Spatio-temporal analysis of potential aquifer recharge: Application to the Basin of Mexico

Abstract

Regional estimates of aquifer recharge are needed in data-scarce regions such as the Basin of Mexico, where nearly 20 million people are located and where the Basin's aquifer system represents the main water source. In order to develop the spatio-temporal estimates of aquifer recharge and to analyze to what extent urban growth has affected aquifer recharge, this work presents a daily soil water balance which uses different vegetation and soil types as well as the effect of topography on climatological variables and evapotranspiration. The soil water balance was applied on a daily time step in the Basin of Mexico for the period 1975-1986, obtaining an annually-lumped potential recharge flow of 10.9-23.8 m 3 /s (35.9-78.1 mm) in the entire Basin, while the monthly values for the year with the largest lumped recharge value (1981 = 78.1 mm) range from 1 m 3 /s (0.3 mm) in December to 87.9 m 3 /s (23.7 mm) in June. As aquifer recharge in the Basin mainly occurs by subsurface flow from its enclosing mountains as Mountain Block Recharge, urban growth has had a minimal impact on aquifer recharge, although it has diminished recharge in the alluvial plain. ª

Valuation of Hidden Water Ecosystem Services: The Replacement Cost of the Aquifer System in Central Mexico

“…Consistent with Burns et al [69], Carrera-Hernández and Gaskin [27] find that the major portion of the basin's recharge flow occurs in the Sierra Nevada, Chichinautzin and Sierra de Guadalupe. Similar conclusions are found in the studies by Ortega and Farvolden [70] and in Angeles-Serrano [26].…”

“…Carrera-Hernández and Gaskin [27] suggest that the basin's geology has protected the aquifer system from pollution (due to the impermeable clay layer below Mexico City, a conclusion also reached by Edmunds et al [73] and by Bojórquez et al [71]), and as shown by urbanization (due to the differentiated slopes of the mountain range). However, these conclusions are to be taken cautiously: Carrera-Hernández and Gaskin calibrated their data for the period between 1971 and 1981, when the urban sprawl still did not invade the forested areas, as it has done afterwards.…”

“…Aquifer recharge is a complex environmental process that depends on a combination of factors, including precipitation and temperature patterns, the infiltration capacity and transport of different rock types, soil retention capacity, and vegetation cover [27]. Several studies on the Valley of Mexico Basin conclude that, given the particular occurring combination of these factors, the forested area known as the Water Forest is an important source of recharge flows for these aquifers [24,30,31,68].…”

“…Similar conclusions are found in the studies by Ortega and Farvolden [70] and in Angeles-Serrano [26]. These conditions, favorable to high recharge rates, are met with the highest concentration of yearly precipitation in the Valley of Mexico Basin, which can be 70% higher than elsewhere in the basin: 1200 mm for the Sierra de Las Cruces, 900 mm in the Sierra del Ajusco, 800 mm in the Sierra Nevada and the Sierra del Chichinautzin [71], and 700 mm in the lower altitudes of the basin [27]. The study by Ortega and Farvolden [70] reports regional water balances in which aquifer recharge represents 42% of the precipitation volume in the Sierra del Chichinautzin, between 30% and 40% in the Sierra de Las Cruces, and between 40% and 50% of the Sierra Nevada.…”

“…Thirdly, if Mexico's central aquifer system collapsed, the demand for water would require the construction of the said alternative system since the other sources (regional surface water and the Lerma-Cutzamala system) are not sufficient. This study computes the minimum costs based on data by Carrera-Hernández [68], and by Carrera-Hernández and Gaskin [27], updated to represent prices of 2016 utilizing linear programming techniques. We also complement it with a financial analysis based on the methodology utilized by CONAGUA to assess investments on water infrastructure.…”