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To study the effect of different physical and economic factors including capital investment in the form of concrete lining and the labor cost for dredging services, upon the outflow of water from the Ghanats of Fars Province, one hundred Ghanats have been selected from four different counties of Fars province, through a stratified random sampling. The results obtained show that both concrete lining and dredging effort have a significant effect upon the water flow from the Ghariats and that a one Rial investment in concrete lining yields on the average 12 Rials; While the average rate of return from the latter is less than one. The results indicate,however, that capital stockenboddied in the Ghanats in the form of concrete lining is less than the optimum level. Therefore, the main recommendation of this study is further allocation of financial resources by public authorities for the investment in lining activities.