[Indonesia] Extreme rainfall and its effects on flood risk in Indonesia
Lead Research Organisation:
Newcastle University
Department Name: Sch of Engineering
Abstract
Indonesia suffers from severe flood risk due to a combination of its climate (intense monsoon rainfalls), geography (steep mountains and rivers) and the mega-cities built at the outlet of rivers. This risk is already severe and it is feared it will become worse as climate change takes affect and the population of the cities grows even larger with uncontrolled development.
When floods strike, they are often the combination of several sources: high river flows, intense rainfall on impermeable ground in cities and storm surges from the sea. Even worse, they often affect several cities and towns at once - stretching emergency responses and disaster recovery even further.
The project aims to understand how these flood events happen so that planning and mitigation strategies can be developed. This understanding includes:
- when floods occur, and what warning can be given
- what controls the spatial extent (how many cities may be damaged at once)
- how large the river flows can be and how often they happen
- what effect land use (deforestation, urbanisation) has on the size and speed of floods
- how the flood size and frequency of occurrence may change in the future
- how much damage is caused in cities by the floods
Strategies to manage the flood risk will be informed by better understanding, and may take the form of:
- better insurance cover
- better warning systems for areas likely to be flooded
- changing and controlling land use
- building flood diversions, defences, or detention reservoirs
The approach being taken for the research is to use computer models of rainfall, climate, river flows and cities, so that the effects of different floods and management strategies can be simulated safely. The project team is therefore made up of experts in meteorology, climate change, hydrology and computer modelling.
When floods strike, they are often the combination of several sources: high river flows, intense rainfall on impermeable ground in cities and storm surges from the sea. Even worse, they often affect several cities and towns at once - stretching emergency responses and disaster recovery even further.
The project aims to understand how these flood events happen so that planning and mitigation strategies can be developed. This understanding includes:
- when floods occur, and what warning can be given
- what controls the spatial extent (how many cities may be damaged at once)
- how large the river flows can be and how often they happen
- what effect land use (deforestation, urbanisation) has on the size and speed of floods
- how the flood size and frequency of occurrence may change in the future
- how much damage is caused in cities by the floods
Strategies to manage the flood risk will be informed by better understanding, and may take the form of:
- better insurance cover
- better warning systems for areas likely to be flooded
- changing and controlling land use
- building flood diversions, defences, or detention reservoirs
The approach being taken for the research is to use computer models of rainfall, climate, river flows and cities, so that the effects of different floods and management strategies can be simulated safely. The project team is therefore made up of experts in meteorology, climate change, hydrology and computer modelling.
Planned Impact
The Government of Indonesia (GoI) has climate change mitigation and adaptation as a national priority agenda and will be a major beneficiary. This proposal is aligned with this GoI agenda in strengthening flood resilience and will involve local authorities and national policymakers as well as business communities. Project outputs are expected to become new national and local policies and will engage with a range of project partners and end users.
Key end users have been invited to join the project and will be involved in designing the research and maximising the benefits: These include:
Jasa Tirta 1 public corporation who manage some river basins as well as water infrastructure. By implementing project findings in their managed basins, they will benefit from the project and develop long-term sustainable economic growth in Indonesia.
The Agency for Assessment and Application of Technology (BPPT), will inform the implementation of project findings in the National Planning Policy Framework.
Focus group discussion and a series of workshops will be conducted with other key end-users, such as the Hydrology and Water System, Ministry of Public Works, the National Agency for Disaster Management (BNPB) and the Agency for Meteorology, Climatology, and Geophysics (BMKG).
We expect our recommendations will be adopted as flood mitigation strategies for national and local policymakers and water managers.
The project will also benefit the insurance and re-insurance industry. Flood risk models are in particular demand for Indonesia (and elsewhere in SE Asia) due to a gap in insurance caused by severe risk as well as low penetration of insurance products. This development is severely restricted by lack of both data on hazards and understand of the hydrosystems and exposure of city populations. Newcastle University as members of the Willis Research Network are in a uniquely advantageous position to disseminate research findings efficiently into the CAT modelling and insurance industries to effect a step change in capability, with major benefit then accruing to the population and economy of Indonesia as effective and affordable insurance becomes available.
Key end users have been invited to join the project and will be involved in designing the research and maximising the benefits: These include:
Jasa Tirta 1 public corporation who manage some river basins as well as water infrastructure. By implementing project findings in their managed basins, they will benefit from the project and develop long-term sustainable economic growth in Indonesia.
The Agency for Assessment and Application of Technology (BPPT), will inform the implementation of project findings in the National Planning Policy Framework.
