GLOBAL MONTHLY ENVIRONMENTAL FLOW REQUIREMENT BASED ON THE NET PRIMARY PRODUCTIVITY OF RIVERS

Abstract

 A constant environmental flow requirement (EFR) is insufficient to protect river ecosystems supported by seasonal flow fluctuations. The objective of this research is to estimate global monthly environmental flow requirements using a fluvial plant biomass model to highlight the timing and magnitude of the maximum flow requirements. The average global EFR estimated by this model was 45% of mean annual discharge. In contrast, the maximum monthly EFR was 149% which was tripled to the average EFR. The maximum monthly EFR is larger in the area where the primary productivity as well as seasonal fluctuation of flow are large. For such regions, not only base flow but also maximum EFR should be considered. In order to validate this model, we compared the EFR calculated by three global models and 28 places in 17 countries. The verification indicated that our model has the highest accuracy among the compared global models.