Hartbeespoort Dam Integrated Biological Remediation Program

Transcription

Hartbeespoort Dam Integrated
Biological Remediation Program, Phase I
Peer Review and Follow-up Report
March 2013
Juha Keto
Limnologist
Director of Lake Vesijärvi
Remediation Project, Finland
(retired)
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Foreword
Water protection and lake remediation has been one
of the key focus areas of the North-South Co-operation
project between City of Lahti (Finland) and Bojanala
Platinum District Municipality (South Africa) since it
started in 2002.
The author of this peer review, Mr. Juha Keto, has over
four decades’ experience of lake restoration. Since his
graduation as a M.Sc. in Limnology in 1973, he has had
extensive experience as a planner and research manager
for lake remediation research, mainly in the city of Lahti.
Mr. Keto has authored and co-authored numerous scientific publications as well as books for the general public.
He has also attended the World Limnology Congress
(SIL) three times: in 1982, 1990 and 2004.
Through the North-South Co-operation, Mr. Keto has followed the development and progress of the Harties Metsi
a Me program since its beginning. The colleague-tocolleague expertise exchange between the Finnish and
South African lake remediation programs has been mutually beneficial, as ideas and solutions have been shared
and developed further.
This report is a first-person account by Mr. Keto regarding his experiences and insight into the progress made
in Phase I of the Harties Metsi a Me program, as well as
his views on the way forward. In the peer review process,
the reviewers act as a critical friend, giving feedback on
the success as well as the challenges.
The North-South Co-operation Project hopes that the
Harties Metsi a Me program and its stakeholders find
this peer review process valuable. Eutrophication is a
challenge shared by North and South; let us continue to
find the solutions together!
In Lahti, Finland 16th of April, 2013
Ms. Anna Aalto
Northern Coordinator
North South Local Government Cooperation Project
Lahti Region Development LADEC Ltd
email: [email protected]
mob: +358 (0)50 559 4046
Table of Contents
Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Peer Review of Harties Metsi a Me Phase I. . . . . . 4
Integrated monitoring. . . . . . . . . . . . . . . . . . . . . . . . 4
Biomass harvesting, debris
removal and treatment. . . . . . . . . . . . . . . . . . . . . . . 5
Shoreline rehabilitation
and floating wetlands . . . . . . . . . . . . . . . . . . . . . . . . 6
Food web restructuring. . . . . . . . . . . . . . . . . . . . . . 6
Sediment management. . . . . . . . . . . . . . . . . . . . . . . 7
Reduction of the external nutrient load. . . . . . . 7
Information and Communication Centre. . . . . . 7
Discussion and recommendations. . . . . . . . . . . . . . 8
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Annexes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13–19
Hartbeespoort Dam Integrated Biological Remediation Program, Phase I
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Background
Since 2006, the North-South Local Government Cooperation program has carried out numerous peer reviews concerning various environmental issues in turns
between the cooperation partners, namely the City of
Lahti, Finland and the Bojanala Platinum District Municipality, South Africa. In the curriculum of the 2013 cooperation program, there was a follow-up plan of a peer
review on the results of the first phase of Hartbeespoort
Dam Integrated Biological Remediation Program 2007–
2012, later referred as Harties Metsi a Me.
Hartbeespoort Dam is a lake of exceptional scenic beauty
and deserves to be conserved. It is heavily overloaded.
Since the 1970s it has suffered from increasing eutrophication problems and, with a current surface load of
10 g P/m2/a and over according to the traditional limnological models, it falls in the category of hypertrophic
lakes. Harties Metsi a Me started more than five years ago
with the main objective of relieving the burden of the dam.
The following data and documents of Harties Metsi a Me
are used as peer review material
• Business Plan 2010–2015, Draft June 2009,
Final November 2011
• Foodweb Monitoring Progress Report: Phase I,
October 2012
• Integrated Monitoring Progress Report: Phase I,
November 2012
• Sediment Management Progress Report: Phase I,
December 2012
• Consolidated Progress Report: Phase I,
December 2012
• Electronic data on Harties Metsi a Me DVD,
November 2012
• Harties Metsi a Me web pages
http://www.harties.org.za/
• SAICE Civil Engineering, August 2012 Vol. 20 No 7,
9-55. ISSN 1021-2000
The results of the successful Lake Vesijärvi Remediation
Project are utilized as reference material.
During the three-day site visit in February 2013, I met
many of the Harties Metsi a Me personnel, the management staff, monitoring team, management fishing team
and information-communication team. At the dam I
talked with workers managing the dam and the littoral,
manufacturing floating wetlands, skimming algal scum
and removing water hyacinth and debris.
