Stima evapotraspirativa dei fabbisogni irrigui nelle principali aree agricole della Sardegna

ETP calculation for three important irriguous areas of Southern (39°17' N. I), Central (39°53' N. I) and Northern (40°41' N. I) Sardinia through F.A.O. method shows too much high values with originai Blaney-Criddle equation, reduced differences with Penman (original and F.A.O.) equation, Radiation method and B.-C. F.A.O. equation respectively. The last method, believed the most suitable according to the first lisimetric measurements, estimates annual mean ETP equal to 1194 mm, 1077 mm and 1022 mm for Southern, Central and Northern Sardinia. Effective rainfall successive analysis shows they are 50% of total rainfall (in case of grasses) and they hold ETP for about 22%. Therefore seasonal irrigation requirements, calculated through F.A.O. crop coefficients, are among 841 mm, 791 mm and 706 mm concerning grasses, and 353 mm, 322 mm and 311 mm concerning olive tree, for Southern, Central and Northern Sardinia.