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Soil moisture plays a vital role in slope stability. As water infiltrates into the soil, shear strength decreases eventually leading to failure. However, most of the existing regional-scale landslide early warning systems (LEWS) rely solely on rainfall information and use rainfall thresholds to determine if the landslide triggering conditions are met. The original version of the Catalonia region LEWS combines real-time rainfall observations and susceptibility to compute warnings. The LEWS applies a set of rainfall intensity-duration thresholds to determine if the rainfall conditions have the potential to trigger a landslide. This work explores the potential of using modelled soil moisture data in the Catalonia region LEWS. Volumetric water content (VWC) from the LISFLOOD hydrological simulations of the European Flood Awareness System and rainfall estimates have been analysed at the location of recent landslide events. Based on this data, a set of empirical hydrometeorological thresholds combining rainfall and soil moisture information has been obtained for their application into the Catalonia region LEWS. The LEWS has been run for nine months (April–December 2020) using two approaches: (i) combining susceptibility and rainfall intensity-duration (I-D) thresholds and (ii) combining susceptibility and the new hydrometeorological thresholds including soil moisture information. Generally, both LEWS approaches issued moderate or high warnings in the areas where significant rainfall accumulations were recorded. The outputs have been compared at specific locations where landslides were reported during the analysed period. Results show that at the analysed locations false positives are generally reduced when employing the hydrometeorological thresholds in the LEWS. Therefore, this approach is promising and could help improve regional scale LEWS in Catalonia., Open access funding provided by Norwegian Geotechnical Institute. This work has been partly funded by the EC H2020 project ANYWHERE (DRS-01–2015-700099) and the Spanish research project EROSLOP (PID2019-104266RB-I00/AEI/10.13039/501100011033). The first author received support by a grant from the Secretariat of Universities and Research of the Ministry of Business and Knowledge of the Generalitat de Catalunya., Peer Reviewed, Postprint (published version)

Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles, Objectius de Desenvolupament Sostenible::4 - Educació de Qualitat, Objectius de Desenvolupament Sostenible::6 - Aigua Neta i Sanejament, Postprint (published version)

This research analyses multiple anthropogenic pressures in the Bernesga River, a gravel-bed river in Northwestern Iberian Peninsula. Among the causes of river incision in Bernesga River are extensive mining during the second half of the twentieth century, a 100 years-long history of channelization and river training starting around 1900, and to a lesser extent, land-use changes in the basin. As a result of these impacts, reach-averaged incision exceeds 8.5 m. Severe incision occurred simultaneously with a dramatic change in channel pattern: from 450 m-wide braided morphology around middle of the twentieth century to a narrow single-thread 40 m wide) channel in 2017. Quaternary alluvial deposits have been mostly depleted exposing the underlying bedrock. Unlike other rivers, bedrock outcrops have not stopped incision. Extremely narrow channels (12 m wide) have developed and incised at rates of 0.11 m/yr into bedrock materials, headcuts have formed on bedrock deposits and have rapidly retreated (at 33 m/yr) and the channel has incised forming adverse slopes under the presence of bed sills. Cause-effect relationships of cumulative impacts have been established between the recent evolutionary trajectory of the Bernesga River and multiple and simultaneous anthropogenic pressures., Peer Reviewed, Postprint (author's final draft)

Aquest article presenta la síntesi actualitzada de la recerca que s’ha dut a terme a la Tordera des de 2005. S’hi fa un resum dels impactes més importants que ha sofert el riu, principalment de les grans extraccions de material realitzades entre les dècades de 1960 i 1980. Hem dut a terme l’anàlisi de la incisió fluvial, és a dir de l’efecte d’aquestes extraccions sobre la llera, tot comparant informació cartogràfica de diferents períodes dels segles xx i xxi. Aquesta informació demostra que: 1) la incisió del riu assoleix magni- tuds mètriques, se superen els 3-4 m, 2) aquesta erosió generalitzada no s’ha aturat malgrat que les grans extraccions van finalitzar fa més de 35 anys tot i que 3) el ritme s’ha esmorteït d’ençà 2002. S’espera que aquest ritme continuï reduint-se durant els propers anys. La reducció del subministrament de material sòlid del riu cap a la costa, produïda per les extraccions de material al·luvial, és la causa principal de la regressió del delta, que ha reculat més de 200 m en algun punt., Postprint (published version)

A potential control of downstream channel width variations on the structure and planform of pool–riffle sequence local bed topography is a key to the dynamics of gravel bed rivers. How established pool–riffle sequences respond to time-varying changes in channel width at specific locations, however, is largely unexplored and challenging to address with field-based study. Here, we report results of a flume experiment aimed at building understanding of how statistically steady pool–riffle sequence profiles adjust to spatially prescribed channel width changes. We find that local bed slopes near steady-state conditions inversely correlate with local downstream width gradients when the upstream sediment supply approximates the estimated transport capacity. This result constrains conditions prior to and following the imposed local width changes. Furthermore, this relationship between local channel bed slope and downstream width gradient is consistent with expectations from scaling theory and a broad set of field-based, numerical, and experimental studies (n=88). However, upstream disruptions to coarse sediment supply through actions such as dam removal can result in a transient flipping of the expected inverse correlation between bed slope and width gradient, collectively highlighting that understanding local conditions is critical before typically implemented spatial averaging schemes can be reliably applied., Postprint (published version)

The aim is the reconstruction of the October 2019 flash flood, that was documented through extensive field work: rainfall (300 mm in just a few hours), flood marks, times of flood passage and witnesses' snapshots and reports, channel changes, log drift (20,000 trees) and woody debris at bridges, as well as large damage and six fatalities. The methods are: hydrological model built for the rainfall-runoff in the basin and the flood routing in the river, use of hydraulic principles such as flow at waterfalls, flow against obstacles (trees), etc. and finally 1D/2D free surface numerical models. The uppermost 100 km2 produced discharges of 700 m3/s (up to 50 m3/s/km2, locally). Three bridges failed, but their cascading failure (when one failure triggers the next one downstream) was not proved. The main channel widened more than 10 times, dragging away soil and vegetation like a bulldozer. The resulting large wood debris that clogged two bridges worsened the inundation. An anomalous flow downstream, probably a surge of around 1090 m3/s, due to the failure of a woody jam at a narrow bridge, took two lives. Water Authority is now warning flood planners that vegetated, torrential basins may cause catastrophic floods in the valley towns, if their narrow bridges are sensitive to woody debris., Catalan Water Authority and its Tarragona officers, Meteoprades and Fons Signatus, Joan March and a number of witnesses. The UPC's contribution was funded by the contract CTN2000029 of the “Agència Catalana de l′Aigua”. The UB's contribution has been developed within the framework of the AGORA project, funded by the "Agència Catalana de l′Aigua". Our thanks to the "Museu de la Vida Rural", in l′Espluga de Francolí, and all the citizens who contributed to the return of experience. The UIB's research has been supported by the Ministerio de Ciencia, Innovación y Universidades (CGL2017-82868-R and PID2020-113036RB-I00/AEI/10.13039/501100011033 research projects, which are partially supported by the European Regional Development Funds)., Peer Reviewed, Postprint (published version)

