| Wadi El Arish is the largest drainage system in Sinai Peninsula, Egypt. The Wadi was subject
to severe thunderstorms on 17 and 18 January 2010 followed by an extreme and
violent flood that had not been known in Sinai since 1980. The flood claimed six
victims, injured tens of people, and devastated vital infrastructure and hundreds
of houses. Hydrologic characteristics of the Wadi are not fully understood due to
substantial lack of the detailed hydro-meteorological information. Hence, remote sensing
and GIS techniques were used to provide better spatial understanding of rainfall
characteristics and drainage basin response. The study was based on the analysis
of the TRMM images and 6 hourly average HYDIS data of rainfall analyses. A
hydrological model was constructed using ASTER DEMs. The empirical black box
model was used depending on the curve number approach to predict stream runoff.
Landcover and hydrological soil groups were identified from the Landsat ETM+ mosaic
using multispectral supervised classification. The curve numbers were adjusted
to ARC I (dry condition) as the total rain in a 5-day period preceding the storm
were very low (-¤5 mm). We found, that the Wadi received a total rain volume
of 665.4 x 106 m3. Most of it fell on 17 January, when the rain intensity ranged
between 4–8 mm/hr. The estimated total surface runoff Q was 123.3 x 103 mm and
the total runoff volume was 124 x 106 m3 that constitutes 18.8 % of the total rain
volume. The results are in agreement with the observed values in the Wadi and highly
required for many applications related to water harvesting and flood protection studies. |