Investigation of the Quality and Quantity of Groundwater Resources and their Relationship with the Geological Formations (Case Study: Yazd-Ardakan Basin)

This research was an attempt to investigate the quality and quantity of groundwater resources in Yazd-Ardakan plain as the biggest watershed in Yazd Province and its relationships with the geological formations. For this purpose, qualitative data of the wells in the plain for the decades of 80 and 90 (according to the Iranian calender for the pre- and post-water transfer from Zayandehroud River to Yazd) were studied. Furthermore, the geological formations map of the region was prepared based on the geological maps and Google-Earth images. Then, the type and facies of water for each well was determined using Aq.QA 1.1 software. The suitability of water usage for agriculture and drinking purposes was also evaluated. Results showed that the chloride type of the groundwater was dominant in the southern and central parts of the watershed and also in 90s rather than 80s. Results of the qualitative zoning showed that the amount of EC was increased as 3 dSm-1 from 80s to 90s. Quantitative zoning of the groundwater showed that the elevation of the water surface decreased toward northern part of the watershed. The water depth in the wells was also decreased on the average of 10 m from 80s to 90s. Results also showed that the wells were dug often on the alluvium formations. Correlation analysis between water quality and frequency percentages of geologic formations revealed that the highest correlation (r=0.99) was observed between calcareous geologic (Ktl) unit and EC of the groundwater; whereas, there was the least correlation between Acidic volcanic rocks (Pc-cr) geologic unit and EC of the groundwater (r=0.07).