Floods can arise from a variety of physical processes. Although numerous risk assessment approaches stress the importance of taking into account the possible combinations of flood types (i.e. compound floods), this awareness has so far not been reflected in the development of early warning systems: existing methods for forecasting flood hazards or the corresponding socio-economic impacts are generally designed for only one type of flooding. During compound flood events, these flood type-specific approaches are unable to identify overall hazards or impacts. Moreover, from the perspective of end-users (e.g. civil protection authorities), the monitoring of separate flood forecasts – with potentially contradictory outputs – can be confusing and time-consuming, and ultimately impede an effective emergency response. To enhance decision support, this paper proposes the integration of different flood type-specific approaches into one compound flood impact forecast. This possibility has been explored through the development of a unified system combining the simulations of two impact forecasting methods: the Rapid Risk Assessment of the European Flood Awareness System (EFAS RRA; representing fluvial floods) and the radar-based ReAFFIRM method (representing flash floods). The unified system has been tested for a recent catastrophic episode of compound flooding: the DANA event of September 2019 in south-east Spain (Depresión Aislada en Niveles Altos, meaning cut-off low). The combination of the two methods identified well the overall compound flood extents and impacts reported by various information sources. For instance, the simulated economic losses amounted to about EUR¿670 million against EUR¿425 million of reported insured losses. Although the compound impact estimates were less accurate at municipal level, they corresponded much better to the observed impacts than those generated by the two methods applied separately. This demonstrates the potential of such integrated app, This research has been supported by the Horizon 2020 project ANYWHERE (H2020-DRS-1-2015-700099), which financed the initial period of this study and the 4-month visiting stay of Josias Láng-Ritter at the European Commission Joint Research Centre in Ispra (Italy). The study has been finalised in the framework of the TAMIR project (UCPM-874435-TAMIR)., Peer Reviewed, Postprint (published version)

The recent extreme rainfall events in Spain such as the storm Gloria have highlighted the gaps in emergency communication, particularly the disconnect between the available impact-based early warning systems (IBEWSs) and the steps communities take during emergencies. This paper presents a community-centred framework named ‘site-specific early warning system’ (SS-EWS) to co-design and co-evaluate with communities an IBEWS for vulnerable locations within high-risk areas. The components of the framework guide communities in identifying and evaluating local impacts; establishing impact and advisory tables; deriving impact-based rainfall thresholds and warning levels; and configuring the SS-EWS with radar-based nowcasting and numerical weather prediction (NWP) models. A first implementation and evaluation of the SS-EWS have been done for a public school, two ford crossings and the city of Terrassa, Spain. The SS-EWS shows promising results in triggering location-based or site-specific warnings compatible with the reported impacts and proposing actions to reduce the local risk. Furthermore, the combination of NWP and radar-based nowcasting improved the capacity of the SS-EWS to monitor the evolution of the precipitation and capture highly intense rainfall. The SS-EWS can be a straightforward and cost-efficient complement for regional EWS to increase the preparedness of communities., The study has been carried out mainly in the H2020 project ANYWHERE (H2020-DRS-1-2015-700099). The authors extend their gratitude to the municipality of Terrassa and Vicenta Villar, the Civil Protection of Catalonia, the Consorcio de Compensación de Seguros (CCS) and Josep Maria Gibert for kindly providing data., Peer Reviewed, Postprint (published version)

The Gloria storm rainfalls affected Catalonia from 20 to 23 January 2020 and triggered multiple landslides, some of which affected buildings and infrastructures (such as roads and railways). This paper presents the rainfall and landslide datasets collected during the event, and evaluates the performance of a regional landslide early warning system (LEWS) during the Gloria storm applying a fuzzy verification method. The majority of the inventoried landslides can be classified as slides, involving a limited volume of sediment (up to 10 m3), and were triggered in cut slopes along linear infrastructures. Rainfall accumulations were significant in the whole region, especially in the Montseny area, where over 450 mm were registered in 96 h. Generally, the LEWS computed moderate and high warnings in the areas where large rainfall amounts were recorded, and showed good correspondence with the locations where landslides were reported. The fuzzy verification method has been applied using neighbouring windows of different sizes to obtain scale-dependant information on the LEWS performance. The skill of the LEWS considerably improves when enlarging the neighbouring window size from 500 m to 1 km., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The first author is supported by a grant from the Secretariat of Universities and Research of the Ministry of Business and Knowledge of the Generalitat de Catalunya. This work has been partly funded by the EC H2020 project ANYWHERE (DRS-01–2015–700099) and the Spanish national projects SMuCPhy and EROSLOP (BIA 2015–67500-R and PID2019–104266RB–I00/AEI/)., Peer Reviewed, Postprint (published version)

The version of record os available online at: http://dx.doi.org/10.1007/s10346-020-01568-3, Time trends and their statistical significance for daily minimum, Tmin, and maximum, Tmax, temperatures recorded at the Fabra Observatory (Barcelona) along 102 years (1917–2018) permit to analyse the evolution of every one of the 365 calendar days along the recording period. Relevant changes in the daily temperature regime have been quantified not only by time trends and the Mann–Kendall test, but also by the multifractal analysis applied to consecutive segments of daily temperature data. The evolution of several multifractal parameters (the central Hölder exponent, the spectral asymmetry and spectral amplitude, the complexity index and the Hurst exponent) provides a complementary viewpoint to describe the evolution of the thermometric regime along the 102 recorded years. At monthly scale, the effects of the climate change are characterised by significant positive trends from September to December and very moderate negative trends from April to July. With respect to changes in the calendar-day structure, it is noticeable a shift of the highest minimum and maximum daily temperature from July to August (year 2018) to the beginning of September (projections for years 2030 and 2050) and the projected highest maximum calendar-day temperature exceeding 30 °C., Peer Reviewed, Postprint (published version)

