Characterising flow regimes in a semi-arid region with limited data availability: The Nil Wadi case study (Algeria)

Study region: Mediterranean catchment in Algeria Study focus: A procedure to characterise the flow regimes of non-perennial rivers in regions with limited data availability was defined. The specific aims were to adapt the Soil and Water Assessment Tool (SWAT) for simulating time series of daily streamflow in a basin with a temporary river network and to characterise flow regime in a number of the river reaches. An inexpensive streamflow monitoring program was implemented to collect a basic dataset to calibrate the hydrological model. Regional databases, surveys, and images from Google Earth were used to integrate the available data to set up the model. Flow regime was characterised by using a number of metrics describing the aquatic phases (AS) (flow, pool, and dry permanence). New hydrological insights for the region: This study provides a contribution to the unsolved question of the management of temporary rivers under the Mediterranean climate. The Nil Wadi is characterised by perennial and temporary flow regimes. The analysed reaches were classified as "intermittent-pool" and "intermittent-dry", they showed "alternate-fluent" (AF) aquatic phase upstream and in the middle course, and a gradient from AF to "fluent-stagnant" phases downstream. The AS "oligorheic" (low flow or pools connected) and "arheic" (pools disconnected) mainly occurred from May to October. "Dry" condition that includes the ASs "hyporheic" and "edaphic" mainly occurred in summer.