تحويل مجرى وادي نساح جنوب مدينة الرياض : مقترح جيومورفولوجي تطبيقي في درء أخطار السيول

Abstract EN

Objective: This study aims to measure the extent of the geomorphological possibility of diverting the stream of Wadi Nisah to save the urban area of Al Hayathim city in the south of Riyadh city.

Methods: Geological and geomorphological maps, digital elevation models DEM, and old published maps were studied.

Also, the morphometrics of the Wadi networks and the morphology of the area were analyzed.

Results: the study results indicated that the level of the Wadi Awsat channel at its estuary in the wadi Ba'aija is lower than the main channel of Wadi Nisah, so the diversion of the Nisah main channel is possible from a geomorphological point of view.

This is because the difference of the level reaches more than 10 meters along the winding Shuaib Al Mikhlaf, which is 8 km long.

Therefore, this area represents the old channel of Wadi Nisah before the tectonic movement in the early quaternary era.

The study proposes a partial or complete diversion of the flow from Wadi Nisah through the Shaib Al Mikhlaf and returning it to its old course, and therefore there are two tracks: The first track is directly through Al-mikhlaf and it needs to reduce some area approximately 3 meters along a distance of 2 km.

It is considered the longest path and the lowest in the cost of excavation.

The other track is through the geological weakness in the highlands that separate Wadi Nisah from the Shaib al-Mikhlaf, and the stream runs directly to the Faidhat of Al-Mikhlaf.

This path is considered the shortest in distance, but it is more expensive in physical terms due to cutting to expand the mountain gorge.

Conclusion: To avoid the effect of the Wadi Nisah diversion on increasing the water level in Lake Al-Ha'ir, located near the mouth of Wadi Baija in Wadi Hanifa, the study proposes to divert the course of the upper basin of Wadi Baijah before reaching its estuary through the Daho depression eastward to the lower basin of Wadi Hanifa.