Pit Recharge Influenced by Subsurface Spreading

Abstract

Artificial recharge from pits, trenches, or basins ordinarily is not considered feasible in situations where a thick layer of slowly permeable material exists near the surface. Results of a field investigation of recharge from an irrigation tail‐water pit indicate that pit or trench recharge is feasible under this condition provided that a much more permeable stratum exists above the less permeable one. The more highly conductive layer acts as a subsurface spreading basin which greatly enhances the opportunity for recharge. The potential for recharge from pits penetrating a highly conductive layer underlain by a slowly permeable stratum can be calculated from the results of a simple theoretical analysis which is presented. The importance of subsurface spreading is demonstrated by a numerical example using conditions similar to those encountered during the field investigation. Under these conditions a narrow pit or trench 525 feet long and 10 feet deep has the potential for recharging at a rate of 1 million gpd or about 700 gpm. Subsurface spreading occurs over nearly 10 acres for this case. Evaporation is reduced because the need for spreading the water over large areas on the land surface is eliminated. Since the length of pit perimeter and not the surface area is the important factor for design, the volume excavated can be minimized by constructing long narrow pits or trenches.

Assessment of artificial aquifer recharge potential in the Kucuk Menderes River Basin, Turkey

“…The steps and factors that should be taken into account for locating, designing, and operating artificial recharge projects can be summarized by many as: selecting a suitable location with respect to geology, specifying soil textures in the recharge area, acquisition of sufficient land area, silt control, maintenance of percolation rates, quality of recharged water, degree of necessary prior treatment, etc. (Banks et al 1954;McWhorter and Brookman 1995;Bouwer 2002). From a hydrogeological point of view, the type of aquifer, the permeability of geologic formations overlying the aquifer, the characteristics of the unsaturated zone, and the heterogeneity are factors that most affect recharge rate and design of an artificial recharge system (Bouwer 2002;Reddy 2008).…”