## 3 Results and Discussion
### Prediction Model
#### 3.2.2 Assessment of Exploitable Groundwater Resources in the Zhem Basin--Second Scenario Prediction
The exploitable groundwater resources and the resulting maximal groundwater head drawdown modeling consider the adjusted corrections (Table 9). While the approved exploitable groundwater resources for these four aquifer segments are 122,560 m\({}^{3}\)/day, the model calculates that exploitable groundwater resources, with maximal permissible drawdown, amount to just 37,000 m\({}^{3}\)/day. The aquifer's dynamic model indicates that the decrease in the total water withdrawal on the Bogdanovsk, Zharyk, and Keregen-Sagyz segments will not completely drain them. Thus, the total exploitable groundwater resources of the Upper Cretaceous and Quaternary sediments of the Zhem Artesian Basin will be 629,400 m\({}^{3}\)/day. \begin{table}
\begin{tabular}{c c c c c c} \hline  & & \multicolumn{2}{c}{**25 Years**} & \multicolumn{2}{c}{**50 Years**} \\ \cline{3-6}  & **Balance Items** & **Thousands** & **\%** & **Thousands** & **\%** \\  & **m\({}^{3}\)/Day** & **\%** & **m\({}^{3}\)/Day** & **\%** \\ \hline \multirow{5}{*}{**Fresh**} & Storage recharge & 636 & 10.5 & 406 & 6.9 \\  & Recharge & 5347 & 87.8 & 5347 & 91.3 \\  & River leakage & 104 & 1.7 & 105 & 1.8 \\  & **Total input** & 6087 & 100 & 5858 & 100 \\  & Storage discharge & 3871 & 64.4 & 3559 & 61.7 \\  & Groundwater withdrawal & 715 & 11.9 & 715 & 12.4 \\  & Groundwater discharge to rivers & 352 & 5.8 & 351 & 6.2 \\  & Evapotranspiration & 1081 & 17.9 & 1138 & 19.7 \\  & **Total output** & 6020 & 100 & 5764 & 100 \\  & **Input–output** & 67.2 & 1.1 & 94.9 & 1.6 \\ \hline \end{tabular}
\end{table} 
Table 7: The groundwater flux balance of the Zhem Basin, calculated over prediction periods of 25 and 50 years. Second scenario prediction. \begin{table}
\begin{tabular}{c c c c c c} \hline  & & \multicolumn{2}{c}{**25 Years**} & \multicolumn{2}{c}{**50 Years**} \\ \cline{3-6}  & **Balance Items** & **Thousands** & **\%** & **Thousands** & **\%** \\  & **m\({}^{3}\)/Day** & **\%** & **m\({}^{3}\)/Day** & **\%** \\ \hline \multirow{5}{*}{**Fresh**} & Storage recharge & 552 & 11.6 & 383 & 8.4 \\  & Recharge & 4118 & 86.3 & 4118 & 90.3 \\  & River leakage & 91.8 & 1.9 & 49.3 & 1.1 \\  & Influx from a brackish groundwater & 7.7 & 0.2 & 7.8 & 0.2 \\  & zone & 7.7 & 0.2 & 7.8 & 0.2 \\  & **Total input** & 4769 & 100 & 4558 & 100 \\  & Storage discharge & 2777 & 59 & 2505 & 55.5 \\  & Groundwater withdrawal & 702 & 14.9 & 702 & 15.5 \\  & Groundwater discharge to rivers & 320 & 6.8 & 315 & 6.9 \\  & Evapotranspiration & 875 & 18.6 & 965 & 21.3 \\  & Outflow to a brackish groundwater & 32.8 & 0.7 & 34.4 & 0.8 \\  & zone & 4706 & 100 & 4521 & 100 \\  & **Input–output** & 62.8 & 1.3 & 36.4 & 0.8 \\ \hline \end{tabular}
\end{table} 
Table 8: Fresh groundwater distribution zone flux balance is calculated for prediction periods of 25 and 50 years. Second scenario prediction. The limitations of the created model are related to the grid spacing, time discretization, parameter structure, insufficient calibration data, and the effects of processes not simulated by the model. These factors, along with unavoidable errors in observations, result in some uncertainty in model predictions. Thus, the size of the computational block of the model (5 \(\times\) 5 km) does not allow modeling pumping from a single well, but only from a water wellfield of significant dimensions. Combining several aquifers into one model layer does not provide the ability to reproduce water extraction from different depths of filter installation, as well as the variability in filtration properties vertically in the sediment section. The time step size of 1 year does not allow for seasonal fluctuations in groundwater heads. However, given the stated aims of the model, these limitations do not have a significant impact on the reliability of the prediction solutions.