ANALYSIS OF WATER TABLE FLUCTUATIONS TO IMPROVE UNDERSTANDING AND QUANTIFICATION OF THE GROUNDWATER RECHARGE PROCESS IN THE SHALLOW AQUIFER OF THE GULF OF URABÁ (COLOMBIA)

Abstract

This paper presents the quantitative and qualitative analysis of water table fluctuations of shallow aquifer of Gulf of Urabá in Antioquia–Colombia, using the hourly water table records and daily aggregated records from December 2016 to May 2018 in 14 monitoring points spatially distributed in a 1,206 km2 extension of the aquifer system. The obtained data are graphically and statistically related with other meteorological variables such as precipitation, evaporation and tides on the coast of Gulf of Urabá. Using the soils characterization, pedotransfer functions and a water balance approach, specific yield scenarios are determined and together with daily water table fluctuations series, detailed estimates of groundwater total recharge are obtained applying the Water Table Fluctuation method (WTF). The most influential meteorological variable in the water table fluctuations is the precipitation, showing high statistical correlations with a lag of less than 5 days on the daily scale. Evaporation and atmospheric pressure also influence fluctuations, but mainly in the diurnal cycle with small level variations compared to those caused by precipitation. The tides in the Gulf of Urabá show a strong influence on the water table fluctuations in the portion of the aquifer near the coastline. Total recharge rates in the area show spatio-temporal variability, influenced by the cited meteorological variables and soils properties (texture and specific yield), showing greater magnitudes in the south-central zone of the aquifer and lower ones in the east zone and close to the coastline of the Gulf of Urabá in Turbo municipality.