Associate Professor

University of Aarhus, Department of Earth Sciences

Ny Munkegade building 520, 8000 Aarhus C

+45 8942 3643

sc@geo.au.dk

Research interests:

Hydrogeology (water balance, groundwater/surface water interaction, urban hydrology, pumping test analysis, density dependent groundwater flow).

Groundwater modeling (quantification of parameter and prediction uncertainty, influence of structural error on model prediction, data requirements in model calibration, use of geophysical data in model calibration)

Advisor for PhD students:

Theis Sejer Andersen (ongoing): Geology and groundwater flow in buried valleys.

Søren Erbs Poulsen (ongoing). Geology and groundwater on a coastal barrier.

Jan Jeppesen (ongoing). Integrated modelling of the urban hydrological cycle.

Jesper Heidemann Langhoff (2005). Ground water surface water interaction with focus on streams on alluvial plains in West-Jutlkand, Denmark.

Dorte Dam (2002). Incorporation of geophysical data in parameter estimation of groundwater flow models.

Thomas Nyholm (2000). Stream-flow depletion caused by groundwater abstraction near alluvial streams.

Ulla Lyngs Ladekarl (2000). Soil moisture, evapotranspiration and groundwater recharge in forest and heathland. (Co-supervision)

Bo Elberling (1996). Transport og forbrug af ilt i jordens umættede zone. (Co-supervision)

Key publications:

Christensen, S., and J. Doherty (2008): Predictive error dependencies when using pilot points and singular value decomposition in groundwater model calibration. Advances in Water Resources, vol. 31, no. 4, p. 674-700.

Christensen, S., and J. Doherty (2008): Using many pilot points and singular value decomposition in groundwater model calibration. In: Calibration and Reliability in Groundwater Modelling: Credibility in modelling (ed. J.C. Refsgaard, K. Kovar, E. Haarder, and E. Nygaard). Proc. ModelCARE 2007 (Copenhagen, September 2007). IAHS Publ. no. 320, p. 235-239.

Christensen, S., C. Moore, and J. Doherty (2006): Comparison of stochastic and regression based methods for quantification of predictive uncertainty of model-simulated wellhead protection zones in heterogeneous aquifers. Calibration and Reliability in Groundwater Modelling: From Uncertainty to Decision Making (Edited by M.F.P. Bierkens, J.C. Gehrels, and K. Kovar), Proceedings of ModelCARE’2005, The Hague, The Netherlands, June 2005,. IAHS Publ. 304, p. 202-208.

Cooley, R.L. and S. Christensen (2006): Bias and Uncertainty in Regression-Calibrated Models of Groundwater Flow in Heterogeneous Media. Advances in Water Resources, vol. 29, no. 5, p. 639-656.

Langhoff, J.H., K.R. Rasmussen, and S. Christensen (2006): Quantification and regionalization of groundwater-surface water interaction along an alluvial stream. Journal of Hydrology, vol. 320, no. 3-4, p. 342-358.

Christensen, S. (2005): Comment on ”Senisitivity analysis and determination of streambed leakance and aquifer hydraulic properties” by X. Chen and X. Chen. Journal of Hydrology, vol. 303, no. 1-4, 316-321.

Ladekarl, U.L., K.R. Rasmussen, S. Christensen, K.H. Jensen, & B. Hansen (2005): Groundwater recharge and evapotranspiration for two natural ecosystems covered with oak and heather. Journal of Hydrology, vol. 300, no. 1-4, 76-99.

Poeter, E.P., Hill, M.C., Banta, E.R., Mehl, S., and Christensen, S. (2005): UCODE_2005 and Six Other Computer Codes for Universal Sensitivity Analysis, Calibration, and Uncertainty Evaluation: U.S. Geological Survey Techniques and Methods 6-A11, 283p.

