(Solved): 1. The geologic map in the figure below shows a river valley filled with 30 m of fluvial sand and gr ...

1. The geologic map in the figure below shows a river valley filled with 30 m of fluvial sand and gravel. The fluvial deposits are underlain by 200 m of clayey alluvial-fan deposits that are underlain by bedrock. The climate is humid and the river gains water from groundwater discharge as it flows southwest through the valley from Black Canyon. The water table is located about 3 m below land surface in most of the valley. A well field is proposed to tap the unconfined sand and gravel aquifer. The owners of the property where the well field is to be located would like to know if the flow (discharge) of the river will be affected if the discharge from the well field is 500 m3/min. The estimated annual recharge is 0.1 m/y. Local consultants suggest the XYZ fault be used as a boundary.

a. Develop a conceptual model of the system by specifying boundaries; hydrostratigraphy and hydrogeological parameters; flow directions and sinks and sources appropriate for addressing the owners’ question. Justify your choices. Make a start on tabulating the groundwater budget and indicate the type of information needed to complete the budget.

b. As you formulated your conceptual model, you probably noticed that with such limited hydrogeological information you needed to rely on your knowledge of the principles of hydrogeology to support a conceptual model. In this situation, another conceptual model might represent the system equally well, particularly with respect to placement of boundaries. Generate an alternative conceptual model with different boundaries. Justify your choices.

c. List additional information that would be helpful in refining your boundary assignment.