An integrated 1D–2D hydraulic modelling approach to assess the sensitivity of a coastal region to compound flooding hazard under climate change

Coastal regions are dynamic areas that often lie at the junction of different natural hazards. Extreme events such as storm surges and high precipitation are significant sources of concern for flood management. As climatic changes and sea-level rise put further pressure on these vulnerable systems, there is a need for a better understanding of the implications of compounding hazards. Recent computational advances in hydraulic modelling offer new opportunities to support decision-making and adaptation. Our research makes use of recently released features in the HEC-RAS version 5.0 software to develop an integrated 1D–2D hydrodynamic model. Using extreme value analysis with the Peaks-Over-Threshold method to define extreme scenarios, the model was applied to the eastern coast of the UK. The sensitivity of the protected wetland known as the Broads to a combination of fluvial, tidal and coastal sources of flooding was assessed, accounting for different rates of twenty-first century sea-level rise up to the year 2100. The 1D–2D approach led to a more detailed representation of inundation in coastal urban areas, while allowing for interactions with more fluvially dominated inland areas to be captured. While flooding was primarily driven by increased sea levels, combined events exacerbated flooded area by 5–40% and average depth by 10–32%, affecting different locations depending on the scenario. The results emphasise the importance of catchment-scale strategies that account for potentially interacting sources of flooding

A framework to assess quality and uncertainty in disaster loss data

There is a growing interest in the systematic and consistent collection of disasterloss data for different applications. Therefore, the collected data must follow a set oftechnical requirements to guarantee its usefulness. One of those requirements is theavailability of a measure of the uncertainty in the collected data to express its quality for agiven purpose. Many of the existing disaster loss databases do not provide such uncertainty/qualitymeasures due to the lack of a simple and consistent approach to expressuncertainty. After reviewing existing literature on the subject, a framework to express theuncertainty in disaster loss data is proposed. This framework builds on an existinguncertainty classification that was updated and combined with an existing method for datacharacterization. The proposed approach is able to establish a global score that reflects theoverall uncertainty in a certain loss indicator and provides a measure of its quality

Hydrometeorological impact of climate change in two Mediterranean basins

The impact of climate change in specific hydrological issues is investigated in two Mediterranean watersheds of the island of Crete, Koutsoulidis, and Giofyros, by using the HBV hydrological model. Koutsoulidis basin is analysed in terms of future water resources availability under climate change, as it supplies the dam of the surrounding area that provides its irrigational water needs. Giofyros is a basin prone to flooding, hence, it is analysed in terms of spring flood risk under climate change. At first, the HBV model is calibrated using as input the historical data. Next, the climate change impact is studied, using the HBV with climate data from 11 GCM–RCM combinations for 3 RCP scenarios (2.6, 4.5, and 8.5 W/m2) and 3 time windows (1981–2010, 2021–2050, and 2071–2100). The climate change impact to the hydrological systems’ behaviour is projected using several hydrometeorological parameters and hydrological signatures. Specifically, in Koutsoulidis basin, projections of future water resources availability show that the period of May to November is a high-risk period of water shortage for all RCPs in all time windows. In Giofyros basin, spring flood risk analysis reveals higher flooding risk in 2021–2050 time window. In addition, February is the most frequent month of spring flood start point in all climate scenarios. The above findings could be used in strategic planning for a sustainable water resources management in the Mediterranean basins

An agricultural flash flood loss estimation methodology: the case study of the Koiliaris basin (Greece), February 2003 flood

Δημοσίευση σε επιστημονικό περιοδικόSummarization: River flooding causes significant losses to crops and negatively affects local agriculture economies, particularly in rural riverine areas. In this work, a techno-economic methodology for the monetary estimation of crop losses due to flash flooding is presented. The methodology takes into account flood depth and flow velocity, as provided by MIKE FLOOD, as well as the season of flood occurrence, and provides monetary estimates of crop damage based on synthetic logistic flow velocity–flood depth–crop damage surfaces. The development of the flood damage surfaces involved a questionnaire survey targeting practicing and research agronomists. Subsequently, a weighted Monte Carlo simulation was performed in order to enhance the questionnaire-based loss estimate information. Finally, synthetic flow velocity–flood depth–crop damage surfaces were developed for every crop under study and for every month using logistic regression analysis. The damage surfaces are an essential component of the developed model which was implemented in Python, enabling the GIS visualization of the estimated agricultural damage. The aforementioned methodology was applied for estimating the damage caused by a flash flood that took place in the Koiliaris River Basin in Crete for which no historical data exist. The novelty of the proposed methodology is the development of local synthetic flow velocity–flood depth–crop damage surfaces. Furthermore, the velocity parameter, which is taken into account, makes the methodology suitable for flash flood events, where significant discharges and high velocities dominate, or for flood event cases which are characterized by high flow velocities. The methodology identifies rural areas and agricultural land uses that are most prone to flooding and serious crop damages and thus require greater attention. Furthermore, the methodology aptitude for developing local damage surfaces could be modulated in order to confront different flood scenarios on various crops distributions and be used to address agricultural planning activities.Presented on: Natural Hazard