Flood and Drought
The flooding of the Mekong River is a recurrent event. Every year the Lower Mekong River Basin (LMB) experiences flooding, which brings both positive and negative impacts. The annual flood pulse drives the basin’s fisheries, maintains river morphology and deposits sediments to improve soil fertility. The average annual value of flood benefits is approximately US$8-10 billion.
Whilst the regular flood cycle is seen as a source of livelihood, it has the potential to adversely affect economic and human activities, often endangering the lives and causing damage to important infrastructure, human settlements and essential services. The negative effects of flood regularly counteracts efforts for economic development and poverty reduction in various locations throughout the LMB. The average annual cost of floods in the LMB ranges from US$60-70 million. Cambodia and Viet Nam alone commonly account for approximately two-thirds of the region’s total annual flood damage.
As climate and weather patterns become more volatile, flood and drought events in the Mekong River Basin have become more frequent and intense with growing potential to cause devastating damage to the region’s food security and economies. Those communities that were unprepared have suffered the most.
Flood risks can be minimised through various forms of land-use, development and building controls, regional flood emergency planning, and improved preparedness. Flood preparedness requires coordinated management by all concerned parties such as water resource managers, policy-makers, and the private sector to change course from a ‘traditional’ flood management approach towards an approach that coordinates the needs of different stakeholders, including national agencies and affected provinces.
The MRC plays an important role in basin-wide coordination of flood mitigation activities and encouraging an approach that benefits its Member Countries. During the wet season, for example, the MRC takes data from 138 hydro-meteorological stations to predict the water levels of 22 forecast points on the Mekong mainstream. This information is then disseminated to National Mekong Committees, national forecasting agencies, Civil Society Organisations, the media and the public.
Unlike flood, drought only brings socio-economic hardship to riparian countries, especially riverine communities. The LMB has been experiencing severe drought hazards with serious economic losses due to damages of agricultural crops, negative impacts on the environment, and effects on people’s livelihoods. Yields of rice and other lifeline crops plummet as a result of water shortages and saltwater intrusion in the Mekong Delta. Annual fish catches decline. Water levels become critically low, making transport of goods and services at some parts of the river difficult and at other points impossible.
The duration and magnitude of the impacts have significantly increased over the past two decades if comparing the drought hazards from one event to another. In addition, with different climate scenarios, the LMB is likely to see more severe droughts in the next 30, 60, and 90 years due to less precipitation, high air temperature, and high evapotranspiration. The increase of population, from currently around 65 million people relying on the Mekong water to about 100 million people in ten years’ time, also increases water demands from all sectors.
In response to the threat of flood and drought, efforts have been made by the MRC and its Member Countries to formulate a regional strategy for drought management and mitigation that aims to decrease the vulnerability of people in the basin, especially in agricultural communities. The MRC supports the Member Countries through:
- Regional strategies such as the Flood Management and Mitigation Strategy that aims to prevent, minimise or mitigate people' suffering and economic losses due to floods, and the Drought Management Strategy that seeks to help the lower Mekong countries combat the present and future droughts that have both national and transboundary impacts.
- Technical guidelines that provide flood risk assessment and tools for drought monitoring and forecasting.
- Studies and assessments on drought impacts and vulnerability as well as water balance between water demand and availability for agricultural crops to better support the development of drought management strategies.
- Forecasting and early warning that provide daily river flood forecasting for the Mekong and flash flood guidance information for the LMB during the wet season. The systems also provide weekly river flow monitoring during the dry season and weekly and monthly drought forecasting and early warning. This helps government agencies and communities to better prepare for flood and drought events. The MRC shares these daily bulletins by e-mail and on the MRC home page, the flood forecasting website, and drought forecasting and early warning website to National Mekong Committees, Non-Governmental Organisations, the media, and the public.
- Capacity building which promotes information sharing and first-hand learning experiences. It allows decision-makers to share the lessons they have learnt and support the development of region-specific solutions.
