Balanço hídrico do projeto de irrigação de São Desidério.

Abstract

The hydric balance was based in seven -year data obtained a t the UEP/Barreiras Weather Station. The e va p o tra n sp ira tio n was c a lc u la te d by the Hargreaves method and the evaporation by the class A tank with a 0.75 coefficient . The crop irr igation requirem ent was obtained by the difference between the tank evaporation and the e ffective rain fall. The monthly h yd ric balance presented a hum idity d e f i c i t fo r the crops from May to October; fo r 5-day in te r n a ls the d e fi c i t s were from Ja n 10 to 20, from A p r il 5 to O ct. 15, from O ct. 25 to Nov. 5 and from Dez. 5 to 10. The h ig h e st g ro ss irr ig a ti_ on requirem ent occurred in August (329.2mm) w ith a c o e f f ic ie n t o f 1 .2 1/sec/ha. As the P r o je c t has an ir r ig a b le area o f 2.000 ha, the crops water requirem ent i s 2 .4m3/ se c .