Sjoerd van der Zee

Full professor of Ecohydrology
Chair of the Soil Physics, Ecohydrology, and Groundwater Quality Group
of
Environmental Sciences Group
Wageningen University
Netherlands


☼ Some of my background
☼ Research interests
☼ Publications

Some of my background

I am Wageningen University educated, and received my Bsc (1978), MSc (Soil Physics and chemistry, 1981), and PhD  (Agricultural and Environmental Sciences, 1988)(cum laude) at this university. In 1988, I became assistant professor, in 1992 associate professor (personal title), and in 1998 full professor (personal title) in Soil Pollution and Soil Protection. In 2005, I got the opportunity to become full professor in Ecohydrology, and responsible for the education and research programs in soil physics, ecohydrology, and groundwater quality and management.

Over the years, I have benefitted from being a guest at a number of other universities and institutions, such as Universities of Trento & Padova (Italy), KTH Stockholm (Sweden), NLH Ẳs (Norway), CNPDIA Embrapa São Carlos SP (Brasil), CSSRI Karnal (India), and WARDA St. Louis (Senegal). In addition, I have taken office as Director Research of SENSE (Graduate School Socio-Economic and Natural Sciences of the Environment 2000-2003) and General Director of WIMEK (Wageningen Institute of Environment and Climate Research (2003-2005). From 2001 till 2004, I was President of the Dutch Soil Science Society (www.bodems.nl). Since 2005, I am chair of the Scientifc Advisory Board and member of the General Board of UFZ Leipzig-Halle in Germany (www.ufz.de). Also, I am in the board of CCB and CESAR.

Research interests

  • Transport processes in (natural) porous media
  • Density driven flow in (natural) porous media
  • Availability of water for natural and agricultural ecosystems and feedbacks
  • Irrigation: salinity, sodicity, alkalinity, and waste water re-use
  • Upscaling and downscaling
  • Regional and watershed hydrology and mass transport

Transport processes in (natural) porous media

Over the years, my primary interest has been to understand the transport phenomena in porous media, such as soil and groundwater, of reacting chemicals (solutes). These solutes may interact with each other, in the aqueous phase, or with the solid matrix, biota (e.g. Micro-organisms and plant root systems). These interactions are commonly named adsorption/desorption, chemical precipitation/dissolution, and transformation or degradation. Most chemicals that are environmentally of interest are reactive, and most reactions are nonlinear with regard to the solutes' concentration in the solution. This work has been considered together with my students Boekhold, Bosma, Beltman, Temminghoff, and French, and co-workers such as A. Leijnse, C.J. Van Duijn, P. Knabner).


Besides the effect of reaction nonlinearity, on how the concentration slug or front moves, also the effect of such nonlinearity in combination with soil or groundwater heterogeneity has been my interest. To understand what happens, we (my PhD students Boekhold, Bosma, Beltman, French, Keijzer, Acharya, and Janssen; myself, and co-workers such as A. Bellin, A. Rinaldo, A. Leijnse, C.J. Van Duijn, R. Schotting, and O. Cirpka) studied how spatial and temporal moments of the solute slug or front change as a function of variability of physical and chemical properties of the (sub)soil. Nonlinearities that we considered so far, concerned the hydraulic properties of soil and aquifers, as well as the chemical sorption capacity and the parameters in the multi-component Monod degradation rate equation. In recent work, also the inverse problem, of parameter estimation, has been considered (Janssen, Valstar).


Our methods range from experimental work, to numerical 2 and 3D simulations, and stochastic and mathematical analysis.


Density driven flow in (natural) porous media

Starting in 2006, Sara Eeman will begin her PhD research on the flow dynamics of fresh water rainfall lenses floating on brackish or saline groundwater, in low lying areas in a deltaic environment. Aim is to assess the thickness of these lenses, as a function of different system parameters and to investigate how future changes (e.g. Climate) affects the dynamic balance of such lenses. Also, we address how crop yield and vegetation composition are affected by subsoil salinity. This work is strongly based on the mathematical analyses of Rink Van Dijke on multiphase flow (oil, water, air). This work is in close cooperation with prof. A. Leijnse.


In his PhD thesis, Rink Van Dijke studied two types of problems in which oil, water, and air displace each other in 2 or 3 dimensional porous media: air sparging (air injection below the phreatic water level) and the dynamics of a light oil (LNAPL) lens at the phreatic water level. For the latter problem, he presented an analytical approach for the growth of such a lense in the horizontal direction as a function of time, taking capillarity into account. Additionally, if such a lens is being removed by pumping in a bore hole or trench, also analytical expressions could be derived, which greatly extended previous analyses in the literature.


This line of work was continued by Louise Wipfler who gave more emphasis to experimental work (together with Annemieke Marsman and Gijs Breedveld; the latter working at NGI, Oslo, Norway). She presented an analytical treatment of oil infiltration in a layered soil.


