The Development of a Computerized
System for Auditing Real Time or Historical Water Use from Large
Reservoirs in Order to Promote the Efficiency of Water Use
Report No. 1300/1/05
July 2005
EXECUTIVE SUMMARY
Introduction
South Africa is a water scarce country. The water situation
reports contained in the National Water Resources Strategy (NWRS, First
Edition 2004) indicate that an alarming number (more than 50%) of South
Africa’s water resources are considered to be either
fully-allocated or over-allocated. The statistic is
concerning given the fact that few economically viable water
augmentation options (e.g. the building of dams and inter-basin
transfers) exist, as most viable sites have already been
developed. Given the limited potential to address the
situation with a supply-side solution, focus has shifted to the
improvement of water use efficiencies and water resource
management. Improved levels of water use efficiency may
liberate water with little to no reductions in the production levels
associated with the use of the water. However, it has been
documented that improved levels of water use efficiency may in fact
reduce the water available to downstream water users as a result of
reduced return flows associated with gains in water use efficiency
(Grové, 1997).
The efficient operation of large dams is particularly important as dams
increase the yield of catchments by retaining water during periods of
water abundance for use during periods of scarcity. The
underlying objective of this research project was to assess options
with which efficiencies related to the use of water could be improved,
with particular reference to the efficiency of water use from large
dams. The original thinking was that water use
efficiencies would be improved by the introduction of the water audit
system for the following reasons:
- The intensified monitoring of water releases from the dam
(associated with the water audit system) would potentially reveal
inefficiencies associated with water releases from dams,
- The monitoring of actual water use by downstream users
could reveal over-use by water users
- The monitoring of river flows downstream of the dam could
reveal the presence of unauthorised water use upstream of the
monitoring point. In this way unauthorised users could be
prosecuted by water managers.
Clearly, improved monitoring networks and a system (auditing
procedures) of reconciling actual water use against the entitlements of
the water users to the use the water were central to the originally
envisaged water audit system. In the course of the project
however, it was discovered that a
“use-it-or-lose-it” principle is generally adopted
for the management of water use from large dams in South Africa. The
implication of the principle is that if a given water user does not use
his water use entitlement in a certain time-period (generally a year),
the entitlement is lost in that time-period. An investigation
of the potential impact of this principle on water use efficiency
revealed that the principle does not promote improved water use
efficiency.
In contrast, the principle may in fact induce the inefficient use of
water. The reasoning relates to the fact that different
categories of water users are identified in South Africa (e.g. high,
medium and low assurance users). Irrigators, who are
responsible for over 50% of South Africa’s water use (NWRS,
First Edition 2004), are generally awarded lower levels of assurance
than industrial and domestic water users. Low assurance water
users pay lower water use charges than users with higher water use
charges. The assurance levels influence (i) priority levels
with which water users are to receive water in times of water scarcity,
and (ii) the level of water restrictions faced by the respective
categories of water users during periods of water restrictions.
The inefficiency results from the fact that water users do not have
incentive to use water more efficiently. The low assurance
users in particular have every incentive to use all the water they can,
particularly when dams levels start dropping and the impostion of
restrictions starts being discussed by water resource managers and
stakeholders. These water users will try to use as much water
as they can before restrictions are imposed. This action
paradoxically leads to dam levels which draw down quicker than they
would have if no restrictions were imminent. The quick draw
down in dam levels as restriction levels are neared then results in the
imposition of restriction levels. Bear in mind that there may
be several dam restriction levels, with restrictions becoming more
severe as the dam levels lower.
The realisation of the potential negative impact of the
use-it-or-lose-it principle of water use from dams on water use
efficiency changed the course of the project to a large extent, as an
alternative “use-it-or-bank-it” principle was
explored, as this was believed have a number of benefits over the
existing system, including:
- A water management system based on the
“use-it-or-bank it” principle would promote the
adoption of water use efficiency by water users. Irrigators
for example may adopt irrigations systems and scheduling practices
which are more water use efficient, thus requiring less
water. The liberated water could then be banked by the
irrigator, which could be used at a later stage, or could be traded
with other water users.
- The definition of water use entitlements is far clearer
under a system based on the “use-it-or-bank-it”
principle as opposed to a system based on the
“use-it-or-lose-it” principle. One is
thus more able to successfully implement a water audit system, which
reconciles water use against the entitlements to use the water by
various individuals, based on a “use-it-or-bank-it”
management system as opposed to the
“use-it-or-lose-it” system.