The development of early warning systems (EWSs) is a key element for the effective mitigation of flash flood impacts. Emergency managers and other end-users increasingly recognise the benefit of tools that automatically translate the forecasted flash flood hazard (e.g. expressed in terms of peak discharge or return period) into the expected socio-economic impacts (e.g. the affected population). While previous studies aimed at forecasting flash flood impacts at local or regional scales, this paper presents a simple approach for estimating in real time the flash flood impacts at pan-European scale. The proposed method – named ReAFFINE – is designed to be integrated into an EWS for end-users operating over large spatial domains (e.g. across regions or countries). ReAFFINE uses the pan-European flash flood hazard estimates from the ERICHA system to retrieve the potentially flooded areas from the national flood maps (generated in the framework of the EU Floods Directive). By combining the potentially flooded areas with socio-economic exposure information, ReAFFINE estimates in real time the exposed population and critical infrastructures. For two catastrophic flash flood events affecting Europe in recent years, ReAFFINE has demonstrated the capability to identify impacts over large spatial scales. Also at sub-regional level, the method has mostly been able to locate the areas and municipalities where the most important impacts occurred. The results also show that the performance is sensitive to the quality of the rainfall estimates that drive the hazard estimation, and to the comprehensiveness of the employed flood maps., The EU Horizon 2020 project ANYWHERE (H2020-DRS-1-2015-700099) financed the initial period of this work. The study was finalised in the framework of the TAMIR project (UCPM-874435-TAMIR). We would like to express our gratitude to OPERA, WMO and the Spanish State Meteorological Agency (AEMET) for the provision of meteorological data, and the Spanish National Geographic Institute (IGN) and the German Federal Institute of Hydrology (BfG) for access to the national flood maps. Furthermore, we would like to thank OpenStreetMaps, Milan Kalas, and the Joint Research Centre for providing the pan-European exposure datasets, and the European Severe Weather Database (ESWD), the Bavarian Environment Agency (LfU), the Spanish Insurance Compensation Consortium (CCS), the Spanish Directorate-General for Civil Protection and Emergencies (DGPCE), and Jens de Bruijn (Vrije Universiteit Amsterdam) from the Global Flood Monitor for meticulously reporting the impacts of the analysed flood events., Peer Reviewed, Postprint (published version)

La Agència Catalana de l’Aigua (ACA) está promoviendo el desarrollo de una herramienta para disponer de predicciones probabilísticas de caudales, en estaciones de aforo, y de evolución de volúmenes, en embalses. Esta herramienta se plantea como un elemento adicional a ser integrado en el conjunto de recursos para la ayuda a la toma de decisiones durante el seguimiento, gestión y tareas de comunicación propias de situaciones de avenidas, tanto en cuencas reguladas por embalses como no reguladas. El conocimiento previo de la variación de niveles en embalses y caudales máximos puntuales en estaciones de aforo se pretenden conjugar para analizar la conveniencia de generar avisos y/o resguardos activos mediante unos oportunos desembalses preventivos. El objetivo principal es la gestión óptima del recurso hídrico optimizando resguardos de laminación y la mejora en la gestión de la seguridad de las presas y en la reducción de riesgos por inundación., Postprint (published version)

Preprint

Esta investigación se centra en validar y definir la metodología Particle Tracking Velocimetry (PTV) para la medición de perfiles de velocidades en flujos de alta pendiente, con sumergencias relativas (Rn/D50) muy bajas. Para tal fin se realizan mediciones en un canal de pendiente variable con PTV y con una metodología previamente contrastada por Fernández (2019) mediante Velocímetro Acústico Doppler (ADV). Una vez validada se procede a corroborar la aplicación del PTV en flujos macro rugosos, en los que ADV no puede ser utilizado., Postprint (published version)

The Ciénaga Grande de Santa Marta (CGSM) is a coastal complex in northern Colombia comprising interconnected lagoons, bounded by the Magdalena River (RM) and the Caribbean Sea. It is a system of great ecological, economic and ecosystemic wealth, so it has been declared an area of protection by different international organizations. However, its quality has gradually deteriorated due to multiple factors obstructing the connection channels between the RM and the CGSM. That led to hypersaline lagoons, as the Caribbean makes up for the missing volume. Solutions have focused on opening new channels or expanding existing ones that connect the CGSM with the RM, yet the problems have not stopped. This research calls to guarantee a minimum flow rate and a gradient so that the flow is effectively carried out in the desired direction and not in the opposite direction. That by analyzing the flow series in the lower basin for different contexts, both temporal and ENSO events., Objectius de Desenvolupament Sostenible::13 - Acció per al Clima, Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles, Postprint (published version)

The data have been acquired during the experimental campaign carried out in the Steep Slope Flume at Morphodynamics Laboratory I of the GITS group in BarcelonaTech-Universtitat Politècnica de Catalunya. Data published here comprise the measurements carried out in the laboratory related with velocity profiles in steep channels with low relative submergence. Flume slope ranged between 2-10% and same bed material had been used (a basaltic gravel of 1.45 mm of main diameter) for all the experiments. 30 experiments were carried out with 165 velocity profile measurements., 2

The final publication is available at Springer via http://dx.doi.org/10.1007/s11004-020-09882-1, Automatic interpolation of precipitation maps combining rain gauge and radar data has been done in the past but considering only the data collected at a given time interval. Since radar and rain gauge data are collected at short intervals, a natural extension of previous works is to account for temporal correlations and to include time into the interpolation process. In this work, rainfall is interpolated using data from the current time interval and the previous one. Interpolation is carried out using kriging with external drift, in which the radar rainfall estimate is the drift, and the mean precipitation is set to zero at the locations where the radar estimate is zero. The rainfall covariance is modeled as non-stationary in time, and the space system of reference moves with the storm. This movement serves to maximize the collocated correlation between consecutive time intervals. The proposed approach is analyzed for four episodes that took place in Catalonia (Spain). It is compared with three other approaches: (i) radar estimation, (ii) kriging with external drift using only the data from the same time interval, and (iii) kriging with external drift using data from two consecutive time intervals but not accounting for the displacement of the storm. The comparisons are performed using cross-validation. In all four episodes, the proposed approach outperforms the other three approaches. It is important to account for temporal correlation and use a Lagrangian system of coordinates that tracks the rainfall movement., This work has been done in the framework of the Spanish Project FFHazF (CGL2014-60700) and the EC H2020 project ANYWHERE (DRS-1-2015-700099). Thanks are due to the Meteorological Service of Catalonia for providing the radar and rain gauges data used here., Peer Reviewed, Postprint (author's final draft)

