Zoning of Mokhtaran Plain’s Groundwater for Irrigation Using Analytical Network Process (ANP)

Groundwater is one of the most important water resources for irrigation usage in arid and semi-arid regions like Iran. So, in order to determine groundwater potential zones, it is important to specify its quality variations over a plain. The aim of this study was to zoning the groundwater quality of Mokhtaran plain, Iran, for irrigation using network analysis (ANP) method.

Regarding this purpose, this research was conducted to zone Mokhtaran Plain’s groundwater located at latitude between 32˚ 13’-32˚ 46’ N and longitude between 58˚ 40’-59˚ 45’ E in South-Khorasan, Iran, in 2015. Sodium adsorption ratio (SAR), total hardness (TH), sodium solubility percentage (SSP), residual sodium carbonate (RSC), permeability index (PI), magnesium adsorption ratio (MAR) and kellyes ratio (KR) were used to create water quality layers in GIS. Analytical network process (ANP) was utilized to implement these layers.

  The results showed that quality of groundwater was better at the east region compared to the west. According to the results, appropriated region for irrigation covered about 40.72% of the plain (consist of sub-categories: 3.28, 17.09 and 20.35% in the class of very appropriate, appropriate and semi-appropriate, respectively) and non-appropriate one covered 50.28% (consist of sub-categories: 49.11, 7.35 and 2.82% in the class of semi non-appropriate, non-appropriate and very non-appropriate, respectively).

Regarding the results, it is necessary to extract groundwater at north and east part of the plain. Indeed, rainfed agriculture must be considered in other parts of the plain.