Building the future by doing more together

ERLAND – Direct and indirect impacts of climate change on soil erosion and land degradation in Mediterranean watersheds
Coordinator - João Pedro Carvalho Nunes
Programme - Projetos de Investigação Científica e Desenvolvimento Tecnológico - 2008 (PTDC/AAC-AMB/100520/2008)
Execution dates - 2010-06-01 - 2014-05-31 (48 Months)
Funding Entity - FCT - Fundação para a Ciência e a Tecnologia
Funding for CESAM - 102444 €
Total Funding - 197988 €
Proponent Institution - Universidade de Aveiro
Participating Institutions
Universidade de Évora

Soil erosion is a critical driver for desertification in Mediterranean regions, degrading the soil's capacity to sustain vegetation under marginal conditions (Vogiatzakis et al., 2006). Global climate change could have significant impacts on soil erosion, but these impacts have received little research attention since they involve complex interactions between multiple factors governing erosion rates (Kundzewicz et al., 2007). 


One the few existing studies on future soil erosion in the Mediterranean was carried out by this project's Principal Investigator (PI). It showed that, due to the increasing aridity expected from climate change, the impacts on soil erosion will depend on the interaction between lower rainfall and lower vegetation biomass productivity (Nunes et al., 2008). Similar results were obtained in U.S. regions where climate is expected to become drier (Nearing et al., 2004). However, these studies have important limitations, as reviewed by Nunes and Nearing (in press):


1) Climate change scenarios are not properly downscaled in space and time, which can have significant impacts on the predictions made by erosion models (Zhang, 2007);


2) Most studies focus on hillslope or (in rare instances) channel processes, ignoring gully erosion, while climate change could impact each of these processes in different ways (Nunes et al., in press);


3) The lack of sufficient erosion data limits the proper evaluation of the erosion models used in these assessments, a problem which is common in other fields of soil erosion research (Boardman, 2006).


The main aim of the ERLAND project is therefore to address these gaps, continuing the PI's research line (e.g. Nunes et al., 2008, in press) in a subject which has so far received limited attention. To this end, the proposal seeks to estimate the impacts of climate change on soil erosion in representative Portuguese agroforesty watersheds, due to changes in rainfall, runoff generation and vegetation cover.


Ecohydrological modeling will be the main analysis tool, and one key innovative element of this project. A new vegetation, runoff and erosion model will be built, aiming to continuously simulate sediment detachment and transport within catchments in a simplified way. The innovation of this model will be the detailed simulation of spatial patterns of soil erosion without the complexity of current event-based models, allowing it to be applied for much longer time-spans: years instead of single storms. The model will be built by joining together existing and widely tested concepts for vegetation (Williams, 1995), hydrological and erosion modeling (Morgan and Duzant, 2008) in an innovative way, taking advantage of the model-building capacity present in the team (Nunes et al., 2005).


The project will focus on two catchments that correspond to typical combinations of climate and land cover/use under humid and dry climate conditions. They are therefore expected to reveal distinct erosion responses under the same climate change scenarios and will provide valuable information on region-specific adaptation strategies.


Data on climate, vegetation, hydrology and soil erosion will be collected at different spatial scales (hillslope, gullies, catchment), to allow for a correct calibration of the model in simulating the most important erosive processes. The field monitoring methodology will follow previous approaches implemented by the team (project EROSFIRE 2; PTDC/AGR-CFL/70968/2006). The model will then be used for diagnostic purposes to characterize the study areas for a control period (1961-1990), using where possible long-term hydrological records, agricultural statistics and satellite imagery to validate model results.


Climate change scenarios for 2071-2100 will be downscaled for the study areas based on existing regional climate models, downscaled through a statistical approach developed by the team (Qian et al., 2002). The model will be forced with the downscaled climate scenarios. The analysis of results will focus on the erosive impacts of changes in key erosive factors, i.e.: rainfall regime, vegetation cover (including increased wildfire frequency), soil moisture and hydrological regimes. The impacts will be assessed in terms of soil loss at the slope scale, gully erosion processes and catchment sediment yield. This will be one of the few analysis performed for Mediterranean conditions, and one of the first worldwide to explicitly include gully erosion and sediment connectivity. Scenarios of adaptation and land-use changes due to climate change will also be developed for both study areas and tested using the model.


The results of ERLAND will allow a characterization of the most important impacts of climate change could cause on different erosive processes within Mediterranean catchments, and help define the costs and benefits of different adaptation options.




Members on this project
Jan Jacob Keizer
Consultant

Principal Investigator

Research fellowship: field data collection and modelling
Research fellowship: field data collection and modelling
Field Hydrologist
Field Monitoring
Nelson J. Cabaços Abrantes
Agriculture and Nutrient Processes
Peter Cornelis Roebeling
Socio-economic scenarios

Research fellowship: socio-economic scenarios

CESAM Funding: