AQUASIM Short Program Description

Short Program Description (version 2.1a, March 2001)

In order to support environmental scientists in finding an «adequate» model of the system they are investigating, a computer program is necessary, which allows its users to perform simulations using different models, to assess the identifiability and to estimate the values of model parameters (using measured data), and to estimate prediction uncertainty. The computer program AQUASIM was developed to perform such analyses for technical and natural aquatic systems.

AQUASIM allows its users to define the spatial configuration of the system to be investigated as a set of compartments, which can be connected to each other by links. Currently, the available compartment types include mixed reactors, biofilm reactors (consisting of a biofilm and a bulk fluid phase), advective-diffusive reactors (plug flow reactors with or without dispersion), saturated soil columns (with sorption and pore volume exchange), river sections (describing water flow and substance transport and transformation in open channels) and lakes (describing stratification and substance transport and transformation in the water column of the lake and in adjacent sediment layers). Compartments can be connected by two types of links (lakes can not be linked to other compartments yet). Advective links represent water flow and advective substance transport between compartments, including bifurcations and junctions. Diffusive links represent boundary layers or membranes, which can be penetrated selectively by certain substances. The user of the program is free in specifying any set of state variables and transformation processes to be active within the compartments. For the model as defined by the user, the program is able to perform simulations, sensitivity analyses and parameter estimations using measured data. These features make the program a very useful research tool. Calculated results can be plotted to the screen (window interface version only), written to a Post-Script file for transfer to a printer, or written to a text file for external post-processing.

Due to the possibility of starting with a simple model and gradually increasing model complexity later on by considering additional variables and processes, AQUASIM is also well suited for application by students in exercises accompanying a lecture on environmental modelling. The possibility of comparing different models and the capability of the program to estimate the uncertainty of calculated results (for a given, certain model) also stimulate discussions on the limits of the reliability of model predictions.

Three versions of the program are available. The window interface version (w) uses the graphical user interface of a machine, the character interface version (c) can be run on a primitive teletype terminal, and the batch version (b) is designed for long calculations to be submitted as batch jobs.

AQUASIM was developed mainly for internal use, but it is also available to commercial companies at a price of CHF 2000 (ca. US$ 1720) and to university institutes at a price of CHF 1000 (ca. US$ 860). This price includes binary versions of the program for one platform, a user manual and additional documentation. Error reports and suggestions for program improvements are welcome, but technical support for program usage is not provided (however, an electronic user group is established to facilitate communication among program users and since 1996 AQUASIM courses are organized regularly). With the license mentioned above, the program may be used by several members of the same research group on several machines and for teaching purposes. Additional licenses must be obtained for different platforms and for program usage by other research groups. All warranties concerning the use of this software are disclaimed.

Refer to the following table for an overview of the currently supported platforms:

Hardware	Operating System	Window System	w	c	b
Sun SparcStation	Solaris 2.x	-	-	x	x
IBM RS/6000	AIX 3.2.x	-	-	x	x
HP 700 series	HP-UX 9.0	-	-	x	x
DEC Alpha series	VMS 6.x	-	-	x	x
DEC Alpha series	DEC Unix	-	-	x	x
Intel 80486/Pentium	Windows 95/98/NT/2000	native	x	x	x
Intel 80486/Pentium	Linux 7.0		-	x	x

x Platform supported
- Platform not supported
AQUASIM system files may be exchanged between all of these platforms.

References

Survey of program features
Reichert, P., «AQUASIM - A tool for simulation and data analysis of aquatic systems», Water Sci. Tech., 30(2), 21-30, 1994.

Survey of programming techniques
Reichert, P., «Design techniques of a computer program for the identification of processes and the simulation of water quality in aquatic systems», Environmental Software 10(3), 199-210, 1995.

Detailed technical report including manual for version 1.0
Reichert, P., Concepts underlying a computer program for the identification and simulation of aquatic systems, Schriftenreihe der EAWAG Nr. 7, Swiss Federal Institute for Environmental Science and Technology (EAWAG), CH-8600 Dübendorf, Switzerland, 386 p., 1994.

Manual and tutorial for version 2.0/2.1:
Reichert, P., AQUASIM 2.0 - User Manual, Swiss Federal Institute for Environmental Science and Technology (EAWAG), CH-8600 Dübendorf, Switzerland, 214 p., 1998.
Reichert, P., AQUASIM 2.0 - Tutorial, Swiss Federal Institute for Environmental Science and Technology (EAWAG), CH-8600 Dübendorf, Switzerland, 213 p., 1998.