modelling flow regimes of a temporary river with limted data availability

The flow regime plays an important role in the river ecosystem influencing water chemistry, morphological and physical factors, and ecological functioning. Flow regime characterization is a fundamental stage for river type classification and river basin management. The reference condition (un-impacted or least impacted) used as the baseline for the ecological status assessment varies across the river types, therefore, a wrong river type classification may lead to an unreliable assessment of the ecological status of the river and to inadequate management operations. In this work, 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 (Nil wadi, Algeria) and to characterise the 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. The flow regime was characterised by using a number of indicators describing the aquatic phases (AS) (flow, pool, and dry permanence). The metrics were computed on the basis of long-term time series of modeled daily streamflow. The Nil Wadi resulted characterised by perennial and temporary flow regimes. The analysed river 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" conditions mainly occurred in summer. This study provides a contribution to the unsolved question of the management of temporary rivers under the Mediterranean climate.