Assessment of land capability for different irrigation systems by parametric and fuzzy approaches in the Mashhad Plain, northeast Iran

Water quality and quantity in agricultural systems of arid and semi- arid regions of the world are of great importance. In this regard the trend to pressurized irrigation systems compared to surface irrigation, elevating water use efficiency, has drastically increased in the agriculture sector. The present study aimed to assess land capability for different types of irrigation systems including surface, drip, and sprinkler practices by parametric and fuzzy approaches to evaluate the capability of cultivated lands on 6131 km2 of the Mashhad Plain, Khorasan Razavi Province, northeast Iran. In this regard land qualities (drainage and slope), soil physical and chemical properties (texture, depth, salinity, drainage, calcium carbonate and gypsum percentage) and climate conditions (wind velocity) were evaluated by using the Geographic Information System (GIS). Based on parametric approach, some 1116.5 ha of the study area were classified as highly suitable (S1 class) for surface irrigation, while the corresponding values by fuzzy approach accounted for 6099.7 ha of the region. The moderately suitable class of S2, assessed by parametric and fuzzy approaches, included 5014.5 and 31.3 ha of the plain, respectively. It was revealed that the land capability indices were in higher classes (S1 to S2) by drip and sprinkler irrigation compared to the surface irrigation system and the soil texture was detected as the most limiting factor for using the surface irrigation system. With respect to current soil and climate conditions in the study area, the most efficient irrigation systems are drip and sprinkler practices.