I interviewed Harties Metsi a Me Project Leader P Venter
and Project Manager S Morar about the results and challenges of the project. Allof the issues mentioned in this
report were covered. I also had discussions with
Dr. Z Cukic and Dr. J Koekemoer concerning the sediment
management and food web re-structuring questions.
• Fish Health and Edibility Progress Report,
November 2012
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Peer Review of
Harties Metsi a Me Phase I
This peer review is limited by the time and funds available. A more comprehensive review should be carried out
in order to fully justify such a complex program as the
Harties Metsi a Me, a huge multifaceted project offering
numerous opportunities for research and education of
eutrophication scientists and professionals.
The Harties Metsi a Me Business Plan is a holistic, ambitious and innovative approach which is also limnologically sound. It addresses historical, current and future pollution dealing not only with the dam itself, but also with
the dam’s catchment and beyond. It offers a sustainable
and comprehensive philosophy of a bigger picture for
meeting the challenges of the global change. It is nationally and transnationally important and interesting, as it is
also the pilot biomanipulation project in South Africa.
Considering eutrophication as one of the main issues to
face with South Africa’s Water Resources Management,
this program correctly would serve as a great national importance for the development of South Africa’s
eutrophication abatement strategy and interesting as
the pilot bioremediation undertaking in specific climate
conditions.
It is also a program of international significance, particularly for the sub-Saharan countries suffering of similar
or even worse eutrophication of increasingly scarce and
limited water resources.
The overall goal of Harties Metsi a Me is to minimize both
the external and internal nutrient loading of the dam in
order to recover disturbed ecosystem and to balance it
at a lower trophic levels thus suppressing cyanobacteria,
excessive hyacinth growth and to relieving numerous
nuisances of eutrophication and limitations in water
uses.
Following the international experiences this approach is
suitable and probably the only appropriate one for given
climate conditions. In comparison with other alternative
dam remediation measures, it is sustainable on a long
term and cost-effective offering also new jobs creation,
a fact that carries great weight and importance for the
given socio-economic conditions in South Africa.
It should be pointed out that the Harties Metsi a Me Program has created and implemented various pioneering
ideas and innovations (Annex 1) that could be applied
nationally and internationally as well.
The program includes several sub-programmes that are
reviewed and discussed lower down.
Self-evidently the success of the plan is dependent of
the execution of the pollution control standards in the
drainage area. Harties Metsi a Me is challenging all the
authorities and actors having regulatory power over the
waste water treatment and catchment area management
for better efficiency.
Integrated monitoring
Integrated Monitoring Program (IMP) widely benefits
various national and regional monitoring programs and
fills the gaps in water quality data base through its own
monitoring program. IMP is designed to provide data
required for considering eutrophication and for dealing
with mass balances in specific runoff patterns and climate conditions. It serves Harties Metsi a Me itself but is
supposed to also serve authorities, scientific community,
specialists and numerous interested parties.
The main objective of IMP is the generation of quantitative information on the physical, chemical and biological
characteristics of the Crocodile River as the main tributary as well as characteristics of various sub-catchments
and the Hartbeespoort Dam water body. In addition,
weather stations intended to provide data on weather
conditions were installed around the dam area, otherwise very important to understand changes of water
quality and changes observed in the dam water body.
The objectives and related outcomes of IMP are supposed to be achieved by means of an aligned and coordinated approach ensuring
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• monitoring to be performed in accordance with set
protocols
• define state of upstream rivers.
• define initial trophic level of the dam and changes
occur in local-specific conditions
• monitor effects of implemented measures
• set Resource Quality Objectives for the dam and upper
sub-catchments
• faster identification of sources of pollution and
response time
• a cost effective web-based integrated monitoring
system
• web-based data capturing, reporting and analysis
system
• internal audit and compliance monitoring to be cross
checked by up and down stream water users,
Due to the complex monitoring systems that are required to quantify the ongoing in variability in flow and
the associated dynamics in water quality, there were in
the past a number of obstacles in the way of accessing
relevant data, especially the data on external loading
from the catchment. As a response to these challenges
a sophisticated web based monitoring station with a
auto-sampler able to monitor several basic parameters
(i.e. flow, water temperature, pH, EC, DO) was installed
at the Crocodile River three kilometres upstream of the
river mouth.
