An integrated geophysical (GPR + seismic) and sedimentological analysis for the selection of sustainable locations for fish farms in the Amazon region of northern Brazil

The selection of an appropriate site is fundamental for the sustainability and success of any fish farming operation. The present study was based on the integration of direct (sedimentological analysis) and indirect methods (GroundPenetrating Radar [GPR] and seismic surveying) to evaluate the characteristics of a proposed fish farming site in the Amazonian town of Braganca, northern Brazil. The geophysical GPR data revealed that the subsoil of the study site has horizontal to subhorizontal layers, with the presence of a local water table at a depth of 6-7 m. This method also provided a qualitative diagnosis of the site, which revealed that it had a sandy substrate mixed with clay, as confirmed by the shallow refraction seismic data. The sedimentological analysis also confirmed the diagnosis of the substrate, which was dominated by sand (mean = 66.97%), with clay (mean = 16.78%) and silt (mean = 16.25%) in smaller proportions. These percentages are well below the recommended values (20% clay and 45% clay + silt) needed to ensure a minimum loss of water from the excavated substrate through infiltration. The analysis confirmed that the site surveyed here was not adequate for the installation of fish farming ponds. The integrated tools (GPR + Seismic + Sedimentology) employed in the analysis performed well in the diagnosis of the characteristics of the proposed fish farm for aquaculture operations in the region.