Abstract

This study aims to analyze the geomorphological and hydrological characteristics of the drainage systems in a group of drainage basins in the city of Al-Ma’alla-Aden, using the geographic information systems data, represented by the available digital elevation modules (DEM) for the study area and integrating it with the hydrological analysis methods of flow from the drainage basins, and deducing the most important hydrological parameters and calculating the maximum flow from them at a rain frequencies 10, 25, 50, and 100 years, in order to contribute to providing a database on flow systems that will benefit the city in future. As a result of this work, the study reached a geomorphological and hydrological analysis of a number of drainage basins in the city of Al-Ma’alla, most of them at the northern slopes of Shamsan mountain south of study area. The watershed areas (catchments) of these basins range from 0.340 to 4.331 km². Through the geomorphological analysis, it was found that most of the drainage basins in the study area have high slope angles, reaching more than 30%, especially those located south the study area along Shamsan mountain northern slopes. As a result of the hydrological integration of the geomorphological characteristics the maximum calculated flow from some of these basins reached to 62.16 m³/s for the rain frequency of 10 years, and reached to 116.92 m3/s for a rain frequency of 100 years. Most of the drainage basins took ratios of high ruggedness, indicating an increase in sediment load during flow. The study recommended conducting complementary environmental studies for the study area and employing the use of modern technologies such as geographic information systems and digital elevation modules, and moving away from the old traditional study pattern. The study also recommended making use of the available data to improve the management of rainfall water, and developing strategies to reduce the risks of potential floods based on the estimates maximum flows reached by the study.