Rainfall Thresholds for Flow Generation in Desert Ephemeral Streams

• Published in: Water resources research 2018-12, Vol.54 (12), p.9935-9950
• Main Authors: Kampf, Stephanie K., Faulconer, Joshua, Shaw, Jeremy R., Lefsky, Michael, Wagenbrenner, Joseph W., Cooper, David J.
• Format: Article
• Language: English
• Subjects: Area; Atmospheric precipitations; Bedrock; Dependence; desert hydrology; desert pavement; Deserts; Drainage; Drainage area; ephemeral stream; Ephemeral streams; Flash flood warnings; Flash flooding; Flash floods; Flood warnings; Gauges; Ground cover; Heavy rainfall; Hydrologic data; overland flow; Plant cover; radar precipitation; Rain; Rain gauges; Rainfall; Rainfall data; Rainfall intensity; rainfall‐runoff threshold; River beds; Rivers; Rocks; Runoff; Shrubs; Soil; Stream discharge; Stream flow; Thresholds; Vegetation; Vegetation cover; Watersheds
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2018WR023714

Rainfall thresholds for streamflow generation are commonly mentioned in the literature, but studies rarely include methods for quantifying and comparing thresholds. This paper quantifies thresholds in ephemeral streams and evaluates how they are affected by rainfall and watershed properties. The study sites are in southern Arizona, USA; one is hyperarid and the other is semiarid. At both sites rainfall and streamflow were monitored in watersheds ranging from 10−3 to 102 km2. Streams flowed an average of 0–5 times per year in hyperarid watersheds and 3–11 times per year in semiarid watersheds. Although hyperarid sites had fewer flow events, their flow frequency (fraction of rain events causing flow) was higher than in semiarid sites for small (