Flood Early Warning Systems: A Review Of Benefits, Challenges And Prospects

Abstract

Floods are major water-related disasters that affect millions of people resulting in thousands of mortalities and billiondollar losses globally every year. Flood Early Warning Systems (FEWS) - one of the floods risk management measures - are currently operational in many countries. The UN Office for Disaster Risk Reduction recognises their importance and strongly advocates for an increase in their availability under the targets of the Sendai Framework for Disaster Risk Reduction, and Sustainable Development Goals (SDGs). However, despite widespread recognition of the importance of FEWS for disaster risk reduction (DRR), there’s a lack of information on their availability and status around the world, their benefits and costs, challenges and trends associated with their development. This report contributes to bridging these gaps by analyzing the responses to a comprehensive online survey with over 80 questions on various components of FEWS (risk knowledge, monitoring and forecasting, warning dissemination and communication, and response capabilities), investments into FEWS, their operational effectiveness, benefits, and challenges. FEWS were classified as technologically “basic”, “intermediate” and “advanced” depending on the existence and sophistication of FEWS` components such as hydrological data = collection systems, data transfer systems, flood forecasting methods, and early warning communication methods. The survey questionnaire was distributed to flood forecasting and warning centers around the globe; the primary focus was developing and least-developed countries (LDCs). The questionnaire is available here: https://inweh.unu.edu/questionnaireevaluation-of-flood-early-warning-systems/ and can be useful in its own right for similar studies at national or regional scales, in its current form or with case-specific modifications. Survey responses were received from 47 developing (including LDCs) and six developed countries. Additional information for some countries was extracted from available literature. Analysis of these data suggests the existence of an equal number of “intermediate” and “advanced” FEWS in surveyed river basins. While developing countries overall appear to progress well in FEWS implementation, LDCs are still lagging behind since most of them have “basic” FEWS. The difference between types of operational systems in developing and developed countries appear to be insignificant; presence of basic, intermediate or advanced FEWS depends on available investments for system developments and continuous financing for their operations, and there is evidence of more financial support — on the order of USD 100 million — to FEWS in developing countries thanks to international aid. However, training the staff and maintaining the FEWS for long-term operations are challenging. About 75% of responses indicate that river basins have inadequate hydrological network coverage and back-up equipment. Almost half of the responders indicated that their models are not advanced and accurate enough to produce reliable forecasts. Lack of technical expertise and limited skilled manpower to perform forecasts was cited by 50% of respondents. The primary reason for establishing FEWS, based on the survey, is to avoid property damage; minimizing causalities and agricultural losses appear to be secondary reasons. The range of the community benefited by FEWS varies, but 55% of FEWS operate in the range between 100,000 to 1 million of population. The number of flood disasters and their causalities has declined since the year 2000, while 50% of currently operating FEWS were established over the same period. This decline may be attributed to the combined DRR efforts, of which FEWS are an integral part. In lower-middle-income and low-income countries, economic losses due to flood disasters may be smaller in absolute terms, but they represent a higher percentage of such countries’ GDP. In high-income countries, higher flood-related losses accounted for a small percentage of their GDP. To improve global knowledge on FEWS status and implementation in the context of Sendai Framework and SDGs, the report’s recommendations include: i) coordinate global investments in FEWS development and standardise investment reporting; ii) establish an international hub to monitor the status of FEWS in collaboration with the national responsible agencies. This will support the sharing of FEWS-related information for accelerated global progress in DRR; iii) develop a comprehensive, index-based ranking system for FEWS according to their effectiveness in flood disaster mitigation. This will provide clear standards and a roadmap for improving FEWS’ effectiveness, and iv) improve coordination between institutions responsible for flood forecasting and those responsible for communicating warnings and community preparedness and awareness.

The role of multi-criteria decision analysis in a transdisciplinary process: co-developing a flood forecasting system in western Africa

“…More than 1.7 million people were affected, 94 000 people displaced, and 152 000 houses destroyed (OCHA, 2020). Good flood early warning systems (FEWSs) help minimize flood impacts (Perera et al, 2019); "good" means they give accurate, timely, and understandable information and are affordable. Several FEWSs have been set up in western Africa, some being very useful.…”

Advanced Technologies for Offering Situational Intelligence in Flood Warning and Response Systems: A Literature Review

“…However, it should be noted that there are many barriers to implementing such systems [16,99,100]. Some barriers and challenges include (i) the inadequate coverage of IoT sensors due to capital and maintenance costs and the unavailability of internet connections [16], (ii) the lack of accurate flood simulation models running on high-performance computers to provide near-real-time responses [99], and (iii) the limitations of acquisition and the limited coverage of near-real-time satellite images [100].…”

“…However, it should be noted that there are many barriers to implementing such systems [16,99,100]. Some barriers and challenges include (i) the inadequate coverage of IoT sensors due to capital and maintenance costs and the unavailability of internet connections [16], (ii) the lack of accurate flood simulation models running on high-performance computers to provide near-real-time responses [99], and (iii) the limitations of acquisition and the limited coverage of near-real-time satellite images [100]. Although many developing countries have access to the International Charter for Space and Major Disasters, Copernicus System, and Sentinel Asia System, the average time for satellite activation for receiving the first image is three to four days [101].…”

“…Such information systems for flood warning and response systems should offer hazard detection, forecasting, warnings, and responses [15]. A study of global early warning systems within developed and developing countries [16,17] has found that the availability of such technology platforms is an important factor that influences the effectiveness of early warning systems in addition to policy, institutional, and societal factors.…”

Contributing Factor Influencing Flood Disaster Using MICMAC (Ciliwung Watershed Case Study)

“…Moreover, the infrastructure approach alone does not address the main causes of flooding, which are believed to be a combination of reduced water catchment areas and high rainfall intensity (Shi, 2020). Early warning system factors in detecting a disaster and monitoring a hazard (Perera et al, 2019) can reduce the incidence of disasters when applied properly. However, Indonesian institutions do not yet have adequate rules and instruments for designing cities that are safe from the threat of flooding, both from spatial planning, drainage systems, or wastewater management to return to the ground.…”