The impact of changes in agricultural land use and practices as a controlling driver of hydrologic response and as a source of diffuse pollution, are studied in the Joumine River basin, discharging into the Ichkeul Lake, northern Tunisia, a UNESCO World Heritage site since 1979. The lake is characterized by a very specific hydrological functioning based on a seasonal alternation of water levels and salinity through its link to the Mediterranean Sea. Three Landsat images, in situ surveys and SWAT modelling were used to simulate and assess streamflows and nitrate loads under retrospective land uses.

River networks are structural and functional backbones of river basins. They frequently display general scaling properties through their hierarchical topology. Their mathematical description further feeds geomorphology-based hydrological analyses and modelling approaches that require little calibration. Nevertheless, particular river basins display widely diverse geomorphometric structures in relation to relief, geology, climate and anthropogenic constraints, as well as various hydrological structure-function relationships. A robust, flexible and systematic approach is thus needed to allow for joint spatial, topological and scaling analyses, in order to explore the hydro-geomorphological diversity. The HydroStruct software application is dedicated to such analyses, and to easily link geomorphometric observations with hydrological analysis and modelling approaches, such as geomorphology-based transfer functions, accounting for rainfall variability within rainfall-runoff modelling, and impact assessment of landscape and hydraulic changes. HydroStruct was developed within the generic OdefiX framework, which provides Java software components to allow co-development and interfacing of object-oriented models.