Deltaic Development

SITE PLANNING & LANDSCAPING

AR SYED ZAHID

DELTAIC DEVELOPMENT Esther Kiruba | 19171NB002

CONTENTS OUTLINE OF TOPICS What are Deltas?

Types of Deltas Guidelines regarding Deltas in India Deltas & People Deltas & Wildlife Deltas & Land Deltas & Natural Disasters Deltas & Man Made Interventions Deltas & Vegetation Deltas & Global warming Mitigation of problems

WHAT ARE DELTAS? Deltas are wetlands that form as rivers empty their water and sediment into another body of water, such as an ocean, lake, or another river.

Although very uncommon, deltas can also empty into land.

A river moves more slowly as it nears its mouth, or end. This causes sediment, solid material carried downstream by currents, to fall to the river bottom.

Like most wetlands, deltas are incredibly diverse and ecologically important ecosystems.

Not all rivers form deltas. For a delta to form, the flow of a river must be slow and steady enough for silt to be deposited and build up.

Many, many animals are indigenous to the shallow, shifting waters of a delta. Fish, crustaceans such as oysters, birds, insects, and even apex predators such as tigers and bears can be part of a delta's ecosystem.

DELTAS National Geographic Society

TYPES OF DELTAS There are two major ways of classifying deltas.

One considers the influences that create the landform, while the other considers its shape.

INFLUENCES

SHAPE BASED

Wave-dominated Tide-dominated Gilbert Estuarine

Arcuate Cuspate Bird Foot Inverted National Geographic Society

Tide Dominated Tide-dominated deltas usually form in areas with a large tidal range, or area between high tide and low tide.

The massive Ganges-Brahmaputra delta, in India and Bangladesh, is a tide-dominated delta, shaped by the rise and fall of tides in the Bay of Bengal.

Ganges-Brahmaputra Delta

Wave Dominated In a wave-dominated delta, the movement of waves controls a delta's size and shape.

The Nile delta (shaped by waves from the Mediterranean Sea) and Senegal delta (shaped by waves from the Atlantic Ocean) are both wave-dominated deltas.

National Geographic Society

Senegal Delta

Estuarine

The Yellow River

Estuarine deltas form as a river does not empty directly into the ocean, but instead forms an estuary. An estuary is a partly enclosed wetland that features a brackish water (part-saltwater, part-freshwater) habitat.

The Yellow River forms an estuary, for instance, as it reaches the Bohai Sea off the coast of northern China.

Gilbert Gilbert deltas are formed as rivers deposit large, coarse sediments.

Gilbert deltas are usually confined to rivers emptying into freshwater lakes. They are usually steeper than the normal flat plain of a wave-dominated or tide-dominated delta.

Utah's Great Salt Lake is the only remnant of Lake Bonneville.

Utah's Great Salt Lake Delta

Cuspate Delta Stronger waves form a cuspate delta, which is more pointed than the arcuate delta, and is tooth-shaped.

The Tiber River forms a cuspate delta as it empties into the Tyrrhenian Sea near Rome, Italy.

The Tiber River Delta

Arcuate Delta The term delta comes from the upper-case Greek letter delta (Δ), which is shaped like a triangle. Deltas with this triangular or fan shape are called arcuate (arc-like) deltas.

The Nile River forms an arcuate delta as it empties into the Mediterranean Sea. National Geographic Society

The Nile River Delta

Inverted Delta

The Sacramento-San Joaquin Delta

Another untraditional looking delta is the inverted delta.

The distributary network of an inverted delta is inland, while a single stream reaches the ocean or other body of water.

The delta of the Sacramento-San Joaquin River in northern California is an inverted delta.

The Mississippi Delta

Bird Foot Delta Not all deltas are triangle-shaped. A bird-foot delta has few, widely spaced distributaries, making it look like a bird's foot.

The Mississippi River forms a bird-foot delta as it empties into the Gulf of Mexico.

The Mississippi River Delta

GUIDELINES

Various Indian Laws & Notifications ENVIRONMENT PROTECTION ACT 1986

WATER POLLUTION ACT 1974

Imposing certain

for the prevention and

restrictions and

control of water

prohibitions on new

pollution and the

projects or activities, or

maintaining or restoring

on the expansion or

of wholesomeness of

modernization of

water and research

existing projects or

relating and prevention,

activities based on their

control or abatement of

potential environmental

water pollution and

impact

problems

Environmental Laws

FOREST (CONSERVATION) ACT, 1980 & CONSERVATION RULES, 2003 gives a background on usage of the lands around rivers and forest areas some of which encompass deltaic regions. It also takes care of rehabilitation of such areas if necessity arises.

