We propose the novel integrated modelling procedure 3H-EMC for the determination of the environmental
flow in rivers and streams; 3H-EMC combines Hydrological, Hydrodynamic and Habitat
modelling with the use ofthe Ellvironmental Management Classes (EMCs) that are defined by the Global
Environmental Row Calculator. We apply 3H-EMC in the Sperchios River in Central Greece, in which
water abstractions tor irrigation cause significant environmental impacts. Calculations of the
hydrodynamic-habitat model, in which the large and the small chub are the main fish species, suggest
discharge values that range from 1.0 m3/s to 4.0 m3/s. However, hydrological modelling indicates that it is
practically difficult to achieve discharges that are higher than approximately 1.0-1.5 m3/s. Furthermore,
legislation suggests significantly lower values (0.4-0.5 m3/s) that are unacceptable From the ecological
point of view. This behaviour shows that a non-integrated approach, which is based only on
hydrodynamic-habitat modelling does not necessarily result in realistic environmental flows, and thus
an integrated approach is required. We propose the value of 1.0 m3/s as the "optimum" environmental
flow for Sperchios River, because (a) it satisfies the habitat requirements, as expressed by the values oF
weighted useable area that are equal to 2180 and 1964 m2 for the large and small chub, respectively, and
correspond to 82 and 95% oftheir respective maximum values, (b) it is consistent with the requirements
of Environmental Classes A and B, whose percentiles are higher than 75% for discharge (77.2%) and For
habitat availability (>83.5% For the large chub and >85.0% for the small chub), (c) it is practically
achievable from the hydrological point of view, and (d) it is higher than the value proposed by the Greek
legislation. The proposed modelling approach can be applied to any river or stream using the same or
similar modelling tool5, which should be linked via suitable coupling algorithms.
«
We propose the novel integrated modelling procedure 3H-EMC for the determination of the environmental
flow in rivers and streams; 3H-EMC combines Hydrological, Hydrodynamic and Habitat
modelling with the use ofthe Ellvironmental Management Classes (EMCs) that are defined by the Global
Environmental Row Calculator. We apply 3H-EMC in the Sperchios River in Central Greece, in which
water abstractions tor irrigation cause significant environmental impacts. Calculations of the
hydrodynamic-hab...
»