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• Jiménez-Valera, José Antonio; Alhama, Iván; Calvache, Carlos Duque & Labat, David (2025). Interdependence Between River Aquifer Groundwater Flow and Temperature–Depth Profiles: Type Curves Based on Pi Theorem and Numerical Simulations. Applied Sciences. 15(2). doi: 10.3390/app15020596. Full text in Research Archive Show summary

  The interaction between surface water and groundwater has been extensively studied due to its water management implications and the potential environmental impacts arising from it. Experimental studies and numerical modeling have supported analytical solutions; these solutions have been proposed for specific cases in which the aim has been to understand discharge/recharge and aquifer characterization. In this study, new graphical solutions or type curves are provided to estimate the subsurface flow and thermal–mechanical parameters in anisotropic porous media. Using the non-dimensionalization technique of the governing equations, new dimensionless groups (lumped parameters) that govern the solution of both the mechanical problem (uncoupled) and the thermal problem are obtained. From these groups, and by applying the pi theorem and examining numerical simulations of numerous cases, user-friendly type curves are obtained. The recharge flow and hydraulic conductivity are calculated when the thermal properties, geometrical parameters, and temperature variables are known. To evaluate the reliability of the type curves, two real case studies are presented: the interaction between the Guadalfeo River and the Motril-Salobreña coastal aquifer, and the artificial recharge program in the coastal aquifer of Agua Amarga in southern Spain. For verification, the groundwater flow obtained from the type curves is compared with the recharge data. In the case of the river–aquifer interaction, the recharge flow obtained is 13% less than that estimated in previous studies. Regarding the artificial recharge of the coastal aquifer, the flow obtained is 21% less than the volume irrigated over the salt marsh. The uncertainties related to hydrogeological features are considered to have the greatest influence on the error.

• Calvache, Maria L.; López-Chicano, Manuel; Blanco-Coronas, Angela M.; Torre, Beatriz de la & Calvache, Carlos Duque (2024). Applicability of Single-Borehole Dilution Tests in Aquifers with Vertical Flow. Water. 16(9). doi: 10.3390/w16091305. Full text in Research Archive Show summary

  A set of experimental field single-borehole dilution tests were completed in the Motril–Salobreña detrital aquifer (Spain) in a sector with coarse material in four different moments under variable hydrological conditions. The comparative study of the tracer washing, and the temperature profile patterns for the tests carried out in two wells located hundreds of m from each other, revealed the presence of ascending vertical flows in one of the wells (not detected by other means) that compromises the reliability of the tracer test. The values of both the apparent horizontal velocity and hydraulic conductivity obtained in the affected well were less than half of those estimated in the well not affected by the upward vertical flows. The repetition of the test eight times during different seasons showed that the hydraulic conductivity calculated from the apparent horizontal velocity can vary; therefore, to approximate to a representative hydraulic conductivity value, using this method is recommended to carry out tests under different hydrological conditions and average the results. The difference generated by the changes in conditions for the specific setting of the study area was 25%. Taking this into account, it was considered that an approximation to the more representative value would be an average under variable hydrological conditions, resulting in a horizontal velocity of 6.7 m/d and hydraulic conductivity of 337 m/d. This information is critical for the management of the aquifer as it has strategic resources against droughts that are becoming more frequent in the Mediterranean area.

• Jiménez-Valera, José Antonio; Alhama, Iván & Calvache, Carlos Duque (2024). Advanced type curves for vertical groundwater flow estimation from temperature profiles. Applications to real scenarios. Journal of Hydrology. ISSN 0022-1694. 631. doi: 10.1016/j.jhydrol.2024.130860. Full text in Research Archive Show summary

  Groundwater discharge or recharge in aquifers can be obtained from the analysis of temperature profiles, a cost-efficient method widely applied in hydrogeology. In this study we proposed a set of type curves that can be used for estimating the vertical velocity flow, and have the potential to allow, in certain cases, the assessment of the thermal diffusivity of the soil matrix. The solutions, represented graphically, establish the dependencies of the basic parameters involved in the process: groundwater velocity, thermal conductivity, specific heat, aquifer depth and harmonic temperature period. Using the non-dimensionalization technique, the mentioned parameters were organized in dimensionless groups which are verified by numerical simulations. For the estimates of the groundwater velocity, transient temperature-depth measurements or steady state amplitudes of the harmonic oscillation were used as input data. In this last case, a particular type curve solution allows us to assess the depth from which temperature oscillations have a negligible amplitude compared to the amplitude at the ground surface. The resulting dependencies have been applied to estimate the groundwater velocity in real aquifers and laboratory experiences.

