maintenance of the highway and flyover

increased

By 2002

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• Restoration Project was announced on 1st July 2001

• Total length: 5.84 km• Restoration of upper reaches of CGC on a

long term basis• Divided into 3 sections to reduce the

construction schedule• Covered structure and highway: 5.4 km• Waste (concrete+asphalt): 872,400ton

(96% recycled)

The Restoration Process

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Design Criteria

• Secure the stream capacity for 200 years frequency rainfall (118mm/hr)• Access to Water: Install sidewalks along the lower level of the bank• Basic design: secure flood capacity for 200 years frequency rainfall and

introduce lower terrace to enhance easy access to water

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Sewer System• Combined sewer system for rainfall and wastewater• Capacity : 3 times of estimated wastewater

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Concepts• New green belt with waterfront: West to East• Gradual transformation from urban landscape to natural environment• Create ecological biotop and environment• Thematic places: waterfall and fountains

Challenges

Cheonggye road & highway• Urban backbone corridor• 170,000 vehicles/day• Traffic disaster warned• Media, interest group• Traffic simulation• Project delay

• Transportation• Neighboring Merchants

Challenge 1: Transportation

• Discourage driving cars in the city centre: Leave cars at home one out of 10 days

• Improve traffic flow systemOne-way streets

• Improve public transport: Bus-only lanesDowntown shuttle buses

Solution for transportation

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• Stimulate business activityReduce parking feeImprove parking system for loading & unloadingPromote Cheong Gye Cheon stores

• Financial support and subsidiesLow-interest loansGrants for the market remodeling

• Special arrangement for street vendors

Solutions to merchants

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• Business declineAccess difficulty: traffic congestionWorse environment: noise & dust due to construction

Challenge 2: Neighboring Merchants

Restoration Progress and Process

Stage 1: Scaffolding (July 2003)

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Stage 2: Highway Demolition (Aug 2003)

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Stage 3: Covered Road demolition (Jan 2004)

Stage 4: Sewer, road and bridge construction (Sep 2004)

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Stage 5: Landscaping of the recovered area (May2005)

Final Finishes and opening on Oct 2005

May2005 to 1 Oct 2005

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Monitor the changes due to the project from Jan 2003~May 2006 (before, during and after the project)Monitoring areas• Land use• Industry• Environment• Ecology• Traffic• Public opinion• Ripple effect

• Speed in CBD15.5 to 3.6 km/hr (-12.3%)– Morning peak: 17 km/hr– Evening peak: 12 km/hr

• Car in/out flow1.56M to 1.27M (-18.6%)

• Public transport rider-shipBus: + 6~10 % Subway: + 6~9 %

Monitoring

Traffic

• Air: NO₂: 69.7 to 46.0 ppb (-34%)

• Water quality: BOD: 100~250 to 1~2 ppm

• Noise level reduced• Heat island effect relieved• Wind corrider created

Environment

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Thermal Image 27 July, 2005

Reduction of 3 degrees in temperature

Public Survey by government for environmental improvement

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Changes in Ecology

6 to 25 species

6 to 36 species

15 to 125 species

Insects

Birds

Fishes

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Enhanced Public life

Case Study: 2

Osho Ecological Park- Osho Teerth, Pune

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• Famously called the nala park • An example of how wastelands

could be aesthetically transformed into parks and could prove a boon for our town and cities.

• Tastefully laid out Japanese-style garden

• The site was a piece of barren land. • A nala ran through it carrying black sludge.• Used oils was also being disposed into it by the nearby railway yard.• Human waste from a nearby slum also flowed into it. • Putrid wastes emitted foul smell.

The need to restore and revitalize

The process of restoration

• The Ashram management took it over in 1989 to revitalise the area.

• The nala flowed from north to south, discharging 500 gallons of water a minute at a particular point.

• First a barricade was raised to keep off the cattle.

• It was then meshed off with iron grills to catch the floating solid garbage once it entered the proposed park.

• The stream was then made to course like a serpent over the land to allow maximum oxygenation of water.

• It was planted with water hyacinth and stocked with fish such as gambusia and silver carp which eat pollutants and mosquito larvae.

• It was then passed through a sand filter.

• The oxygenation and filtering made the water almost 90 per cent pure, perfectly okay for irrigation and fish culture.

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• Local contractors were invited to dump their debris to create hills and dales.

• Trees and shrubs that already existed on the site were pruned.

• Helped by Pune’s climate, the foliage blossomed into a thick vegetative cover.

• With fine hedges and pools and fountains, the Osho Park serves as an inspiration for creating an environmental project.

• The key element in the planning was slowing down the water stream in order to allow the natural cleaning process to be re-established.

• The polluted water was purified naturally, using holding ponds with selected plants and stone.

• The purified water is distributed throughout the garden with underground irrigation.

• The sparkling stream flows throughout the length of the ashram.

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The revitalisation of the stream and creation of the park has greatly improved the ecology and the quality of life of the surrounding areas.

Sabarmati River Front DevelopmentCase Study: 3

Ahmedabad was established on Sabarmati in 1411

Sabarmati has been an important river for Ahmedabad:• As a source for drinking water• As a place for recreation• As a place for the poor to build their hutments• Place for washing and drying clothes• A place for holding the traditional ‘Sunday Market’• A place for farming

Traditional Sunday Market and as space for recreation For Framing

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For daily activities

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Growth of Ahmedabad along Sabarmati

Source: Sabarmati Riverfront Development, Integrated Environmental Improvement and Urban Revitalization, India Urban Conference, Mysore, November 2011

The city initially grew along the eastern coast of the river and the development gradually spread across the river on the western side with the river playing a major part in the development of the city

• Encroachments reduced the river’s flood carrying capacity

• Sewage from the slums flowed directly into the river• A few nalas brought sewage into the river

Storm water drains spewed untreated sewage into the riverIt became a place to dump garbage

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Haphazard and dull development came up along the riverfront

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• The city turned its back to the river

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• The river became insignificant in the life of the city

The river became inaccessible to the public

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• In order to reconnect the city with the river the first known proposal for developing the riverfront was given in 1961 by prominent Ahmedabad citizens and the French architect Bernard Kohn.

