Ecology, Environment and Conservation Paper

SENSITIVITY ANALYSIS OF POTENTIAL EVAPOTRANSPIRATION IN SOUTHERN REGIONS OF IRAN USING CROPWAT MODEL

Seyed Amir Shamsnia and Reza Afshin Sharifan

Abstract

Determination of the crop water requirement and irrigation scheduling, in arid and semi-arid regions is considered as a necessity. In the present search, in order to consider this subject more accurately, southern and central parts of Iran were studied. These regions are the most arid climates of Iran, and the temporal and spatial distributions of precipitation are inappropriate. According to effective parameters in potential evapotranspiration, which contain minimum and maximum of temperature, relative humidity, sunshine hours and wind speed, the amount of evapotranspiration was calculated. In order to scheduling the irrigation more accurately, sensitivity analysis of potential evapotranspiration was performed, using evaluation index method and the most sensitive parameters, in different climates and regions, were recognized. Consequently a pattern for irrigation scheduling was presented. Results showed the 25% increase in maximum temperature in hot and humid climates and also in hot and arid climates, demonstrated the highest sensitivity. This parameter has the greatest effect in determining the potential evapotransporation. Regardless of this parameter, in these climates, the greatest sensitivity belonged to humidity and wind speed. But in Moderate climate, in summer, by increasing in the maximum temperature, the most sensitivity occurred and in other seasons humidity and wind speed were very effective.