Biomass harvesting, debris removal
and treatment
Harties Metsi a Me has been successful in algae and hyacinth biomass harvesting, debris removal and treatment,
particularly through new methods and innovations of
the project (Annex 1). During the first phase, altogether
32 000 m3 of algal scum, 65 000 m3 of hyacinths and 2
000 tons of debris are removed from the dam, turned to
compost and vermicast, which were reused for shoreline
remediation and floating wetlands, and the debris were
recycled and disposed. In terms of nutrient balance and
according to the unpublished data, it means roughly 60 t
of total phosphorus removed by the hyacinths and 3 t by
algal mass as well as the inherent energy that would have
played a significant role in the additional mobilization of
the internal load of the dam if not removed.
Besides of removal of phosphorus and organic carbon
the aesthetic and recreational issues are also important
to consider as one of positive outcomes of this sub-project. With much less floating particles on dam surface did
not only improve the aesthetics and safety on the dam
for boating and water skiing but would also potentially
resulted in less stink bombs that bothered business, residents and tourists passing over the dam wall area.
With biomass harvesting tools and equipment, Harties
Metsi a Me can protect swimming and recreational sites
from undesired conditions. The rate of harvesting of
hyacinth and algal soup as well as the rate of processing
(i.e. converting to biomass) is still lower than required
one. It should be additionally improved by hiring of
appropriate machinery and enlarging processing capacities at other critical points around the dam. Shredding
of the hyacinths prior to the vermiculture would greatly
enhance the process.
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Shoreline rehabilitation and floating
wetlands
Harties Metsi a Me has rehabilitated 9 000 m² of shoreline and constructed 5 000 m² of floating wetlands. The
ambitious goal is to establish 42 ha of wetland within the
dam at the eastern shore of the dam (Ifafi wetland).
From the point of view of ecological lake management,
the scale of shoreline rehabilitation and construction of
floating wetlands is globally significant, especially as it
deals with a highly regulated dam which is also under
a great pressure to sustain economic growth and development. An additional positive outcome of shoreline
rehabilitation and floating wetlands is a considerable
increase in the overall diversity on all trophic levels.
Food web restructuring
Food web restructuring by removal of coarse fish is
successfully used to manage eutrophicated boreal lakes
in order to increase energy flow through the nutrient
web and decrease the internal loading caused by the
benthivorous fish. Harties Metsi a Me follows that pattern. It aims to bring current fish population back to the
indigenous one and desired fish species (Mozambique
Tilapia, Yellow Fish and other small species) instead of
the common carp and catfish that currently dominate the
fish stock of the dam with 70 % of the population.
Although only about one ton of total phosphorus is
removed by the fish biomass, this should not be used as
an indicator for the impact on the nutrient balance in the
dam. The removed fish have allowed for less pressure
on other fish species, as well as other components in the
food web, and the change in the fish population structure
has already shown to have improved conditions considerably in terms of increased zooplankton which would
further suppress and control the algal growth within the
dam.
Since the introduction of the shoreline and food web
reconstruction, the declining trends of chlorophyll concentrations (NEMP website, Harties Metsi a Me Foodweb
Monitoring Progress Report: Phase I, 2012) and Microcystis dominance are observed. Clear water states are
more prevalent and prolonged (Harties Metsi a Me Foodweb Monitoring Progress Report: Phase I, 2012), with
the dominant species being filamentous green algae Spirogyra sp. and followed by the growth of aquatic plants
Potamogeton pectinatus and Potamogeton crispus.
The positive response of the ecosystem is also observed
in the increase in both zooplankton and macro-invertebrate species diversity and numbers, especially under
the floating wetlands as opposed to the ambient water
(Kokkinen & Siri 2010 (unpublished data), Harties Metsi
a Me Foodweb Monitoring Progress Report: Phase I,
2012).
A total management fishing catch of Harties Metsi a Me
Phase 1 has been 200 t (catfish 110 t, carp 90 t) or 100
kg/ha. Harties Metsi a Me fishing team intends to double
the coarse fish catch.
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Sediment management
This sub-project deals with nutrient rich sediments built
up within the dam that contribute in nutrient recycling
but also with allochthonous sediment and nutrient load.
The conclusion of the studies of dam sediments within
the project together with the findings of the research
in 1980’s (CSIR 1984) was to transfer the nutrient rich
sediments from an aquatic environment where they
are harmful to a terrestrial environment where they
could be beneficial. Dredging and hydraulic transport of
sediments, their processing at areas close to the dam and
manufacturing of environmentally valuable and marketable products are adoptable and should be additionally
developed.
