I work as Associate Professor within the research department  Ecosystem and Landscape Dynamics  of the Institute of Biodiversity and Ecosystem Dynamics (IBED).

My research interests are related to geomorphological, hydrological, soil and land degradation processes (see button 'research interests').
I'm especially interested in:
1) the development of emergent landscape properties as a result from the interaction between different physical, chemical or biological processes at different scales in space and time
2) regreening of degraded environments, both by active measures and spontaneous landscape processes
3) the role and fate of organic carbon in erosion and sedimentation, both by field and laboratory research
4) planetary science, using terrestrial processes to understand analogue situations under non-terrestrial gravity and atmospheric conditions
I'm involved in teaching in the MSc Earth Sciences as well as in the BSc Future Planet Studies and incidentally in the BSc Biology, and the MSc Forensic Sciences.
I'm also acting as programme director of the MSc Earth Science education programs.
I'm Chair of the Editors in Chief of CATENA, an interdisciplinary journal of Soil Science-Hydrology-Geomorphology, focusing on Geoecology and Landscape Evolution
For more information click the research button (top page) or go to:

Links

Research Interests

1) the interaction of physical, chemical or biological processes in landscape processes, connectivity of landscape processes and landscape evolution.
2)  the development of emergent landscape properties as a result from the interaction between different processes.
3) the role and fate of organic carbon in erosion and sedimentation both in the field as well as in the laboratory.
4) comparative geomorphology using terrestrial geomorphology to understand analogue situations on Mars.

Hydrological Connectivity in Degrading Semi-Arid and Sub-humid Environments

Influencing the connectivity of water and sediment transfer networks in abandoned andsemi-natural lands

Within the RECONDES project connectivity between different land units is studied, with emphasis on abandoned and semi-natural lands. By influencing connectivity i.e. by increasing disconnectivity, water and sediment can be retained on site, preventing degradation, soil quality loss  and water loss, and off site problems. This can be achieved by applying appropriate revegetation strategies or by improving land management strategies at stretegic points in the landscape where degradation processes are prominent (Erosion Hotspots). This study is carried out at two regions in the Mediterranean which are under the threat of desertification: in Murcia SE Spain, at the dry end of the Mediterranean climates and Tuscany in Italy a more wet Mediterranean environment. Results from ongoing measurements in the Guadalentin basin will be adapted for use to quantify environmental dynamic processes.

In the Murcia region work was concentrated on the joint Carcavo fieldwork site, south of the city Cieza. It has many types of land use including  seminatural scrubland and forest, abandoned orchards and cereal fields, reforested areas and rain-fed agriculture (olive and almond orchards and cereals). There are traces of ancient mining activities.  The area is strongly degraded and various attempts have been made to restore the area by reforestation of hillslopes and by building dams in the channel. Many small terraces have been abandoned and are now prone to erosion.

This work has also been extended to the Sanmatenga region in Burkina Faso focusing on the coupling and decoupling of hydrological and erosion processes.

Furthermore a NWO-SANPAD funded project has been carried out titled

"Vegetation invasions: implications for hydrological and erosion response, land degradation and climate change" 

looking at the  impact of the invading P. Incana bush species in abandoned grasslands in the Eastern Cape province of South Africa, leading to increased degradation of these grassland and accelerated erosion (see photo below).

Recently a new project has been started (MedAfforest) on "the global effect of afforestation on landscape structure, soil properties and carbon sequestration, and hydrological and geomorphological dynamics. The project includes a comparison with the consequences of naturally revegetated areas (shrubs and forests) using different experimental areas in Mediterranean mountain areas". This project has been funded under Marie Curie grant obtained by Dr. Estela Nadal-Romero. See also the web link below

Scale effects, thresholds and connectivity in geomorphological processes in humid sub-humid and semi-arid environments.

The last years I have been working on aspects of land degradation of Mediterranean environments in S Europe. This work concentrated on process-pattern relationships between three levels of scale: the plot scale, the hillslope or Response Unit scale and the catchment scale.

In  SE Spain the Alqueria field station ( 3°47'06 N, 1°49'53 W) is maintained where measurements commenced in 1996. Runoff and sediment are measured in a nested measurement set-up.

At the fine scale (plot) the relationships between vegetation pattern and top soil characteristics, such as soil aggregation and infiltration have been studied, as well as soil hydrological processes. At the response unit scale (hillslope) the incorporation of finer scale processes is being studied in relation to pattern development. Intrinsic and external characteristics of these units are being quantified.  

