deterministic methods

Modeling the spatial-temporal variation of water quality and analyzing the effects of land use changes on the qualitative parameters of groundwater is very important. In this research, the ability of various deterministic and geostatistical techniques in the prediction of spatial-temporal qualitative parameters regarding drinking, agriculture usages and effects of infiltration rate of water into the soil  in Mashhad’s plain were investigated by using statistical data of 62 observation well from 1996 to 2016. The land use maps were prepared by ENVI5.1 using Landsat images. Analysis of isoline maps showed that the water quality had been dropped considerably in terms of chlorine and total hardness and the area with class of sever restricted usage had been increased. Investigation of EC isoline maps showed that in the year 2016, the area of regions with moderate and sever restricted usage was the highest in comparison to 1996 and 1986. The pH isoline maps showed that the major part of study area is located in the moderate restricted class. According to SAR isoline maps, all part of the study area is located in non-restricted class and it has approximately remained constant during the years. The geological maps of study area showed that the formations have good effects on groundwater quality. Analysis of Land use maps showed that rangeland and agriculture have received the most area of land use.  During the studied period, rangeland and agriculture had the most decrease (6.61 %) and increase (2.16%) equivalent to 643.29 and 235.46 square kilometer, respectively. By moving from center to northeast part of Mashhad’s plain, the agricultural lands and the number of illegal wells and urban industrial land use is increased which altogether have led to the significant loss of water quality.

Selection and accuracy of the appropriate methods for zonation and preparing the map of groundwater quality parameters depend on regional condition and availability of data which is an important stage for groundwater management of the region. The purpose of this research is determining the most suitable interpolation method for determining salinity (EC)، nitrate (NO3)، pH and total dissolved salts (TDS) parameters of groundwater and mapping of them by using of geographic information systems in Neyriz plain located in southeast of Fars province. For this aim، different methods of geostatistics including ordinary kriging (OK) and simple kriging (SK) as well as deterministic methods such as inverse distance weights (IDW)، radial basis function (RBF)، local polynomial interpolation (LPI) and global polynomial interpolation (GPI) were used. The result based on the lowest root mean squared error (RMSe) and mean absolute error (MAE) showed that simple kriging (SK) method is the most appropriate method for salinity (EC) mapping (RMSe=3907. 53 and MAE=2911. 05)، TDS mapping (RMSe=2587. 19 and MAE=1936. 48)، pH mapping (RMSe=0. 196 and MAE=0. 143) and NO3 mapping (RMSe=4. 868 and MAE=3. 839) among all the methods in the study area. Finally، the results of this research indicated that geostatistical methods have higher priority than deterministic methods and thus are selected as suitable methods in Neyriz plain.

Rainfall erosivity is one of the effective factors on rainfall erosion which is very important in water erosion. Preparing rainfall erosivity mapping is an important issue in soil conservation، erosion control and land management. The objective of this research is evaluation of geostatistical methods for rainfall erosivity mapping in Fars province. First، 92 meteorological stations having at least 20 years data and relevant distribution over the region were selected and the modified Fournier index was calculated for each station. Then several interpolation methods including Ordinary Kriging (OK)، Simple Kriging (SP) and deterministic methods such as Inverse Distance Weights (IDW)، Radial Basis Function (RBF)، Local Polynomial Interpolation (LPI) and Global Polynomial Interpolation (GPI) were used in order to extend point data to spatial information in the process of preparing rainfall erosivity map. The evaluation of the results based on higher R value and lower MAE and RMSE values showed that among the studied methods، the OK method has higher R value and lower RMSE and MAE values (R=0. 87، MAE=13. 09، RMSE=18. 52)، then it was selected as the most appropriate method for rainfall erosivity mapping in Fars province. Also the results revealed that 0. 24% of the province has negligible erosivity، 27. 06% has low erosivity، 43. 62% has moderate erosivity، 14. 48 have high erosivity and 14. 6% has very high erosivity.

Ground Water quality change is due to mismanagement in use of groundwater resources. Main objective of this research was to investigate spatial variability of chemical properties of ground water. In this research chemical properties such as cation, anion, sulphate and carbonate were studied. Normality of data investigated based on Kolmogeraph- Smirnov test. Then, variogeraphy analysis was done in geostatistical methods. Accuracy assessment was investigated based on mean absolute error (MAE), residual mean square error (RMSE) and correlation coefficient (R). Results showed that geostatistical methods have more accuracy than determinestic methods. However, global polynomial interpolation was the best method for mapping cation. In addition, for the most parameters, Cokriging method was the best method for interpolation.