lake models - Unesco

WQMCAL
Description of the CAL programme on Water Quality Modelling
Version 2
Basic river and lake water quality models
(with an outlook to "ecohydrological" applications)
Final report prepared by Dr. Géza Jolánkai
(with contribution by István Bíró) in the framework of the IHP-V Projects 8.1, 2.3, and 2.4
of the United Nations Educational Scientific and Cultural
Organization,
financed by UNESCO Venice Office
[pic]
Budapest, May 2000
This written material is the "hard copy" of the text and
equations of a Computer Aided Learning (CAL) programme).
Most of the text therefore appears separately from the
equations and this may make the reading through this "hard
copy" a little cumbersome. On the screen, however, the
presentation is better harmonised, as the author hopes. It
is also hoped that lucidity and understanding will be even
more enhanced by the graphs of the actual model runs, that
the user can control The author also wishes to emphasise that the software and
the models are not intended for use in practical work
(design, water pollution control planning, environmental
impact assessment, etc) and serve solely for teaching
purposes. The author therefore, also wishes to state that
he does not assume any responsibility for failures, faults
or damages caused by such non-intended use of the software.
This is a computer aided learning software (CAL) which has been prepared by Géza Jolánkai and István Bíró for UNESCO in the framework of the IHP-V projects ("teaching" project 8.1
and "ecohydrology" projects 2.3 and 2.4), to aid university teachers and
students in teaching respectively, and learning the basis of river and lake
water quality modelling. The authors wish to express herewith their gratitude towards UNESCO Venice
Office, Regional Office for Science & Technology for Europe for financially
supporting the development of this recent version of the software. They
also wish to thank the support of the International Hydrological Programme
of UNESCO for the publication of this document and the related software on
CD-ROM. The authors wish to thank herewith the support of their home institution,
the Water Resources Research Centre VITUKI, Budapest, Hungary, where the
knowledge needed for the preparation of this software has been gained in
the framework of actual water quality modelling and other environmental and
hydrological projects during many decades. Experiences gained by the first
author during some 30 years of teaching subjects related to the
"Environmental Hydrology" in various Hungarian and foreign universities and
international courses have also been utilized to a great extent. The authors also wish to emphasise that the software and the models are not
intended for use in practical work (design, water pollution control
planning, environmental impact assessment, etc.) and serve solely for
teaching purposes. Therefore the authors also wish to state that they do
not assume any responsibility for failures, faults or damages caused by
such non-
intended use of the software and the programme.
Content
page Foreword 1 Introduction 3 Basic theory of water quality models 6 Mass transport terms for deriving the basic model 8 The mass-balance equation of an elementary water body 8 The basic water quality model equation 10 Derivation of practical models from the basic model equation 11 The most simple water quality models 12 The general dilution equation 13 BOD-DO River Models 16
General Description of BOD-DO river models 16
The traditional BOD-DO model, the "oxygen-sag curve" 16
Expanded, modified, BOD-DO river models 25 DISPERSION RIVER MODELS 32
The longitudinal dispersion model 32
The transversal mixing model 36 LAKE MODELS 40
Introduction to basic lake ecosystem processes 40
General introduction to lake models 44
Input load model 46
Lake hydrology, regulation model 48
Experimental lake model. Lake model No.1 49
Dynamic nutrient budget model. Lake model No. 2 50
P balance model with sediment interaction, Lake model No. 3 52
P budget model coupled with experimental eutrophication model, Lake-Model
No.4 55
Dynamic algae growth model, Lake model No.5 57 Water quality limit values 61 Exercises for using the programme for teaching/learning 62 Testing your knowledge 90 References 93 Appendix I Pollutant transport processes in lakes i Description of the CAL programme on Water Quality Modelling
Basic river and lake water quality models Foreword This programme is the second extended version of the former computer aided
learning software (WQMCAL version 1.1, UNESCO series Technical Documents in
Hydrology NO. 13, SC97/WS/80) which has been prepared by the same authors
for UNESCO in the framework of the IHP-IV Project on the preparation of
didactic materials in hydrology (CAL), to aid university teachers and
students in teaching respectively, and learning the basis of river water
quality modelling.
This present CAL version, which includes lake eutrophication models (with
an outlook to "ecohydrological" applications) was made in such a way as to
fit into the frames of UNESCO/IHP's "Ecohydrological" programme (Projects
2.3 and 2.4 of IHP-V). The basis, or rather basics, of river and lake water quality modelling
means for the purpose of this programme and software:
1. General theoretical background (Basic theory),
2. BOD-DO models; -the traditional "oxygen sag" curve and two more
sophisticated versions
3. Dispersion-advection models: -a one dimensional pollutant-spill model
version and a 2D transversal mixing model.
4. Lake (eutrophication) models: -spanning from simple experimental
regression models to dynamic algae-phosphorus models, including a sub-
model for input load calculation and a lake-water budget (regulation)
model. The authors wish to state that no existing, commercially available river or
lake water quality softwares have been utilized for writing this programme.
The authors have developed all model softwares presented below. This means,
that the software is a genuine product, involving no copyright matters
whatsoever and that all property rights of this material and software
programme stay with the authors and UNESCO. The authors also wish to emphasise that the software and the models are not
intended for use in practical work (design, water pollution control
planning, environmental impact assessment, etc), neither in the present nor
in any of the future forms, and serve solely for teaching purposes.
Therefore the authors wish to state that they do not assume any
responsibility for failures, faults or damages caused by such non-intended
use of the softwares and the programme!! Moreover the authors will consider
such use, when discovered, the violation of their respective rights as
owners of design softwares that relay on the same or similar principles. This document and software is the second version of the earlier software by
the same authors (Basic River Water Quality Models, WQMCAL version 1.1)
expanded to deal also with the basics of lake water quality modelling, with
special regard to plant nutrient budgets and eutrophication. This also
means that all important features of version 1.1 are also included,
although in an improved, modified way. This CAL was made in such a way as to fit into the frames of UNESCO/IHP's
"Ecohydrological" programme (Projects 2.3 and 2.4 of IHP-V). In the view of
the author one of the basic tasks of ecohydrology is to trace the fate of
pollutants and especially of plant nutrients through the water-
(hydrological) and ecological systems. In doing so a major task is to
describe, as quantitatively as possible, the input-response (nutrient input
- trophic state response) relationships of lakes and standing water bodies.
This means, with other words "eutrophication modelling", the basics of
which is included in this software. Eutrophication models describing
trophic state of standing waters in function of inflow, outflow, water
level, water volume, with examples of analysing the likely outcome of
management scenarios, will be the ecohydrological core of this CAL
programme. In addition to this, a very simple catchment (watershed) model
is also included in order to facilitate the calculation of input load
(which drives the lake models) and the proportion of point-source and non-
point source components of this load. This is also an important
"ecohydrological" element of the software. Nevertheless, this watershed
model is of the "wired-in" or fixed type, where the user cannot change thy
hydrological and nutrient washoff parameters. The reason is, that in a
later third stage of the software development the authors intend to include
a relatively complex integrated catchment-modelling block, to add more
flavours to the "ecohydrological" concept of this software. It is to be noted that the ecohydrological objective will be fully met when
this third part of the series