Problem 4. water budget for albuquerque aquifer (30 pts) the residents of the city of albuquerque have been utilizing their shallow aquifer for decades. prior to development, the sand and gravel aquifer (santa fe group formation) had an average saturated thickness of about 100 feet. the average porosity of the santa fe group is about 22%. porosity is the ratio of the volume of void space to the total of sediment. the average precipitation in the sandia mountains is about 10-25 inches per year, but on average, only a small percentage( 10 to 30%) of this precipitation recharges the aquifer albuquerque sin qmr a' water table 100 ft bottom of santa fe group aquifer figure 1. conceptual plan-view diagram and cross section of albuquerque's aquifer. up arrows in the cross section indicate out-flows from the aquifer. down arrows indicate in-flows. we will assume that the water level in the aquifer is about 3 feet lower than the rio grande water level, on average, such that the rio grande is losing water to the aquifer. likewise the agricultural drains are 8 feet lower than the water table, so that the aquifer is losing water to the drains. assuming upstream subsurface aquifer inflows are balanced by downstream outflows (and can therefore be neglected), we can write the water budget for the santa fe group aquifer of the albuquerque basin as follows: ar pump where qus is mountain front recharge in ft'/year, qon is drain seepage losses in ft/year, qes is river seepage inflows in ft3/year, qr is irrigation seepage that recharges the aquifer in ft/year, qpump is groundwater pumping in ft3/year, qer is riparian zone forest evapotranspiration losses in ft'/year, ar is area of the albuquerque basin aquifer system in ft, ф is aquifer porosity, his average aquifer water level in feet, and t is time in years. one acre-foot equals 43,560 ft