Landslides falling into water can trigger tsunamis, which are particularly destructive in the proximity of the landslide impact and in narrow water bodies. The energy transfer mechanism between landslide and water wave is complex, but its understanding is of fundamental importance for the numerical modeling which aims to predict the induced wave hazard. In order to study the involved physical processes, we set up an experimental facility consisting of a landslide generator releasing gravel at high speed in a wave basin. With the aim of estimating the landslide–wave energy transfer, we implemented a simplified 1D conceptual model of landslide motion, including the 3D landslide deformations. We optimized the model with the experimental results. The model results explain that the deformable landslide has an average drag coefficient of 1.26 and a relatively inefficient energy transfer from landslide to wave. Of the landslide energy at impact, the 52% is dissipated by Coulomb basal friction between the slide and the water basin bottom, 42% is dissipated by other processes, including turbulence, and only the remaining 6% is transferred to the wave thus formed., Postprint (published version)

supplemental_data_wr.1943-5452.0001159_ritter.pdf (492 KB), This study explores the ways to introduce physical interpretability into the process of optimizing operating rules for multireservoir systems with multiple objectives. Prior studies applied the concept of direct policy search (DPS), in which the release policy is expressed as a set of parameterized functions (e.g., neural networks) that are optimized by simulating the performance of different parameter value combinations over a testing period. The problem with this approach is that the operators generally avoid adopting such artificial black-box functions for the direct real-time control of their systems, preferring simpler tools with a clear connection to the system physics. This study addresses this mismatch by replacing the black-box functions in DPS with physically based parameterized operating rules, for example by directly using target levels in dams as decision variables. This leads to results that are physically interpretable and may be more acceptable to operators. The methodology proposed in this work is applied to a network of five reservoirs and four power plants in the Nechi catchment in Colombia, with four interests involved: average energy generation, firm energy generation, flood hazard, and flow regime alteration. The release policy is expressed depending on only 12 parameters, which significantly reduces the computational complexity compared to existing approaches of multiobjective DPS. The resulting four-dimensional Pareto-approximate set offers a variety of operational strategies from which operators may choose one that corresponds best to their preferences. For demonstration purposes, one particular optimized policy is selected and its parameter values are analyzed to illustrate how the physically based operating rules can be directly interpreted by the operators., Peer Reviewed, Preprint

Landslides falling into water bodies can generate destructive waves, which can be classified as tsunamis. An experimental facility to study this phenomenon has been set up. It consists of a landslidegenerator releasing gravel at high-speed into a wave basin. A non-intrusive system has been designed ad-hocto be able to measure the high velocity and the geometry of the landslide as well as the generated waves characteristics. The measurement system employs the treatment of images captured by a high-speed camera which records the launched granular material illuminated by a laser sheet. A grid of laser sheets marks thebasin water surface. The water has been filled by a small amount of kaolin to properly reflect the laser lightat water surface. Thus, by filming with high definition cameras the perturbed water surface and successively processing the resulting images, it has been possible to measure the generated waves. The measurement framework employs a versatile camera calibration technique which allows accurate measurements in presence of: (1) high lens distortions; (2) pronounced non-parallelism condition between camera sensor and plane of measurement coincident with the laser sheet. The maximum resolution of the measurement tool is0.01 mm, while the maximum uncertainty due to systematic error has been estimated to be 15% for theworst-case scenario. This work improves the suitability of image-based measuring systems in granular flows and free surface hydraulics experiments, This work was funded by GITS and the 3 years’ national project DEBRIS FLOW (CGL 2009-13039) ofthe Spanish Ministry of Education. Francesco Bregoli has been supported by the 4-years grant FPU2009-3766 of the SpanishMinistry of Education. Authors want to thank Dr. Cecilia Caldini (IDOM Consulting, Barcelona) for the 3D reconstruction ofthe laboratory setup., Peer Reviewed, Postprint (published version)

Accurate and robust short-term rainfall forecasts (nowcasts) are useful in operational flood forecasting. However, the high temporal and spatial variability of rainfall fields make rainfall nowcasting a challenging endeavour. To cope with this variability, nowcasting techniques based on weather radar imagery have been proposed. Here, we employ radar rainfall nowcasting for discharge predictions in three lowland catchments in the Netherlands, with surface areas ranging from 6.5 to 957 km2. Deterministic (Lagrangian persistence) and probabilistic (SBMcast) nowcasting techniques are used to produce short-term rainfall forecasts (up to a few hours ahead), which are used as input for the hydrological model WALRUS. Rainfall forecasts were found to deteriorate with increasing lead time, often due to underestimation. Discharge could be forecasted 25–170 min earlier than without rainfall nowcasting, with the best performance for the largest catchment. When accounting for catchment response time, the best (but most variable) relative performance was found for the smallest catchment. Probabilistic nowcasting effectively accounted for the uncertainty associated with rainfall and discharge forecasts. The uncertainty in rainfall forecasts was found to be largest for the smaller catchments. The uncertainty in how much earlier the discharge could be forecasted (the gain in lead time) ranged from 15 to 50 min., Peer Reviewed, Postprint (published version)

The sensitive mountain catchment of Portainé (Eastern Pyrenees, Iberian Peninsula) has recently experienced a significant change in its torrential dynamics due to human disturbances. The emplacement of a ski resort at the headwaters led to the surpassing of a geomorphological threshold, with important consequences during flood events. Consequently, since 2008, channel dynamics have turned into sediment-laden, highly destructive torrential flows. In order to assess this phenomenon and to acquire a holistic understanding of the catchment’s behaviour, we carried out a field work-based multidisciplinary study. We considered the interaction of the various controlling factors, including bedrock geology, geomorphological evolution, derived soils and coluvial deposits, rainfall patterns, and the hydrological response of the catchment to flood events. Moreover, anthropogenic land-use changes, its consequential hydrogeomorphic effects and the role of vegetation were also taken into account. Robust sedimentological and geomorphological evidence of ancient dense debris flows show that the basin has shifted around this threshold, giving rise to two different behaviours or equilibrium conditions throughout its history: alternating periods of moderate, bedload-laden flows and periods of high sediment-laden debris flow dynamics. This shifting could have extended through the Holocene. Finally, we discuss the possible impact of climate and global change, as the projected effects suggest future soil and forest degradation; this, jointly with more intense rainfalls in these mountain environments, would exacerbate the future occurrence of dense sediment-laden flows at Portainé, but also in other nearby, similar basins., Peer Reviewed, Postprint (published version)

The final publication is available at Springer via http://dx.doi.org/10.1007/s10346-020-01425-3, This work presents a prototype landslide early warning system (LEWS) adapted to real-time performance over the region of Catalonia (NE Spain). The system uses high-resolution rainfall information obtained from weather radar observations and susceptibility maps to issue a qualitative warning level at a regional scale. To study the influence of the mapping unit on the LEWS outputs, susceptibility maps obtained for Catalonia based on (i) pixels of different sizes and (ii) hydrological subbasins have been compared. The susceptibility has been derived using a simple fuzzy logic approach combining slope angle and land cover data. The susceptibility maps for the different mapping units have then been employed to run the LEWS for a period of 7 months (warm season of 2010). For each configuration, the performance, interpretability of the warnings, and computational requirements have been compared to assess the suitability of each mapping unit for their use in the LEWS in real time. The configuration using pixels of 30-m resolution as mapping units seems to be the best as a compromise between resolution, performance, and computational cost. However, from an end-user’s real-time perspective, the interpretation of the warnings can be difficult. Therefore, summarizing and visualizing the warnings, which are computed over the high-resolution grid, by subbasins is proposed as the best option., This work has been partially funded by the EC H2020 project ANYWHERE (DRS-01-2015-700099) and the Spanish project SMuCPhy (BIA 2015-67500-R). Also, the first author is supported by a grant from the Secretariat of Universities and Research of the Ministry of Business and Knowledge of the Generalitat de Catalunya., Peer Reviewed, Postprint (author's final draft)

