Estimating the impact of land use change on catchment fluxes: the Gaiana case study.

Abstract: Agricultural policies try to manage land use change wisely. However such changes do not affect local economies only, but also runoff and sediment yield patterns. In order to estimate the impact of land use change on water and sediment fluxes, the erosion model KINEROS2 was used on the Gaiana basin (8.7 Km2), nearby Bologna, as its outlet was gauged with a monitoring station. The model was calibrated with measured discharge and sediment data and simulations were run using different land use scenarios, which were produced according to changes likely to occur because of “Set Aside” policies. Introduction and aims Agricultural policies do not affect local economies only, but other factors as well, like runoff and sediment yield patterns in natural catchments. It is well known that soil erosion control can be achieved by intervening on agricultural patterns. When farming is replaced by grasslands, bush lands and woods both surface and channelled erosion processes are mitigated. As a consequence, relevant environmental benefit might be achieved if farms were addressed to non-agricultural land covers. Positive results have been gained in many cases via the application of set-aside policies (Reg. CEE n. 1094/88): fields remain uncultivated for five years, either kept lying fallow or reafforested but not used for agricultural purposes. Present study aimed at assessing what effects set-aside policies might have when applied to agricultural areas set on hillsides with unsuitable slope conditions and occurring erosion phenomena, by means of simulations created by the event oriented, physically based hydrologic model KINEROS2.