The objectives of sediment management are
• to extract the active sediment layer in order to reduce
the high internal nutrient load and nutrient recycling
within the dam
• to apply hydraulic transport of dredged materials to
processing areas
• to recover the lost sedimentation and retention
capacity of the Crocodile River inlet section in order
to deal with nutrient and sediment load until preimpoundment barrier would be constructed,
• to process removed sediments and to produce
environmentally valuable and marketable final
products intended for various beneficiary uses
• to carry out all operations in an environmentally
sound and socially adoptable manner
• to create new jobs based on sediment management
activities.
So far several steps toward full development of the
sediment management strategy are completed, i.e. pilot
dredging (50 tons of materials) in Crocodile inlet section
and the excavation of 11 500 tons of shoreline materials
for testing, but some are in progress or pending.
Reduction of the external nutrient
load
The current sediment and phosphorous load to the dam
are estimated to range from 70 000 to 100 000 tons and
350 - 550 t P respectively. The reduction of the external
nutrient load is a crucial factor for the successful rehabilitation of Hartbeespoort Dam and its protection in the
future. The goal of Harties Metsi a Me is to reduce the
external phosphorous loading to a fifth of the present
one. The release of the hypolimnetic water through the
bottom sluices of the dam wall has a positive impact to
the nutrient balance.
In order to meet the goal, strict pollution control
measures should also be implemented throughout the
catchment at every point source and non-point source
including diffuse ones. A barrier between the catchment
and the dam consisting of pre-impoundments and flow
diversion should be constructed as well as the riparian
wetlands upstream.
Information and Communication
Centre
Harties Metsi a Me has constructed a big tent and refurbished an old machine room of the Department of Water
Affairs into an Information and Communication Centre
that serves primarily to inform, educate and increase
the awareness about significance of water resources
protection, water use efficiency, rain water harvesting,
eutrophication and importance of personnel involvement
and ownership in these aspects. The centre presents the
achievements of the project, water conservation and protection, biological processes in biomass treatment, river
basin management, improved storm water management,
protection and remediation of wetlands and riparian and
in-stream river habitats, waste water management, prevention of desertification and, most importantly, sustainable development. The annual number of visitors is over
7 000. The plan for a larger Information, Communication
and Knowledge Centre is in progress
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Discussion and
recommendations
It would be unreasonable to believe that it would be
possible to solve the eutrophication problems of Hartbeespoort Dam – which were created over the course of
decades – in a couple of years. A period of 10 – 15 years
is correctly anticipated by Harties Metsi a Me.
So far Harties Metsi a Me has done a good job within the
Phase I and should be continued onto the next phase. It
has been successful in mitigating and stopping the consequences of dam eutrophication despite of an excessive
internal and external loading that are not addressed yet
by implementation of planned measures.
The project plan concerned with the internal and external nutrient and sediment loading is reasonable and
adoptable. The simultaneous and ecological application
where all the actions are directed toward the very same
goal is in fact the only sustainable way to rehabilitate
the lake. Harties Metsi a Me is an essential part of the
regional development which definitely will pay off once
the full scale implementation would be followed through
and maintained.
Compared to other lake management measures the
approach of Harties Metsi a Me is cost-effective and
based on sustainable development pattern. In European
lakes biomanipulation is widely accepted as one of the
most feasible methods for adapting to global change and
combating eutrofication, especially cyanobacteria. The
improved resilience that is obtained through increased
biodiversity is a well-established principal that need
ongoing persistence.
In Finnish lakes, biomanipulation has out-competed
chemical dosing and artificial aeration or oxygenation
because it is far more cost-effective, ecological and
job-creative. In few lakes the chemicals like calcium peroxide are used only to stop the phosphorus release of the
sediments on a short term basis.
In the case of Lake Vesijärvi, the cost of the alternative
technical and chemical measures was 10 – 100 times of
that of the biomanipulation which unlike other measures is also safe and brings about the improvement of
water quality and fishery management in the very same
project.
Both an excessive external surface load (15 - 20 g P/m2)
and a considerable internal surface load (0.50 - 0.75 g
P/ m2) should be addressed properly if target P load is
going to be attained (Cukic & Venter 2010). The importance of the reduction of the external loading is well
recognized by Harties Metsi a Me but maybe not strongly
enough emphasized in the business plan. The dam is
highly overloaded due the extensive urbanization and
human activities. The pollution control and catchment
area management is a tedious and challenging work but
not an impossible one. The planned actions of Harties
Metsi a Me are highly recommended.
It is important to develop the riparian wetlands and in
stream habitats in order to improve the management of
numerous dams within the catchment as an additional
tool for reduction of an excessive sediment and nutrient
load towards the Hartbeespoort Dam.