In the past, the MRC's flood management activities were limited to the provision of mainstream flood forecasts along the Mekong River. Following the devastation caused by the Flood in 2000, a Flood Management and Mitigation (FMM) Strategy was developed.
Under the strategy, the MRC expanded its support to the Member Countries by providing facilitation on water and related issues, capacity building, and technology transfer for transboundary flooding issues. It assisted the countries in making appropriate use of reliable flood-related information, land-use potential, structural measures, and effective emergency response. The assistance helped minimise economic losses due to floods while preserving the environmental benefits to contribute to the Basin Vision.
Building on this Strategy, the Flood Management and Mitigation Programme (FMMP) was developed in 2004 and implemented to 2010. Through the programme, the Regional Flood Mitigation and Management Centre (RFMMC) was established in 2006. The Centre serves as the MRC’s lead entity in delivering flood forecasting services, and in early 2019 was renamed ‘the Regional Flood and Drought Management Centre (RFDMC)’ to reflect an expansion in the range of services it provides. The renaming signified the MRC’s efforts to address both flood and drought issues in an integrated manner and to provide faster and accurate forecasting and early warning information throughout the year.
Based in Phnom Penh, the RFDMC services fall under four components:
- River monitoring
- River flood forecasting
- Flash flood guidance
- Drought forecasting and early warning
During the flood season, the RFDMC provides daily forecasting by taking data from 138 hydro-meteorological stations to predict the water levels at 22 forecast points on the Mekong mainstream. This information is then disseminated to National Mekong Committees, national forecasting agencies, Civil Society Organizations, the media, and the public. In critical weather conditions, the Centre provides daily flash flood alert and warning. Flash floods can happen along the major tributaries and creeks near the Mekong when heavy rainfall occurs, and the river starts to back up. The accuracy of predictions decreases with each day away from the recorded level. In the dry season, a weekly flow monitoring is provided and weekly and monthly drought forecasting analysis are prepared and disseminated based on three-month seasonal climate perdition.
In addition, five sets of Best Practice Guidelines (BPGs) were developed to address various aspects of flood risk management at the national level. Flood preparedness and emergency management in the Member Countries has been strengthened through targeted capacity building at national, provincial, district, and commune levels. More importantly, annually updated flood preparedness plans have been embedded in provincial and district administrative systems, and the development and use of flood probability information has been demonstrated for better land management.
Building on these successes, the FMMP 2011-2015 was developed to facilitate the operation of the RFMMC and support flood management activities in the Member Countries, which is an integral part of the 2011-2015 MRC Strategic Plan. The programme provided up-to-date flood risk management and mitigation practices enabling the Member Countries to reduce the negative impact of floods.
The MRC is finalising the Flood Management and Mitigation Initial Studies aimed at formulating strategic directions to better manage existing, future, and residual flood risks in selected areas of the LMB. The studies will provide input for the development of the FMM Strategy 2021-2030.
The MRC’s focus on drought management originated with the drought events of 2004-2005 and 2009-2010, when unusually low flows in the Mekong River Basin and seasonal deficiencies in regional rainfall led to severe agricultural losses in north-eastern Thailand and Cambodia, and critical levels of saline intrusion in the Mekong Delta. The MRC set the establishment of the Drought Management Programme (DMP) 2011-2015 as a priority in the Strategic Plan 2006-2010.
The programme helped riparian countries prepare their communities for unpredictable events. This included developing a greater understanding of the region’s drought conditions, and analysis of drought risk and vulnerability for regional drought management and mitigation policy.
Together with the application of drought monitoring and forecasting tools that allow for early detection, drought information helps the Member Countries to identify and understand the key patterns and causes of drought. It also contributes to improve their long-term agriculture plans as well as their preparedness for proactive and emergency responses to drought events.
Under the Strategic Plan 2016-2020, the MRC has taken collaborative action to address drought issues that affect agricultural output, water quantity and quality, and land use. The Drought Management Strategy (DMS) for 2020-2025, which has been long anticipated, was released in December 2019 to build the capacity of the Member Countries to combat drought hazards and assist in drought forecasting and early warning for drought preparedness and water resources planning. The strategy will also help develop regional guidelines on drought adaptation to address both national and transboundary impacts.
