## 5 Application to Case Study and Discussion
### Result Discussion  
In the case of the Agua Amarga coastal aquifer, the effect of regional flow from the continent on the temperature-depth profile was disregarded since possible sources of aquifer recharge were high enough to generate steady temperature-depth profiles near the  
Figure 14: Universal temperature profile registered in April 2002 in borehole A and located on the left margin of the Guadalfeo River, dimensioned and inserted in the set of type curves of Figure 7.  
Figure 13: Mortril-Salobreña aquifer, Guadalfeo River, and borehole A. Background from Google Earth Pro. coastline. The horizontal flow of this aquifer comes primarily from the Campo de Elche region, an agricultural area in the province of Alicante located approximately 15 km from the marshes The effect of the seawater intrusion wedge was also neglected because the depression cone directs seawater flow to the aquifer [14; 36]. The uncertainties were related to the aquifer thickness (ranging from 10 to 60 m inside the aquifer limits) and the hydraulic conductivity parameters, which were estimated using a pumping test between 16 and 150 m/d. Furthermore, the aquifer was assumed to be confined, although the heterogeneity of the Quaternary sediments covering the ground surface made the underlying Tyrrhenian aquifer behave as a free aquifer next to the coastline. It is also important to note that no evaporation from the ponds, which is estimated to be 850 mm/year, was considered. The possible loss of water through Quaternary faults, percolating to the geological formation under the studied Tyrrhenian aquifer, was also not considered. These factors might justify the lower calculated values. Although the real and calculated values were of the same order of magnitude, all these circumstances should have influenced the differences, and a 20% error in the findings would be reasonable. In the previous studies, [PERSON] [14] discussed the influence of artificial recharge on the piezometer D-2 in the 2008-2010 period, supporting the results on the relative shape of the temperature-depth profiles of six piezometers and on the outcomes of a fluid flow and solute transport numerical model made using Moldflow [36]. The results presented here verify his conclusions and match the recharge volumes used. In this scenario, the thermal parameters are well known and there is a very wide range of possible values for hydraulic conductivity. Therefore, the thermal conductivity of the saturated porous media was taken from the input data to estimate the value of the vertical hydraulic conductivity and, assuming an anisotropy value of 10, the value of the horizontal hydraulic conductivity. The estimated value of the vertical hydraulic conductivity was \(\mathrm{k_{y}}=10.8\) m/d, while that of \(\mathrm{k_{x}}=108\) m/d. Both values were within the initially known range [16-150 m/d]; therefore, the results were as expected. The flow obtained in Figure 4 is the flow that directly reaches borehole D-2 from the artificial recharge and, since there is no symmetry (the water goes directly from the marshes to borehole D-2), it is not necessary to multiply the recharge value by two (as would occur in the case of a classic scenario of river-aquifer interaction). As for the Guadalfeo River-Motril-Salobrena aquifer interaction, one of the major difficulties was, on the one hand, the value given to \(\mathrm{l_{r}}\), since there were no aerial photographs of the area in the period in which the temperatures were recorded in piezometer A. It was decided to take an average value that was consistent with the different piezometry values between the river and piezometer A. On the other hand, the exact value of \(\mathrm{H}\) to be considered was not known. In this case, as this value was used to solve the thermal problem, it was easy to accept the depth from which the temperature no longer varied due to thermal changes caused by river recharge as a value.