Groundwater Quality and Water Security for Sustainable Pastoral Development in Arid Central Kazakhstan: Geogenic and Anthropogenic Controls

Sustainable livestock production in the arid regions of Central Asia depends almost entirely on groundwater resources. However, regional groundwater quality remains insufficiently characterized from the perspective of long-term water security and sustainable pasture management. Understanding the interaction between natural hydrogeochemical evolution and anthropogenic contamination is therefore essential for developing climate-resilient groundwater management strategies. This study presents a comparative hydrogeochemical assessment based on 101 groundwater samples collected from 58 sites in the Karaganda region and 43 sites in the Ulytau region during a single dry-season campaign (June–July 2025), with field sampling conducted across 4630 km2 of active pastureland within a combined regional area of 409,070 km2. Groundwater in Ulytau showed substantially greater mineralization, with a median TDS of 1027 mg/L compared with 538 mg/L in Karaganda; the proportion of samples exceeding 1000 mg/L was 53.5% (23/43) and 29.3% (17/58), respectively (Fisher’s exact p = 0.023). Median NO3− concentrations were also markedly higher in Ulytau (35.0 mg/L) than in Karaganda (5.0 mg/L), with the 50 mg/L guideline exceeded in 46.5% (20/43) vs. 19.0% (11/58) of samples (p = 0.004). NO3− and TDS were not significantly correlated in Karaganda (rs = 0.108, p = 0.418), whereas a moderate positive relationship occurred in Ulytau (rs = 0.388, p = 0.010). These results indicate that regional salinization is predominantly controlled by geogenic hydrochemical evolution, while nitrate contamination represents a localized anthropogenic pressure associated with vulnerable water points. The pronounced quantitative contrast between the two regions highlights the need for region-specific groundwater protection and management strategies to support sustainable livestock production and long-term water security in Central Kazakhstan. Rather than providing only a regional hydrochemical description, the present study evaluates groundwater quality as a sustainability indicator for livestock production, groundwater security, and regional adaptation to increasing water stress. Groundwater quality differed significantly between the two regions, with Ulytau exhibiting consistently higher mineralization, more frequent nitrate exceedances, and higher groundwater vulnerability. Statistical analyses confirmed that groundwater quality deterioration is controlled by different combinations of geogenic processes and localized anthropogenic impacts in the two hydrogeological settings. The findings demonstrate that groundwater quality represents a critical component of sustainable livestock production in Central Kazakhstan. The proposed regional groundwater vulnerability framework provides practical guidance for groundwater protection, climate adaptation, and the sustainable management of pastoral water resources under increasing environmental pressures.