# Temporal and Spatial Diversity of Renewable Groundwater Resources in the River Valley
## 6 Conclusions  
1. The calculations of renewable resources were done for variants that refer to average and extreme values of groundwater level in relation to possible climate changes understood as time-variable precipitation. The quantitative assessment of renewable groundwater resources of a shallow aquifer was made based on model tests in 3 variants: variant 1-steady state level, defined as the  
Figure 12: Correlation between groundwater depth and volume of resources in the different variants in geomorphological units: (**A**): Otwock Terrace (I); (**B**): Falenica Terrace (II); (**C**): Praga Terrace (III); (**D**): Higher flood plain (IVa); (**E**): Lower flood plain (IVb); (**F**): Warsaw plain.  
average annual hydrodynamic state for the years 1999-2013, variant 2, the highest groundwater levels in the period 1999-2013, and variant 3, the lowest groundwater levels in this period.
2. For the average groundwater level, the volume of renewable resources was 0.65 L/s km\({}^{2}\) for the area where the groundwater depth is 2.15 m. The amount of resources is spatially variable, both in relation to the identified geomorphological units and within them. The highest values appear in the uppermost Otwock Terrace (I) and are 1.16 L/s km\({}^{2}\), where the groundwater depth is 3.22 m, while the lowest values are 0.05 L/s km\({}^{2}\) in the Falenica terrace (II), where the average depth is 1.41 m.
3. The groundwater renewability is directly related to the depth to groundwater table. In a period of the highest water levels, virtually all geomorphological forms in the valley showed a prevalence of evapotranspiration over recharge. In a drought period, the value of renewable resources in all geomorphological units was positive. The diversity in the volume of renewable resources is associated also with the occurrence of ODEs in the valley. Any resource calculations should be based on geomorphological, hydrogeological and environmental analyses, defined as morphohydrogeological studies.
4. During the periods of hydrogeological drought (variant 2) and flood conditions (variant 3), the renewability of groundwater resources was much lower than in the period 1999-2013. It was 88% lower in the period of the highest levels and 30% less than the average during hydrogeological drought, when reduced precipitation did not influence the reduction in the amount of renewable resources as much as it did during the highest levels. Therefore, intensification of evaporation losses should be considered as the main reason for low (or lack of) renewability in the annual cycle.
5. The groundwater footprint and the footprint index were defined as a quantitative assessment of the use of groundwater in climate change conditions. For the Vistula valley in the study area, the groundwater footprint GF was 80.38 km\({}^{2}\). The water footprint index GF/A, determining the pressure on groundwater, was 0.14, classifying the aquifer as not threatened by excessive abstraction. The groundwater footprint in various calculations ranged from 29.50 to 315.91 km\({}^{2}\). Taking into account the evaporation, the groundwater footprint in various calculations ranged from 674.47 to 1722.30 km\({}^{2}\). For areas of shallow groundwater table in a hydrogeological valley unit, the effect of evaporation should be considered as a key potential factor causing an increase in the groundwater footprint. Studies have shown that evaporation and associated functioning of GD significantly increase groundwater pressure.  
Conceptualization, E.K.; methodology, E.K., S.Z., K.S.; software, S.Z.; validation, E.K., S.Z., K.S.; investigation, E.K., S.Z., K.S.; resources, E.K., S.Z., K.S.; writing--original draft preparation, E.K., S.Z., K.S.; writing--review and editing, E.K., S.Z., K.S.; visualization, E.K., S.Z., K.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Warsaw University support.  
The authors declare no conflict of interest.