Contrasting rainfall-runoff characteristics of floods in desert and Mediterranean basins

Abstract

Abstract. Catchment-scale hydrological studies on drylands are lacking because of the scarcity of consistent data: observations are often available at the plot scale, but their relevance for the catchment scale remains unclear. A database of 24 years of stream gauge discharge and homogeneous high-resolution radar data over the eastern Mediterranean allows us to describe the properties of floods over catchments spanning from desert to Mediterranean climates, and we note that the data set is mostly of moderate intensity floods. Comparing two climatic regions, desert and Mediterranean, we can better identify specific rainfall-runoff properties. Despite the large differences in rainfall forcing between the two regions, the resulting unit peak discharges and runoff coefficients are comparable. Rain depth and antecedent conditions are the most important properties to shape flood response in Mediterranean areas. In deserts, instead, storm core properties display a strong correlation with unit peak discharge and, to a lesser extent, with runoff coefficient. In this region, an inverse correlation with mean catchment annual precipitation suggests also a strong influence of local surface properties. Preliminary analyses suggest that floods in catchments with wet headwater and dry lower section are more similar to desert catchments, with a strong influence of storm core properties on runoff generation.

Multiple Temporal Scales Assessment in the Hydrological Response of Small Mediterranean Catchments

“…Both factors had a combined effect on the generation of high Qmax values as shown by the significant correlation observed between Ptot and Q0 and Qmax. The role of wet conditions over Qmax also was observed in other Mediterranean catchments where antecedent precipitation correlated significantly with Qmax [14,16,70]. (Table 2).…”

“…Spatial variability of runoff generation is also elucidated in the catchment hydrological response as a combination of rainfall distribution [16] and runoff-contribution areas [17]. Under this context, river connectivity is conceptualized as a continuum from fully connected to disconnected over diverse temporal and spatial scales in the different compartments of a catchment [18].…”

Characterising patterns of heavy precipitation events in the eastern Mediterranean using a weather radar and convection-permitting WRF simulations

“…However, our dataset comprises events of different characteristics: local and intense, as well as widespread; rainfall triggering mechanisms and potential hydrologic impact can be quite different. Zoccatelli et al (2019) observed a relatively high correlation between rain depths over a catchments and unit peak discharge in catchment areas ranging between 13-1232 km 2 of Mediterranean and desert environments in the EM. In arid and semi-arid catchments, high correlation was reported between the storm rain core, defined as the largest hourly intensity over a 9 km 2 area in the catchment, and the unit peak discharge.…”

“…This archive was previously used for a series of studies focusing on high intensity precipitation, such as precipitation frequency analysis Marra and Morin, 2015), floods (Rinat et al, 2018;Zoccatelli et al, 2019), and characterisation of convective rain cells (Belachsen et al, 2017;Peleg et al, 2018). Few issues potentially affecting the QPE should be mentioned.…”

Analysis of the observed trends in daily extreme precipitation indices in Gaza Strip during 1974–2016

“…Moreover, analysing the spatial variation between GS stations helps understand how precipitation extremes can be changed within different climatic zones, even in small areas. As shown in Figure 1, GS classified into three climatic zones; hot‐summer Mediterranean (Csa) in the North: hot semi‐arid (BSh) in the middle and the hot desert (BWh) in the extreme southern part (Peel et al ., 2007; Zoccatelli et al ., 2019).…”