• Blanco-Coronas, Angela M.; Calvache, Maria L.; López-Chicano, Manuel; Martín-Montañés, Crisanto; Jiménez-Sánchez, Jorge & Calvache, Carlos Duque (2022). Salinity and Temperature Variations near the Freshwater-Saltwater Interface in Coastal Aquifers Induced by Ocean Tides and Changes in Recharge. Water. 14(18). doi: 10.3390/w14182807. Full text in Research Archive Show summary

  The temperature distribution of shallow sectors of coastal aquifers are highly influenced by the atmospheric temperature and recharge. However, geothermal heat or vertical fluxes due to the presence of the saline wedge have more influence at deeper locations. In this study, using numerical models that account for variable density, periodic oscillations of temperature have been detected, and their origin has been attributed to the influence exerted by recharge and tides. The combined analysis of field data and numerical models showed that the alternation of dry and wet periods modifies heat distribution in deep zones (>100 m) of the aquifer. Oscillations with diurnal and semidiurnal frequencies have been detected for groundwater temperature, but they show differences in terms of amplitudes and delay with electrical conductivity (EC). The main driver of the temperature oscillations is the forward and backward displacement of the freshwater–saltwater interface, and the associated thermal plume generated by the upward flow from the aquifer basement. These oscillations are amplified at the interfaces between layers with different hydraulic conductivity, where thermal contours are affected by refraction.

• Duque, Carlos; Olsen, Jonas Thu; Sanchez-Ubeda, Juan Pedro & Calvache, Maria Luisa (2019). Groundwater salinity during 500 years of anthropogenic-driven coastline changes in the Motril-Salobre?a aquifer (South East Spain). Environmental Earth Sciences. ISSN 1866-6280. 78. doi: 10.1007/s12665-019-8476-9. Full text in Research Archive
• Duque, Carlos; Müller, Sascha; Sebok, Eva; Haider, Kinza & Engesgaard, Peter (2016). Estimating groundwater discharge to surface waters using heat as a tracer in low flux environments: The role of thermal conductivity. Hydrological Processes. ISSN 0885-6087. 30(3), p. 383–395. doi: 10.1002/hyp.10568. Full text in Research Archive
• Puig, S.; Calvache, Carlos Duque; Pabst, Thomas & Aagaard, Per (2016). The use of surface geophysics to determine the aquifer characteristics in the folldal mining site, Norway. EarthDoc. doi: 10.3997/2214-4609.201601951. Full text in Research Archive
• Poulsen, John R.; Sebok, E.; Duque, Carlos; Tetzlaff, D. & Engesgaard, P.K. (2015). Detecting groundwater discharge dynamics from point-to-catchment scale in a lowland stream: Combining hydraulic and tracer methods. Hydrology and Earth System Sciences (HESS). ISSN 1027-5606. 19(4), p. 1871–1886. doi: 10.5194/hess-19-1871-2015. Full text in Research Archive
• Calvache, M.L.; Sanchez-Ubeda, J.P.; Duque, Carlos; Lopez-Chicano, M. & Torre, B. de la (2015). Evaluation of Analytical Methods to Study Aquifer Properties with Pumping Tests in Coastal Aquifers with Numerical Modelling (Motril-Salobreña Aquifer). Water resources management. ISSN 0920-4741. 30(2), p. 559–575. doi: 10.1007/s11269-015-1177-6. Full text in Research Archive
• Sebok, Eva; Calvache, Carlos Duque; Engesgaard, Peter & Boegh, Eva (2015). Application of Distributed Temperature Sensing for coupled mapping of sedimentation processes and spatio-temporal variability of groundwater discharge in soft-bedded streams. Hydrological Processes. ISSN 0885-6087. 29(15), p. 3408–3422. doi: 10.1002/hyp.10455. Full text in Research Archive

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• Wu, Jiapeng; Xiao, Kai; Liu, Yi; Calvache, Carlos Duque & Wang, Qianqian (2023). Editorial: Nutrient biogeochemistry in the land-sea continuum. Frontiers in Marine Science. 10. doi: 10.3389/fmars.2023.1286709. Full text in Research Archive

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