المدلولات الهيدرولوجية للخصائص المورفومترية في حوض وادي السلي

الملخص EN

Wadi Sulay basin considered one of the crucial wadis in Saudi Arabia because it drains a high number of floods in large areas* which cover the northern and eastern area of Riyadh city.

It is well known that flooding risks are one of the morphological characteristics of the drainage system* therefore* this study shed light on analyzing morphometric characteristics of the wadi Sulay basin to evaluate the risks of flooding in this important part of Riyadh city.

In this paper* the quantitative methods were employed spatial analysis to extract the morphometric characteristics of the drainage basin by using the digital elevation model and topographic maps through the geographic information system.

The results show that the morphometric analysis of the drainage system has revealed that the basin area located within the limit of Riyadh at around 1348.8 km2.

Moreover* the drainage basin shape was elongated* which prevents the concentration of discharge at one point of time* and thus lowers the risk of flooding* however* the low relief of the drainage basin increases the risk of flooding.

According to Strahler stream order* the wadi Sulay drainage system is on the fifth order* with 468 streams having a total length of 1040km and a normal bifurcation ratio is 4.4 as well as drainage density of 0.77km/km.

All the mentioned indicators contribute to decreasing the flooding risks and maintaining the drainage system in its natural state.

Unfortunately* 28 districts out of the 58 districts located within the basin do not have any drainage system which increases the risks of flooding in these areas.