Focus group discussion and a series of workshops will be conducted with other key end-users, such as the Hydrology and Water System, Ministry of Public Works, the National Agency for Disaster Management (BNPB) and the Agency for Meteorology, Climatology, and Geophysics (BMKG).
We expect our recommendations will be adopted as flood mitigation strategies for national and local policymakers and water managers.
The project will also benefit the insurance and re-insurance industry. Flood risk models are in particular demand for Indonesia (and elsewhere in SE Asia) due to a gap in insurance caused by severe risk as well as low penetration of insurance products. This development is severely restricted by lack of both data on hazards and understand of the hydrosystems and exposure of city populations. Newcastle University as members of the Willis Research Network are in a uniquely advantageous position to disseminate research findings efficiently into the CAT modelling and insurance industries to effect a step change in capability, with major benefit then accruing to the population and economy of Indonesia as effective and affordable insurance becomes available.
Publications
Suroso S
(2023)
Assessment of TRMM rainfall data for flood modelling in three contrasting catchments in Java, Indonesia
in Journal of Hydroinformatics
Suroso
(2020)
Impact of Land Use Land Cover Changes on River Discharge at Brantas Catchment Area using SHETRAN Model
in IOP Conference Series: Materials Science and Engineering
Suroso
(2020)
Detection of Flood Inundation in the Progo Watershed using the SHETRAN Model
in IOP Conference Series: Materials Science and Engineering
Suroso
(2021)
Estimating of soil moisture using shetran model at Cisanggarung catchment area
in IOP Conference Series: Earth and Environmental Science
Suroso
(2021)
Groundwater depth prediction using Shetran model in Citarum River basin
in IOP Conference Series: Earth and Environmental Science
Description | • Preliminary analysis of extreme rainfall in Java shows some signs of increasing intensity over the last 40 years (1979-2020) . This is clearly of concern for emergency planning in Indonesia if this trend were to continue. Further analysis is needed to establish the robustness of the trend identified. • Rain gauges are the most reliable source of information but have poor coverage in space and are mostly at daily resolution. Satellite data offer better coverage and 3 hour resolution but need careful interpretation as they are "snapshots" not averages over 3 hours. We have developed a method to use the regular diurnal cycle from rain gauges to improve the TRMM estimates. This type of approach would be applicable over much of the region, and would benefit from pooling of data across multiple projects and countries - this includes TRMM data, rain gauges data and atmospheric model reanalysis outputs. • We have demonstrated the utility of state of the art flood and hydrological models for estimating flood risk in major cities in Indonesia using readily available hydrological and physiographic data. |
Exploitation Route | Not yet finalised, but expected to be; - useful statistical models of rainfall extremes - flood models for key rivers and cities - methods for improved use of satellite rainfall data |
Sectors | Environment,Financial Services, and Management Consultancy |
Description | The use of the SHETRAN hydrological modelling system and the CityCAT flood model for applications in flooding have demonstrated the benefits of using more advanced simulation methods for multiple stakeholders and agencies in Indonesia. |
First Year Of Impact | 2021 |
Sector | Environment |
Impact Types | Policy & public services |
Title | Modelled flood depths and river inflow, with associated rainfall data, in Jakarta for the January-February 2007 flood |
Description | The dataset contains model output from the CityCAT hydrodynamic model showing maximum water depths in Jakarta, Indonesia, during the January/February 2007 flood. The hourly rainfall and hourly lateral inflow boundary conditions from rivers used to obtain the flooding depths are also included. |
Type Of Material | Database/Collection of data |
Year Produced | 2022 |
Provided To Others? | Yes |
URL | https://catalogue.ceh.ac.uk/id/8e58f0bb-3ff1-41e8-b8f4-380983ec68bc |
Description | Willis Research Network |
Organisation | Willis Group |
Department | Willis Research Network |
Country | United Kingdom |
Sector | Private |
PI Contribution | Analysis and development of models for extreme rainfall and floods Regular presentations at industry forums on flooding |
Collaborator Contribution | In addition to financial contributions, Willis provide cases studies and datasets, as well as a platform for discussion and presentation of work to the rest of the insurance industry. |
Impact | Models for extreme rainfall, spatial dependence of extremes and "memory processes" in extremes. |
Start Year | 2011 |
Description | Presentation at Willis Flood Club |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Industry/Business |
Results and Impact | Presentation on flood risk assessment and climate change to an insurance industry forum at Willis Insurance Brokers HQ, London. |
Year(s) Of Engagement Activity | 2019 |