<i>Preface</i> Towards practical applications in ensemble hydro-meteorological forecasting

Abstract

We end the first decade of the 21st century with memories of searing, vivid imagery of devastation, havoc and pain brought about by extreme hydro-climatic events. Of all these events, flooding particularly stands out. Pictures of deluges of unprecedented proportions in Australia, South America, Pakistan, West Africa and China, just to mention a few, demonstrate the increasing vulnerability of society and an eerie helplessness whenever our cities, towns and farmland are confronted by extreme floods. As the severity of floods seem to have increased in recent years, possibly due to both climate and landuse change, the need to invest more resources, financial and otherwise in hydro-meteorological forecasting as part of a multi-faceted approach to improving preparedness could not be greater. Engineers and scientists are increasingly under pressure to improve, not only the predictive capabilities of existing forecasting systems, but also the communication of forecast products to the right agencies for effective decision-making. Increasingly, decision makers seek information and the reliability and uncertainty in such forecasts. Ensemble forecasting techniques present an opportunity to enhance the value of current prediction methods especially when deliberate efforts are made at ensuring effective communication and use in decision-making.Correspondence to: Y. He (yi.he@uea.ac.uk) This special volume of Advances in Geosciences "Towards practical applications in ensemble hydrometeorological forecasting" solicited and received a large number of high quality submissions on the use of ensemble hydro-meteorological forecasting in a broad range of practical applications. A total number of 14 contributions are presented in this volume, covering the following areas:1. Hydro-meteorological ensemble forecasting studies with different hydrological and climatic regimes that can lead to a reliable assessment of ensemble techniques;2. Methods or standards developed to assess or benchmark the performance of ensemble rainfall-runoff modelling;3. Pre-and post-processing of ensemble forecasts; and 4. Practical applications of ensembles in operational systems.The contributions describe both the methodological and practical aspects of the topic, for instance, Randrianasolo et al. (2011) investigate the use of information from gauged neighbouring catchments to run a hydrological forecasting system in ungauged catchments and show that neighbouring catchments can help provide good quality forecasts at ungauged sites, especially when parameter sets are transferred for model simulation. In Alfieri et al. (2011a), a staggered approach to flash flood forecasting is developed within the Published by Copernicus Publications on behalf of the European Geosciences Union.

An Advanced Method to Apply Multiple Rainfall Thresholds for Urban Flood Warnings

“…Theoretically, this gradation of warning levels can be accomplished by flood simulations in space and time through the incorporation of meteorological and hydrological models, which, again, is very time-consuming that requires simplification or modification to meet the need for real-time operation [26][27][28][29]. To increase the lead time, attempts have been made by many researchers to incorporate precipitation forecast products into hydrological warning systems, in which ensemble techniques are necessary to address the uncertainties in hydro-meteorological forecasting [30,31]. Usually, the ensemble processes demand much more computer resources to shorten computational time.…”

HESS Opinions "Forecaster priorities for improving probabilistic flood forecasts"

“…Flood forecast systems are the chief instrument used to inform decision makers of oncoming floods. Coupled hydrometeorological prediction systems are the most widely used strategy in operational flood forecasting in which observations and forecasts are used together with hydrological and hydraulic models (Schaake et al, 2006;Addor et al, 2011;Pappenberger et al, 2011;He et al, 2011;Demeritt et al, 2013;Pappenberger and Brown, 2013). These systems are in place in many parts of the world, and examples of operational (or semi-operational) systems are listed in Table 1 (Pappenberger et al, 2013a).…”