Flood hazards at ford stream crossings on ephemeral channels (south‐east coast of Spain)

Abstract

Most road‐stream crossings over ephemeral channels are vulnerable to extreme hydrologic events. Ford stream crossings (FSCs) are usually dangerous for the road traffic during periods of high flow, in particular under flash flood conditions. The present paper analyzes the flood hazards on the Mediterranean coast in the Region of Murcia (south‐east Spain), affecting this type of road‐stream crossing over dry channels, according to hydraulic variables and bedload transport rates estimated for discharges at bankfull and flood‐prone stages. Under such conditions, the safety of people and vehicles was obtained using numerical models, developed by previous researchers; in particular, water levels and flow velocities across ford reaches were compared with different trend curves between water depths and corresponding critical velocities for children and adults, and for various prototype vehicles. Specifically, two approaches to assess this type of hazards were proposed: a specific Hydraulic Hazard Index and an algorithm for estimating the flood hazard from criteria of bed stability and bedload transport capacity (Flood Hazard at Fords, FHF). In addition, different exposure levels were established, using a Flood Vulnerability Index, based on the FHF, the road category, and the annual average daily traffic. The FHF model gave the best results with regard to the magnitude of the damage observed in recent flash floods for flow stages similar to those simulated. According to the danger thresholds established for this index, half‐bankfull flows represent here a high risk: 27.3% of FSCs for mini‐cars and 18.2% for large cars. At bankfull, the FHF exhibits very high values for mini‐cars (77.3% of FSCs) and for large passenger vehicles (50% of FSCs), while at the floodprone stage, extreme FHF values are reached for all kinds of vehicles at most of the ford crossings.

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

“…their differences with common floods, and associated factors can be found in Nogueira de Andrade and Szlafsztein (2018), Ballesteros et al (2018), Camarasa-Belmonte et al (2011), Conesa-García et al (2017), Rozalis et al (2010), Zhong et al (2018), etc.…”

“…Moreover, at the end of the summer the warm water surface temperature of the Mediterranean Sea raises the convective energy of the superimposed air masses and the complex topography from these coastal areas increases the moist convection (Amengual et al, 2015;Ballesteros et al, 2018), leading to very high intensity rainfall events. Consequences of this situation have been widely identified in many studies along most affected provinces in the Southeast of Spain as Almería (Molina-Sanchis et al, 2016), Murcia (Amengual et al, 2015;Conesa-García et al, 2017;Hooke, 2016), Almería and Murcia (Bracken et al, 2008), Alicante (Martínez-Ibarra, 2012;Olcina-Cantos et al, 2010), Murcia and Alicante (Pérez-Morales et al, 2015), Valencia (Camarasa-Belmonte, 2016;Camarasa-Belmonte et al, 2011;Camarasa-Belmonte and Segura-Beltran, 2001) and Barcelona (Ballesteros et al, 2018). Nevertheless, the study of temporal evolution of hydrological response as a consequence of land use changes along time has not yet fully undertaken jointly with high intensity convective storms.…”

Land-use changes and precipitation cycles to understand hydrodynamic responses in semiarid Mediterranean karstic watersheds

“…This is highly remarkable for urban areas, where alterations in the albedo effect create heat islands and greenhouse emissions among others, varying the water balances and surface energy (Jodar-Abellan et al, 2019;Elaji and Ji, 2020;Senciales-González et al, 2020). The consequences of this situation have been widely identified in many studies in the most affected provinces of Eastern and Southeastern Spain such as Almeria, Murcia or Alicante (Molina-Sanchis et al, 2016;Amengual et al, 2015;Conesa-García et al, 2017;Hooke, 2016).…”

Las lluvias torrenciales e inundaciones de los días 17 y 18 de diciembre de 2016 en la Región de Murcia con particular incidencia en el área vertiente del Mar Menor

“…Por último, durante los días 17 y 18 de diciembre de 2016 se registraron abundantes y persistentes lluvias que afectaron a toda la Región de Murcia, y en particular al área vertiente al Mar Menor, cuyo litoral sufrió los efectos destructivos del oleaje y de las aguas desbordadas de numerosas ramblas. Todos estos episodios van generalmente acompañados de importantes efectos sobre la población (Pérez-Morales, 2010;Álvarez Rogel et al, 2010), la actividad económica, el tráfico y las redes de comunicación (Conesa García y García Lorenzo, 2014;Conesa García et al, 2016), y sobre la propia dinámica morfológica de los cauces (Hooke y Mant, 2000).…”