The effect of karstification on water resource hazards management based on physicochemical factors of water (case study: Valiabad – Hezarcham), Iran

Karstic water sources, in addition to their importance in providing water supplies, are highly vulnerable to contamination. Since the pollution in the karst water resources is transferred quickly and considering the tourism situation of this area, the physicochemical factors and the effect of the karst structure on the spread of pollution were investigated and an attempt was made to study the possibility of this area being karst and the factors of the spread of karst pollution. During the field visit, we investigated the type of formations, the structural features of the area, the extent of layering, the stratigraphic sequence at the location where the springs appear, as well as the geometrical and geological components that cause the structural obstacles. Samples from the springs were collected to study the hydrogeochemical characteristics.  AqQA and Phreeqc materials were used to examine the spring water results. We also utilized ArcGIS software and Excel to create the maps and carry out statistical analysis, respectively. The results show that except for S1, all springs have very hard water, indicating that calcium and magnesium are highly dissolved in the Mobarak limestone and Soltanieh dolomite formations. According to Piper's chart, all of the springs are in the classical bicarbonate range, indicating a carbonate source. Stiff diagrams also show that samples S3, S4, S6, and S7 are calcium bicarbonate, while samples S1, S2, S5, and S8 are magnesium bicarbonate. Except for the S6 spring, the region's springs have a low calcium to magnesium ratio, indicating that they are supplied by a dolomite karst aquifer. The Mann-Kendall and Tau-Kendall statistic values derived for most of the springs are negative, indicating a decreasing trend in spring water supply and rainfall in the region. Additional results include a high dissolution of calcium and magnesium in the aquifer's rock, a high relationship between underground water and formation. The region has dolomitic karst aquifers but lacks karst development and diffusion, as revealed by the water's prolonged residence time.  However, the interaction between karst and fractures indicates fractures and faults play an important role in groundwater flow. Water outflow through low-discharge fissures indicates the presence of diffusion flow, either turbulent or linear, in the studied area.