ECO SENSITIVE/ FRAGILE AREAS, ZONES Eco Sensitive Areas and Eco Fragile Areas are notified by the State Governments to the Cental Government.

These areas are then protected with a Shock Absorber or Transiton Belt called Eco Zones

DELTAS & PEOPLE

CONTEXT 24 out of the world's 33 major deltas are sinking.

Around 500 Million People live on Deltaic regions in the World. Deltas flooding, whether from land or from sea are on the rise in recent years.

HUMAN ACTIVITY Most of the world's low-lying river deltas are sinking from human activity People make them increasingly vulnerable to flooding from rivers and ocean storms.

Most of the world's low-lying river deltas are sinking. Because of this tens of millions of people are at risk Deltas are starved of the sediments they need for stability because of upstream dams made by us that trap the material there are a host of human-induced factors that already cause deltas to sink much more rapidly than could be explained by sea level alone.

DELTAS & WILDLIFE

CONTEXT With its variety of landforms and lush vegetation, Deltas support a rich diversity of animal species.

Herbivores thrive within the productive habitats of the delta. These include semi-aquatic and aqauatic animals.

The delta’s lakes and channels form important habitats and ecosystems The shallow waters of the delta provide important spawning, nursery, and overwintering habitats for fish

WILDLIFE DESTROYED BECAUSE OF HUMANS IN DELTAS Because of the rich and diverse habitats that deltas form and the thriving wildlife they also become grounds for wild animals to be poached.

Authorities fear poachers the up to 6,000 locals who enter the deltas everyday for their livelihoods, including to fish and collect wild honey.

2007 Intergovernmental Panel on Climate Change report

DELTAS & LAND

DELTAS RESILIENCE Fluvial-dominated deltas with high sediment supply can survive high rates of sea level rise.

Deltas respond to seal level rise through feedbacks to enhance land gain

DAMAGE TO LAND 85 percent Deltas experienced severe flooding in recent years, resulting in the temporary submergence of roughly 100,000 square miles of land Scientists predict that global delta flooding could increase by 50 percent under current projections of about 18 inches in sea level rise by the end of the century For coastal communities, the sea level rise propelled by melting ice and warming oceans is a major threat along with sinking land.

Coastal deltas are becoming more at risk of flooding due to land subsidence, or the gradual sinking of the Earth's surface, and sea-level rise AAS Science, Paul Voosen

DELTAS & NATURAL DISASTERS

CONTEXT The dynamic nature of coastal deltas means that river flooding and erosion commonly occur alongside coastal hazards, such as tidal flooding, storm surges, cyclones, and sea water intrusion into freshwater agricultural areas.

DESTRUCTION the ability of deltaic communities to prepare for, cope with, and adapt to flooding is often limited or unequally distributed, leaving the most vulnerable most at risk.

Soil salinization in the delta is the high groundwater tables caused by can be caused overirrigation and canal seepage along with sea water intrusion.

Ganges-Brahmaputra delta cyclone, also called Bhola cyclone, catastrophic tropical cyclone that struck, killing hundreds of thousands of people in the densely populated Ganges-Brahmaputra delta.

It was perhaps the deadliest tropical cyclone in recorded history and one of the greatest natural disasters.

Natural and anthropogenic hazards in the Yellow River Delta, ChinaShanzhong Qi THOMSON REUTERS FOUNDATION, TRUST.ORG (TRF)

DELTAS & human action, or inaction, are important drivers of risk for fragile ecosystems and people’s livelihoods in coastal river deltas.

MAN MADE INTERVENTIONS Flooding and its adverse effects,are influenced by changing patterns in rainfall and CONTEXT

sea level,deforestation, upstream hydropower operations rapid urbanization etc

DAMS At a time when coastal areas are already battered by climate change, life-giving deltas are being sacrificed to dam building.

URBANISATION Once roads, buildings, and parking lots replace vegetation, the soil cannot retain as much water and leads to decline of deltas

DEFORESTATION A significant driver of land gain is deforestation that has led to soil erosion and increased supply of sediment to many deltas.

