Hydrogeological Conditions and Mathematical Model of the Area Surrounding Hatra Suggested dam, Northwest Iraq

The area was hydrogeologically studied, it was found that the main aquifer is unconfined, it is located within Fat’ha Formation, and the hydraulic properties of this aquifer were also studied from the analysis of pumping tests data to determine the averages of transimissivity (T=671.027 m²/day), hydraulic conductivity (K=45.449 m/day), and storage coefficient (Sc=0.226). The groundwater levels and flow direction map was drawn, and it was found that the flow corresponds to the topographical slope of the land surface towards Tharthar valley, from the east - west towards the center of the study area, with a slight slope towards the south.

These are some data represent a database that can be used in the design of the proposed dam on Tharthar valley, and the policy of storage and water management in the dam, reservoir as well as to build a mathematical model to predict the future behavior of groundwater in the region.

Especially under the body of the dam to simulate the changes in groundwater conditions in the area of the small Hatra Dam Suggested on Tharthar valley, when storing water in front of a dam, and the expected engineering problems that would occur due to groundwater seepage under or on both sides of the dam body, by raising the water level within the valley – hypothetically, by 1m, 2m, 3m, 4m, 5m, 7m, 9 m and 11 m, assuming no pumping from the Aquifer during the rise of the level in the valley. as well as re-calculation with the same ranges of raising the level on another assumption, which is pumping from the wells in the area by 9 m3/ hour, for a period of time 6 hours per day, and determining the affected area by raising the level for each of the cases. The study indicated that the expected effect on the groundwater level starts when raising the water level inside the valley to four meters, and the clear increase continues at five meters, but the cumulative effect of raising the level from (7-11)m is slight. It also identified the sites that would allow the underground water to be pumped under the dam’s body, and the results were consistent with the geological reality of the area. These results will help in establishing an appropriate design for the foundations and structure of the dam.

The current study is one of the requirements for building a small dam within the plan for managing water resources and developing the region that suffers from desertification, drought and environmental degradation.