The focus of the project thus shifted away from a purely
“operational water audit system”, to an
understanding of what would be required to implement the new water
management system for large dams based on the
“use-it-or-bank-it-principle”. The
management system based on the “use-it-or-bank-it
principle” has been referred to as a Fractional Water
Allocation and Capacity Sharing (FWA-CS) water management system in
this document, whereas the management system based on the
“use-it-or-bank it” principle is referred to as a
Priority-based River and Reservoir Operating Rule (PRROR)
system. The assessment of the FWA-CS arrangement included an
assessment of the National Water Resources Strategy (NWRS, First
Edition 2004) and 1998 National Water Act to ensure that it would be
legally possible to adopt this new water resource management
approach. It was found that nothing in the 1998 National
Water Act or National Water Resources Strategy (NWRS, First Edition
2004) disallowed the adoption of the new FWA-CS water management
approach. Secondly, it was necessary to assess if the
computer models currently used by the Department of Water Affairs and
Forestry (DWAF) could in fact support the new water resource management
approach. It was found that the Water Resources Yield and
Water Resources Planning models used by the DWAF could not in their
current form support the FWA-CS water management approach. A
model was sourced which could support the FWA-CS water management
report. The model, the Mike Basin model, was developed by the
Danish Hydraulic Institute. The authors tailored the Mike
Basin model to include some functionality required for South African
conditions, such as the development of an In-stream Flow Requirement
(IFR) module, as well as a module to derive yield curves for water
resources.
The project research area
The Mhlathuze Catchment was chosen as the research project area, as it
is one of the first catchments in the country in which the Compulsory
Licensing process has been initiated, as the catchment is currently
deemed to be over-allocated. Furthermore, the catchment is
heavily dependent on water stored in a large dam located in the upper
reaches of the catchment, i.e. the Goedertrouw Dam. The
Mhlathuze Catchment was a suitable research area given the reliance on
the Goedertrouw Dam, as well as the fact that the Mhlathuze Catchment
is one of the first catchments to undergo the compulsory licensing
process in South Africa, as a key objective of the project was to share
with the stakeholders and water resource managers involved in the
Compulsory Licensing process any relevant findings from this research.
Project objectives and
activities undertaken
Objective 1: To develop a
water audit system for large dams.
The scope of the deliverable was increased to include the development
of an audit system for a catchment. The option to use the
WRYM supporting the PRROR institutional arrangement for the further
development of the audit system was not pursued as the WRYM was unable
to support the FWA-CS institutional arrangement, and was unable to
operate on a near-real-time basis (which would be required to calculate
water use entitlements during times of water scarcity).
Instead, the decision was taken to purchase the Mike Basin planning
model (for approximately R40,000), as the model can support the FWA-CS
as well as the PRROR institutional arrangements, and can operate on a
daily, weekly or monthly time step. The model was tailored in
order to meet the requirements of water resource planners, as the IFR
and Yield modules were developed to interact with the Mike Basin model
via the COM interface.
Objective 2:
To increase the understanding and knowledge of the practicalities,
strengths and weaknesses, and potential costs and benefits of
developing and implementing a “water audit system”
for use by CMAs. Although a fully operational water auditing
system was not developed in the course of this project, largely as a
result of the increased project scope and assessment and accommodation
of the FWA-CS institutional arrangement, the requirements of this aim
are discussed within this document. Furthermore, persons in
DWAF were consulted on a few occasions to assess if and how the FWA-CS
institutional arrangement could be integrated into the operational
management of water resources. Stakeholders were also
consulted to assess their interest in the institutional arrangement,
and the benefits, strengths and weaknesses of the FWA-CS institutional
arrangement.
Objective 3:
To transfer knowledge/technology to decision makers and stakeholders.
A number of presentations of the FWA-CS institutional arrangement were
held with DWAF: Head Office, DWAF: Regional Office as well as
stakeholders in the Mhlathuze Catchment. The Mike Basin
software has been demonstrated within DWAF.
Objective 4:
To assess the feasibility of implementing the water audit system for
the management of South Africa’s water resources.
Consideration has been given to the 1998 National Water Act, NWRS
(First Edition, 2004) and discussions have been held with DWAF:HO,
DWAF:RO and Mhlathuze stakeholders in order to report on the
feasibility of (i) introducing the FWA-CS institutional arrangement in
order to promote water use efficiency from large dams, and (ii) the
feasibility of developing and implementing a water audit system.
Project outcomes
The following are notable outcomes of the project:
- It has been recommended to the DWAF by Prof A.
Görgens as part of a User Requirements Survey related to the
modelling needs to support the Compulsory Licensing process in the
Mhlathuze Catchment, that a pilot project be undertaken in which the
concept of FWA-CS be further explored.
- In the course of the project the Mike Basin model has been
declared an “emerging model” in the DWAF
"Guidelines for models to be used for Water Resources Evaluation",
Version 2, Nov 2003.
- A few Directorates in DWAF have shown an interest in the
use of the Mike Basin model, and other range of Mike models, resulting
from the exposure given to the model as a result of this project.
- The earlier version of the Mike Basin model did not
accommodate for the fractional allocation of run-of-river flows very
well. As a result of the project and communication with the
DHI, the Mike Basin model is being modified to better accommodate
FWA-CS.
- Modules have been developed which enable the Mike Basin
model to be used by water resource planners. Although
stochastic hydrology has not been included in this development, it is
believed that this will be achievable.
- Stakeholders have been exposed to the concept of FWA-CS, as
well as to the PRROR institutional arrangement
- The monitoring equipment installed in
the Mhlathuze Catchment will remain there for the improved management
of water resources.
Capacity building
During the course of the project the capacity of a number of
individuals and organisations was developed. Details of these
are provided in Appendix A of this report.
