Geomorphological characteristics of the Um-Rimam depression in northern Kuwait

摘要

ABSTRACT Um-Rimam depression is one of the largest depressions in Kuwait. It is about 16.5 km2 and located in northern Kuwait. It consists of a northern and southern playa whose floors cover 0.39 and 0.72 km2 at 50 m and 60 m above sea level, respectively. The two playas are separated by a narrow zone (250 m in width) called the neck area. The depression is developed on alluvial sediments classified under Kuwait Group (Oligo-Pleistocene). The main geomorphological features of the study area are wadis, playas and yardangs. 73 wadis (11 major and 62 minor wadis) were observed in the field with variable orientations. The depression is a mere erosional feature, because no indications of a tectonic origin have been found in the study area. The depression has a variety of surface sediments such as pebbly sheets, active sand sheets, wadi fill deposits, alluvial fans, falling dunes, and nabkha deposits around shrub (Haloxylon salicornicum and Lycium shawii). The surface sediments in the Um-Rimam depression are sandy, poorly sorted, positively skewed and very platykurtic. The amount of aeolian deposits (sand and dust) is low in the study area compared to the average deposited aeolian particles in surrounding areas within Kuwait, but the annual amount of sand trapped in the northern playa (31 kg.yr-1) is higher than the southern playa. The proposed artificial lakes in the depression might be good for improving the vegetation cover and wildlife, but an environmental impact assessment study should be prepared. ??