Abstract

The stages of geology, geophysics, inventory, and leveling of groundwater sources, exploratory drilling, hydrogeochemistry, aquifer testing, and mathematical modeling were performed. In this report, the results obtained with each stage are summarized, the hydrogeological characteristics of the existing formations are mentioned, an analysis of the underground flow is made, and the characteristics of each selected zone are given with the respective recommendations of exploitation and analysis of water costs. The report ends with the conclusions. The report is complemented with the inventory of each existing work, geological map, underground flow map, hydrogeological map with lines of the base of the aquifer and hydrogeological cut, map of clay intercalations, physical records, lithology, and design of exploratory wells drilled.

The aquifers found are made up of recent gravels and sands and Tertiary conglomeratic sandstones and sandstones.

Three zones were identified for groundwater production: El Mosquito, La Libertad, and Villa del Rosario.

In most of the selected areas, there are confining superficial clays and deep intercalations between aquifer horizons.

The groundwater in Cúcuta is hard. For the different uses, softening with ion exchangers or lime is recommended. Additional chlorination is recommended.

Four exploratory wells were drilled in the Mosquito area. Based on the results obtained with these wells, it is recommended to build initially a battery of three wells, which will produce 6600 m3 per day to comfortably supply about 30,000 people in the vicinity of the Guaymaral neighborhood and the future urbanizations that are being built to the north. Furthermore, with a pipeline to the southeast, it is possible to supply a part of Barrio San Luis.

Two exploratory wells were drilled in the La Libertad area. Based on the results obtained with these wells, building five wells at least 200 m apart is recommended. With a pumping per well of 50 m 3/h, and 14 hours of daily pumping, they will produce 3500 m 3/day to supply about 17,500 inhabitants. However, this flow rate should not be exceeded until the reaction of the aquifer to this production has been evaluated.

Two exploratory wells were drilled in the Villa del Rosario area. Based on the results obtained with these wells, the report recommends drilling wells only in recent sediments to establish Quaternary aquifer’s characteristics and propose preliminary exploitation, which will be optimized with the same data collected. For this purpose, it is suggested to use the two wells INSFOPAL will soon drill in the area.

The wells to be constructed in any of the selected areas must follow exactly the exploitation recommendations. In addition, it is recommended that the use of underground water resources in the Project area be regulated, according to current legislation, to avoid problems of over exploitation.

A mathematical simulation of the behavior of a section of the fluvio-deltaic aquifer of the El Mosquito Zone was carried out. Variable flow rates were simulated for a pumping time of 100 days. Up to 50 liters/second, the aquifer supplies water to the well in a dry period, with no drawdown that could indicate dewatering of the aquifer. At 80 liters/second, depletions begin to increase. However, it is possible to pump at this flow rate for 50 days. The influence of the Picha Stream is negligible; the water travel time from this stream to the pumping well is 900 days. Extreme conditions were simulated by pumping 24 hours continuously. The water supplied during the first hours of pumping comes from the aquifer storage; when pumping is interrupted for half a day, the empty storage volume is easily recovered.