Spatial Distribution of Physical and Chemical Factors of Gorgan Gulf in 2011-2012

Gorgan Gulf is one of the rare ecosystems in the country that has ecological and economic features that have special values in comparison with other water resources of the country. monthly in-situ water sampling and analysis of water quality parameters include of Nitrate, Nitrite, Alkalinity, pH, Do, NH3, Salinity and Temperature, in 19 different points in Gorgan Gulf was performed. Monthly water sampling was performed during April, 2011 to March, 2012. Next, water quality data were interpolated by different interpolation techniques (Kriging, Invers distance, Polynomial regression, Local polynomial and Thin Plate Smooth Splines) using Surfer 9.0. These methods were compared using cross validation technique based on Root Mean Square Error (RMSE) evaluation index. The results showed that the Polynomial regression method is better than the other studied methods.  Hence, monthly maps of spatial distribution of water quality parameters were generated using Surfer 9.0 and MATLAB7.10 by Polynomial regression method and consequently, the average of Nitrate, Nitrite, Alkalinity, pH, Do, NH3, Salinity and Temperature in Gorgan Gulf was determined. According to the results of this study, the maximum values of temperature was 30 ° C, pH 8.88, dissolved oxygen 16.07, salinity 17, alkalinity 400, nitrogen 3.96, nitrite 0.19 and amonia 1.5 were measured. Comparison between average of these parameters in Gulf and the standards of the studied species for these parameters indicated that Gorgan Gulf is a suitable environment for aquaculture of Carp, Salmon, Trout, and Huso huso species.