SCHOOL OF CIVIL ENGINEERING AND BUILT ENVIRONMENT
TECHNIKON FREE STATE
PRIVATE BAG X20539, BLOEMFONTEIN 9300
SOUTH AFRICA
A Project Proposal on
IMPACT OF LAND USE ON RIVER BASIN WATER BALANCE: A CASE
STUDY OF THE MODDER RIVER BASIN, SOUTH AFRICA
Submitted to
THE INTERNATIONAL PROGRAM ON THE COMPREHENSIVE
ASSESSMENT OF WATER MANAGEMENT IN AGRICULTURE
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PROJECT TITLE
IMPACT OF LAND USE ON RIVER BASIN WATER BALANCE: A CASE
STUDY OF THE MODDER RIVER BASIN, SOUTH AFRICA
SUMMARY
PROJECT MANAGER
Dr. E. Pretorius
Head, School of Civil Engineering and Built Environment, Technikon Free State
Private Bag X20539, Bloemfontein 9300, South Africa
Email: lpretori@tfs.ac.za
PRINCIPAL INVESTIGATORS
1. Dr. Y.E. Woyessa
Post-Doc Researcher, School of Civil Engineering and Built Environment, Technikon
Free State, Private Bag X20539, Bloemfontein 9300, South Africa
Email: ywoyessa@tfs.ac.za
2. Mr. P. Van Heerden
Consultant, Agricultural Extension and General Irrigation Practice
P.O. Box 11632, Universitas, Bloemfontein 9321, South Africa
E-mail: psvh@mweb.co.za
COLLABORATORS & PARTNERS
1. Dr. L.D. Van Rensburg
Agricultural Research Council – Institute for Soil, Climate and Water
Private Bag X019, Glen 9360, South Africa
E-mail: debruint@glen.agric.za
Dr Van Rensburg is one of the pioneers who participated in the development of the water
harvesting techniques in the Thaba ’Nchu area which is located in the Modder River
basin. He is specialist in soil and water management and has a lot of work experience in
soil and water management related research in that area. His contribution will therefore
be an invaluable asset to this project.
2. Dr M. Hensley
Department of Soil, Crop and Climate Sciences
University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
E-mail: vHeerdGC.SCI@mail.uovs.ac.za
Dr Hensley is a dedicated researcher with extensive research experience in soil and
hydrology at Glen research station, also located in the Modder River basin. He was one of
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the first researchers to develop the idea of water harvesting techniques in that area. This
will be the focus of this study.
ABSTRACT
An integrated approach to water resources management in a river basin would enhance
both productivity and sustainability of natural resource use. Sustainability means that the
concerns about resources use should transcend short-term “on-site” gains, and should
necessarily focus on an environmentally sensitive use of resources including many
possible “off-site” implications. The off-site influences on a water use system, and the
off-site impacts arising from a water use system can both be systematically studied to
identify the factors that affect the performance of the water use system.
The irrigated agriculture in the Modder River basin (South Africa) draws water mainly by
pumping out of river pools and weirs. The Krugersdrift Dam, which is located west of
the City of Bloemfontein (central South Africa), acts as a buffer for stabilizing water
supply to the lower reaches of the Modder River. However, many of the rural developing
farmers rely on rain-fed agriculture for crop production. In the past few years the Institute
for Soil, Climate and Water (ISCW) of the Agricultural Research Council (ARC) has
been developing water harvesting techniques for small farmers in the basin with the
objective of harnessing rainwater for crop production (Hensley et al., 2000). They found
that, with the use of the water harvesting technique developed at the centre on an area of
1m2, the surface run-off was reduced to zero and that evaporation from the soil surface
was reduced considerably resulting in a significant increase in crop yield compared to
conventional practices. Moreover, this practice was also reported to reduce soil loss
significantly, which otherwise would run into the river system. The researchers expect
that many developing farmers in the river basin with limited access to irrigation water
will be able to adapt this practice for crop production. The research question arising from
this scenario is: what will be the consequences of wider use of this practice on the river
water balance and what will be the off-site impact of this practice on the downstream of
the river basin if used on a wider scale? The main purpose of this project is to investigate
possible scenarios or impact of land use practices (aimed at harvesting rain water for crop
production) on the Modder River water balance. The expected outputs are information on
the hydrology of the Modder River basin, inventory of land use practices and their impact
on the river basin, water use practices in the rural area (such as the use of grey water),
and problems for further research. Further expected outputs are training of post-graduate
students from previously disadvantaged communities in civil and agricultural
engineering, as well as in the use of methodology for assessing water use by different
sectors of a community. These factors could influence water use and students would learn
how to include these in water balance studies. The activities that are planned are visits to
the regional offices of the Departments of Agriculture and Land Affairs, and Water
Affairs and Forestry for the obtaining of secondary data. Furthermore, primary data will
be obtained using direct observation, surveys using formal questionnaires and discussions
with small groups of farmers.