The Strategic Plan 2021-2025, attached to the Basin Development Strategy (BDS) 2021-2030, continues to assist the Member Countries in addressing water security – mitigating the impacts of too much water at certain times of year, while not having enough at other times – by promoting coordinated floodwater management and the creation of additional storage in wetlands and behind dams to build climate resilience and manage flood and drought risks. The Strategy will help basin communities better prepared against changing river conditions and more frequent and severe floods and droughts, and promote coordinated water infrastructure operations for better disaster management and adaptation to water resources development and climate risks.
While the RFDMC continues to provide timely and accurate flood forecasting, the MRC has also carried out a number of studies and assessments on drought impacts to better support the development of drought management strategies. Recent studies are highlighted below.
- Current and future scenarios on land and water resources for drought adaptation measures: Conducted in 2017-2018, the study determines the availability for crops and water deficit per catchment in the LMB for both dry and wet seasons to support the development of the Drought Management Strategy 2020-2025. Current and future scenarios on land and water resources for drought adaptation measures: Conducted in 2017-2018, the study determines the availability for crops and water deficit per catchment in the LMB for both dry and wet seasons to support the development of the Drought Management Strategy 2020-2025.
- National assessment on drought impacts and vulnerability: Conducted in 2013 and 2017, the assessment investigates types of drought impacts and magnitude occurring in each Member Country and identifies the root causes of those impacts to understand the core problems of drought. The assessment supports the development of the Drought Management Strategy 2020-2025 and adaptation guidelines.
- National capacity needs assessment on drought management: Conducted from 2015-2017, the assessment identifies the needs for capacity building on drought management among national and provincial line agencies, including departments of water resources, agriculture, irrigation, disaster management and environment. The results were used as input for the development of national capacity development plans.
- Assessment on drought monitoring and forecasting system: Conducted from 2015-2016, the assessment studies the existing drought monitoring, forecasting and early warning systems. Results of the assessment were used to develop the Regional Drought Monitoring, Reporting and Forecasting System for the LMB.
- An initial drought risk and vulnerability assessment of the LMB: Conducted in 2013, the assessment guides the prioritisation of resources and identifies areas at risk, requiring further studies and mitigation efforts. This report details an initial attempt to create a basin-wide drought risk model.
In collaboration with the Member Countries, the MRC has produced a series of tools and guidelines on flood and drought management and mitigation that can be adapted to each Member Country and project context. The guidelines include the following:
- Best Practice Guidelines for Integrated Flood Risk Management in Basin Development Planning : These guidelines were developed in 2009 to guide the process of impact (on flood risk) assessment for each water related development sector. It ensures that the basin development planning process identifies and addresses flood-related impacts and opportunities for potential development scenarios in a way that is technically, socially, environmentally, and financially responsible and effective.
- Best Practice Guidelines for Structural Measures and Flood Proofing: Developed in 2009, the guidelines are intended to improve planning and design of key infrastructure such as roads, bridges, and buildings to ensure that loss of life and damage to such structures are reduced.
- Best Practice Guidelines for Flood Risk Assessment: The guidelines combine theory and practice with a specific emphasis on flooding in the LMB. Formulated in 2009, National planners and project designers can use the guidelines to estimate field-level flood benefits and costs for project analysis and national planning.
- Tools for drought monitoring and forecasting: The tools support the development of a framework for assessing drought conditions in the LMB. As part of the activity, a drought monitoring and forecasting website was established to support communication on drought events. The tools were jointly created with the Asian Disaster Preparedness Centre in 2018, with technical support from the United States National Aeronautics and Space Administration (NASA).
- Drought adaptation guidelines for drought management and mitigation: The guidelines aim to assist the Member Countries in reducing negative impacts of drought on local communities.
The MRC has produced a series of knowledge products listed below to facilitate decision making and stimulate innovations for flood and drought management.