Flash floods evolve rapidly in time, which poses particular challenges to emergency managers. One way to support decision-making is to complement models that estimate the flash flood hazard (e.g. discharge or return period) with tools that directly translate the hazard into the expected socio-economic impacts. This paper presents a method named ReAFFIRM that uses gridded rainfall estimates to assess in real time the flash flood hazard and translate it into the corresponding impacts. In contrast to other studies that mainly focus on in- dividual river catchments, the approach allows for monitoring entire regions at high resolution. The method consists of the following three components: (i) an already existing hazard module that processes the rainfall into values of exceeded return period in the drainage network, (ii) a flood map module that employs the flood maps created within the EU Floods Directive to convert the return periods into the expected flooded areas and flood depths, and (iii) an impact assessment module that combines the flood depths with several layers of socio- economic exposure and vulnerability. Impacts are estimated in three quantitative categories: population in the flooded area, economic losses, and affected critical infrastructures. The performance of ReAFFIRM is shown by applying it in the region of Catalonia (NE Spain) for three significant flash flood events. The results show that the method is capable of identifying areas where the flash floods caused the highest impacts, while some locations affected by less significant impacts were missed. In the locations where the flood extent corresponded to flood observations, the assessments of the population in the flooded area and affected critical infrastructures seemed to perform reasonably well, whereas the economic losses were systematically overestimated. The effects of different sources of uncertainty have been discussed: from the estimation of the hazard to its translation into impacts, which, Peer Reviewed, Postprint (published version)

Risk mitigation for debris flows at regional scale is a challenge. Early warning systems are helpful in depicting the time and the location of future debris flows so that emergency responders can act in advance before the disaster takes place. Herein we present a prototype real-time regional early warning system for rainfall induced shallow landslides and debris flows for the region of Catalonia (northeastern Spain). The model issues a warning level combining susceptibility information and real-time rainfall triggering conditions obtained from weather radar observations and forecasts. Susceptibility maps have been derived using a fuzzy logic approach and two input variables, terrain slope and land cover. These maps have been obtained using (i) grid cells of different resolutions, and (ii) physical catchments (of first order) as terrain units. Although high resolution grid-cell maps show a more accurate representation of susceptibility over the region, maps based on catchments are more intuitive and better characterize the area affected by future debris flows. Rainfall triggering conditions are assessed by means of probabilistic intensity-duration thresholds obtained from literature. Finally, we have validated the early warning system and tested its performance for some important events from the last ten years that were either monitored in specific catchments, or were reported in unmonitored catchments. In general, the system has been able to satisfactorily forecast the time of occurrence of most of the analyzed past debris flow events., Postprint (published version)

The anticipation of flash flood events is crucial to issue warnings to mitigate their impact. This work presents a comparison of two early warning systems for real-time flash flood hazard forecasting at regional scale. The two systems are based in a gridded drainage network and they use weather radar precipitation inputs to assess the hazard level in different points of the study area, considering the return period (in years) as the indicator of the flash flood hazard. The essential difference between the systems is that one is a rainfall-based system (ERICHA), using the upstream basin-aggregated rainfall as the variable to determine the hazard level, while the other (Flood-PROOFS) is a system based on a distributed rainfall-runoff model to compute the streamflows at pixel scale. The comparison has been done for three rainfall events in the autumn of 2014 that resulted in severe flooding in the Liguria region (Northwest of Italy). The results obtained by the two systems show many similarities, particularly for larger catchments and for large return periods (extreme floods)., Peer Reviewed, Postprint (author's final draft)

Extreme precipitation events with high local precipitation intensities, heavy snowfall or extensive freezing rain can have devastating impacts on society and economy. Not only is the quantitative forecast of such events sometimes difficult and associated with large uncertainties, also are the potential consequences highly complex and challenging to predict. It is thus a demanding task to anticipate or nowcast the impacts of extreme precipitation, even more so in situations where human lives or critical infrastructure might be at risk. In recent years, the term “cascading effects” has been increasingly used to describe events in which an initial trigger leads to a sequence of consequences with significant magnitude. We here analyze three examples for different precipitation types where the initial triggering event generated a cascade of events and impacts, namely a convective precipitation event in the Swiss Prealps, a freezing rain in Slovenia, and a heavy snowfall episode in Catalonia. With the aim to improve process understanding of complex precipitation-triggered events, we assess the prediction of the selected events and analyze the cascading effects that caused diverse impacts. To this end, we use a framework of cascading effects which should ultimately allow the development of a better design risk assessment and management strategies. Our findings confirm that damage of extreme precipitation events is clearly related to the knowledge of potential cascading effects. Major challenges of predicting cascading effects are the high complexity, the interdependencies and the increasing uncertainty along the cascade. We propose a framework for cascading effects including two approaches: (i) one to analyze cascading effects during past extreme precipitation events, which then serves as a basis for a (ii) more generalized approach to increase the preparedness level of operational services before and during future extreme precipitation events and to anticipate potential c, Peer Reviewed, Postprint (published version)

Early warning systems (EWSs) help society to prepare for, and respond to, all types of disasters, including those related to hydrometeorological hazards. They save lives and minimize potential economic and environmental damages. Several international initiatives at the regional and global levels address early warning systems. The Sendai Framework for Disaster Risk Reduction 2015–20306 specifically highlights the need to “substantially increase the availability of and access to multi-hazard early warning systems and disaster-risk information and assessments to the people by 2030.” It urges efforts to make forecasting and EWSs more efficient, integrated and sustainable7,8. The WMO governance reform too emphasizes the importance of delivering integrated multi-hazard and impact-based services through EWSs that are scientific and people-centred. In this context, what is the role of young professionals – who would be mid-career by 2030 – in the design and implementation of integrated multi-hazard and impact-based EWS?, Peer Reviewed, Postprint (published version)

This article studies the life cycle of the well-organised mesoscale convective systems (MCSs) that affect Catalonia and surrounding regions, using a weather radar composite with sophisticated corrections and lightning data over a full period of five years. Nearly 350 MCSs were identified and analysed for the 2012–2016 period after applying size and duration criteria to 438,000 radar composites. MCSs are responsible for the majority of flood events in the region of interest and in many other areas around the world. We have analysed the main radar parameters and lightning properties, looking for differences between the systems depending on the season of the year. Autumn and spring show the highest frequency of MCSs, but there are considerable differences between their properties for the two seasons. More specifically, lightning activity, maximum reflectivity and duration are higher in autumn than in winter, although the total accumulated rainfall may be lower. This higher convective activity is associated with the warmer sea surface temperature of the Mediterranean and a large number of cyclones that affect the region of analysis., Peer Reviewed, Postprint (author's final draft)

