التطور الجيومورفولوجي و التحليل المورفومتري لحوض وادي السهل-بمنطقة القصيم : دراسة تطبيقية باستخدام تقنيات الاستشعار عن بعد و نظم المعلومات الجغرافية

Abstract EN

The Qassim’s current Environment represents one of the Desert Environment patterns, that is located in the central district of Saudi Arabia, which is characterized by an ancient dry drainage networks.

Therefore, Wadi Al-Rimah and its tributaries form a multi-flow patterns in a dry environment and it was took most of its final characteristics in the meddle Holocene.

At the present time, these hydrological systems are dried channels, exception some geometric characteristics of them, there is no enough information about their behaviors.

So, this lack of understanding of them in most cases turn out to be sweeping channels at the time of storm rainfall in this Arid environment.

Findings show moderate to middle runoff in Wadi Al-Sahel in semi-moist Environment that characterized by intensive vegetation cover.

However, the main hydrologic network and their tributaries were active, it is likely that the network was drained and received its water from the north western and north eastern slopes of Al-Tysiah Plateau.

In later stages, Wadi Al-Sahel and its tributaries have been started to be like muddy channels and the most lower section of the wadi turned to be received more sand accumulation due to the effects of the northern wind, which was dominated at this time.

On the other hand, at the advanced stages of the Holocene, in most likely, the Wadi Al-Sahel was isolated from Wadi Al-Ajradi by Al-Dahna sand dunes.

On the other hand, the morphometric study is indicated that the basin’s morphometric characteristics are reflecting the impact of inhomogeneous rock units within the basin.

And also indicated that Wadi Al-Sahel is not dangerous during the time of precipitation and in case of cyclonic rainfall, wadi Al-Sahel and its tributaries are less dangerous than other nearby wadies, according to its elongation ratio and its low drainage density.

In addation, there is a huge quantity of its water lost by seepage, infiltration and evaporation processes.

Finally, although wadi Al-Sahel was advanced in its erosion cycle and becoming balanced or close to equilibrium stage, all its tributaries are still in the beginning stages of their denudation cycles.