Evaluation, Mapping and Trend Analysis of Quality and Quantity of Yazd Agricultural Water Resources (Bahadoran Plain)ύ.

Global climate change has accelerated drought occurances and severities in different parts of the Iran, espicially central plateu. Bahadoran plain in Yazd priovince known as one of these cases that has been influenced by this phenomenon, in which quality and quantuity of its groundwater (GW) resources has been degraded in recent years. Main purposes of this study are to evaluate spatio/temporal changes of GW qualities, suitability of these resources for pressurized irrigation systems, in addition to study of drought influences on Bahadoran GW qualities as well as projection of climate change impacts on salinity of its GW resorues in upcoming three decades. For these purposes time series of climate parameters and GW quality and quantity historical data were prepared. Additionally, the parameters were measured through field survey in 2012 and used for updating of the historical database. Afterwards, maps of different groundwater attributes such as electrical conductivity (EC), acidity (pH), langelier Saturation Index (SI), Sodium Adsorption Ratio (SAR) and chloride (Cl) were generated and claissified based on existing guidelines and standards of pressurized irrigation systems. Additionally, impacts of climate change on quality of GW resources were investigated through downscaled SRES data of HadCM3-AOGCM. Ancillary data and indices such as temperature, precipitation and Standardized Precipitation Index (SPI) were used for the projections, as well. Based on SI classification and interpretation, drip system would not be advisable for irrigation of Bahadoran pistachio orchards due to scale forming and rootzone salinity build up, while; extension of babler system is recommended as an alternative for irrigation of agricultural fields. Trend analysis of the qualitative GW parameters shows fluctuation and degradation of these resources along the time. Additionally, impact of climate change on deterioration of GW electrical conductivity is another concern that should be considered in the area of studied.