Zoning of Water Quality Using ANP and FANP Methods (Case Study: Birjand Plain)

Groundwater is the most important water sources in arid and semi-arid regions. Due to its nature, it is difficult to decide about groundwater quality at each part of a basin. Regarding to this, new techniques like multi criteria decision making and fuzzy methods has been used. This research was conducted to zone Birjand groundwater quality by using ANP and FANP methods. 

Birjand plain located at the east of Iran with latitude between 32˚ 30’-33˚ 00’ and longitude between 58˚ 45’-59˚ 41’. In this study, the parameters: Mg2+, Ca2+, SO42-, Cl1-, total dissolved solids (TDS), pH and total hardness (TH) for 18 wells and 9 aqueducts were collected.

  The results indicated that Cl1-, Mg2+ and pH had the most effective on groundwater quality so that these parameters showed the effectiveness as 17.2, 16.1 and 15.9%, respectively. Results of zoning and fuzzy showed that southeast had more quality rather than other regions. Concentrations of mentioned parameters were high in southwest. ANP result revealed that very good, good, moderate, semi inappropriate, inappropriate and bad quality regions were as 5.25, 10.56, 54.52, 15.89, 10.57 and 3.18%, respectively. These parts according to FANP result were 5.97, 22.01, 28.85, 30.16, 9.54 and 3.47%, respectively.

Since FANP assumed uncertainty and spatiality, the area of moderate and semi inappropriate regions were closer in this method compare to ANP. Regarding to the results, it is recommended to dig more wells in east of Birjand basin for achieving better groundwater quality.