Impact of land use changes on flash flood prediction using a sub-daily SWAT model in five Mediterranean ungauged watersheds (SE Spain)

Antonio Jodar-Abellan; Javier Valdes-Abellan; Concepción Pla; Francisco Gomariz-Castillo

doi:10.1016/j.scitotenv.2018.12.034

Impact of land use changes on flash flood prediction using a sub-daily SWAT model in five Mediterranean ungauged watersheds (SE Spain)

Sci Total Environ. 2019 Mar 20:657:1578-1591. doi: 10.1016/j.scitotenv.2018.12.034. Epub 2018 Dec 6.

Authors

Antonio Jodar-Abellan¹, Javier Valdes-Abellan², Concepción Pla³, Francisco Gomariz-Castillo⁴

Affiliations

¹ University Institute of Water and Environmental Sciences, University of Alicante, Carretera San Vicente del Raspeig s/n, 03690, San Vicente del Raspeig, Alicante, Spain. Electronic address: antonio.jodar@ua.es.
² University Institute of Water and Environmental Sciences, University of Alicante, Carretera San Vicente del Raspeig s/n, 03690, San Vicente del Raspeig, Alicante, Spain; Department of Civil Engineering, University of Alicante, Carretera San Vicente del Raspeig s/n, 03690, San Vicente del Raspeig, Alicante, Spain. Electronic address: Javier.valdes@ua.es.
³ University Institute of Water and Environmental Sciences, University of Alicante, Carretera San Vicente del Raspeig s/n, 03690, San Vicente del Raspeig, Alicante, Spain; Department of Civil Engineering, University of Alicante, Carretera San Vicente del Raspeig s/n, 03690, San Vicente del Raspeig, Alicante, Spain. Electronic address: c.pla@ua.es.
⁴ Euro-Mediterranean Water Institute, University of Murcia, Campus de Espinardo s/n, 30100 Murcia, Spain. Electronic address: fjgomariz@um.es.

PMID: 30677923
DOI: 10.1016/j.scitotenv.2018.12.034

Abstract

Flash floods cause severe natural disasters over the world generating property and infrastructures damages, poverty and loss of human life, among others. Mediterranean coastal watersheds are specially sensible to flash floods effects due to their typical drainage basin features (steep slopes, short concentration times, complex orography, etc.) and the high rainfall intensity typical of convective systems. In the present study, the temporal evolution of the hydrological answer in five Mediterranean (SE Spain) ravine basins with sizes from 10.2 km² to 200.9 km² were analysed. A sub-daily SWAT model was used at watershed scale to capture the complex hydrological dynamics. Five land use scenarios corresponding to no-urbanization (baseline), 1990, 2000, 2006 and 2012 were evaluated using GIS-based tools. Additionally, statistical significant differences among the studied scenarios were checked employing the Kruskal-Wallis and post-hoc tests based on Mann-Whitney test with BH correction. Our results show that flash flood risks have increased in the studied catchments due to changes in land uses, particularly affected by a large urban growth. Observed changes in soil uses have been important since the sixties of the last century, because of a high demographic and touristic pressure and specially the urban area has enhanced considerably during the last 22 years. Currently, some of these catchments present around 70% of their surface occupied by urban land uses with high population density producing curve number surpasses 85 and 90 levels. The hydrological response of the studied basins changed to higher flow rate peaks and shorter concentration times. Some discharges increased significantly from the baseline land use scenario (≈50 m³/s, 190 m³/s, 380 m³/s) to the most urbanised scenario (≈235 m³/s, 385 m³/s, 940 m³/s), respectively. These findings provide to urban planning policy makers very useful information in the face of flash flood effects, which have cost even human lifes in the studied ravine basins during last years.

Keywords: Flash floods; Land use changes; Mediterranean ravine basins; SWAT; Sub-daily simulation; Urban development.