River Planning Division, River Bureau, Ministry of Land, Infrastructure, Transport and Tourism (MLIT)
The needs to reduce flood risks caused by climate change
Flood risks reduction through climate change prediction, understanding hazard/vulnerability/risk and systematic adaptaion mesures developing.
- The Ministry of Land, Infrastructure, Transport and Tourism of Japan has developed a manual of basic procedures for deciding on adaptation measures to cope with increasing flood risks caused by climate change. These guidelines describe a framework for procedures to develop adaptation measures against the increases in the intensity and frequency of floods (excluding storm surges) caused by climate change. This manual is based on the experience, strategies and technology accumulated over the years in Japan.
- For use by Practitioners of river and water resources management responsible for developing concrete adaptation plans. The features are as follows:
- River basin-based planning
- Detailed explanations of methods for estimating meteorological external forces such as precipitation that are important for the adaptation to climate change
- Setting goals and selecting a combination of concrete adaptation measures based on hazard, vulnerability and risk assessment
- The flowchart below shows the process for developing adaptation measures.
Figure: The process for developing adaptation measures
Understanding Climate Change and its Impacts (Chapter 2)
2.1 Collecting and Sorting Past Precipitation and Other Data
Observation of precipitation patterns generally includes methods such as groundbased, radar, and satellite rainfall observation. In order to collect long-term consistent data on total precipitation that may cause flooding and rainfall distribution by time and space, it is desired that a monitoring network of ground rain gauges is installed to obtain rainfall observation data according to the basin scales.
2.2 Projecting Precipitation
It is important that the global warming scenarios are developed properly based on projected future precipitation patterns. Note that global warming scenarios will change depending on global efforts to reduce greenhouse gas emissions. Near-future projection results (after 20-30 years) may not vary greatly according to the scenario, so it is possible to reduce the number of scenarios to be considered. However, it is desirable to consider as many scenarios as possible, because long-term projection results will differ according to different scenarios.
2.5 Understanding Hazards, Vulnerabilities and Risks
It is important to assess the conditions of floodplains and the impacts of climate changes in the present and future to obtain basic information for considering the methods to avoid, reduce, transfer and retain risks on floodplains, and for developing adaptation measures. Analyzing hazards, vulnerabilities, and risks contributes to understanding how hazards, vulnerabilities and risks change in each floodplain block in the present and the future and what adaptation measures should be implemented.
Developing Adaptation Measures (Chapter 3)
3.1 Setting Goals for Flood Management Measure
The goals must be made specific, by considering how to avoid, mitigate, transfer or take risks, as well as past disaster damage, natural and social characteristics of basins, future national visions (development goals), and limitations on investment capability (financial strength). It is important to set goals in combination with multiple goals as required.
3.2 Optimal Combination of Adaptation Measures
The major options of adaptation measures are outlined below. Options for adaptation measures below. The goal cannot be achieved through a single measure. It is necessary to combine the optimum options according to each characteristic. Several specific combinations of measures must be formulated, and the impacts and effects of implementing such combinations must be assessed. In addition, an appropriate combination of adaptation measures is selected according to the assessment.
Figure: Options for Adaptation Measures
3.3 Developing Procedures for Implementing Adaptation Measures
- Develop a procedure for implementing a combination of adaptation measures.
- Multiple schemes for implementation procedures should be planned and assessed.
- A roadmap is created after preparing the implementation procedure based on the assessment.
Monitoring (Chapter 4)
It is important to carry out monitoring to understand climate changes and to conform to the PDCA cycle. The monitoring procedure is as follows:
- Observation to collect meteorological, hydrological and hydraulic data such as precipitation, water level, stream flow in each river basin
- Collection of river basin data such as land use and vegetation in the river basin and floodplain data such as property and population
- Verification of the differences between observed and collected data and peojected values
- Collection and analysis of meteorological, hydraulic and hydrologic data associated with floods and flooding damage data
- Use of scientific and technological knowledge gained through research and development efforts to improve the accuracy of climate change projection
The guidelines are intended mainly for countries in Asia-Oceania and elsewhere where urbanization and land use are expected to intensify because of social and economic progress and population growth; production facilities and people are concentrated in alluvial plains; and effective flood control measures are yet to be developed.
River Bureau, Ministry of Land, Infrastructure, Transport and Tourism (MLIT) Practical Guidelines on Strategic Climate Change Adaptation Planning – Flood Disasters -