## 4 Discussion  
In the present study, the soils were humid due to the effects of the local rainy season. The saturation of soils with water increases their electrical conductivity and attenuates the GPR signal. In general, the electrical conductivity of a soil is determined by its content of different types of clay minerals [66]. Low-frequency (<200 MHz) antennas provide a lower resolution and a greater penetration depth, while higher frequency (>200 MHz) antennas obtain a higher resolution [29]. However, the penetration of the GPR signal into the terrain will depend on its conductivity and resistivity, irrespective of the frequency of the antenna used. In environments with low conductivity (or high resistivity), such as dry, sandy soils, the radar signal may reach depths of over 15 m, whereas in conductive environments, such as saturated clay soils, the radar signal may be reduced to depths of less than 1 m [29]. The GPR technique has been used to provide a reliable interpretation of features such as near-surface structures, hydrological processes, and the depth of the water table (e.g., [67; 68; 69; 70; 71; 72; 73]). Reference [74] used GPR to evaluate the conditions of a terrain earmarked for aquaculture in the Montenegro zone of Braganca (Para, Brazil). These authors identified a sequence of normal faults with minor slips, a depression (35m in length at a depth of 2.8 m), and reflectors in the form of hyperboles of energy dispersal, which were assumed to represent the pipes used to install the fish ponds. The amplitude of the electromagnetic signal also varied considerably, with the GPR signature of the local rocky substrate, formed by parallel and supparallel reflectors with a low reflection zone. A horizontal reflector was identified at a depth of 4.48-4.62 m, which corresponds to the top of the water table, according to the depth of the wells drilled at the site. The authors of a number of previous studies have considered the electrical conductivity as an important parameter for the evaluation of the quality of terrains earmarked for aquaculture (e.g., [4; 75; 76]). Reference [4] analyzed several parameters of soil samples of fish ponds of different ages (1-5 years and >5 years) in Noakhali, Bangladesh. The electrical conductivity of the new ponds (334.8 mS.m\({}^{-1}\)) was much higher than that of the older ponds (130.6 mS.m\({}^{-1}\)). In a study of soil samples from the pond at Circuit House in Balochistan, Pakistan, [77] recorded electrical conductivity of no more than 290 mS.m\({}^{-1}\), which was still considered to be favorable for aquaculture, although an overall mean value of 221 \(\pm\) 143 mS.m\({}^{-1}\) was  
Figure 8: Map of the apparent conductivity recorded in Area 2 (Tracuateua), with a Horizontal Dipole (HD) and antennas with a 10m interval between coils. recorded in this study. Reference [75] evaluated the conditions of terrains earmarked for aquaculture in the divisions of Lahore, Gujranwala, Sahiwal, and Sargodha, in the Punjab district of Pakistan. The results of the surveys (electrical conductivity, soil particle size, pH, and salinity) indicated the presence of soils that were suitable for the construction of fish ponds at most of the sites in Lahore, Sargodha, and Sahiwal. In addition to the available geophysical tools, which have their own physical properties, a number of other potential methods based on geotechnology are available [11], which have been integrated with other approaches (e.g., the AHP, ANP, and MCDM methods), to identify the sites most appropriate for inland aquaculture [12; 20; 78; 79; 80; 81; 82]. An integrated approach of this type was applied to select sites for fish farming in M'diq Bay in Morocco [6]. This study applied an integrated approach that involved the GIS-Spatial Multi-Criteria Evaluation (SMCE) and Analytical Hierarchy Process (AHP) methods and the Weighted Linear Combination (WLC) approach to select polygons suitable for fish farming, together with the carrying capacity approach to define the most suitable number of fish farms.