Christensen, S. and R.L. Cooley (2004): User guide to the UNC1NLI1 package and three utility programs for computation of nonlinear confidence and prediction intervals using MODFLOW-2000. U.S. Geological Survey, Techniques and Methods Report 2004-1349, http://pubs.usgs.gov/tm/2004/tm6A10/

¹ Christensen, S. (2004): A synthetic groundwater modelling study of the accuracy of GLUE uncertainty intervals. Nordic Hydrology, vol. 35, no. 1, pp. 45-59. (¹ Winner of the prize for the best article in Nordic Hydrology in 2004-2005, awarded by the Nordic Hydrological Association at the XXIV Nordic Hydrological Conference.)

Nyholm, T., K.R. Rasmussen and S. Christensen (2003): Estimation of stream flow depletion and uncertainty from discharge measurements in a small alluvial stream. Journal of Hydrology, vol, 274, no. 1-4, p. 129 - 144.

Dam, D. and S. Christensen (2003): Including geophysical data in groundwater model inverse calibration. Ground Water, vol. 41, no. 2, p. 178-189.

Christensen, S., and Cooley, R.L. (2003) Experiences gained in testing a theory for modelling groundwater flow in heterogeneous media. In: Calibration and Reliability in Groundwater Modelling: A Few Steps Closer to Reality (ed. by K. Kovar & Z. Hrkal). Proc. ModelCARE 2002 (Prague, June 2002). IAHS Publ. no. 277, p. 22-27.

Nyholm, T., S. Christensen and K.R. Rasmussen (2002): Flow depletion in a small stream caused by ground water abstraction from wells. Ground Water, vol. 40, no. 4, p. 425-437.

Langhoff, J., S. Christensen. and K.R. Rasmussen (2001). Scale dependent hydraulic variability of a stream bed on an outwash plain. In: Impact of Human Activity on Groundwater Dynamics, edited by H. Gehrels, N.E. Peters, E. Hoelm, K. Jensen, C. Leibundgut, J. Griffioen, B. Webb, and W.J. Zaadnoordijk. IAHS Publ. no. 269: 205-212.
Christensen, S. (2000): On the estimation of stream flow depletion parameters by drawdown analysis Ground Water, vol. 38, no. 5, p.726-734.

Christensen, S. and R.L. Cooley (1999): Evaluation of prediction intervals for expressing uncertainties in groundwater flow model predictions. Water Resources Research, vol. 35, no. 9, p. 2627-2639.

Christensen, S. and R.L. Cooley (1999): Evaluation of confidence intervals for a steady-state leaky aquifer model. Advances in Water Resources, vol. 22, no. 8, p. 807-817.

Elberling, B., F. Larsen, S. Christensen and D. Postma (1998): Modelling gas transport in a confined unsaturated zone during atmospheric high pressure cycles. Water Resources Research, vol. 34, no. 11, p. 2855-2862.

Christensen, S., K.R. Rasmussen and K. Møller (1998): Prediction of regional ground-water flow to streams. Ground Water, vol. 36, no. 2, p. 351-360.

Christensen, S. (1997): On the strategy of estimating regional-scale transmissivity fields. Ground Water, vol.35, no. 1, p. 131-139.

Christensen, S. and R.L. Cooley (1996): Simultaneous confidence intervals for a steady-state leaky aquifer groundwater flow model. In Calibration and Reliability in Groundwater Modelling, ed. by K. Kovar & P. van der Heide, IAHS publ. no. 237, p. 561-569.

Christensen, S. (1995): Prediction of Log-Transmissivity - 1. Using Specific Capacity. Nordic Hydrology, vol. 26, no. 1, p. 1-20.

Christensen, S. (1995): Prediction of Log-Transmissivity - 2. Using Lithology and Specific Capacity. Nordic Hydrology, vol. 26, no. 1, p. 21-36.

Christensen, S. (1994): Hydraulic conductivity and transmissivity estimation for groundwater models at various scales. PhD Thesis, English summary. Dept. of Earth Sciences, Aarhus University, 21 p.

Christensen, S. (1994): Hydrological model for the Tude å catch¬ment. Nordic Hydrology, vol. 25, no. 3, p.145-166.

Refsgaard, A., S. Christensen and J. Reffstrup (1988): Finite Element Analysis of Controlled Saltwater Intrusion in Heterogeneous Reservoirs. Nordic Hydrology, vol. 20, no. 1, pp. 25-42.