Life-Giving Deltas Starved by DamsThu, Parineeta Dandekar and Peter Bosshard

CONTEXT Whether river deltas become swamped by rising sea levels will depend on a multitude of factors, including the type of soil and the tectonic action of any nearby plates and human cause and effect factors.

By far, the biggest threat in the long run is the rise in sea level due to global warming as well as increasing rainfall in the region.

SALINITY

Smaller snowpack because of climate change mean less surplus snowmelt runoff at reservoirs and in Deltas in spring. Longer effective dry season for the Delta will require more freshwater releases to repel ocean salinity and maintain suitable water quality.

MIGRATION

DELTAS & GLOBAL WARMING

Temporary and permanent migration is already a widespread phenomenon in deltas, and the fear is that future sea-level rise and sinking land levels coupled with other climate-linked environmental changes (e.g. drought, flooding, etc.) might mobilise large numbers of people and cause mass internal and international migration.

Global warming won't affect all deltas, Richard A. Lovett

SEA LEVEL RISE Would require more freshwater releases from upstream reservoir to repel ocean salinity and maintain suitable water quality Combination of rising sea levels and subsidence will increase pressure on Delta levees and contribute to higher risk of failure Higher risk of overtopping or failure of levees when storm surges combine with rising mean sea levels Bigger floods due to larger winter flood producing areas and more water vapor in atmosphere Farm and landscape water consumption goes up with temperature; 10% for 3oC, other factors constant Higher CO2 reduces water use slightly for most plants With warming, planting dates for annual crops will probably change Global warming won't affect all deltas, Richard A. Lovett

NUTRIENTS In a deltaic lobe, heavier, coarser material settles first. Smaller, finer sediment is carried farther downstream.

The finest material is deposited beyond the river's mouth. This material is called alluvium or silt. Silt is rich in nutrients that help microbes and plants—the producers in the food web—grow.

WETLANDS Deltas are also important wetland habitats. Plants such as lilies and hibiscus grow in deltas, as well as herbs such as wort, which are used in traditional medicines.

Mangroves such as Sunderbans are also a rich source of natural wealth.

DELTAS & VEGETATION

WILDLIFE Wildlife that survive best in relatively shallow marshes with an abundance of aquatic and emergent vegetation thrive in the deltaic regions. The delta’s shorelines and perched basins provide an important summer refuge to low flying birds.

http://www.pademp.com/

CONTEXT Cities are both contributors to and victims of global climate change. Delta cities, in particular, have long been recognized as being extremely vulnerable because they are located where the stresses on natural systems coincide with intense human activity.

POPULATION The world’s deltas are home to over 340 million people, a population greater than that of the United States. These delta communities are highly at risk from flooding, and future sea-level rise will make these risks worse.

THREATS

DELTAS & CITIES

Sea-level rise associated with climate change is rightly considered a major threat to all coastal communities around the world, but deltas face additional challenges due to their unique geological characteristics.

http://www.pademp.com/

URBANISATION Fast urbanization has come with deficiencies in the provisioning of public infrastructure and services, such as delivering water and sewage collection, and lack of housing policies that could have prevented the precarious occupation of flood prone areas.

For Example the Amazon Delta is historically known for the “dictatorship of the water”, where urban areas have increasingly become hotspots of flood risk.

FLOODING Seasonal flooding has always dominated social and environmental dynamics across deltaic landscapes. While periodic variations in flooding cycles have historically marked these cities, these dynamics are fast changing in frequency, scale, and impact.

In the estuary-delta region, where seasonal cycles are compounded by significant variation in daily tides, urban flooding is increasingly commonplace. thenatureofcities.com/2017/04/16/challenges-of-transitioning-to-sustainable-urbaninfrastructure-in-the-amazon-delta-and-estuary/

MITIGATION OF DELTAIC PROBLEMS A critical part of the mitigating problems arising from deltas is analyzing how human communities are affected by changes in these deltas.

Conducting Environmental Impact Assessments of projects, appraising the project for options assessment, environmental clearance, cost benefit analysis or through post clearance monitoring and compliance.

Measures against sediment trapping in dams built near deltaic plains Problematic dams should be considered for decommissioning.

Evacuating people, might prove politically unfeasible as people are likely to be unwilling to relocate. If efforts focus on protecting existing buildings from flooding, though, the delta might be squeezed between the rising sea and inland development.

One way of restoring Deltaic habitat is by deliberately flooding some of the islands to restore habitat, particularly for phytoplankton that might rebuild the natural food web.