Physiographical and Hydrological Analysis of Yalamlam Basin, Makkah Al-Mukarramah Area

Abstract

Wadi Yalamlam is one of the Arabian Shield Wadis, located 70 km south of Makkah Al-Mukarramah city. The main rock units consist of Precambrian crystalline, meta−volcanic and metasedimentary rocks, with local Tertiary and Quaternary basalt flows AEThe geographic setting of Wadi Yalamlam basin can be divided into three main zones: the Red Sea coastal plain (Tihamah), the hills, and the Scarp-Hijaz Mountains. The catchment area starts from the Hijaz Escarpment (Ashafa area) in the east to the Red Sea at the west AEMorphometric analysis of the basin shows that it drains a large catchment area of about 1600 km 2 , very elongated, high relief, and of a moderate drainage densityAE The mean annual and seasonal rainfalls of hydrological stations around the study area have been analyzed AESeasonal rainfall occurs in the mountains area, but varies from year to year. It often occurs as thunderstorms of high intensity during a local storm followed by dry periods. The average annual rainfall exceeds 200 mm in the mountains and decreases to 80 mm towards the Red Sea coast. In addition, Wadi Yalamlam has surface running water in the upstream most of the year. Runoff hydrographs of 0.5 hour duration were constructed, based on Snyder method, for three sub-basins of wadi Yalamlam.

Integration of Point and Remote Sensing Data for Monitoring Surface Runoff around Madinah City, Saudi Arabia

“…Traditionally, the potential of these hydrographic basins to produce flash floods and the associated hazards against land use has been assessed based upon the analysis of their morphometric parameters [1]- [6]. Although these kinds of studies are valuable for the characterization of the flash flood potential, they are considered qualitative approaches for studying and assessing the hydrologic characteristics of a given hydrographic basin.…”