expert on groundwater flow, contaminant and heat transport modelling
Dr. Valstar is an expert in the field of modelling groundwater flow and contaminant and heat transport. His PhD-study at Delft University of Technology in cooperation with Massachusetts Institute of Technology was on inverse modelling of groundwater flow and contaminant transport. At TNO and Deltares he was involved in various projects on groundwater contamination. He can quickly build a conceptual site model from limited field data and translate that in to a numerical model. Moreover, he uses model uncertainty to design monitoring strategies to gain the relevant lacking information. The scale at which he works varies from nanosized particles in the NanoRem project up to the national scale with the OPERA program for storage of radioactive waste. His focus is on saturated groundwater flow and contaminant transport, but he has also experience in related fields such as vapor intrusion, the interaction between soil and plants and oil reservoir modelling and the incorporation of microbiological and chemical processes into reactive transport models. He has also supervised various PhD-students.
A representer-based inverse method for groundwater flow and transport applications
J.R. Valstar, D.B. McLaughlin, C.B.M. te Stroet and F. van Geer (2004). Water Resources Research, 40(5), W051161-W0511612.
Inverse Modeling of groundwater flow using model reduction
P.T.M. Vermeulen, A.W., Heemink and J.R. Valstar (2005). Water Resources Research 41 (6), 1-13.
Inverse modeling of multimodal conductivity distributions
Janssen, G.M.C.M., J.R. Valstar and S.E.A.T.M. van der Zee (2006). Water Resources Research, 42(3), W03410.
Optimal waterflood Design Using the Adjoint Method
J.F.B.M. Kraaijevanger, P.J.P. Egberts, J.R. Valstar & H.W. Buurman (2007).SPE Reservoir Simulation Symposium, 10-24.
Measurement network design including groundwater age observations to minimize contaminant breakthrough uncertainty
Gijs M.C.M. Janssen, Johan R. Valstar and Sjoerd E.A.T.M. van der Zee (2008). Water Resources Research 44(2), W02405.
Sensitivity analysis on parameters and processes affecting vapor intrusion risk
Picone, S., Valstar, J., van Gaans P., Grotenhuis T. and Rijnaarts H. (2012). Environmental Toxicology and Chemistry 31(5), 1042-1052.
The impact of low-temperature seasonal aquifer thermal energy storage (SATES) systems on chlorinated solvent contaminated groundwater
Sommer, W., Valstar, J., Van Gaans, P., Grotenhuis, T., Rijnaarts, H. (2013). Water Resources Research 49(12), 8128-8138.
An adaptive hybrid EnKF-OI scheme for efficient state-parameter estimation of reactive contaminant transport models
Gharamti, M.E., Valstar, J., Hoteit, I. (2014). Advances in Water Resources 71, 1-15.
Optimization and spatial pattern of large-scale aquifer thermal energy storage
Sommer, W., Valstar, J., Leusbrock, I., Grotenhuis, T., Rijnaarts, H. (2015). Applied Energy 137, 322-337
On the efficiency of the hybrid and the exact second-order sampling formulations of the EnKF: A reality-inspired 3-D test case for estimating biodegradation rates of chlorinated hydrocarbons at the port of Rotterdam
Gharamti, M.E., Valstar, J., Janssen, G., Marsman, A., Hoteit, I. (2016). Hydrology and Earth System Sciences 20(11), 4561-4583.
Far-field transport modelling for a repository in the Boom Clay in the Netherlands
Valstar, J.R., Goorden, N. (2016). Geologie en Mijnbouw/Netherlands Journal of Geosciences 95(3) 337-347.
Modeling the Impact of Carbon Amendments on Soil Ecosystem Functions Using the 1D-ICZ Model
Kotronakis, M., Giannakis, G.V., Nikolaidis, N.P. , Rowe, E.C., Valstar, J., Paranychianakis, N.V., Banwart, S.A. (2017). Advances in Agronomy 142, 315-352.
|1998-2000||Shell Pernis, Netherlands Positions held: Model expert||Modelling vulnerability for groundwater contamination at the site of Shell Pernis, Rotterdam, The Netherlands.|
|2000-present||Megasite Port of Rotterdam. Several studies Positions held: model expert, advisor||Feasibility studies and initiation of Regional approach for management of groundwater contamination in the Port of Rotterdam; benzene biodegradation characterization study.|
|2002||Optimization monitoring network Regge & Dinkel, Netherlands. Positions held: model expert||Optimization of groundwater monitoring networks for improving model calibration for the groundwater model for the Water Board Regge & Dinkel.|
|2004||Ford Cologne Positions held: model expert||Modeling biodegradation of groundwater contamination at the Ford site, Cologne.|
|2004||NA-interface, Positions held: model expert||Modeling biodegradation of groundwater contamination at the Ford site, Cologne.|
|2004-2006||NA-interface, Positions held: model expert||Modelling and setting up experiment for oxidation of contaminants passing the interface between groundwater and surface water.|
|2011-2014||SoilTrEC , Positions held: expert, programmer||Combining various model codes to model the soil structure development.|
|2012-2014||Citychlor, Positions held: modeling expert||Modelling a regional approach of groundwater contamination in Utrecht and local vapor intrusion risks.|
|2013-2017||OPERA, Positions held: model expert, consortium leader||Modelling groundwater flow for the entire Netherlands, including deeper geological formations both for the present situations as well as geological scenarios, such as permafrost, glaciation etc.|
|2014-2017||NanoRem, Positions held: model expert||Model behavior of nanoparticles in groundwater.|
|2018-present||Increase density of ATES systems Positions held: consortium leader, expert||Studying the effect of the increase of the number of ATES systems on the costs savings and CO2 reduction of individual ATES systems as well as the total number of ATES systems. Advice for improving the ATES permission system.|