Incorporating Antecedent Moisture Conditions and Intraevent Variability of Rainfall on Flood Frequency Analysis in Poorly Gauged Basins

[Abstract:] Rainfall-runoff models are frequently used for the prediction of flood discharges from extreme rainfall data in poorly gauged basins. However, the conventional methods used to estimate the frequency of flood discharges from precipitation data do not incorporate a realistic representation of the spatial and temporal structure of rainfall at the study site nor of the antecedent soil moisture content. Temporally and spatially idealized rainfall patterns that do not represent properly the intraevent variability of rainfall are in general assumed. In this paper, we propose a methodology for flood frequency analysis based on the hydrological simulation of potentially hazardous real storm events. The aim of the proposed method is to incorporate the impact of the spatial and temporal intraevent variability of rainfall on flood discharge estimates without making strong assumptions about the spatial and temporal patterns of storms. It also includes a calibrated relation between the antecedent rainfall depth and the soil infiltration capacity, in order to consider the combined effect of antecedent soil moisture content and rainfall intensity. The flood frequency estimates obtained with the proposed methodology are compared to those estimated with a conventional method based on the definition of synthetic design hyetographs from local intensity-duration-frequency curves. The analysis is presented in two watersheds of 84 and 353 km2 located in the NW of Spain. Results highlight the role of the antecedent soil moisture in flood frequency analysis and show that the conventional methodology tends to overestimate the flood discharges when compared to the proposed approach.This work was financially supported by the Spanish Ministry of Economy and Competitiveness (Ministerio de Economía y Competitividad) within the project “CAPRI: Probabilistic flood prediction with high resolution hydrologic models from radar rainfall estimates” (CGL2013-46245-R). Ignacio Fraga received financial support from the Xunta de Galicia (Centro Singular de Investigación de Galicia accreditation 2016–2019) and the European Union (European Regional Development Fund-ERDF). The historical rainfall data from the pluviometers used in this work, as well as the discharge data at the two gauge stations, can be freely downloaded from the webpage of the Galician Meteorological Agency MeteoGalicia (http://www.meteogalicia.gal/observacion). The DTM of both catchments can be freely downloaded from the webpage of the Centro Nacional de Información Geográfica (http://centrodedescargas.cnig.es)

Flood risk in urban areas: modelling, management and adaptation to climate change. A review

[Abstract:] The modelling and management of flood risk in urban areas are increasingly recognized as global challenges. The complexity of these issues is a consequence of the existence of several distinct sources of risk, including not only fluvial, tidal and coastal flooding, but also exposure to urban runoff and local drainage failure, and the various management strategies that can be proposed. The high degree of vulnerability that characterizes such areas is expected to increase in the future due to the effects of climate change, the growth of the population living in cities, and urban densification. An increasing awareness of the socio-economic losses and environmental impact of urban flooding is clearly reflected in the recent expansion of the number of studies related to the modelling and management of urban flooding, sometimes within the framework of adaptation to climate change. The goal of the current paper is to provide a general review of the recent advances in flood-risk modelling and management, while also exploring future perspectives in these fields of research

Orden social e imaginarios sociales (una propuesta de investigación)

A partir de los problemas actuales para definir las situaciones globales que condicionan los sistemas sociales, se detecta una tendencia generalizada de sustitución de los mecanismos de argumentación racional por los de seducción propios del discurso mediático. La elaboración de los nuevos discursos hegemónicos y de resistencia a la dominación exige una doble reconstrucción de la teoria y del método. En el articulo se hace una de investigación que parte de la vinculación entre las formas del orden social y los mecanismos de construcción (y desconstrucción) de los imaginarios sociales. Estos tendrían como función primaria la elaboración y distribución generalizada de instrumentos de percepción de la realidad social construida como realmente existente. Se incluyen en el texto algunos materiales de definición conceptual de los imaginarios, cuestiones de método y fuentes bibliográficas.This piece of research tries to define global situations which condition social systems. New hegemonic discourses, through mass media, and new resitance forms to domination are needed in order to construct and deconstruct social imaginaries

Editorial: flood susceptibility and risk maps as a crucial tool to face the hydrological extremes in developing countries: technical and governance aspects linked by a participatory approach

[Abstract:] In summary, this Research Topic wants to draw attention to two points of reflection: 1) The need to involve stakeholders at all levels in the planning of actions aimed at reducing the risks associated with floods is preponderant, given the considerable increase in urban settlements in high-risk areas of developing countries. 2) Likewise, we hope that new lines of research will open up to explore innovative solutions that help in risk management without having to resort to costly methods, which involve manpower or require continuous maintenance

Improving the predictive skills of hydrological models using a combinatorial optimization algorithm and artificial neural networks

[Abstract:] Ensemble modelling is a numerical technique used to combine the results of a number of different individual models in order to obtain more robust, better-fitting predictions. The main drawback of ensemble modeling is the identification of the individual models that can be efficiently combined. The present study proposes a strategy based on the Random-Restart Hill-Climbing algorithm to efficiently build ANN-based hydrological ensemble models. The proposed technique is applied in a case study, using three different criteria for identifying the model combinations, different number of individual models to build the ensemble, and two different ANN training algorithms. The results show that model combinations based on the Pearson coefficient produce the best ensembles, outperforming the best individual model in 100% of the cases, and reaching NSE values up to 0.91 in the validation period. Furthermore, the Levenberg-Marquardt training algorithm showed a much lower computational cost than the Bayesian regularisation algorithm, with no significant differences in terms of accuracy.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This study is financed by the Galician government (Xunta de Galicia) as part of its pre-doctoral fellowship program (Axudas de apoio á etapa predoutoral 2019) Register No ED481A-2019/014.Xunta de Galicia; ED481A-2019/01

Regional streamflow prediction in northwest Spain: A comparative analysis of regionalisation schemes

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract:] Study Region: The present study was conducted in 24 watersheds located in the region of Galicia, in the northwest of Spain, covering an extension of approximately 13,000 km. Study focus: This study is focused on the application and evaluation of different schemes for streamflow Prediction in Ungauged Basins (PUB). The MHIA model (Spanish acronym for Modelo HIdrológico Agregado), is first used to reproduce the observed time series of discharge in several gauged basins. Then, six different regionalisation schemes are applied to transfer the hydrological model parameters to ungauged catchments. For that purpose, we explore and compare two physical similarity, two spatial proximity and two regression-based regionalisation schemes. Output averaging (also known as ensemble modelling) as well as parameter averaging implementations of the physical similarity and spatial proximity methods are analysed. New hydrological insights: The most efficient methods are those based on output averaging, with acceptable success rates (SR) in 88% of the cases. On the other hand, the parameter averaging-based methods have the lowest SR. The methods based on spatial proximity output averaging provide the best performance when the receptor basin has a sufficient number of nearby donor basins. On the other hand, the methods based on physical similarity output averaging show a better performance in areas where there is a low density of donor catchments. The regression-based methods showed the lowest performance in all cases. The existence of correlations between the performance of the regionalisation schemes and the area of the receptor catchments was observed, with higher performances in large basins than in small basins.This study has received financial support from the Galician government (Xunta de Galicia) as part of its pre-doctoral fellowship program (Axudas de apoio á etapa predoutoral 2019) Register No ED481A-2019/014. Funding for open access charge: Xunta de Galicia (project No ED431C 2022/010) and Universidade da Coruña/CISUGXunta de Galicia; ED481A-2019/014Xunta de Galicia; ED431C 2022/01