The catchment area management of Hartbeespoort
Dam should be seen as a national effort and exercise of
water conservation where all available pollution control
resources are activated and enforced. The various administrative levels, Water Management Area and Catchment
Area Agency, regional and municipal officials, scientific
communities, engineering capacities and all groups of
stakeholders and individuals concerned with the dam
should cooperate and join the common efforts.
It takes years to minimize the loading of every single
point and non-point source and to upgrade the operation
of waste water treatment plants but it is worthwhile.
The 1 mg/l P limit of discharge is low according to the
European standards.
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Note:
• In sensitive locations in Finland, the standard of 0.2
mg P/l is promulgated
• Modern waste water treatment plants are able to
produce effluent with 0.1 mg P/l.
The implementation of stricter phosphate standards in
the catchment area of Hartbeespoort Dam focused on the
Crocodile River catchment is recommended. The target
level of load of 60-80 t P/a can be met if all actions and
activities planned within Harties Metsi a Me would be
strictly and persistently implemented.
Due the reduction of internal loading and activities
(biomass harvesting, shoreline rehabilitation, floating
wetland establishments, food web restructuring) carried
out by Harties Metsi a Me, the response of the aquatic
ecosystem is promising (Van Ginkel 2012, Harties Metsi
a Me Foodweb Monitoring Progress Report: Phase I,
2012). The clear water periods have extended and the
positive shift in the species composition of phytoplankton and algal communities as well as in zooplankton is
clearly revealed. In addition, a considerable increase of
bird population and improvement of diversity have been
observed.
Note:
In South African reservoirs in general, the top-down
influence induced by biomanipulation measures has
turned out to be weak (Hart 2011). In case of Lake Vesijärvi, the reduction of the bottom-up impact was originally the most important one but the top-down effect
has come up as an extra bonus. The research results of
Hartbeespoort Dam also refer to the bottom-up impact
as a major factor of fish-related maintenance of internal
loading.
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The shoreline rehabilitation and construction of floating
wetlands is the most remarkable part of Harties Metsi a
Me. The tolerance and resilience of the ecosystem seem
to have been strengthened but the efforts for restructuring the composition of fish stocks are not yet concerted.
A particular asset of Harties Metsi a Me, connected with
challenging pioneering work and in line with latest
global and national environmental legislation, is the
approach to reprocess and recycle nutrient rich products
to valuable environmental materials (soil, compost, soil
conditioners). These measures are particularly important for sub-tropical areas and offer various regional
socio- economic development aspects.
The biomanipulation by fish removal gives the best
results in the lakes where eutrophication is mainly
fish-stock originated and the external load is around
the critical level (Annex 2). It is important to be familiar
with the food web functioning in order not to increase
carnivorous zooplankton by fishing and algal problems
due to that. Fish stock restructuring may need supportive activities like increase of the catch length of valuable
and predatory fish, management of spawning areas and
predatory fish stockings.
Annual fish removal catch is based on the assessment of
the fish biomass. Initially, the fishing effort over three to
four years, is extensive, up to 50 – 70 % of the fish biomass, and should lead to positive and tangible results. After the achieved status, the annual fishing in the maintenance phase can be about 20 - 30 % of the fish biomass.
Too low effort may even increase the reproductive power
of cyprinids. Too great effort - especially with trawl - can
lead to deterioration of fish stocks, an increase in the
number of small fish and an increase in the relative number of cyprinids and decrease in the value of fish catch.
It is possible to combine commercial fishing with management fishing. The commercial utilization of management fishing catches is breaking through (Annex 2).
Note:
a) The phosphorus concentrations are also used for
catch estimation (Jeppesen & Sammalkorpi 2002).
By P level less than 50 µg/l, the catch should be
50-100 kg/ha, by P level 100 µg/l the catch should
be 150-200 kg/ha etc. In the intensive phase of the
biomanipulation at Hartbeespoort Dam, the annual
fish removal catch of target fish should according
the assessments be 350 – 500 t or 175 - 250 kg/ha.
If higher catches are not possible to obtain, other
benefits of management fishing such as increasing the
value of fish stock may also be achieved with a lower
yield.
b) The detection of target fish and their schools is effective by the latest echo sounding technology (down
scan, side scan, structure scan). The natural spawning
and schooling behavior of target fish is utilized as far
as possible. Spawning and schooling sites are identified and the most appropriate fishing techniques and
gears are used. The gathering of water fowl indicating
the locations of fish schools can also be detected by
the remote-sensing technology. For the continuity of
management fishing, it is important to support local
activity and voluntary work.
