Water supplying in dry season is a very interesting problem for water balancing study in small and medium catchment areas. This study concentrates on extracting the NDVI values from remote sensing data such as LANDSAT-TM or SPOT, and then on determining the correlation between vegetation with NDVI values and water recharge. The result of the study shows that if the NDVI value of minimum 30% of the transited area in the catchment exceeded 0.3 then the regulation capacity of vegetation would be strongly effective and it is an index which can be stored in the data set for water balance study.
