Application of the L-moments approach to the analysis of regional flood frequency in Northern Algeria

Abstract

Algeria is periodically affected by severe and repeated flooding. Flood hazard studies require the estimation of extreme flood flows. To predict and estimate the characteristics of maximum flows, knowledge of their distribution law is essential. The L-moments method was used to determine homogeneous regions and the appropriate distribution for these regions. Three homogeneous regions were delineated. This technique produced a Pearson type III distribution for the coastal region and the Tell Atlas and a Pareto distribution for the steppe regions and high plateaus of Eastern and Western Algeria. To estimate maximum flow at ungauged sites for different return periods, the 'index-flood' method was used. An empirical formula was developed that uses the average annual maximum flow as a function of catchment area and the average slope of the main channel to estimate maximum flow at any point on the Oued. The coefficient of determination and the Nash criterion, for the three regions, are superiors to 88% and 83% respectively. The root mean squared error, for the three regions, is less than 12%. These values show the robustness of the developed models.

Complete multivariate flood frequency analysis, applied to northern Algeria

“…Indeed, the stream flow is very irregular and low flow is insignificant in the dry period, as it is discussed in different previous papers (e.g. Bouanani, 2004; ABH‐OCC, 2006; Touazi, Bhiry, Laborde, & Achour, 2011; Hallouz, Meddi, & Mahe, 2013; Meddi et al, 2017).…”

“…This can provide information on the existence of a possible connection between these three variables that may be identified in the multivariate analysis. According to Meddi et al (2017) in a univariate regional study, Ghazaouet station fits in region II which is characterised by rugged terrain that favours the formation of rapid and catastrophic floods. Timgad station belongs to the third region where the flash floods are dominated importantly on autumn season.…”

“…Soultes wadi (Timgad station) is characterised by a complex hydrological regime under a semi‐arid climate. A simple hydrological regime dominates the other studied basins (Meddi, Toumi, & Assani, 2017).…”

Comparison of conceptual rainfall–runoff models in semi‐arid watersheds of eastern Algeria

“…During the second half of the 20th century (in particular, 1969, 1971, and 1984), Algeria experienced catastrophic floods in the east of the country. These floods caused a large number of deaths and enormous damage to infrastructure (Meddi, Toumi, & Assani, 2017; Yahiaoui, 2012). Therefore, flood protection and water management require a good understanding of the phenomenon of runoff as well as the different factors that can influence this phenomenon locally, hence the interest of rainfall–runoff (RR) models, which are essential tools for flash flood prediction and real‐time forecasting.…”

“…Therefore, flood protection and water management require a good understanding of the phenomenon of runoff as well as the different factors that can influence this phenomenon locally, hence the interest of rainfall–runoff (RR) models, which are essential tools for flash flood prediction and real‐time forecasting. Despite the importance of the development of these tools, only a few studies have dealt with this topic in Eastern Algeria, most of which have focused on the analysis of the flood frequency (e.g., Hebal & Remini, 2011; Meddi et al, 2017). In addition to stochastic models, in Algeria, models developed for other climate conditions are generally used to estimate peak flows.…”