Previous research has found that users fail to comprehend flood hazard warning messages as well as the possible impacts of the forecast events. A proposed way to improve understanding and uptake is the implementation of impact-based warning services. However, even though extensive qualitative research has been done on the provision of these impact-based warnings (IBWs) for different types of hazards and extreme events, there is still little scientific evidence that the additional information on impacts in flood warnings positively affects decisions made by the general public. The research reported here explores whether including messages of potential impacts increased the general public's likelihood of making a protective decision when provided with a flood warning. Nine hypothetical flood scenarios were presented to participants who were then asked to score their likelihood of making a specific protective decision. Participants were either presented IBWs or hazard flood warnings (HWs). Results show that IBWs indeed led to higher likelihoods of participants making a protective decision than HWs. Interestingly, we found that key factors identified in previous studies as influential elements in the decision-making process had little impact on their decision. These factors include gender and previous experience with flood warnings., Peer Reviewed, Postprint (published version)

Monitoring continental precipitation over Europe with high resolution (2 km, 15 min) has been possible since the operational production of the OPERA composites from the European weather radar networks. The OPERA data are the essential input to a hazard assessment tool for identifying localized rainfall-induced flash floods at European scale, and their quality determines the performance of the tool. This paper analyses the OPERA data quality during the warm seasons of 2015–2017 by comparing the estimated rainfall accumulations with the SYNOP rain gauge records over Europe. To compensate the OPERA underestimation, a simple spatially-variable bias adjustment method has been applied. The long-term comparison between the OPERA and gauge point daily rainfall accumulations at the gauge locations shows the benefit of the bias adjustment. Additionally, the daily monitoring shows gradual improvement of the OPERA data year by year. The impact of the quality of the OPERA data for effective flash flood identification is demonstrated for the case of the flash floods that occurred from 29 May to 3 June 2016 in central Europe., Peer Reviewed, Postprint (author's final draft)

Attenuation due to liquid water is one of the largest uncertainties in radar observations. The effects of attenuation are generally inversely proportional to the wavelength, i.e. observations from X-band radars are more affected by attenuation than those from C- or S-band systems. On the other hand, X-band radars can measure precipitation fields in higher temporal and spatial resolution and are more mobile and easier to install due to smaller antennas. A first algorithm for attenuation correction in single-polarized systems was proposed by Hitschfeld and Bordan (1954) (HB), but it gets unstable in case of small errors (e.g. in the radar calibration) and strong attenuation. Therefore, methods have been developed that restrict attenuation correction to keep the algorithm stable, using e.g. surface echoes (for space-borne radars) and mountain returns (for ground radars) as a final value (FV), or adjustment of the radar constant (C) or the coefficient a. In the absence of mountain returns, measurements from C- or S-band radars can be used to constrain the correction. All these methods are based on the statistical relation between reflectivity and specific attenuation. Another way to correct for attenuation in X-band radar observations is to use additional information from less attenuated radar systems, e.g. the ratio between X-band and C- or S-band radar measurements. Lengfeld et al. (2016) proposed such a method based isotonic regression of the ratio between X- and C-band radar observations along the radar beam. This study presents a comparison of the original HB algorithm and three algorithms based on the statistical relation between reflectivity and specific attenuation as well as two methods implementing additional information of C-band radar measurements. Their performance in two precipitation events (one mainly convective and the other one stratiform) shows that a restriction of the HB is necessary to avoid instabilities. A comparison with vertically pointing micr, Peer Reviewed, Postprint (author's final draft)

Peer Reviewed, Postprint (published version)

The most widely used technique for nowcasting of quantitative precipitation in operational and research centers is the Lagrangian extrapolation of the latest radar observations. However, this technique has a limited forecast skill because of the assumptionmade on its formulation, such as the fact that the motion vectors do not change and, evenmore important for convective events, neglect any growth or decay in the precipitation field. In this work, the McGill Algorithm for Precipitation Nowcasting by Lagrangian Extrapolation (MAPLE) errors have been computed for 10 yr of radar composite data over the continental United States. The study of these errors shows systematic bias depending on the time of day. This effect is related to the solar cycle, whose heating energy results in an increase in the average rainfall in the afternoon. This external forcing interacts with the atmospheric system, creating local initiation and dissipation of convection depending on orography, land use, cloud coverage, etc. The signal of the diurnal cycle inMAPLEprecipitation forecast has been studied in different locations and spatial scales as a function of lead time in order to recognize where, when, and for which spatial scales the signal is significant. This information has been used in the development of a scaling correction scheme where the mean errors due to the diurnal cycle are adjusted. The results show that the developed methodology improves the forecast for the spatial scales and locations where the diurnal cycle signal is significant., Peer Reviewed, Postprint (published version)

Landslides falling into water bodies can generate impulsive waves, which are a type of tsunamis. The propagating wave may be highly destructive for hydraulic structures, civil infrastructure and people living along the shorelines. A facility to study this phenomenon was set up in the laboratory of the Technical University of Catalonia. The set-up consists of a new device releasing granular material at high velocity into a wave basin. A system employing laser sheets, high-speed and high-definition cameras was designed to accurately measure the high velocity and geometry of the sliding mass as well as the produced water displacement in time and space. The analysis of experimental data helped to develop empirical relationships linking the landslide parameters with the produced wave amplitude, propagation features and energy, which are useful tools for the hazard assessment. The empirical relationships were successfully tested in the case of the 2007 event that occurred in Chehalis Lake (Canada)., Peer Reviewed, Postprint (author's final draft)

Los procesos torrenciales como las corrientes de derrubios o flujos hiperconcentrados causan frecuentemente daños importantes e incluso muertos en zonas montañosas. Para afrontar este peligro, los sistemas de alerta son una herramienta muy útil en la mitigación de los impactos de estos procesos hidro-morfológicos. El presente estudio ha desarrollado, implementado y validado un sistema de alerta a escala regional que determina en tiempo real el nivel de alerta en cada subcuenca de una zona seleccionada. Los principales datos de entrada son un mapa de susceptibilidad y la situación meteorológica que se obtiene mediante el radar. Mediante la aplicación de la técnica de lógica difusa y funciones de pertenencia, el mapa de susceptibilidad y el campo de lluvia se determina en cada subcuenca una de tres posibles clases, y finalmente con una matriz de alerta se calcula uno de los tres niveles de alerta (baja, media o alta). Los resultados del sistema de alerta y su validación han sido muy positivos y demuestran la gran utilidad de estas herramientas., Postprint (published version)

