Construction of reservoirs within the Ebro basin with a total capacity of 6,28 hm3 throughout the 20th century has caused the initial regulation of this freshwater system. The mean flow characteristics of the lower Ebro river have changed from the pre-dam to the post-dam period. A balance has to be reached between offstream water uses such as agriculture, industry etc. and inflow requirements in order to maintain the habitat for riparian or aquatic life. With the Tennant method, the Range of Variability Approch (RVA) and a physical habitat model (Phabsim) three models have been applied in this work for the lower Ebro reach in order to estimate instream requirements.Combining habitat modelling with a 2D or 3D hydraulic model is very likely to allow for specific remodelling of river morphology to improve habitat availability as a metegating measure. This activity would allow for meeting EU Water Directive demands.