Comparing historical-hydrogeomorphological reconstitution and hydrological-hydraulic modelling in the estimation of flood-prone areas – a case study in Central Portugal

P P Santos,A O Tavares,A I A S S Andrade

doi:10.5194/nhess-11-1669-2011

P P Santos, A O Tavares + Show 1 more

Open Access

https://doi.org/10.5194/nhess-11-1669-2011

Copy DOI

Abstract

Abstract. The Arunca River basin in Central Portugal has a historical record of hazardous events related to floods, causing widespread disturbance. This article describes the application of two approaches based on well-known methods for the estimation of flood-prone areas: (i) historical-hydrogeomorphological reconstitution, applied to the entire Arunca River basin, and (ii) hydrological-hydraulic modelling, applied to four sections selected from different (upper, middle and lower) sectors of the basin and including urban and rural areas along the Arunca River. The mapping of the flood-prone areas obtained by these two methods was compared in order to identify the main differences and similarities. Human interventions (river channel and floodplain morphological changes) were found to be the main factor explaining the differences and similarities between the results obtained by both methods. The application of hydrological-hydraulic modelling proved important in reinforcing the results of the historical-hydrogeomorphological method; it also helped in complementing the results produced by the latter method in urban areas and in areas with insufficient historical records. The application of the historical-hydrogeomorphological method, in turn, allowed for the size of the flood-prone areas to be determined where the primary data (e.g. geometry, roughness and flow) was not accurate enough for hydrological-hydraulic modelling. The methodological approach adopted demonstrates the strong complementary relationship between the different existing methods for estimating flood-prone areas, and may be reproduced for other drainage basins.

Highlights

River floods, associated with social and economic damage and loss (UNISDR, 2009), are a major concern in many regions of the world and have been featured in a statement on scientific strategies and public policy management (USGS, 2007; IFRCRCS, 2009)
4.1 Results of historical and hydrogeomorphological methods. These methods enabled the representation of the historical flood-prone area based on past evidences, and the identification of a total of 253 critical runoff points (CRPs)
With the historical-hydrogeomorphological method, the specific results for the area studied show a very significant floodprone area in the Arunca River basin area, corresponding to almost 9 % of the total basin area and affecting the main urban areas located near water streams

Summary

Introduction

River floods, associated with social and economic damage and loss (UNISDR, 2009), are a major concern in many regions of the world and have been featured in a statement on scientific strategies and public policy management (USGS, 2007; IFRCRCS, 2009). The use of historical data for past floods has been cited in different studies as an improvement on the uncertainty of extreme events (Barriendos et al, 2003; Coeur and Lang, 2008; Sudhaus et al, 2008) and hydrogeomorphological reconstitution has made descriptions of anthropogenic flood control possible (Spaliviero, 2003; Forte et al, 2005; Nirupama and Simonovic, 2007) These approaches and resources have been used to support hydrological and hydraulic calculations (e.g. Ballais et al, 2005; Vijay et al, 2007; Apel et al, 2009; Neal et al, 2009)

Objectives

Results

Conclusion