Transparent and accurate information and communication are very important issues in a lake management
project. It is of vital importance to comprehensively get
across the message of the efforts, findings, achievements
and problems to raise awareness, environmental responsibility and funding, thus committing all parties involved
to a constructive and beneficial cooperation.
Harties Metsi a Me seems to be reaching many sectors
of the community through the Information, Communication and Knowledge Centre. However, up to this point,
the research component in the program does not seem
as visible as might be expected from the outcomes of the
program. Harties Phase 1 presents a favorable substrate
for scientific publications, and a Harties Metsi a Me book
would even be worthwhile. It is clearly recognized that
the holistic and integrated approach of Harties Metsi a
Me has a strong research component with permanent
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involvement of both research and engineering capacities.
It is thus recommended that the project would publish
more peer reviewed articles in scientific magazines.
It should be of great value for both local and international eutrophication specialists to organize an international
workshop about Harties Metsi a Me with involvement
of recognized international experts that would allow an
exchange of knowledge acquired through Harties Metsi a
Me with international ones and provide an international
peer review of the project objectives, applied strategy
and implementation measures. At the moment, two European teams of lake management scientists and experts
of EU-funded projects LakeAdmin and JärviHoi might be
an option.
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Conclusions
Harties Metsi a Me is a limnologically sound and holistic
program that not only deals with the minimization of the
external and internal loading of the dam but also relevant
in the context of global change and sustainable development.
In comparison with other alternative lake remediation
measures, Harties Metsi a Me is cost-effective and strongly
oriented toward job creations. Harties Metsi a Me provides
opportunities for social and economic development in the
area and increase social and business trust around the
dam and in wider area.
After a five-year of operation the project became able
to mitigate to some extent the consequences of severe
eutrophication of Hartbeespoort Dam, and is on the right
track.
The participation of various administrative levels, Integrated Water Resource Management and Integrated
Catchment Management, regional and municipal officials,
scientific communities and all the various groups of stakeholders and individuals concerned with the dam is crucial
for a positive outcome of the program. The catchment
area management of Hartbeespoort Dam should be seen
as a nationwide water conservation challenge where all
water authorities, users and stakeholders in the catchment and beyond are fully aware of their co-responsibility
for the management of the water resources. They should
cooperate and contribute to achieve the objective of attaining a clear-water state in the dam being aware that no
quick solution for remediation of the dam is possible and
only long term persistent effort can be fruitful.
New methods and innovations for algae and hyacinth biomass harvesting, as well as debris and biomass removal,
treatment and reuse applied within Harties Metsi a Me are
valuable contributions to the management of eutrophicated lakes.
The shoreline rehabilitation and construction of floating
wetlands carried out within Harties Metsi a Me is of broad
and international importance. The results are promising
and the innovative work done within Harties Metsi a Me
should be supported and continued.
The total fishing catch made within the project seems to
be too low for biomanipulation to be a successfully used
as an eutrophication mitigation method. It is thus recommended that the catch should be increased significantly.
Harties Metsi a Me Phase 1 has been successful in many
aspects. It carries national and attracts international interest. The remediation of the highly eutrophicated Hartbeespoort Dam could be an extraordinary international
success and a great recognition for South African water
professionals and institutions.
In order to sustain the results achieved and meet the
objectives of Harties Metsi a Me, it is vital that the program
will move to the second phase. In Finland at least, the
whole lake management community has faith in Harties
Metsi a Me also in the future.
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References
Cukic, Z. & Venter, P. 2012. Characterisation and Managing of Internal Nutrient Load (Sediments) of Hartbeespoort Dam. Proceed. WISA Biennial Conference,
Durban 2010.
Kokkinen, S. & Siri, M. 2010. Development proposals to
the water monitoring and management of Hartbeespoort
Dam. Lahti University Of Applied Sciences. Degree Program in Environmental Technology. 68 p.
Dillon, P.J. & Rigler, F.H. 1974. The phosphorus–
chlorophyll relationships in lakes. Limnol. Oceanogr.
19(5):767–773.
Van Ginkel, C.E. 2011. Eutrophication: present reality and
future challenges for South Africa. Water SA
vol. 37(5): 693–701.
CSIR 1984. The Limnology of Hartbeespoort Dam. SA
National Scientific Programmes, Report No.110.
Hart, R.C. 2011. Zooplankton biomass to chlorophyll ratios in relation to trophic status within and between ten
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Hartbeespoort Dam Integrated Biological Remediation
Programme: Foodweb Monitoring Progress Report,
Phase I, October 2012. Department of Water Affairs &
Rand Water.
