Linking land use and landscape process modelling: a case study for the Alora region (south Spain)

Changing land use is increasingly known to affect on-site landscape propert ies, nevertheless off-site effects are often neglected. A single process la ndscape evolution model (LandscApe ProcesS modelling at mUlti dimensions an d scaleS (LAPSUS)) is used to explore the impacts of land use changes on la ndscape and soil properties. Examples are shown for both on-site as well as off-site effects of land use change and the influence of different pathway s of change. A case study area near Alora, in the province of Malaga, south Spain is selected. In this area the main land use consists of citrus, oliv e/almond, wheat, semi-natural vegetation and a rest group (bare, river beds , urban). For a period of 10 years LAPSUS calculates soil redistribution (e rosion and sedimentation) for different scenarios of input parameters. Thes e inputs are a digital elevation model (e.g, slope lengths and angles), pre cipitation, soil erodibility, and land use related infiltration. For each s cenario, different assumptions are made on direction and rate of land use c hange. As an example, effects of abandonment of olive orchards are demonstr ated, simulating both a fast and gradual change for a period of 10 years. E ach scenario produces different spatial and temporal patterns of total amou nts of erosion and sedimentation throughout the landscape. As a result, pot ential land use related parameters like soil depth, infiltration and floodi ng risk change significantly too. The scenario of an abrupt change produces the highest erosion rates compared to the gradual change scenario and the baseline scenario. However, because of the multi-dimensional characteristic s of the landscape, not only the area suffering from land use changes is af fected. Increasing erosion and run-off rates from upstream-located olive or chards have an impact on down slope local run-on, erosion and sedimentation rates. In this case, the citrus orchards situated in the valley bottom loc ally suffer damages from re-sedimentation events but benefit from the incre ase in run-on water and nutrients. Concluding, off-site effects from an exo genous driven change in land use (EC subsidies) can trigger endogenous land use changes in adjacent areas. (C) 2001 Elsevier Science B.V. All rights r eserved.