The impact of rainfall distribution patterns on hydrological and hydraulic response in arid regions: case study Medina, Saudi Arabia

Rainfall distribution patterns (RDPs) are crucial for hydrologicdesign. Hydrologic modelingis based on Soil ConservationServices (SCS) type RDPs (SCS type I, IA, II, and III). SCS type II method is widely used by hydrologists in aridregions. These RDPs were designed for the USA and similar temperate regions. There is no scientific justification for using SCS type II method in aridregions. The consequences of using SCS type II have impacts on the hydrologicand hydraulic modeling studies. The current paper investigates the validity of the SCS type II and in aridregions. New temporal RDPs were applied and compared with SCS type II RDPs. The produced peak discharges, volumes, maximum inundation depths, top widths, and velocities from both approaches were analyzed. An application is made on the protection channel in Taibah and Islamic Universities campuses in Medina, Saudi Arabia. A methodology was followed which included frequency analysis, catchment modeling, hydrological modeling, and hydraulic modeling. Results indicated that there are considerable consequences on infrastructural design, and hydrologicand hydraulic parameters if inappropriate RDPs are used. The investigation confirmed that the SCS type RDPs do not reflect the actual flood features in aridregions.