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CE 573 Groundwater Fall 2007 Comments on homework 1 1. All groups realized that the total volume out of the well remains constant and considered the total volume out of the region. The well volume is constant because the pumping rate is fixed. You will have a chance to reconsider the effects of changing the parameters. 2. No problems. 3. Only minor confusion. 4. The representative elemental area needs to be large enough so that the porosity is stable but small enough that large scale variations in the aquifer are not included. 5. In dimensional analysis, one writes K = f (d, g, ρ, µ). With 5 variables and 3 dimensions (mass, length, and time), one gets two dimensionless groups. To proceed further, argue that (1) since the weight drives the flow, the density and gravity should be considered together as ρg and (2) since K does not have dimensions of mass, the mass units must cancel. Therefore, write K = f (ρg/µ, d) and conclude that there is only one group, which must be constant. Then K ∝ ρgd2 /µ. 7. No problems.