• A 9 km stretch of the riverfront extending from Subhash bridge to Vasna barrage was identified and it was proposed to reclaim 162 hectares (400 acres) of the riverbed.

• The Ahmedabad Municipal Corporation (AMC) set up the Sabarmati Riverfront Development Corporation Ltd (SRFDCL) in May 1997.

• SRFDCL planned to sell or lease out a part of it to finance the project. In 2003, it extended the project to cover a 20 km stretch from the Narmada main canal to Vasna barrage.

Main features are the following:

• The reduction of the riverbed from a variable width of 600-300 m to a fix width of 275 m, thus reclaiming 185 ha of land.

• The construction of RCC diaphragm walls (10-20 m depth) and anchor slabs (10 m) to prevent the riverbanks from erosion. After the finishing the anchor slab is turned in the so-called lower promenade.

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Reduction of river bed

Diaphragm wall and anchor slab

• The construction of RCC retaining walls (2.5 - 9 m) to protect the city from flooding. The height of the walls is determined by the 100-year flood level. An upper promenade is created on top of the retaining walls.

• The dredging of the river bed in order to provide soil for the filling of the space behind the RCC retaining walls. At least 67.500 cubic meters are required for the filling.

River RestorationConstruction of retaining wall

• The construction of interceptor sewers on both the riverbanks able to prevent the waste water to flow directly into the river and diverting it to the two sewage treatment plants of Vasna and Pirana.

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• The relocation of slum dwellers and the provision of better living conditions to them. The first proposal was to relocate them in three sites along the riverbanks, but the plan has changed afterwards and the relocation sites are now far from the river.

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The entire length of Sabarmati is returned back to public

Renewed the surrounding areas

The use of the reclaimed land for private residential and commercial developments with a view on water to be sold to finance the project (the percentage has decreased from 20 to 15% because of the high increase of the land value), two major roads, one on each riverbank (30%), gardens (26%), promenades (6%), informal market (3,6%) and the rest for other public facilities

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Stitched east and west Ahmedabad

Facilitated the improvement of the surrounding residential neighborhoods

Potential for new formal and informal commercial development

Potential for organizing trade fairs etc. Created a mile of cultural institutes, museums and hospital facilities

Potential for new recreational spaces like parks, promenade, open air theaters etc.

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Restoration of Sabarmati river and by developing its river front, the thus project achieves the following goals which it aimed at the conception of the riverfront development idea:

• Elimination of the danger of floods in the current context of climate change.

• Establishment of better hygienic conditions through a new sewerage system.

• Increase the ground water recharge through the storage of water within the river bed.

• Improvement of the living conditions of the slum dwellers.

• Renewal of the surrounding areas to cater the future development of the city.

The case of the Sabarmati river shows therefore the “politics of scale” (Smith, 1984) around which a large debate has risen in the last two decades. Questioning one of the core issues of the Sabarmati River Front Development Project - the origin of water - a whole range of new issues come into the picture.

Criticism for the project

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ConclusionRiver restoration takes into consideration all the aspects of sustainability like • Ecology and Environment• Economy,• Social life of the citizens, • History and culture of the city • Addresses the growth trends and urbanization

• The river restoration in any city not only improves the quality of river and its ecology but also affects the other sphere of sustainability i.e social and economic life of the city and its citizens.

• Helps to return the valuable land for public use, recreation and general activities of the citizens;

• It creates opportunities to give respect to the heritage and ecology of the city as it considerably improve the air quality, water quality and the surrounding environment

• It helps to orient development of the city in integration with river.

• It regenerates and renews all the precinct around it as it enhance the quality of life , provides economic boost to the surrounding areas , gives an impetus to improve the general economy of the city in larger context and saves the ecology by curbing the further deterioration of the river.

Hence river restoration and appropriate measure to revitalize the surroundings in the cities having degenerated streams can assist to enhance sustainable development of the city and effectively contribute to mitigate climate change.

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Reference:

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• Association, D. o. (March, 2004). Ecological River Front Design. Wasington DC: American Planning Association.

• centre, T. r. (January, 2009). London Rivers Action Plan. London.• Habitat, U. (n.d.). Urban patterns for a green economy, working with nature. Kenya: UN

Habitat.• J. L. Cassin & L. Tear, R. F. (n.d.). Sustainable river restoration in urban streams - using

biological indicators to establish environmental flow targets in the Pacific Northwest.• Khorshed Alam, D. M. (2006). Sustainibility and river restoration. 35 th Australian

Conference of economist (ACE), (pp. 1-21). Perth.• Paukert, J. L. (2009). Urbanization in great plains river: Effects on fishes and food webs.

Wiley inter science, 1-12.• Redondo, M. D. (2003). Social Impact assesment for river restoration: A more sustainable

perspective. Thesis.• Yuan Wen, P. J. (2006). Impact of urbanisation on structure and function of river system-

Case Study of Shanghai,China. Chinese Geographical Science.• http://link.springer.com/content/pdf/10.1007/s11769-006-0002-9.pdf• http://onlinelibrary.wiley.com/doi/10.1111/1467-9493.00117/abstract

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