Examples of my/our Research Projects:

• Climate change and the effects on mud bank migration and Mangroves forests at the Guiana coasts

The coastal region of Suriname is low-lying, flat and vulnerable for anticipated sea level rise and increasing storm frequencies. This area is also essential for agriculture, for fresh drink water from the sandy sediments and for human settlements. Managing such vulnerable and valuable environment requires in-depth understanding of governing processes and interactions steering the system. The coastal system is extremely complex: large mud supplies from the Amazone results in mud banks migrating along the coast influenced by complex wind patterns.

• We study this ecosystem using timeseries of satellite images in Google Earth Engine (GEE) and by modelling currents, winds and mangrove development.
• A short movie is available at: https://www.youtube.com/watch?v=tn7bVCln0Yk&t=43s

The photo shows the tidal mud flats and mangroves at 'Weg naar Zee' in Suriname.

• Studying glacier dynamics using Unmanned Airborne Vehicles

We study debris-covered glaciers in the Himalaya and their contribution to melt water. These debris-covered glaciers remain relatively unstudied because of the inaccessibility of the terrain and difficulties of doing fieldwork. Using hundreds of RGB images acquired by UAVs we create timeseries of very detailed, i.e.15 cm pixel resolution, orthomosaics and orthoDEMS. Such imagery enables us to study glaciers dynamics over the monsoon, the development and disappearance of supra-glacier lakes and the role of ice cliffs on the glacier. One of our study areas is the Lirung glacier in the Langtang National Parc.

• See also: http://mountainhydrology.org/
• A short movie is available at: http://www.youtube.com/watch?v=3XNs1pcMEes

The photo shows the drone ready for launch at the lateral moraines of the Lirung glacier

• Laboratory experiments to study spectral response of plants under stress

In a laboratory experiment we investigated the spectral response in the solar part of the electromagnetic spectrum, 400 to 2500 nm, of plants (Buxus sempervirens) to different types of stress. We put six groups of plants to five types of stress: 1) total saturation by water, 2) chlorine poisoning, 3) light deprivation, 4) water deprivation, 5) water deprivation and heat, and one control group. The experiment lasted 52 days.

• Every three days we measured spectral reflectance of all plants and studied 1) the visual effects of stress and 2) the effects on the spectral signature over time. Visible signs of stress are curling and shrinking of leaves, decoloring of leaves and leaves become breakable.
• Spectral effects start by reduced radiance absorption in the 1400 and 1900 nm water absorption bands and next in the visible red and blue wavelengths followed by reduced NIR reflectance. The effects of different types of stress started at varying moments in time but did not differ in spectral response. Spectral indices that showed best early signs of stress are the mSR705 and the CTR2.
• Published as: De Jong S.M., E.A. Addink, P. Hoogenboom & W. Nijland, 2012, The spectral response of Buxus sempervirens to different types of environmental stress, a laboratory experiment. ISPRS Journal of Photogrammetry & Remote Sensing 74, pp.56-65.

The photo shows a Near Infrared Photo of a Buxus plant under our ASD Spectrometer.

• ERT to detect soil moisture extraction by vegetation

In semi-arid areas with rocky soil substrates it is difficult to determine from what depth vegetation extract water during the growing season. Since water is often limiting vegetation growth in semi-arid areas, information on water extraction depth is pertinent.

• We used Electrical Resistivity Tomography (ERT) over the dry and hot summer gap (June - September) and for different geological substrates: dolomite, flysch, basalt and calcareous sandstone. The test site is located in the Peyne watershed in southern France. The difference in measured resistivity over the dry summer period is an indicator for water extraction.
• It is concluded that tree and plant roots deeply penetrate into the fractured and weathered bedrock and that water extraction takes place from as deep as six meters while soil depth is often not more than 50 cm.
• Published as Nijland W., M. van der Meijde, E.A. Addink & S.M. de Jong, 2010, Detection of soil moisture and vegetation water abstraction in a Mediterranean natural area using electrical resistivity tomography. CATENA 81(3), 209-216.
• Published as Alamrya, A.S., M. van der Meijde, M. Noomen, E.A. Addink, R. van Benthem, S.M. de Jong, 2017, Spatial and temporal monitoring of soil moisture using surface electrical resistivity tomography in Mediterranean soil. Catena 157, 388-396. 

The figure ilustrates the concept of Electric Resitivity measurements

• Using remote sensing to create distributed maps of rainfall interception by vegetation

Water balance models often works with lumped values for rainfall interception by vegetation e.g. one interception value per agricultural field or for an entire forest. We developed a method to produce spatial continuous maps of rainfall interception by vegetation using remotely sensed Leaf Area Index values (LAI), canopy moisture storage values (Smax) and linear spectral unmixing to assess fractional coverage per pixel (Cp). The methods is based on Ashton's interception model (1979). The map on the left shows interception values between 0 and 3.7 mm for a 30 mm rainfall event in the Peyne area in southern France.

• Published as: De Jong S.M. & V.G. Jetten, 2007, Estimating Spatial Patterns of Rainfall Interception from Remotely Sensed Vegetation Indices and Spectral Mixture Analysis. International Journal of Geographical Information Science 21, 529-545.

The figure shows a spatially distributed rainfall interception map for part of the Peyne area in France.

• Using Remote Sensing and Object-Based Image Analysis techniques to survey Bubonic Plague in Kazakhstan

Bubonic plague is potentially an enormous health threat. It wiped out about half of the European population in the 14th century. Nowadays there are around 100 fatalities per year worldwide. Plague is spread by a bacteria, Yersina pestis, living on fleas which are living on Gerbils. By mapping the abundance of Gerbils burrows and the occupancy of the burrows on the Steppes of Kazakhstan using high resolution earth observation imagery and object-based image analysis techniques the public health risk in the region is evaluated and the hot spots for bubonic plague are identified.

Published as:

Addink E.A., S.M. de Jong, S.A. Davis, V. Dubyanskiy, L.A. Burdelov & H. Leirs, 2010, The use of high-resolution remote sensing for plague surveillance in Kazakhstan. Remote Sensing of Environment 114(3), 674-681.

Wilschut L.I., E.A. Addink, J.A.P. Heesterbeek, L. Heier, A. Laudisoit, M. Begon, S.A. Davis, V.M. Dubyanskiy, L.A. Burdelov & S.M. de Jong, 2013. Potential barriers and corridors for plague spread in central Asia. 2 July 2013 to International Journal of Geographical Health 12(1):49.

Wilschut L.I., E.A. Addink, J.A.P. Heesterbeek, V.M. Dubyanskiy, S.A. Davis, A. Laudisoit, M.Begon and S.M. de Jong, 2013. Mapping the distribution of the main host for plague in a complex landscape in Kazakhstan with an object-based approach using SPOT-5 XS, Landsat 7 ETM+, SRTM and multiple Random Forests. International Journal for Applied Earth Observation and Geo-information 23, 81-94.

Photo of a Gerbil (R. opimus) on the steppes of Kazakhstan, a potential host of the Yesina pestis bacteria, a carrier of Plague.

• Soil erosion and runoff modelling in Mediterranean catchments

The photo shows soil erosion at work during an intense rain/hail event close to Lac Salagou.

Filling this further soon......