title: Evaluating the impact of lower resolutions of digital elevation model on rainfall-runoff modeling for ungauged catchments.
abstract: Geomorphological instantaneous unit hydrograph (GIUH) usually uses geomorphologic parameters of catchment estimated from digital elevation model (DEM) for rainfall-runoff modeling of ungauged watersheds with limited data. Higher resolutions (e.g., 5 or 10 m) of DEM play an important role in the accuracy of rainfall-runoff models; however, such resolutions are expansive to obtain and require much greater efforts and time for preparation of inputs. In this research, a modeling framework is developed to evaluate the impact of lower resolutions (i.e., 30 and 90 m) of DEM on the accuracy of Clark GIUH model. Observed rainfall-runoff data of a 202-km2catchment in a semiarid region was used to develop direct runoff hydrographs for nine rainfall events. Geographical information system was used to process both the DEMs. Model accuracy and errors were estimated by comparing the model results with the observed data. The study found (i) high model efficiencies greater than 90% for both the resolutions, and (ii) that the efficiency of Clark GIUH model does not significantly increase by enhancing the resolution of the DEM from 90 to 30 m. Thus, it is feasible to use lower resolutions (i.e., 90 m) of DEM in the estimation of peak runoff in ungauged catchments with relatively less efforts. Through sensitivity analysis (Monte Carlo simulations), the kinematic wave parameter and stream length ratio are found to be the most significant parameters in velocity and peak flow estimations, respectively; thus, they need to be carefully estimated for calculation of direct runoff in ungauged watersheds using Clark GIUH model.
authors.affiliation: Department of Civil Engineering, College of Engineering, Qassim University, Buraydah, 52571, Saudi Arabia. abdul.razzaq@uettaxila.edu.pk.|On leave from University of Engineering and Technology Taxila, Taxila, Pakistan. abdul.razzaq@uettaxila.edu.pk.
authors.forename: Abul Razzaq
authors.initials: AR
authors.lastname: Ghumman
authors.affiliation: Department of Civil Engineering, College of Engineering, Qassim University, Buraydah, 52571, Saudi Arabia.
authors.forename: Ibrahim Saleh
authors.initials: IS
authors.lastname: Al-Salamah
authors.affiliation: Department of Civil Engineering, College of Engineering, Qassim University, Buraydah, 52571, Saudi Arabia.
authors.forename: Saleem Saleh
authors.initials: SS
authors.lastname: AlSaleem
authors.affiliation: Department of Civil Engineering, College of Engineering, Qassim University, Buraydah, 52571, Saudi Arabia.
authors.forename: Husnain
authors.initials: H
authors.lastname: Haider
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D040362:Geographic Information Systems; D008962:Models, Theoretical; D011891:Rain; D014872:Water Movements
keywords: Digital elevation model; Geographical information system; Geomorphological instantaneous unit hydrograph; Monte Carlo simulations; Rainfall-runoff models