Comparison of Corrected and Uncorrected Land Indices in Parametric Method of Land Suitability Evaluation

Performance of land suitability evaluation and land production potential prediction are very important in land use planning. The study region with a surface area of about 3050 hectares is located in Aghili plain، Gotvand، Khuzestan province، between 32° 07¢and 32° 10¢ N latitude and 48° 52¢ and 48° 56¢ E longitude. The aims of this research were to compare effects of corrected and uncorrected land indices on land suitability classes and accuracy of land production potential prediction. Land index was calculated using Storie and square root formulas. Based on the obtained results، the corrected land indices calculated by Storie and Square Root formulas of parametric method showed higher values compared with uncorrected ones and upgraded land suitability classes. The share of land suitability classes S1، S2، S3، and N، using square root formula for uncorrected land indices، were determined as، respectively، 0. 0%، 88%، 9%، and 3%. These values using the corrected land indices were obtained as، respectively، 32%، 63%، 5%، and 0. 0%. The share of land suitability classes S1، S2، S3، and N، using Storie formula for uncorrected land indices، were، respectively، 0. 0%، 4%، 55% and 5%. By using the corrected land indices، these percentages were obtained as، respectively، 55%، 38%، 6%، and 1%. Another conclusion was that the upgrading of the land suitability classes was more when Storie formula was used for the corrected land index، compared with the square root formula. This higher upgrading is more in accordance with conditions of the studied area. For validation of the methods used in this research، regression correlation was established between predicted yield for corrected and uncorrected land indices، using both Storie and square root formula and the observed yield. Root mean squared deviation (RMSD) was also used for evaluation of the methods and showed the higher accuracy of uncorrected square root method، with RMSD= 738 kg/ha، compared to other methods.