Master project of Esther van Baaren

Addition of salt migration to a simulationprogram for groundwater flow

Esther van Baaren

Site of the project:
Royal Haskoning
Hoofdweg 490
3067 GK Rotterdam

start of the project: August 2006

In December 2006 the Interim Thesis has been appeared and a presentation has been given.

The Master project has been finished in June 2007 by the completion of the Masters Thesis and a final presentation has been given. For working address etc. we refer to our alumnipage.

Summary of the master project:

Introduction

Triwaco is a software package for hydrological model simulations. The development started 30 years ago with a collection of programs for groundwater flow. Thereafter many options are included and a graphical user interface has been added. The package has been developed and maintained by Royal Haskoning and is used by water control company and institutes in The Netherlands and abroad.

Triwaco offers an integrated modelling environment for unsaturated, saturated, drainage/infiltration and surface water flow.

The simulator is suitable for the specific circumstances in The Netherlands and takes into account the density variations due to salt concentrations in the groundwater. However, the simulator is not able to simulate the instationary development of the salt concentrations. There is a need to include this in order to predict the effects of the expected sea water level.

Rise in groundwater level after the first inflow in the dam and the subsequent artificial recharge (Omaruru, Namibia).

Technical background

Triwaco subdivided the underground in domains based on geological layers. The lateral groundwater flow is computed per layer by a finite element method based on triangular elements. The vertical transport between layers is done by a finite difference method. The right-hand-side term is used to implement the transport between the layers. This mixture of finite element and finite difference methods is very suitable to simulate the groundwater flow.

The question is if this approach also works for the salt migration in the groundwater. To answer this question we consider two steps:

Determine the best numerical method to simulate salt migration on a finite element grid, which consists of triangular elements;
Implement this approach in a simulation program for Triwaco.

The Triwaco-simulation programs are written in Fortran, mostly -77 with some extensions to Fortran90.

Contact information: Kees Vuik

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