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Abstract
Flash floods in hot deserts are characterized by high velocity and
low duration with a sharp peak discharge. Large sediment loads may be
carried by floods threatening fields and settlements in the wadis and even
people who are living there. The main objective of this research is to
build a hydrologic model to calculate runoff hydrograph and peak
discharges based on the geomorphologic characteristics of the catchment
and temporal distribution of the rainfall.
The developed model is able to determine the valleys’ streams
depending on Digital Elevation Model (DEM). The procedure of
delineating watershed is modeled. The model is able to fill the valleys
gabs, detect the critical bath and calculate the geometric properties of the
basin. The model calculates the excess rainfall, lag time , time of
concentration, peak discharge and runoff hydro graph for any watershed
by different empirical methods. The model exports the watershed
boundary and its streams as GIS file. The developed model was
calibrated using the outputs of one of the common software for two
hypotheses catchment areas.
The calibration process indicates that the developed model is an
accurate tool that predict the runoff hydrograph. Moreover, the model
was applied to one of the main wadis in Sinai peninsula (i.e., Wadi sudr,
Sinai, Egypt). All hydrological parameters for the studied area are
calculated. It was found that, for Nash equation, shape parameter (n) = 2
and the scale parameter (k) = 1.27 hr. For Clark equation, Clark
coefficient (K) = 0.2, Finally for geomorphologic instantaneous unit
hydrograph (GIUH ) equation, Stream area ratio (RA) = 9, Bifurcation
ratio (RB) = 3 and Stream length ratio (RL) =2.65.