Developing water quality maps of a hyper-saline lake using spatial interpolation methods

Urmia lake, the second largest hyper-saline lake in the world, has experienceda signicant drop in water level during the last decade. this study was designed to examinethe water quality of urmia lake and to characterize the spatial heterogeneity and temporalchanges of the physiochemical parameters between october 2009 and july 2010. twospatial interpolation methods, inverse distance weighting (idw) and ordinary kriging(ok), were used and compared with each other to derive the spatial distribution of ionicconstituents as well as tds and density along the lake. results showed that the maindominant cations and anions in urmia lake were na+, mg++, k+, ca++, cl??, so???? 4 ,and hco??3 , respectively. although water quality of the lake is homogeneous with depth,it diers between the northern and southern parts. water quality also varies seasonally,determined by river inows and the lake bathymetry. moreover, with the present salinitylevel, salt precipitation is likely in urmia lake and is becoming one of the principal factorsdetermining the distribution of solutes within the lake. this study shows that the combineduse of temporal and spatial water quality data improves our understanding of complex, largeaquatic systems like urmia lake.