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Mapping groundwater discharge to a coastal lagoon using combined spatial airborne thermal imaging, radon ( 222 Rn ) and multiple physicochemical variables
Author(s) -
Coluccio Katie,
Santos Isaac,
Jeffrey Luke C.,
Katurji Marwan,
Coluccio Steve,
Morgan Leanne K.
Publication year - 2020
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.13903
Subject(s) - groundwater , hydrology (agriculture) , radon , groundwater discharge , environmental science , tracer , geology , wetland , surface water , submarine groundwater discharge , inflow , oceanography , aquifer , groundwater flow , ecology , environmental engineering , physics , geotechnical engineering , quantum mechanics , nuclear physics , biology
Coastal lagoons are significant wetland environments found on coastlines throughout the world. Groundwater seepage may be a key component of lagoon water balances, though only a few studies have investigated large (>100 km 2 ) coastal lagoons. In this study, we combined airborne thermal infrared imagery with continuous measurements of radon ( 222 Rn—a natural groundwater tracer), conductivity, water temperature and dissolved oxygen to map groundwater seepage to a large coastal lagoon in New Zealand. We found evidence of seepage along the margins of the lagoon but not away from the margins. Our findings confirmed previously known seepage zones and identified new potential locations of groundwater inflow. Both point source and diffuse seepage occurred on the western and northwestern margins of the lagoon and parallel to the barrier between the lagoon and sea. These observations imply geologic controls on seepage. The combination of remote sensing and in‐situ radon measurements allowed us to effectively map groundwater discharge areas across the entire lagoon. Combined, broad‐scale qualitative methods built confidence in our interpretation of groundwater discharge locations in a large, dynamic coastal lagoon.