Rivers:Additional Detailed Specific Examples

Detailed specific example - River flooding

Detailed specific example - River flooding

Mekong River

• The Mekong River flows through six countries

• The river drains water from an area covering 795,000 km²

• The mouth of the Mekong River drains the water into the South China Sea through the Mekong Delta

• Every year the Lower Mekong River Basin experiences flooding

• Causes of flooding on the Mekong River

• The flooding has both positive and negative impacts

Causes of flooding on the Mekong River

• There are both natural and human causes of flooding on the Mekong River

Natural causes

• Monsoon

  • The wet season (May to November),brings significant rainfall and river flows, leading to annual flooding

• Tropical Storms and Cyclones

  • Severe tropical storms and cyclones can generate significant rainfall and runoff, leading to major flooding events

    • Tropical Storm Phyllis (1966), led to major flooding in Cambodia and on the Mekong Delta 

• Snowmelt

  • Snowmelt from the Tibetan Plateau adds water to the river flow, increasing flood risks

• Tidal Flooding

  • Storm surges, especially during storms, can contribute to flooding in the Mekong Delta

Human causes

• Dam Construction

  • The building of dams, particularly in the upper Mekong River basin alters river regimes

  • In 2015, water was released from the Nuozhadu Dam due to dangerously high levels in the reservoir

    • This led to flooding lower down the river valley

• Hydropower Management

  • The release of water from dams for hydropower generation can affect flood levels

• Land Use Changes

  • Deforestation and increased urbanisation can increase surface runoff, leading to more frequent and severe flooding

• Interference with Drainage

  • Changes to river channels, increased runoff from land, and blocked drainage systems can worsen flood risks

• Climate Change

  • Climate change is impacting rainfall patterns, potentially leading to more intense rainfall

• Sinking of the Mekong Delta

  • The Mekong Delta is sinking due to groundwater extraction and reduced sediment deposition

    • This makes it more vulnerable to flooding

• Population Growth

  • Increased population and water demands can exacerbate flood risks and strain water resources

Impacts of flooding on the Mekong River

Negative impacts

• Economic Losses

  • Damage to infrastructure, agriculture, and businesses, leads to millions of dollars in economic losses

• Human Displacement

  • People are forced to evacuate their homes

• Health Risks

  • Floodwaters can be contaminated, leading to outbreaks of waterborne diseases

• Biodiversity Loss

  • Flooding can negatively impact the Mekong's biodiversity, including fish populations

Positive impacts

• Soil Fertility

  • Flooding deposits fertile silt, increasing agricultural productivity in the Mekong Delta

• Fisheries Support

  • The natural flooding supports the Mekong's diverse fish populations and fisheries

• Water Resources

  • Flooding can replenish water resources, particularly in dry seasons

Strategies to manage flooding on the Mekong River

• Land use zoning

  • Restricted development on floodplains

• Building controls

  • Increase the number of buildings constructed to withstand flooding

    • Floating homes

    • Homes on stilts

• Mekong River Commission (MRC)

  • An inter-governmental organisation which has established monitoring stations at 138 points along the river

    • To forecast flooding and provide early warnings

    • The Mekong Flood Forecasting and Early Warning System (MFFS)

• Flood defences

  • Dikes, levees and flood walls have been constructed to increase the capacity of the river

• Education

  • Communities have been educated on flood preparedness

Detailed specific examples - River pollution

Detailed specific examples - River pollution

Ganges River

• The Ganges River is 2,510km long

• The river flows through China, India, Nepal and Bangladesh

• The source of the Ganges in the Himalayas

• Approximately 400 million people live in the Ganges drainage basin

• The Ganges is one of the most polluted rivers in the world

Domestic waste

• Much of pollution is from urban areas

• Informal settlements do not have adequate sewage systems

  • An estimated 3,000 million litres of sewage is discharged into the river every day

  • Much of the sewage is untreated

• The river contains a range of pollutants including:

  • plastics

  • sewage

  • petrochemicals

  • disinfectants

  • detergents

Industrial waste

• Several industrial cities, such as Kanpur and Varanasi along the river contribute large amounts of waste

• Types of industrial waste include:

  • Tannery waste from leather production

  • Chemical waste

  • Heavy metals such as lead

Agricultural waste

• Fertilisers and pesticides from the agricultural land wash into the river

• This leads to:

  • Eutrophication

  • Toxic chemicals

  • Increase in aquatic weeds

Religious and cultural practices

• Pollution is increased by:

  • Mass bathing during festivals

  • The disposal of dead bodies and cremation remains in the river

Impacts of pollution in the River Ganges

• There are many effects on health because the Ganges is a key source of water for drinking, cooking and bathing

  • This leads to waterborne diseases such as cholera and typhoid

  • Exposure to heavy metals and toxins leads to increased rates of cancer, neurological disorders and birth defects

• Environmental impacts include:

  • Eutrophication

  • Excessive growth of water hyacinth

  • Reduction in biodiversity because animals are affected by toxins and heavy metals including the Ganges river dolphin

  • Methane emissions cause foul odours

• Economic impacts include:

  • Polluted water contaminates crops and soil affecting yields

  • Declining fish stocks

  • Tourism decreases

Strategies to manage pollution in the Ganges

• Despite several initiatives, river cleanup has been hindered by:

  • Corruption and bureaucratic delays

  • Underfunding and poor project execution

  • Lack of enforcement of environmental regulations

  • Public unawareness or disregard for the impacts of pollution

Current and Ongoing Initiatives

• The Namami Gange Programme (2014), was an initiative aiming to:

  • Treat urban sewage through the construction and upgrading of Sewage Treatment Plants (STPs)

  • Improve solid waste management

  • Enforce regulations relating to industry waste

  • Promote afforestation and biodiversity conservation along the riverbanks

  • Educate and involve local communities and religious leaders

• Recent efforts include:

  • Deployment of river surface cleaning machines

  • Promotion of eco-friendly rituals (e.g. biodegradable offerings)

  • Installation of bio-toilets in rural areas

• The programme has shown progress in selected stretches of the river

• The extent of the river basin means that there has not been large-scale