Conclusions
The following conclusions can be drawn from this research
- Due to the water scarcity in South
Africa, the efficient use of the water resources we have available to
us is vital.
- The Priority-based River and Reservoir
Operating Rule (PRROR) is the currently adopted water management system
in South Africa. The PRROR system is founded upon the
“use-it-or-lose-it” principle for water use from
large dams. This water management system is believed to
result in the inefficient use of water from dams. A new water
management system, which is based on a
“use-it-or-bank-it” principle for water use from
large dams was explored, upon which an a water audit system can be
developed to promote further water use efficiency.
- The NWRS (First Edition, 2004) and 1998
National Water Act do not prohibit the adoption of an institutional
arrangement such as FWA-CS. The FWA-CS institutional
arrangement is however a new potential management option, and one which
can not be supported by the Water Resources Yield Model (WRYM) and
Water Resources Planning Model (WRPM) in their current form.
- The Mike Basin model was purchased and further developed in
order to
accommodate for FWA-CS in a manner suitable for water resources
planning purposes. Without this development the FWA-CS
institutional arrangement would be of little value to
stakeholders in the Mhlathuze, as water resources planning is a key
component of the Compulsory Licensing process.
- The Mike Basin model was not fully
developed into a water auditing system in the course of this project,
for either the FWA-CS or the PRROR institutional arrangements, however
details of how the auditing system could be developed were discussed.
- Many of the stakeholders in the
Mhlathuze Catchment showed an interest in the FWA-CS institutional
arrangement, and the Sugar Association of South Africa (SASA), recently
renamed to the South African Sugar Research Institute (SASRI), has
formally requested that the institutional arrangement be further
explored in the course of the Compulsory Licensing process.
- It may be the case that due to the
newness of the FWA-CS institutional arrangement, and also due to the
pressure to complete the Compulsory Licensing process, particularly in
stressed catchments in South Africa, that the FWA-CS institutional
arrangement is not initially adopted. However, as the value
of water increases in catchments and monitoring systems are improved,
and the CMAs become operational and established it is believed that the
FWA-CS institutional arrangement will become increasingly more
attractive to implement.
- The FWA-CS institutional arrangement is
viable in relatively small catchments where water users receive the
bulk of their water from dam releases (and not from tributary
flows). The flows from tributaries complicate the FWA-CS
institutional arrangement in that more monitoring is required, and the
apportionment of flows from the tributary flows will be important as
water users will want to use as much tributary flow as possible in
order to maximise the banking of water in dams.
- It must be highlighted that water
banking has been undertaken in the Mhlathuze Catchment during the
drought experienced in the 1990’s. Furthermore the
Catchment is one of the only catchments where water users pay for
actual water use, as opposed to paying for their full
entitlements. This, combined with a monthly and six monthly
water management report related to the water usage in the catchment
have resulted in high water use efficiency within the Mhlathuze
Catchment.
Recommendations
The following recommendations, resulting form this project, are made:
- Weather data collected using the
Automatic Weather Station installed at the Goedertrouw Dam as part of
this project showed a very poor correlation with DWAF recorded
data. Details for this poor correlation are not clear, and it
may be appropriate for this to be further investigated.
- The 1998 National Water Act and NWRS
(First Edition, 2004) make very little mention of the exact details in
which water resources are managed, i.e. how the rules that govern the
apportionment of water amongst competing water users are reflected in
computer models, and how the results are used in the licensing
process. Although this is a very technical discussion, it may
be one which is required in order to build the capacity of stakeholders
in catchments, so that they can better understand how their
entitlements are influenced by upstream water users, and how their
activities influence downstream water users.
- Accurate weather forecasts could
improve the water use efficiency from large dams in that water users
may require less water to be released from dams if they know with a
suitably high level of confidence that rainfall is expected in the
near-future. Due to the travel time associated with water
released from the Goedertrouw Dam, it can take up to 2.5 days for the
released water to reach water users. In the Mhlathuze
Catchment water users will thus require high confidence 3 day forecasts.
- The Mike Basin model makes use of a
different solver to the WRYM. A recommendation is that
further research be undertaken related to the solvers used for various
node and channel hydrological models used locally and internationally,
and that the advantages and disadvantages of the respective solvers be
compared.
- It is recommended that the ACRU model
be integrated via the COM interface with the Mike Basin
model. This link will enable ACRU to gain the functionality
of a multi-user, multi-reservoir planning model (such as Mike Basin),
which even be used on an operational level, as the Mike Basin model can
operate at on a daily time-step, and can be hot-started.
- It is recommended that a more detailed
legal review be undertaken regarding FWA-CS to assess if slight
amendments may be required to the wording of clauses in the 1998
National Water Act to better accommodate FWA-CS.
- It is recommended that the full link
between Mike Flood Watch and Mike Basin be explored in order to
complete a fully functional water auditing system for catchments, for
both PRROR and FWA-CS institutional arrangements. This
development will enable the water resource planning model to be
operated at an operational (i.e. near real time level). This
functionality is required for water audits to be undertaken on a
near-real time basis, which is often required during very dry periods.