Calibration and Reliability in Groundwater Modelling: From Uncertainty to Decision Making (Proceedings of ModelCARE’2005, The Hague, The Netherlands, June 2005). IAHS Publ. 304, 2006. pp.261–267.

Simulation of groundwater–seawater interactions in the Aral Sea basin by a coupled water balance model

JERKER JARSJÖ1, Irina Alekseeva2, Corinna Schrum3 & GEORGIA DESTOUNI1

1 Dept of Physical Geography and Quaternary Geology, Stockholm University,
SE-106 91 Stockholm, Sweden

jerker.jarsjo@natgeo.su.se

2 Institute of Oceanography, University of Hamburg, Center of Marine and Climate Research, Bundesstrasse 53, D-20146 Hamburg, Germany

3 Geophysical Institute, University of Bergen, Allégaten 70, N-5007 Bergen, Norway

Abstract Large-scale irrigation has resulted in a dramatic shrinking and salinization of the Aral Sea. These changes also affect the groundwater discharge into the sea and the evaporative outflow from the sea surface. With the overall aim to quantitatively understand the processes governing the Aral Sea water balance and their effects on the groundwater discharge into the sea, we develop a 3-D coupled sea–groundwater budget model, forced by meteorological and river inflow data. The balance estimations performed indicate that the groundwater discharge into the sea must be between 2 and
6 km3 year-1. For the 15-year simulation scenarios considered, the groundwater inflow increases as the sea surface level drops. In addition, the model successfully reproduces seasonal cycling of the Aral Sea and predicts seasonal groundwater discharge fluctuations on top of the continuous long-term sea surface level drop.

Keywords Aral Sea; ECOSMO; groundwater; numerical modelling; sea model; water balance