Analysis of flow to pumping wells in a saline coastal aquifer, Puerto Peñasco, Sonora, Mexico

• Main Author: Dunn, Alison Leeds.
• Other Authors: Ince, Simon
• Language: en
• Published: The University of Arizona. 1981
• Online Access: http://hdl.handle.net/10150/191733

A line of pumping wells, 100-175 m from the shore in a shallow coastal aquifer east of Puerto Petasco, Sonora, Mexico, supplied salt water at a rate of 7,500 to 11,500 m³/day to a shrimp aquaculture facility. This water exhibited salinities as high as 41.5 parts per thousand (ppt) and the well farthest inland yielded the most saline water. Effluent was discharged from the facility at an average rate of 6,000 m³/day to two lakes 400 m inland from the wells. In 1979, the salinity in the first lake ranged between 39 and 42 ppt and in the second lake between 41 and 78 ppt. Measurements of ground-water levels were made in nine smalldiameter well-points. A steady-state numerical model was used to simulate flow conditions in the study area and calibrated against these measurements on three separate dates. The best fit was obtained by modeling the effluent lakes as zones of semi-pervious leakage to the main aquifer and assuming a uniform transmissivity of 575 m²/day. Flow-net analyses indicated that 30 to 50 percent of the pumped water was contributed from the direction of the effluent lakes. The regional gradient could not be determined, and further research would be needed to identify its influence on the local flow regime.