Seasonality in Intermittent Streamflow Losses Beneath a Semiarid Mediterranean Wadi

Abstract

Intermittent and ephemeral streams are predominant in arid-semiarid Mediterranean regions (Gutiérrez-Jurado et al., 2019). Their occurrence in watersheds has steadily increased due to increasing groundwater pumping as well as general decadal scale drying of these watersheds, possible linked to climate change. Both ephemeral and intermittent streams are classified as nonperennial channels with zero-flow periods (Magand et al., 2020;Nikolopoulos et al., 2011), alternation between dry and wet phases, extreme flow variations and flashfloods (Tzoraki et al., 2013;Vivoni et al., 2006) with high suspended sediment transport (Alexandrov & Laronne, 2003;De Girolamo et al., 2015). Compared to ephemeral streams, intermittent streams often experience shorter zero-flow periods over the hydrological year and typically longer wet seasons of steady streamflow. Semiarid regions characterized by long duration, wet season streamflows in winter and spring are particularly prone to intermittent flow. In wet seasons, intermittent streams are fed by rainfall or snowmelt and may flow continuously or intermittently, either as normal flow (baseflow) or floods. In dry seasons, they are generally dry or flow as flashfloods in response to episodic storms thus showing a strictly ephemeral behavior.In semiarid regions, the demand for water resources has steadily increased with growing populations, which has increased a need to study streamflow losses considered as the main source of groundwater recharge (Simmers, 2003;Shentsis & Rosenthal, 2003). Hence, streamflow infiltration and subsequent potential recharge beneath nonperennial streams have been a topic of great interest in recent decades. Various methods were used to study these processes (

Classification of flood-generating processes in Africa

“…Consequently, it is not the antecedent soil moisture that plays a role for flood generation in these basins, but a rainfall event lasting several consecutive days which has the potential to gradually saturate the soil during an event 63 – 65 . The relatively low proportion of short rains in the classification could be partly explained by the daily step of our analyses, which prevents representing flash flood events triggered by short but intense rainfall 66 – 69 . Therefore, it is likely that the importance of short rainfall events is underestimated in the present work due to this limitation.…”

Quantifying Intermittent Flow Regimes in Ungauged Basins: Optimization of Remote Sensing Techniques for Ephemeral Channels Using a Flexible Statistical Classification

“…The dam is intended to support irrigation needs and artificial recharge through channel infiltration, leading to dam releases when the channel lacks consistent flow [44]. Previous work on ephemeral channel transmission loss has identified prior sediment moisture as crucial for infiltration and sustained aquifer recharge [13]. Flood events concentrated within the wet season thus may have a higher likelihood of recharging the regional aquifer, as transmission losses have the potential for deeper percolation.…”

“…Limited characterization is a specific concern within dryland environments, where intermittent and ephemeral channels are the dominant hydrologic feature [2,4,11,12]. Ephemeral channels experience episodic flow only in response to storm events; streamflow is closely tied to precipitation seasonality and is spatially and temporally variable [13]. Transmission loss, the vertical infiltration of surface water through channel sediments, represents the primary form of aquifer recharge within arid zones [14][15][16].…”

“…Flow may further be spatially discontinuous across the channel, with stationary gauges poorly suited to capture flow heterogeneity [10]. In arid regions with already limited water resources, even minor shifts in onset, duration, and distribution of precipitation may have profound implications for ephemeral channel flow and resulting recharge [13]. Failure to quantify spatial and temporal patterns of surface flow impedes modeling efforts and water-balance estimates, increasing the likelihood of mismanagement [19].…”

Using Baseflow Ensembles for Hydrologic Hysteresis Characterization in Humid Basins of Southeastern China

“…Accurate estimation of BFI significantly impacts the assessment of water resource allocation in a basin. However, a natural hydrological year can be separated between the wet and dry seasons, with precipitation showing the most visible changes between the two periods (Fakir et al., 2021; Mallakpour et al., 2018). The conversion from point rainfall to basin‐wide surface rainfall, which is less precise than the BFI, is not only less accurate but also difficult to compute because precipitation is frequently irregularly distributed in space and intermittent in time.…”