4.2 Validation of the model
The validation of the model was carried out by both the ground investigations and the existing salt crust maps with referenced to the same locations. The ground investigations included the soil salinization appearance, the component factors and their associated information. The resultant maps were compare with the existing salt crust maps made by the Land Development Department (LDD). The LDD maps
based on the salt crust were manually performed by field observation of remote sensing bases. The comparison of the results with the LDD maps is presented in table 4. The selection of 63 locations was randomly checked and compared. Of the 63 locations, mismatch of 13 locations for the 10-50% salt crust and non-salinity potential. More detailed investigation is needed for the salt crusts exist on the areas beyond the Mahasarakham Formation. Within the Mahasarakham Formation the reliability of the result is satisfactory. To achieve a more reliable map detailed
map layers of ground water and geology should be made available preferably at the 1:50,000 scale. It may need other thematic layers i.e. ground water pumping locations and hydro-geological and geochemical data of the areas to be added for the overlay process.