Hydrological and geomorphological connectivity between land units plays a key role in this research. At various scales different thresholds are involved in the connectivity between land units or hillslope components. Connectivity is related to rainfall characteristics, land unit characteristics as well as land use and management. Response units are used as basic land units with specific responses to scale up to broader scales: the catchment scale, using GIS, remote sensing and (landscape) modelling techniques. A field station has been managed in the Guadalentín basin  from 1995 till 2012 where measurements were being carried out at three scales ( plant scale and hillslope scale; subcatchment scale; and catchment scale) related to rainfall, soil moisture, runoff and sediment generation. From 2005 on also soil organic carbon transport was measured.
This work has been partly  funded by the EU MEDALUS projects and the NWO-ALW programme Hierarchy of Degradation Processes in Mediterranean Environments.

The photo below shows full hydrological connectivity in the catchment after a 1 in 10 year rainfall event, breaching soil and water conservation dams (Canada Hermosa, Murcia, 15-09-2009)

Experimental research on the fate of soil organic carbon

In the new soil erosion laboratory facility of IBED currently research is carried out on the fate of soil organic carbon in relation to erosion and sedimentation processes. Under controlled rainfall and temperature conditions the solid, dissolved and gas phase of organic matter and derived organic carbon containing components like carbondioxide and DOC, is studied. The fate or organic carbon is studied during erosion, transport and deposition processes.
With the results of this research we hope to contribute to the ongoing scientific discussion on the fate of organic carbon in soils in relation to erosion and deposition as it is not clear whether it is a sink or source in the global carbon budget. This research is part of the PhD work of Xiang Wang who focusses on the the fate of organic carbon in relation to erosion and deposition processes as well as MSc student Paul Romeijn.

Degradation rates and fate of organic carbon

Evaluation of current degradation rates with respect to past historical degradation rates by coupling current erosion rates at various levels of scales to proxy records of recent sediments in shallow reservoirs and historical rainfall data including the production, transport and deposition of organic carbon (see photo below). Also the study of truncated soil profiles and calcretes is being used to assess past degradation rates. Current production, transport and (temporary) storage of soil organic matter is monitored in a nested catchment set-up.

Using vegetation to  reduce adverse hillslope processes, including mass wasting.

Within the project EU Framework 5 ECOSLOPES project (http://construction.ntu.ac.uk/ecoslopes/) the possible applications of eco-engineering were explored in problems of erosion, slope failure and tree uprooting. Field site were studied with regard to slope failures and erosion in relation to land abandonment and natural re-vegetation of fields and slopes. Land abandonment influenced slope stability leading to slumping and mudflows. The role of water pathways and water availability in relation to vegetation was studied as well as the role of roots with respect to soil mechanical properties. The change in soil and vegetation parameters as linked to degrading processes was studied over time upon natural vegetation succession on abandoned lands. Furthermore the role of roots was studied on improving slope stability.

Erosion processes on Iceland and Mars

In 2008 research has been initiated to understand the role of aeolian erosion in the development of scree cones on Iceland. These erosion processes affect hyaloclastite rock formations of tuya's (subglacial volcanic table mountains) and scree cones develop when finer material is deflated and the courser textured material falls down (See photo below).
Similar processes are expected to occur on Mars as comparable deposits and landforms exist, only the processes occur under different gravity and atmospheric conditions.
Research is currently carried out and developed to unravel the effects of gravity and low atmospheric pressure on aeolian processes and scree cone development, and links to comparable Martian environments.

Degradation of Andean environments in Peru

The high Andean neo-tropical grassland ecosystems (paramo, jalca and puna) are under threat of degradation as a result of climate change, encroaching population and land use change, increased water withdrawal and mining.
Research is carried out in the Peruvian Andes partly within the context of the PPA project on the vulnerability of these fragile ecosystems, focusing on gathering basic data on soils, water, geomorphology and geo-conservation.
Furthermore the impact of land use change on the hydrology and carbon stock of the soils are important aspects of study.

In cooperation with the Instituto de Montana in Peru studies of geo-ecological systems are carried out in the Cordillera Blanca in Ancash, Peru with respect to the impact of climate change on water quality, landscape vulnerablity and land use. This is actually done in the Rio Quillcay catchment upstream of Huaraz and in the Rio Negro ctachment, upstream of Olleros.

The research is connected to the bi-annual MSc course "Field Course Geo-ecological Systems" an elective course within the MSc Earth Science programme of the University of Amsterdam, which was organized in Cajamarca in 2008 and 2010, and in Huaraz in 2012 and 2014.