التحليل الجيومورفولوجي للمعطيات الطبيعية المحددة لظاهرة الفيضانات النهرية في وادي الجرذان

الملخص EN

The aim of the current research is to study the natural causes of the river floods in Al-Jurthan valley depending on analyses of the physical characteristics of the catchment area and its geomorphological role in increasing the magnitude of the river floods in different areas in the valley.

The study also aims to prepare maps showing the geographical distribution in areas subjected to flooding risk.

The current study used different methodological approaches to tackle the river floods issue: descriptive, investigation and analytical approaches.

The first approach was used to describe the physical characteristics of the catchment area and their impact on floods in the area.

The investigation approach was used to analyze data obtained from topographical and geological maps (1–50000) for the year 2006, Ariel photos (1-25000) for 2003 and satellite images (1-250000) for 2006.

The third analytical approach was mainly used to examine hydrological and climatological data responsible for floods in Wadi Al-Jurthan during the period from 1964 to 2006.

Moreover, morphometric, hydrological and vegetation data elicited from topographical maps, Ariel-photos and field work are discussed in this study.

This study came out with the following findings : There is a positive relationship between the average of intensive rainfall on the basin and the water discharge of river floods that are formed in the valley, the floods whose water discharge average is about 30 to 120 m3 per second are related to rainfall average which is about 4.9 to 17.3 mm per hour.

The findings of the study also show that there is a possibility of increasing the number of floods repeatedly in the streams of the valley with increasing its stream order because of the increase in the amount of its water discharge, the water discharge in the river streams is about 0.17 m3 per second for the first order and 0.85 m3 per second for the fifth order ; which represents the main stream of the river.