VEGETATION INDEX IN THE SÃO GONÇALO IRRIGATED PERIMETER - PB

The municipality of Sousa is cut by rivers Piranhas and River Fish , and holds a great potential for exploiting its water resources, aiming at the improvement of agriculture . The Irrigated Sao Goncalo - PISG is located 15 km from the city of Sousa - PB located approximately 444Km from the capital Joao Pessoa . The weir Sao Goncalo is inserted in the watershed of Alto de Piranhas , sub -basin of the Rio Piranhas in western Paraiba in northeastern Brazil , whose construction works started in 1932 and completed in 1936 . Its hydro capacity is 44.6 million cubic meters , with the objective of attenuating the effects of drought suffered by the local population . The main objective of this work was to study the variability of NDVI obtained by the product MODA13 MODIS / Terra and monthly precipitation in March and September 2008 to 2012 with the aim of detecting possible changes in vegetation in the rainy months and dry region . For this we applied the algorithm SEBAL (Surface Energy Balance Algorithm for Land) which is one of the most used to extract information from satellite sensors . The study area includes areas of native vegetation ( caatinga ) , rice cultivation and irrigated areas with fruit , especially the production of coconut and bananas. The results MODIS to month dry and wet area PISG apresentam average for the three targets studied , ie consortia banana / coconut, rice and native vegetation NDVI values of 0.39, 0, 43 and 0.40 for the dry month and 0.63 , 0.62 and 0.77 for the rainy month . Given the results found that MODIS / Terra presented a mean correlation coefficient ( r ) of the order of approximately 0.88 and average error of 9 % between NDVI and rainfall for the months of March and September . This shows that the rains are important in the development of vegetation , even in the case of irrigated period.