Debris-flow monitoring sites provide many important inputs on their mechanics and strongly improved the understanding on this hazardous process. Monitoring data are the basis for future early warning systems (EWS) and alarm systems (AS). In this study, results from the Rebaixader monitoring are presented and evaluated for the implementation in an EWS and AS at catchment scale. The key parameters are the rainfall thresholds for the warning and the ground vibration produced by the moving debris flow for the alarm emission. At regional scale, a preliminary EWS for a test area in the Central-Eastern Pyrenees is evaluated. The EWS is based on quantitative precipitation estimates obtained from the weather radars and a simple susceptibility model, which is applied in each basin of the test area. The experiences gathered in the Pyrenees show that the knowledge on initiation and flow behaviour of debris flows has strongly advanced and facilitate the set-up of operational EWS or AS. However, there are still remaining various uncertainties (especially related to the adequate definition of thresholds), which must be evaluated and continuously eliminated., Peer Reviewed, Postprint (published version)

Torrential flows like debris flows or debris floods are fast movements formed by a mix of water and different amounts of unsorted solid material. They generally occur in steep torrents and pose high risk in mountainous areas. Rainfall is their most common triggering factor and the analysis of the critical rainfall conditions is a fundamental research task. Due to their wide use in warning systems, rainfall thresholds for the triggering of torrential flows are an important outcome of such analysis and are empirically derived using data from past events. In 2009, a monitoring system was installed in the Rebaixader catchment, Central Pyrenees (Spain). Since then, rainfall data of 25 torrential flows (“TRIG rainfalls”) were recorded, with a 5-min sampling frequency. Other 142 rainfalls that did not trigger torrential flows (“NonTRIG rainfalls”) were also collected and analyzed. The goal of this work was threefold: (i) characterize rainfall episodes in the Rebaixader catchment and compare rainfall data that triggered torrential flows and others that did not; (ii) define and test Intensity–Duration (ID) thresholds using rainfall data measured inside the catchment by with different techniques; (iii) analyze how the criterion used for defining the rainfall duration and the spatial variability of rainfall influences the value obtained for the thresholds. The statistical analysis of the rainfall characteristics showed that the parameters that discriminate better the TRIG and NonTRIG rainfalls are the rainfall intensities, the mean rainfall and the total rainfall amount. The antecedent rainfall was not significantly different between TRIG and NonTRIG rainfalls, as it can be expected when the source material is very pervious (a sandy glacial soil in the study site). Thresholds were derived from data collected at one rain gauge located inside the catchment. Two different methods were applied to calculate the duration and intensity of rainfall: (i) using total duration, Dtot, and, Peer Reviewed, Postprint (author's final draft)

In this work we present a Water Availability Prediction System [WAPS] developed and implemented within two EU-FP7 projects: UrbanWater and WatERP. The aim of the WAPS is to provide information for management purposes, and as a source of information for other modules of the Decision Support Systems integrating the project platforms. General description of the WAPS, including data sources needed, processing algorithms and techniques used, and implementation examples are presented., Postprint (published version)

The mitigation of debris flow (DF) risk can be achieved by the means of reliable warning systems. At present time, operational warning systems are mostly based on critical rainfall thresholds (CRT) derived through the elaboration of past event records. The prediction ability of these systems strictly depends on the quality and availability of historical data. In order to overcome these limitations, in this work the CRT curves are derived from mathematical and numerical simulations carried out using a coupled hydrological-stability model. The CRT curves thus obtained are combined with rainfall nowcasts based on the observations of meteorological radar network. A case study in central Switzerland is presented. The performances of the proposed system are tested through a playback analysis of a past event. It results that the use of nowcasting allows for a crucial increment of the advance time interval., Peer Reviewed, Postprint (published version)

During the second week of September 2013, a seasonally uncharacteristic weather pattern stalled over the Rocky Mountain Front Range region of northern Colorado bringing with it copious amounts of moisture from the Gulf of Mexico, Caribbean Sea, and the tropical eastern Pacific Ocean. This feed of moisture was funneled toward the east-facing mountain slopes through a series of mesoscale circulation features, resulting in several days of unusually widespread heavy rainfall over steep mountainous terrain. Catastrophic flooding ensued within several Front Range river systems that washed away highways, destroyed towns, isolated communities, necessitated days of airborne evacuations, and resulted in eight fatalities. The impacts from heavy rainfall and flooding were felt over a broad region of northern Colorado leading to 18 counties being designated as federal disaster areas and resulting in damages exceeding $2 billion (U.S. dollars). This study explores the meteorological and hydrological ingredients that led to this extreme event. After providing a basic timeline of events, synoptic and mesoscale circulation features of the event are discussed. Particular focus is placed on documenting how circulation features, embedded within the larger synoptic flow, served to funnel moist inflow into the mountain front driving several days of sustained orographic precipitation. Operational and research networks of polarimetric radar and surface instrumentation were used to evaluate the cloud structures and dominant hydrometeor characteristics. The performance of several quantitative precipitation estimates, quantitative precipitation forecasts, and hydrological forecast products are also analyzed with the intention of identifying what monitoring and prediction tools worked and where further improvements are needed., Postprint (published version)

The hydrological and hydraulic processes of the flash flood that affected Atrani village (Amalfi Coast of Southern Italy) on 9 September 2010 are analysed using post-flood surveys and numerical modelling. Observations in this case are particularly challenging because of the small spatial and temporal scales of the event, relative to the sampling characteristics of conventional rain and discharge measurement networks. Given these aspects, some of the relevant characteristics of the event were deduced by analysing field data that were collected immediately after the event. A width function instantaneous unit hydrograph (WFIUH) rainfall-runoff model is applied to derive a flow hydrograph for the area immediately upstream of the village. This hydrograph is inputted as an upstream boundary condition for the simulation of the propagation processes. A two-dimensional innovative hydraulic model is used to reproduce the flood within the village. The use of an unstructured mesh enabled a detailed simulation of water flow within the narrow and winding alleyways of the village. The results of the simulations indicate agreement with the field observations. The implemented approach is suitable for simulating flash floods in similar contexts and, therefore, may be used to predict potential future events., The work described in this study was supported by the European Community Seventh Framework Programme through the grant of the Collaborative Project IMPRINTS (IMproving Preparedness and RIsk maNagemenT for flash floods and debriS flow events), Contract FP7-ENV-2008-1- 226555. The authors would like to thank: G. Amato, journalist and citizen of Atrani, for having kindly provided essential information about the event; E. Dell’Isola, citizen of Atrani and author of the video V2; the Autorità di bacino regionale Campania Sud; and the CEMPID of Campania region., Peer Reviewed, Postprint (published version)

