Flood Hazard Mapping with Distributed Hydrological Simulations and Remote-Sensed Slackwater Sediments in Ungauged Basins

José David Del Moral-Erencia,Patricio Bohorquez,Francisco José Pérez-Latorre,Pedro Jesus Jimenez-Ruiz

doi:10.3390/w13233434

Abstract

We present a basin-scale method to assimilate hydrological data from remote-sensed flood evidence and map civil infrastructures with risk of flooding. As in many rural areas with a semi-arid climate, the studied catchments do not contain stream gauge, and precipitation data does not capture the spatial variability of extreme hydrological events. Remote-sensed flood evidence as slackwater sediments were available at the whole basin, allowing the paleohydrological reconstruction at many sites across the catchment. The agreement between the predicted and observed inundation area was excellent, with an error lower than 15% on average. In addition, the simulated elevations overlapped the observed values in the flooded areas, showing the accuracy of the method. The peak discharges that provoked floods recorded the spatial variability of the precipitation. The variation coefficients of the rainfall intensity were 30% and 40% in the two studied basins with a mean precipitation rate of 3.1 and 4.6 mm/h, respectively. The assumption of spatially uniform precipitation leads to a mean error of 20% in evaluating the local water discharges. Satellite-based rainfall underpredicted the accumulated precipitation by 30–85.5%. Elaborating an inventory of the civil infrastructures at risk was straightforward by comparing the water surface elevation and transport network. The reconstructed maps of rainfall rate were used in the distributed hydrological model IBERPLUS to this end. Recent flood events that overtopped the infrastructures at risk verified our predictions. The proposed research methods can be easily applied and tested in basins with similar physical characteristics around the Mediterranean region.

Highlights

Both the frequency and magnitude of pluvial floods with a duration lower than one day have increased during the last decade in the southern Mediterranean area of Spain, corroborating the predictions of the Intergovernmental Panel on Climate Change [2] and the European Environmental Agency [3]
Because of the increase in frequency and magnitude of short-rain floods in ungauged basins with a drainage area lower than 1000 km2 in southern Spain, we have developed an approach to infer their hydrological characteristics
The outputs are the spatial distribution of the precipitation intensity, the dynamics of surface waters, and flood hazard maps at the local scale

Summary

Introduction

Both the frequency and magnitude of pluvial floods with a duration lower than one day have increased during the last decade in the southern Mediterranean area of Spain (see Moral-Erencia et al [1]), corroborating the predictions of the Intergovernmental Panel on Climate Change [2] and the European Environmental Agency [3]. IBERPLUS [11], SERGHEI-SWE [12], TRITON [13] and LISFLOOD-FP [14] Such distributed hydrological models use a physical-based approach to simulate complex physical processes leading to runoff, routing the water through all the elements of the drainage network, and generating even flood maps

Methods

Results

Conclusion