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 properties, nevertheless off-site effects are often neglected. A single process landscape evolution model (LandscApe ProcesS modelling at mUlti dimensions and scaleS (LAPSUS)) is used to explore the impacts of land use changes on landscape 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 pathways 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, olive/almond, wheat, semi-natural vegetation and a rest group (bare, river beds, urban). For a period of 10 years LAPSUS calculates soil redistribution (erosion and sedimentation) for different scenarios of input parameters. These inputs are a digital elevation model (e.g. slope lengths and angles), precipitation, soil erodibility, and land use related infiltration. For each scenario, different assumptions are made on direction and rate of land use change. As an example, effects of abandonment of olive orchards are demonstrated, simulating both a fast and gradual change for a period of 10 years. Each scenario produces different spatial and temporal patterns of total amounts of erosion and sedimentation throughout the landscape. As a result, potential land use related parameters like soil depth, infiltration and flooding 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 characteristics of the landscape, not only the area suffering from land use changes is affected. Increasing erosion and run-off rates from upstream-located olive orchards have an impact on down slope local run-on, erosion and sedimentation rates. In this case, the citrus orchards situated in the valley bottom locally suffer damages from re-sedimentation events but benefit from the increase in run-on water and nutrients. Concluding, off-site effects from an exogenous driven change in land use (EC subsidies) can trigger endogenous land use changes in adjacent areas.

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