Availability of water for natural and agricultural ecosystems and feedbacks

For many years, my new research group has worked on the availability of water for crops. Since this group has been renamed, where Agro-hydrology was replaced by Ecohydrology, in 2005, we also address more explicitly natural ecosystems. Water availability is for different reasons of importance for agro and natural ecosystems: indirectly also pH, redox potential, salinity, and nutrient status are affected by flow and by where the water comes from. This makes agro- and ecohydrology a basic issue with regard to the potential of plants to grow at a certain place. Additionally, not only does water availability affect plant growth potential, but also the vegetation cover affects the local hydrological balance. All these feedbacks can be well addressed with experimental techniques, remote sensing (e.g. Radar), and numerical modelling which is pursued either locally (1D), or in a regional setting (2D, 3D). The effect of such feedbacks, is of primary interest to this group.


Irrigation: salinity, sodicity, alkalinity, and waste water re-use
Although Wageningen University has a chair group that is specifically aimed at irrigation, in all its width, we feel comfortable in our joint efforts to address adverse effects of irrigation with regard to salinity, sodicity (which may affect soil structure), and alkalinity. These effects are known to be detrimental to crop yields, and vegetation development, due to water stress, soil structure deterioration, and toxicity/shortage of nutrient elements. These issues, as well as specific issues related to using waste water (treated/untreated) for irrigation water, are of primary interest to our group. Both accumulation in soil of different chemicals, its effects on soil as a growing medium, and the influences on groundwater quality are being studied, with partners throughout the world. For instance, sodicity transport was experimentally and numerically studied by Kaled honkar,CSSRI, Karnal, India.


Upscaling and downscaling
Most work so far has been done on upscaling of processes from the local process scale to the larger scales of field, watershed and region. Together with Jos Boesten and Wim Beltman, we considered the leaching and transport in the coupled soil-groundwater system, for pesticides. This was done numerically and analytically. With Willem Jan Bosma, I considered the transport of reactive (sorbing, degrading) compounds in physically and or chemically heterogeneous aquifers. This work was later extended to account for the coupled transfer of a nonlinearly degrading (Monod kinetics) contaminant, an electron acceptor or reductor, and microbial mass (Henriette Keijzer, Gijs Janssen).


A quite fundamental study was done with Ram Acharya, who considered flow and transport in pore networks. After first developing an innovative way to construct a heterogeneous pore network, and checking that this network behaves hydraulically according to accepted theory, we assessed the displacement of inert and reacting (linear, nonlinear) solutes. It appeared, that linear solutes transport according to Fickian theory at the core (network) scale. However, for nonlinear solutes, this is not the case. Neither Fickian nor Traveling Wave (TW) type of displacement was observed for the chosen initial and boundary conditions. Since the TW behaviour would be expected at the larger scale, if we extend the convection dispersion equation (CDE) with a nonlinear reaction term, we conclude that upscaling from pore to core leads to another core-scale transport equation than the CDE.


A similar conclusion was reached by Gijs Janssen, in his upscaling from (homogeneous) cores to a physically heterogeneous formation, for the case of Monod kinetics degradation. CDE and TW type of behaviour appeared to form two extremes, and in the transition parameter domain that may be of most importance, the macroscopic transport equation is yet unidentified. The implication may be that most current software for larger scale transport may be based on ‘unproven’ transport equations.


Regional and watershed hydrology and mass transport
At the moment, Tessa van Wijnen is looking at the watershed scale flow and solute transport. In the first phase of her research, she is considering mainly flow and transport in hill slopes, using numerical and analytical approaches. For instance, the applicability of the Hill Slope Boussinesq (HsB) model for inert solute displacement is currently being assessed.


Other research interests

Whereas the other research themes form the majority of my current research, I have been involved in research on the bioavailability of nutrients and contaminants. For instance, Mari Marinussen assessed the nonlethal uptake of heavy metals by earthworms, and in particular considered two major questions in detail: 1. does mixed exposure to a cocktail of metals affect their uptake, and 2. do laboratory assays with homogenized soil samples have relevance for the uptake in heterogeneous soil environments outside? Referring to our papers, we may answer ‘yes’ to both questions.


In later work, we addressed an unresolved question of why the pH-dependency of heavy metal binding in soil was not reflected in a bio-assay of Springtails, in which Mari Marinussen and Erwin Temminghoff were involved. With these two colleagues, I was able to show that this was due to an artefact in the bio-assay.


Both Thomas Schröder and Petra van Vliet were involved in the behaviour and uptake of heavy metals by organisms and plants in the Dutch floodplains of the major rivers. In papers that are currently being published, we were able to purely predict metal sorption for some metals (Cd, Cu, Zn) by such soils, without any fitting, to about an order of magnitude. Furthermore, we were able to derive quite simple expressions for the uptake of these metals by a range of organisms. This understanding is now being used to assess the causes of Zn-availability decline in rice cropping, if we turn from ponded to aerobic rice cultivation (Xiaopeng Gao, who is co-supervised by Prof. Ellis Hoffland).


Latest Publications


2008

2007

All publications

  
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