Intermittent river

Intermittent, temporary or seasonal rivers or streams cease to flow every year or at least twice every five years.^[1] Such rivers drain large arid and semi-arid areas, covering approximately a third of the Earth's surface.^[2] The extent of temporary rivers is increasing, as many formerly perennial rivers are becoming temporary because of increasing water demand, particularly for irrigation.^[3] Despite inconsistent water flow, intermittent rivers are considered land-forming agents in arid regions, as they are agents of significant deposition and erosion during flood events.^[4] The combination of dry crusted soils and the highly erosive energy of the rain cause sediment resuspension and transport to the coastal areas.^[5] They are among the aquatic habitats most altered by human activities.^[6] During the summer even under no flow conditions the point sources are still active such as the wastewater effluents,^[7][8] resulting in nutrients and organic pollutants accumulating in the sediment. Sediment operates as a pollution inventory and pollutants are moved to the next basin with the first flush.^[9] Their vulnerability is intensified by the conflict between water use demand and aquatic ecosystem conservation.^[10] Advanced modelling tools have been developed to better describe intermittent flow dynamic changes such as the tempQsim model.^[5]