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Undoubtedly, one of the most important cases of floods occurrence and increasing floods discharge in northern part of Iran, in recent decades, is charging in land use and inconsistency between present land uses and land capacity. The economical losses due to these floods and distracting control flood hydraulic structures that were designed and were calculated based on design flood discharge are very considerable. In this research using SCS method and the model of Curve Number, and flood maximum discharge in two positions of present land use and land using based on land capacity were estimated in three types of soil moisture (low I, middle II, moist III). Comparing obtained results, the effect of land use changes on estimation uncertainty of flood design were determined. The cause of choosing this hydrological method was consideration of soil characteristics, plants covering, physiography and topography and land use in this model. Consider basic and environmental studies in Madarsoo watershed basin and providing land use and land capacity maps and estimating flood discharge in that situations led to following results:
1- Changing in land use in this watershed basin, especially in lands with D and C hydrologic soils and severe destruction caused flood maximum discharge increased 70 percent due to present land use in proportion to expected discharge due to land capacity in antecedent moisture condition (A.M.C) II and III. 2- Flood discharge in present land use in the proportion of appropriate using consistence with land capacity increase form 79 percent in 2 years return period to 31 percent in 100 years return period resulting in due to floods discharge with return period less than design flood discharge. 3- The most important effect of land use changes of flood discharge was in middle antecedent moisture condition