Jeppesen, E. & Sammalkorpi, I. 2002. Lakes. In publication: Davy, A.J. & Perrow, M.R. (ed.). Handbook of ecological restoration. Vol. II. Restoration in practice. Cambridge
University Press: 297–324.
NEMP website: www.dwaf.gov.za/iwqs/eutrophication/
NEMP/report/Chart_nemp_90240.png
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past, present and future. African Journal of Aquatic
Science. Volume 37, Issue 1: 17–25.
Vollenweider R.A. 1975. Input-output models with
special reference to the phosphorus loading concept in
limnology. Schweizerische Zeitschrift für Hydrologie,
37, 53–84.
Vollenweider R.A. 1976. Advances in defining critical
loading levels for phosphorus in lake eutrophication.
Memorie dell’Istituto Italiano di Idrobiologia, 33, 53–83.
Annexes
Annex 1:
Pioneering ideas and innovations of Harties Metsi a me.
Annex 2:
The management of Lake Vesijärvi 1984–1994 Phase 1.
Annex 3:
Pictures taken during peer review visit.
14
Annex 1
Pioneering ideas and innovations
of Harties Metsi a me
Pioneering ecological lake
remediation project
• Construction of algal scum skimming boats
• Harties Metsi a me is the first approach based on
food-web management in a subtropical lake
• Solutions of operational management fishing
methods and gear
Pollution control
• Plan for a barrier between the catchment and the dam
• Construction of a pre-impoundment at the Crocodile
River mouth
• Plans for ecological dredging methods
• Construction of riparian wetland systems upstream
• Litter and debris containment and removal at the
inlets and dam wall
Food-web restructuring
• Pilot measures for shoreline rehabilitation
• Re-creation of natural littoral zones
• Solutions of functional floating wetlands on
a large scale
• Stopping the chemical spraying of water hyacinths
• Solutions of hyacinth collection using hand labour,
removal devices, utilization of wind and collecting
curtains towards harvesting points around the dam
and at the dam wall
• Treatment of biomass through composting and
vermiculture
• Solutions for algae collection and removal devices
• Harvesting algal surface blooms, utilization of wind,
concentration of scum through algal blooms and
floating curtains
• Solutions of small pumps and ‘super suckers’
for algal scum
• Commercial vermiculture in order to produce safe and
reusable compost material free of toxins, parasites and
hyacinth seeds
Information, Communication and
Knowledge Centre
• The existing Centre delivers information and
communication to get across the message of project
results, water ecology in Hartbeespoort Dam and
sustainable development
• Planning of the holistic Information, Communication
and Knowledge Centre
• Offering live demonstrative learning experience and
inter-phasing knowledge hubs on water use efficiency,
rainwater harvesting, retention of surface water, waste
minimization and re-use, vermiculture, organic debris,
and re-use and increase of organic material and
moisture in soil
• Learning experience walkways on aquatic ecosystem
monitoring, the history and heritage of the dam
including the old hydro power station, the cycle of
water use in the dam, and links to the future UNESCO
Biosphere Area “The Cradle of Mankind”
Electronic water use registration and licence application (online web page)
15
16
Annex 2
Memorandum Nov 1994
The management of
Lake Vesijärvi 1984–1994
Phase 1
Juha Keto
Introduction
Vesijärvi Project (the ecological management and research of the lake) was initiated in 1987 by a 15-member
cooperative strategic group (including local environmental authorities, university scientists and national water
and fishery authorities) and by a 30-member operational
group (of the Lake Vesijärvi Fishery Area, the Regional
Rural Center, local fishing associations, fishery advisors
and village associations). The project was managed
by the Environmental Centre of Lahti. The goals of the
program were to stop the eutrophication, to eliminate
the toxic blooms and mass developments of blue-green
algae, to restore the recreational value and to re-establish a sustainable fishery in the lake.
Lake Vesijärvi is 25 km long, covers an area of 110 km2
and has a mean volume of 700 million m3. It is located
in Southern Finland and surrounded by the City of Lahti
and the Municipalities of Asikkala and Hollola. Over the
past 50 years, it has become badly polluted due to the
manifold sewage load. In early 1970s it was one of the
most eutrophicated lakes in Finland. In the late 1970s
the sewage of domestic and industrial origin was diverted and the minimization of diffuse loading was started,
resulting in a temporary recovery in the water quality.
The surface nutrient load of the Enonselkä basin was reduced to one seventh of its level in the past. The surface
load of total phosphorus fell from values of 2–3 g P/m2/a
to 0.4 g P/m2/a – close to the level of the critical load.