This work presents a technique for debris-flow (DF) forecasting able to be used in the framework of DF early warning systems at regional scale. The developed system is applied at subbasin scale and is based on the concepts of fuzzy logic to combine two ingredients: (i) DF subbasin susceptibility assessment based on geomorphological variables and (ii) the magnitude of the rainfall situation as depicted from radar rainfall estimates. The output of the developed technique is a three-class warning (“low”, “moderate” or “high”) in each subbasin when a new radar rainfall map is available. The developed technique has been applied in a domain in the eastern Pyrenees (Spain) from May to October 2010. The warning level stayed “low” during the entire period in 20 % of the subbasins, while in the most susceptible subbasins the warning level was at least “moderate” for up to 10 days. Quantitative evaluation of the warning level was possible in a subbasin where debris flows were monitored during the analysis period. The technique was able to identify the three events observed in the catchment (one debris flow and two hyperconcentrated flow events) and produced no false alarm., Peer Reviewed, Postprint (published version)

In this work we present WiBasin, a cloud platform for basin and dam management. It includes different sources of precipitation (both observed and forecasted), integration over the catchment domain (to provide an aggregated value of potential rainfall accumulated over the basin) , and a complete dissemination environment (web-viewer, capability of issuing hazard warnings with configurable thresholds, SMS, mails, etc.), Peer Reviewed, Postprint (author’s final draft)

In this work we present FloodAlert, a simplified flood Early Warning System [EWS] based on the use of radar observations and radar nowcasting to issue local flood warnings. It is a web-based platform and it is complemented with a flexible and powerful dissemination module., Postprint (author’s final draft)

Dense radar networks offer the possibility of getting better Quantitative Precipitation Estimates (QPE) than those obtained with individual radars, as they allow increasing the coverage and improving quality of rainfall estimates in overlapping areas. Well-known sources of error such as attenuation by intense rainfall or errors associated with range can be mitigated through radar composites. Many compositing techniques are devoted to operational uses and do not exploit all the information that the network is providing. In this work an inverse method to obtain high-resolution radar reflectivity composites is presented. The method uses a model of radar sampling of the atmosphere that accounts for path attenuation and radar measurement geometry. Two significantly different rainfall situations are used to show detailed results of the proposed inverse method in comparison to other existing methodologies. A quantitative evaluation is carried out in a 12 h-event using two independent sources of information: a radar not involved in the composition process and a raingauge network. The proposed inverse method shows better performance in retrieving high reflectivity values and reproducing variability at convective scales than existing methods., Peer Reviewed, Postprint (author's final draft)

The objective of this study is to assess the skill of a precipitation nowcasting (very short range forecasting) system, with particular emphasis on hig-impact Heavy Precipitation Events (HPE). A threshold amount of 20 mm in 30 minutes is adopted, according to the first warning level issued for high rainfall rates by the Meteorological Service of Catalonia (NE Spain). These type of events are relatively frequent during autumn in the Mediterranean area and may produce flash-floods and substantial socio-economic losses when affecting densely populated areas in small catchments near the coast. Moreover, they can also produce local damage due to severe weather induced by winds of convective origin such as tornadoes or microbursts. Therefore, under these circumstances nowcasting systems producing very-short range (<3h) quantitative precipitation forecasts (QPF) are particularly necessary. Recent studies have pointed out the benefits of combining or blending the information from radar-based nowcasting systems and high resolution Numerical Weather Prediction (NWP) models to fill the gap between the lead-times of forecasts provided by each type of system - see for example Atencia et al. (2010), Berenguer et al. (2012) or the review by Pierce et al. (2012). Here we focus on assessing the quality of precipitation forecasts to examine realistic lead-times provided in four selected cases (see Table 1) for different precipitation amounts. The evaluation is done in two ways. Firstly forecasts are compared against radar based Quantitative Precipitation Estimates (QPE). Secondly the QPF fields are compared against actual raingauge data. Results are presented for all events together and for individual cases., Peer Reviewed, Postprint (published version)

Identification and elimination of clutter is necessary for ensuring data quality in radar Quantitative Precipitation Estimates (QPE). For uncorrected scanning reflectivity after signal processing, the removed areas have been often reconstructed by horizontal interpolation, extrapolation of non-contaminated PPIs aloft, or combining both based on a classification of the precipitation type. We present a general reconstruction method based on the interpolation of clutter-free observations. The method adapts to the type of precipitation by considering the spatial and temporal variability of the field provided by the multi-dimensional semivariogram. Six different formulations have been tested to analyze the gain introduced by each source of information: (1) horizontal interpolation, (2) vertical extrapolation, (3) extrapolation of past observations, (4) volumetric reconstruction, (5) horizontal and temporal reconstruction, and (6) volumetric and temporal reconstruction. The evaluation of the reconstructed fields obtained with the 6 formulations has been done (i) over clutter-free areas by comparison with the originally observed values, and (ii) over the real clutter-contaminated areas by comparison with the rainfall accumulations from a raingauge network. The results for 24 analyzed events (with a variety of convective and widespread cases) suggest that the contribution of extrapolation of past observations is not fundamental, and that the volumetric reconstruction is the one that overall adapted the best to the different situations., Peer Reviewed, Postprint (author’s final draft)

Quantitative Precipitation Nowcasting (QPN) is one of the main applications of radar observations. On one hand, one of the most used nowcasting algorithms is Lagrangian extrapolation. It shows skill in specifying the timing and location of precipitation over short time periods, but shows low skill when using past precipitation trends to predict changes in precipitation intensity. On the other hand, Numerical Weather Prediction (NWP) models have roof skill at predicting the precise timing and location of precipitation, although they provide useful information about the intensity trends. It is therefore to investigate whether this additional information provided by NWP could be used to improve QPN. SBMcast (Berenguer et al., 2011) is an ensemble nowcasting algorithm based on Lagrangian extrapolation of recent radar observations. It generates a set of future rainfall scenarios (ensemble members) compatible with observations and preserving the spatial and temporal structure of the rainfall field according to the String of Beads model (Pegram and Clothier, 2001). This study shows the first results obtained with a methodology to constrain the spread of SBMcast ensembles with the additional information provided by NWP., Peer Reviewed, Postprint (author’s final draft)

The dynamic network loading problem is crucial for performing dynamic traffic assignment. It must reproduce the network flow propagation, while taking into account the time and a variable traffic demand on each path of the network. In this paper, we consider a simulation-based approach for dynamic network loading as the best-suited option. We present a multiclass multilane dynamic network loading model based on a mesoscopic scheme that uses a continuous-time link-based approach with a complete demand discretization. In order to demonstrate the correctness of the model, we computationally validate the proposed simulation model using a variety of laboratory tests. The obtained results look promising, showing the model's ability to reproduce multilane multiclass traffic behaviors for medium-size urban networks., Peer Reviewed, Postprint (author's final draft)