Erosion Rates in Dam Catchments in Jordan—Effects of Topography, Geology, and Urbanizations

Erosion as a natural process produces soils, which are very important natural resources for the fest land plant- and animal kingdoms. Loss of the soil cover reduces agricultural production, biodiversity, and the role of soil as a filter for infiltrating water to replenish the groundwater. It also threatens the food supplies. The knowledge of erosion rates of rocks and terrains is important for developing proactive measures to protect soils from erosion and loss. In this study, erosion rates of catchment areas were calculated based on dams’ catchment extensions and the sediment loads transported by flood flows into dams’ lakes. The study results show that the chemically, via floodwater, transported quantities of materials are negligible compared to the solid materials transported by the water. It calculates erosion rates ranging from 0.013 to 0.212 mm/yr (13 - 212 m/106 yr) for the different catchment areas. Erosion rates in Jordan are, generally, higher than those calculated for the different parts of the world ranging from 2.5 to 60 m/106 yr. This fact can be explained by the very steep topography, calcareous rock cover of the catchment areas and the barren rock exposures.

Groundwater Vulnerability Assessment for the Corridor Wellfield Using DRASTIC and Modified DRASTIC Models: A Case Study of Eastern Jordan

Groundwater vulnerability maps were created for the Corridor wellfield (~300 km2) in the eastern Jordan using the DRASTIC and modified DRASTIC groundwater vulnerability assessment models. The study area is considered as one of the most important well fields therein providing partially three governorates with the needed drinking water. Detailed geological and hydrogeological parameters as well as the land-use map of the area were obtained from various sources to utilize both models. ArcGIS software was used for calculations and maps preparation. As a result, the generic DRASTIC vulnerability index ranges between 109 and 168. Thus, two vulnerability classes were observed, moderate (9.9%) and high (90.1%) vulnerability classes. On the other hand, the modified DRASTIC model (risk map) is taking into account the land-use map classes in the study area. The output risk map reveals two main classes, the moderate and high-risk areas. The moderate-risk areas occupy 9.3% of the total volume of the study area while the high-risk areas are 90.7%. Due to the high depth to groundwater within the area (between 90 m and 390 m), the depth to groundwater intervals was modified in the model to become more comfortable with the situation in Jordan. The high percentage of the high vulnerable areas against pollutants reflects the need to do more investigation for the studied area.