The artificial aeration of the lake took place in 1979–84.
However, in the 1980s the eutrophication problems
began to increase again and the lake experienced continuous blooms of toxic blue-green algae both in summer
and in winter. Most of the recreational and fishing value
of the lake was destroyed. The ecological restoration
experiments, representing the very first biomanipulation
project in Finland, were started by the City of Lahti in
1984 and the larger cooperation in Lake Vesijärvi Project
was launched in 1987.
Results
The City Council of Lahti realized in the early 1980s that
addressing the problems affecting the lake required
a new approach, which would involve all the various
groups and individuals impacting the lake, as well as the
various actors with regulatory authority over various
aspects of lake ecology and lake management. The Lake
From 1987–1993, over 1 200 metric tons of coarse fish
(mainly roach and smelt) was removed from the lake
by professional fisheries (mainly trawling) and by local
fishermen. From 1989–1993, the annual catch of coarse
fish was around 100 kg/ha. The internal load maintained
by huge benthivorous fish stocks was cut down. The
pike-perch and other predatory fish stocks were intro-
The Lake Vesijärvi Project
The project combined the goals of water quality control
and fishery management in an ecological management
strategy. The strategy involved the employment of
conventional pollution control measures on discharges
to the lake, such as environmental protection planning
covering the whole drainage area and including systematic monitoring of the external loading, as well as the
ecological restoration (biomanipulation) of the lake. It
was chosen instead of chemical or technical methods because of its significantly lower costs as revealed through
a cost-benefit analysis.
17
duced from 1984, and resulted in natural reproduction.
The spawning areas of pike were largely managed. These
measures have resulted in the increase of the natural
stocks of predatory fish (pike, perch, burbot and pikeperch) and economically important planktivorous fish
(species of vendace and white fish). The noble crayfish
has also benefited from the management.
The commitment of local people to the management of
Lake Vesijärvi brought about a considerable decrease in
the external loading of the lake. For example, over 50 %
of the planned protection zones between the watercourses and cultivated areas were established during
the project. Environmental protection was planned in
all 300 of the farms in the catchment area. Moreover, the
storm-water loading of Lahti has decreased through a
new technique.
The pollution control and biomanipulation measures enacted have resulted in an increase in the clarity of water;
the transparency of the water increased during the project, from 0.5 m to 3.5–4 m. Since 1991, the blooms and
mass developments of blue-green algae have vanished.
The recreational value of Lake Vesijärvi was restored.
The post-project management of Lake Vesijärvi now employs some 20 people in management fishing and other
activities.
The project has also resulted in the development of new
management fishing gear and new commercial products for the coarse fish catch, such as minced roach and
canned fish. In addition, the manufacture of fishing gear
and mowing activities, have employed over 100 people in
the Lake Vesijärvi Area. The project now serves as a model for a number of similar lake restoration projects which
have been initiated throughout Finland. In the vicinity
of Lake Vesijärvi, within the Municipalities of Asikkala,
Hollola and Nastola, 20 other lakes are managed in a
similar manner.
The final cost of the project was 15 million Finnish marks
(approx. 2.5 million euro). The project was financed
by the City of Lahti (80 %), the government of Finland
(12 %) and the other local municipalities in the Greater
Lahti Area (8 %).
Due to the recovery, the professional fishery has rehabilitated at Lake Vesijärvi. The project has restored the recreational value of the lake and has stimulated the tourist
fishing and farm tourism sectors in the local economy.
The land value around the lake has risen. Professional
fishing has started again; five fishermen are employed.
Recreational fishing has increased massively. The water
traffic from ships and boats has proliferated considerably. The City of Lahti has constructed a new harbor and
new residential areas on the lake and, in many ways,
has turned its focus towards the lake.
18
Annex 3:
Pictures
PICTURE 1. General view on Hartbeespoort Dam.
PICTURE 2. View of the dam. P. Venter on the left.
PICTURE 3. Constructing the frames for the floating
wetlands.
19
PICTURE 4. The wetland frames are transported
to the lake.
PICTURE 5. The wetlands are set to float. The vegetation of
floating wetlands is on the background.
PICTURE 6. The application of the wetlands
requires specific skills.
PICTURE 7. As a result of the Harties metsi a Me program,
9 000 m² of shoreline has been rehabilitated.
PICTURE 8. Water hyacinth vegetation in the Magalies River.
www.ladec.fi

Hartbeespoort Dam Integrated Biological Remediation Program

Transcription

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