Managing hydro-meteorological risks is a multi-disciplinary task, requiring understanding of the various processes that eventually determine the impact.  
Hans de Moel, Institute for Environmental Studies, VU University, Amsterdam

Novel concepts for improved impact and risk assessments

Hydro-meteorological risks such as floods and droughts can have huge repercussions on the well-being of human society, both in terms of human suffering and economic impact.

Risk assessments form the basis for decision-making in the management of hydro-meteorological risks. With risk management approaches becoming more prevalent, there is a clear need for improved knowledge and methods to assess the risks.

IMPREX will further develop four promising novel concepts related to hydro-meteorological risk assessment. In addition to methodological developments, the concepts will be tested in case study areas with stakeholders in order to gain experience on their practical applicability and to illustrate their usefulness for decision-making.

 

Listen to Hans de Moel, IMPREX Project Partner from the Institute of Environmental Studies (Free University of Amsterdam), explain the novel concepts from the IMPREX study tackling hydro-meteorological risks.

 

Novel concept 1: Climate variability and flood/drought risks

Our capability to prepare for disasters is challenged by large uncertainties and our limited understanding of important driving forces of hydro-meteorological hazards, such as climate variability.

Large-scale indices of climate variability (e.g. El Niño Southern Oscillation or the North Atlantic Oscillation) are often used for seasonal forecast models to predict upcoming weather conditions in monthly to seasonal scale.

However, little knowledge exists about the relationships between these large-scale indices and their impacts on society, such as flood damages and crop productivity. Combining improved weather variability predictions with empirical models on potential impacts will create opportunities for the management of hydro-meteorological risks.

IMPREX will explore the direct relationships between natural climate variability and flood and drought impacts, allowing for fast and practical impact assessments on the basis of known climatic oscillations.

The developments can feed into risk outlooks and early warning systems in areas that are prone to floods and droughts for a variety of sectors (i.e. agriculture, hydropower, emergency aid, etc.). The seasonal predictions will enable better disaster prevention, mitigation and preparedness by stakeholders and will improve the climate resilience and sustainability of these sectors.

Climate variability and flood/drought risks
Climate variability and flood/drought risks

Novel concept 2: Future weather and compound events

Conventionally, to assess climate risks, univariate climate statistics (e.g. return periods of precipitation or water levels) are derived from either historical observations or (downscaled) climate model simulations. However, this approach does not give insight into future changes in the joint occurrence of two or more events (e.g. extreme precipitation and a storm surge at the same time), also known as compound events.

A realistic simulation of compound events requires the use of high resolution weather models, as opposed to coarser climate models, to have the right (spatial and temporal) resolution and processes relevant for extreme weather events. This can be run under the climate conditions of interest (such as a future climate) and coupled to impact models (hydrologic and/or hydraulic).

This new concept, called Future Weather (FW), has been developed to complement the traditional approach in climate impact research. The concept adds to the physical understanding of drivers of high impact hydro-meteorological events by using numerical weather prediction models to project high impact weather events in a future climate.

Moreover, Future Weather provides information to stakeholders at the local scale where climate change is experienced as changes in high-impact weather. The concept may also aid in increasing awareness of climate change and its impacts by visualising future weather cases and relating these to present day experiences.

Within IMPREX, FW will be applied in case studies in the Netherlands and the UK. Risks to compound flooding will be analysed in the current and future climate in consultation with the stakeholders. 

Future weather and compound events
Future weather and compound events

Novel concept 3: Methods to support drought risk management

Drought is one of the major natural hazards frequently causing large impacts worldwide. To prepare for future droughts, proactive drought management – a systematic process to prevent, mitigate and cope with drought-induced disaster management – is promoted over reactive emergency management.

While becoming well embedded in flood management, the application of risk management in drought and water resources management is much more complex because of the many users and sectors involved and the different ways in which a shortage of water can cause damage.

Within IMPREX, a conceptual framework for the quantification of drought-related risks, taking into account both the probability of drought-related hazards and their possible impacts, will be further developed. In moving this framework forward, IMPREX will consider a variety of end-users/sectors and make a step towards a decision-support tool. The framework will be developed in cooperation with end-users in concrete case studies in the Rhine-Meuse delta region.

Based on this concept, tools can be designed to support quantitative risk-informed decision-making for fresh water management in the Netherlands. Within the IMPREX project, such methods and tools will provide decision-making support to the Dutch Delta Programme on water supply levels.

Methods to support drought risk management
Methods to support drought risk management

Novel concept 4: Probabilistic impact assessment

The basis for efficient risk management is a comprehensive and reliable risk assessment. Risk assessments extend the hazard analysis with an analysis of potential impacts (i.e. damage to buildings/crops) and as such investigate exposure and vulnerability/susceptibility of elements at risk, like companies or residential buildings.

Currently, assessments of potential impacts in the framework of hydro-meteorological risk analyses have in common that complex damaging processes are described by relatively simple, deterministic approaches, which are associated with high uncertainty.

Probabilistic (as opposed to deterministic), multi-variable flood damage models have the potential to significantly improve the description of damaging processes and inherently provide uncertainty information. Within IMPREX, the research agenda will focus on further developing these models to enable their applicability in medium- and large-scale flood risk analyses.

Decreasing the uncertainty present in stakeholders’ risk analyses with quantitative information and improved impact assessments will lead to better risk management decisions, for instance related to cost-benefit evaluations and management of insurance portfolios (i.e. setting premiums and covering by re-insurance).

Probabilistic impact assessment
Probabilistic impact assessment

 

For more information about the four novel concepts, please see the project deliverable White paper - novel concepts in hydro-meteorological risk assessments