HIGHLIGHTS. Urban development has triggered natural groundwater recharge depletion.Potential recharge was estimated for the Mexico City groundwater supply area.

In recent years, due to various anthropogenic activities, such as agriculture and livestock, the presence of nitrogen-associated contaminants has been increasing in surface- and groundwater resources. Among these, the main compounds present in groundwater are ammonia, nitrite, and nitrate. However, it is sometimes difficult to assess such effects given the scarcity or lack of information and the complexity of the system. In the current study, a methodology is proposed to assess nitrate in groundwater from diffuse sources considering spatiotemporal patterns of hydrological systems using a coupled SWAT/MODFLOW/MT3DMS model. The application of the model is carried out using a simplified simulation scheme of hydrological and agricultural systems because of the limited spatial and temporal data. The study area includes the Cuitzeo Lake basin in superficial flow form and the Morelia–Querendaro aquifer in groundwater flow form. The results within the methodology are surface runoff, groundwater levels, and nitrate concentrations present in surface- and groundwater systems. The results indicate that the historical and simulated nitrate concentrations were obtained within acceptable values of the statistical parameters and, therefore, are considered adequate.

A common approach for calculating the spatial distribution of groundwater level changes consists in choosing a set of different times, interpolating the groundwater level data available at each time over a spatial grid, and then calculating changes in each period by subtracting the interpolated values for these times. However, this can produce misleading results when the data are available in different positions for consecutive times. This paper presents an alternative procedure based on the interpolation of the groundwater level with spatio-temporal kriging, the assessment of the temporal groundwater elevation changes over a regional semiconfined aquifer, and the estimation of their error standard deviations. A comparative analysis of cross-validation results and error standard deviations provides a quantitative measure of the superiority of the introduced approach with respect to the one given in the literature. Moreover, the spatio-temporal case produces more reasonable estimates than the spatial kriging, notably fewer extreme recoveries and drawdowns, in an area under high water stress, such as the upper aquifer of the southern part of the Basin of Mexico aquifer system.

Groundwater models serve the function of predicting and analyzing aquifer behavior. They require input information, such as hydrogeological parameters like hydraulic conductivity and storage coefficient, which are used to calibrate the model, and elementary actions that include recharge and extracted volumes. There are cases in which it is insufficient to know the homogeneous recharge entering through the surface basin, referred to as traditional recharge, since, in many instances, the distribution is altered by changes in land use. For this reason, based on the geomorphological characteristics of the basin, weighting is proposed for sites with greater recharge capacity. The present work shows a solution to the recharge distribution using the potential groundwater recharge (PGR) map, which is formed by weighting spatially distributed information: (i) drainage, (ii) precipitation, (iii) land use, (iv) geological faults, (v) soil type, (vi) slope, and (vii) hydrogeology. A comparison is made between groundwater modeling using traditional recharge and PGR recharge. It is noted that the modeling perform similarly for both recharges, and the errors do not exceed 5% absolute error, which validates the model’s reliability. This manuscript demonstrates how to model and calibrate groundwater in aquifers with scarce information and variable recharge, making it reproducible.