Poster: Temperature profiles to measures groundwater discharge to Ringkøbing Fjord

Event: 33rd Nordic Geological Winter Meeting 2018
Poster by Joel Tirado-Conde, Carlos Duque, Peter Engesgaard and Sachin Karan


Groundwater discharge or upwelling plays an important role in the ecological and hydrological dynamics in coastal areas, bringing fresh water inputs to saline water systems. However, locating it both in space and time as well as quantifying how much groundwater flows upward to coastal areas requires a big effort since these are very heterogeneous systems. Seasonal changes in rainfall, temperature and water level lead to temporal variability, while variations in the hydraulic properties and hydrological processes can generate spatial heterogeneity, making the process of measuring those fluxes complicated and requiring multiple measurements to obtain accurate results.

Furthermore, the non-steady position of the fresh water-salt water interface increases the uncertainty surrounding these processes. Using temperature as a tracer, the groundwater inputs to a surface water body can be calculated by means of solving analytically the conduction-convection equation, shortening considerably the amount of field work needed to obtain groundwater upwelling fluxes.

In this work, groundwater upwelling in the Ringkøbing Fjord coastal area was obtained using two methods: direct upward flow measurements and indirect flow calculations with shallow fjord bed temperature profiles. These two different sets of data are compared in order to assess their feasibility to map and quantify upwelling. Addressing the strengths and weaknesses of each method, we aim to better constrain the reliability of them in order to improve the quality of the data collection process.


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