## 3 Results and Discussion
### Prediction Model
#### 3.2.4 Prospects for Utilizing Cretaceous Groundwater Resources as a Water Supply  
Water withdrawal for household and drinking purposes in the most water-scarce administrative regions of western Kazakhstan in 2021 was (in m\({}^{3}\)/day) 112,190 in Aktobe, 122,070 in Atyrau, and 969,900 in Mangistau. From a total water withdrawal of 331,000 m\({}^{3}\)/day, 140,000 m\({}^{3}\)/day was accounted for by groundwater, while the remaining demand was covered by surface water (in the Mangistau and Atyrau regions). Moreover, the total demand for these administrative units in 2010 was 640,360 m\({}^{3}\)/day, almost twice the actual water withdrawal in 2021. At the same time, the estimated river flow reduction by the model at the end of the forecast period (50 years) is about 77 thousand m\({}^{3}\)/day, which is less than 4% of the total river flow. The prospective water demand in these administrative regions for 2030, 2050, and 2070 is shown in Table 10. The prospective demand for drinking water in three administrative regions of western Kazakhstan, oriented towards the groundwater basin for 2030, 2050, and 2070, was estimated based on the trend of increasing total water consumption due to population growth and improvements to the water infrastructure, as well as taking into account prospective plans for the development of economic sectors [44]. By 2070, the freshwater demand for domestic and drinking water supply will increase from 640,000 to 901,000 m\({}^{3}\)/day, where the maximum groundwater usage for household and drinking water supply is in the Aktobe region. The exploitable fresh groundwater resources in the Mangistau and Atyrau regions are significantly smaller; therefore, their water supply is fulfilled to a greater extent from surface water, with treatment used to \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Administrative Region** & **2030** & **2050** & **2070** \\ \hline Aktobe & 321 & 355 & 393 \\ Atyrau & 195 & 223 & 253 \\ Mangistau & 201 & 226 & 255 \\
**Total** & **717** & **804** & **901** \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Prospective water demand for domestic and drinking water supply, thousand m\({}^{3}\)/day. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Deposit** & **Exploitable** & **Maximal** & **Additional** & \multicolumn{2}{c}{**Maximum Calculated**} \\
**Groundwater** & **Permissible** & **Drawdown** & **Drawdown** & \multicolumn{2}{c}{**Drawdown with Correction, m**} \\ \cline{3-6}  & **Resources, m\({}^{3}\)/Day** & **Drawdown, m** & **Correction, m** & **25 Years** & **50 Years** \\ \hline Kenkiyak & 4000 & 59.9 & 1.4 & 52.7 & 60.2 \\ Kandagach & 16,000 & 36.8 & 2 & 30.7 & 38.9 \\ Dzhurun PTV & 11,000 & 57.2 & 30 & 50.6 & 54.7 \\ Zharkamys & 6000 & 70 & 5 & 67.3 & 69.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: The model calculates exploitable groundwater resources. improve their quality to the appropriate standards. Full surface runoff utilization is restricted in these regions since a significant portion is accounted for mandatory release to neighboring countries, evaporation and filtration losses, environmental sanitary releases to the lower reaches of rivers, and other runoff losses. The runoff available for use in low-water level years (95%) for the entire Aktobe region is only 0.12 km\({}^{3}\)/year, which is less than the prospective need for 2070 (Aktobe and Atyrau regions), which will amount of 612.6 thousand m\({}^{3}\)/day or 0.22 km\({}^{3}\)/year. Consequently, such water withdrawal will lead to a decrease in river flow and wetland extent and to environmental degradation. As such, the most promising water supply for both areas is the fresh and slightly brackish groundwater of the Zhem Artesian Basin Albian-Cenomanian aquifer complex. At the same time, the exploitable groundwater resources with mineralization of 1-3 g/L are 12,400 m\({}^{3}\)/day or 2% of their total amount.