HGS RESEARCH HIGHLIGHT – Sequential surface and subsurface flow modeling in a tropical aquifer under different rainfall scenarios
Jimenez, M., Velásquez, N., Jimenez, J. E., Barco, J., Blessent, D., López-Sánchez, J., Castrillón, S. C., Valenzuela, C., Therrien, R., Boico, V. F., & Múnera, J. C. (2022). Sequential surface and subsurface flow modeling in a tropical aquifer under different rainfall scenarios. In Environmental Modelling & Software (Vol. 149, p. 105328). Elsevier BV. https://doi.org/10.1016/j.envsoft.2022.105328
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A January 2022 study highlights many of the strengths and flexibility offered by HydroGeoSphere, as the authors evaluate water resources in a watershed in Colombia. The study area includes a number of geologic faults which are represented in the HGS model as discrete fracture networks, and the region has one of the highest rainfall rates in all of Colombia. As the region has not been studied in high detail at this time, the authors have approached the modelling tasks in a sequential manner, first using the Water Modeling Framework (WMF) to estimate groundwater recharge rates using rainfall observations and two alternative synthetic scenarios based on dry and wet conditions. Three aquifer recharge cases were evaluated (base/wet/dry), with results indicating that the changes in the rainfall induce complex variations in recharge.
The modelled recharge rates were then applied to subsurface HGS model (without integrated surface hydrology) to evaluate the impact of recharge on groundwater levels. The hydrogeology of the study area was evaluated with/without regional faults/discrete fractures, and with/without spatial variability in the recharge mapping. “The main results can be summarized as follows: 1) the comparison between uniform and spatially variable recharge highlights the importance of its proper assessment to simulate groundwater dynamics; 2) the selection of a suitable conceptual model for the fractured aquifer is also evidenced by the relevant variation of simulated hydraulic heads considering or neglecting the discrete fractures representing the two fault zones identified in the study area, and 3) dry and wet scenarios are shown to be an appropriate tool to quantify the impact of climatic variability on groundwater recharge.”
This paper demonstrates how HGS is flexible enough to model specific regions/domains of interest (i.e. including discrete fracture networks, but without integrated surface hydrology) and can be used in conjunction with other hydrologic modelling platforms. Click here to read another example of using HGS as one part of a larger modelling framework.
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Abstract:
The La Miel River watershed is an area of high hydrological interest in Colombia due to its abundant water resources, high annual precipitation, and hydroelectric power generation. This work proposes a sequential modeling framework to quantify the spatially and temporally variable groundwater recharge and to analyze its impact on piezometric fluctuations in the study area, where the groundwater flow is affected by geological faults. Water Modeling Framework (WMF) and HydroGeoSphere (HGS) models have been used to calculate groundwater recharge and distribution of hydraulic heads, respectively. Recharge computed with WMF is used as input to HGS to compare groundwater flow 1) with uniform and spatially variable recharge, 2) with and without discrete fractures, and 3) during dry and wet conditions. The results generate valuable knowledge for water resource management and highlight the importance of groundwater recharge estimation and a proper representation of fractured aquifers.