Geomorphological land form  quantification is the basical land use classification. Automatic land form quantification is used based on zoning criteria. Automatic land form quantification is applied by fitting a fundamental linear form to the surface in order to delineate the best flood spreading area in Gohar plain and Garbaigan - Fassa of Fars province. To find the best fundamental structure, a second order formula was fitted in a 3*3 window to the surface using 10 meter DEM resolution. To determine the fitting order of fundamental structures the RMSE were used. The degree of suitability of land form for flood spreading have been studied using geomorphological approach. The zoning map shows that the down slope in alluvial fan and all low plain represent the best flood spreading area in the region.