Case Studies: Contrasting Examples of Flood Mitigation (DP IB Geography)

Case Study – Jakarta, Indonesia

Map of Jakarta, Indonesia

• Jakarta is the current capital city of Indonesia

Causes of flooding

• It faces significant flooding challenges because:

  • There is rapid urbanization

  • Many parts of the city are below sea level 

  • Many parts of the city have an average height of just seven metres above sea level

  • The city experiences both tidal and river flooding

  • About half of the city is sinking at a rate of nine inches per year

• Various factors affect the severity of flooding in the area:

  • Intense rainfall

  • Land subsidence

  • Poor urban planning

Impacts of flooding

• On 1st January 2020, Jakarta experienced over 400mm of precipitation

• Ciliwung and Cisadane rivers flooded:

  • In total, 66 people were killed

  • Around 60,000 people were displaced

  • In some parts of the city, floodwaters reached two metres

• Landslides in areas on the outskirts of Jakarta buried people and buildings

• Blackouts and lack of communication slowed the rescue efforts

Responses to flooding and mitigation

• Cloud seeding planes were used to increase rainfall over the oceans 

  • This aimed to reduce the amount of rain over the land and therefore reduce flooding

• Over 11,000 health workers provided medical care

• Disinfectant sprayed to reduce the spread of disease

• Emergency shelters provided 

• Strategies to mitigate future flooding included:

  • Widening and deepening the river channels to reduce flooding

  • Construction of the East Flood Canal 

  • Jakarta Emergency Dredging Initiative to increase the capacity of the rivers

  • Creating more urban green spaces to reduce surface runoff and increase infiltration

  • Creating an advanced warning system which uses real-time alerts for residents and businesses

  • Community workshops for poorer communities living along the river to explain how to protect themselves from future flooding

  • Preparation for disaster response, including megaphones, life vests and emergency kits

Case Study – River Severn, England

Map of River Severn

Causes of flooding

• Storm Ciara produced heavy rainfall of 75mm in 48 hours in February 2020

• Storm Dennis added 125mm falling in the Severn’s tributaries 

• The Met Office UK advised that February 2020 was the wettest on record

• Some areas experienced a month of rain in 24 hours

Impacts of flooding

• Over 1600 properties were flooded in the West Midlands

• Homes were evacuated

• Impact on transport infrastructure due to road and rail closures

• Financial impact on businesses

Responses to flooding and mitigation

• Nearly 30,000 warnings were given to property owners by the Flood Warning Service

• Over 380 staff from the Environment Agency and DEFRA responding to incidents across the Midlands

• Over 86 Aid staff from across the country helped manage the flood risks at pumping stations and prepare evacuation plans

• An incident room was set up to help people affected

• Demountable barriers used to help reduce flooding

• A pumping station helped reduce surface runoff

• Reservoirs being pumped down to reduce water levels

• Strategies to mitigate future flooding include:

  • £4.5million now being invested along the catchment area to reduce flooding

  • Construction of embankments

  • Additional culverts to let surface water out and stop river water coming in

  • Afforestation