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TOTAL COST OF PROJECT: US$75 000, AMOUNT REQUESTED FOR THE
PROJECT: US$61 000
DURATION OF PROJECT: 1 year
LOCATION OF PROJECT: Technikon Free State
BACKGROUND
In a new paradigm shift related to integrated water resources management (IWRM) in the
context of a river basin, attention is being drawn to consider the upstream “off-site”
influences on the various water use entities, as well as the downstream “off-site” impacts
arising from them. Along the path of water flowing in a river basin are many waterrelated human interventions, including water storage, diversion, regulation, distribution,
application, pollution, purification and other associated acts to modify the natural
systems. All of these have one common effect, and that is that they impact on those who
live downstream (Sunaryo, 2001). This concept of river basin analysis of water would
enhance the common understanding of the issues on overall productivity of water and
related strategies.
With the recognition of significant reuse of water, the river basin is increasingly
acknowledged as the appropriate unit for the analysis and management of water
resources, especially as water availability at the basin level becomes the primary
constraint to agriculture. Growing scarcity of good-quality water in most river basins
results in intense inter-sectoral competition for water. The efficiency of water use can be
seen in a more comprehensive manner if the allocation of water in a basin among various
users is considered. Similarly, a more comprehensive analysis requires the adverse effects
of a rapid degradation of the environment and other ecological problems arising from
severe competition for water to be studied, along with the irrigation-induced
environmental problems. It also tends to highlight the importance of equity and
sustainability issues related to IWRM (Bandaragoda, 2001).
The neglect of this type of wider consideration of the resources base has, up to now,
clouded the inherent limitations of existing institutional arrangements to deal with
irrigation systems. As countries experience growing water scarcity, water-sector
institutions need to be reoriented to cater for the needs of changing supply-demand and
quality-quantity relationships and the emerging realities (Saleth and Dinar, 1999). It is
inevitable that irrigated agriculture, the largest water user in many river basins, will be
called upon to reassess its water requirements in view of the competition for water from
other users. There is now wide acceptance of the necessity to focus on higher level
institutions, generally at the basin level.
The river basin is a geographical unit that defines an area where various users of the
basin’s water interact, and where most of them live. A basin perspective helps include in
the analysis the interactions among various types of water uses and users, and in the
process, it helps in better understanding the physical, environmental, social and economic
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influences that impinge on the productivity of agricultural water management. In a basin
context, interrelated issues of quantity and quality of surface water and groundwater, and
the extraction, use and disposal of water resources can be more comprehensively
analysed. Participation of a larger number of stakeholders can be sought, and water
resources planning can be more effectively carried out. The broader view through a river
basin is able to capture dimensions that are not normally included in an irrigation system
management approach, such as the causes (and not only the effects) of water scarcity,
water quality, water-related disputes and inequitable water distribution and use.
An integrated approach to water resources management in a river basin would enhance
both productivity and sustainability of natural resource use. Sustainability means that the
concerns about resources use should transcend short-term “on-site” gains, and should
necessarily focus on an environmentally sensitive use of resources including many
possible “off-site” implications. For instance, in many irrigation systems, the act of water
use is limited to achieving system objectives, such as obtaining highest crop yields, and is
rarely concerned with downstream drainage problems or pollution caused by fertilizer
and other chemical inputs. The off-site influences on a water use system, as well as the
off-site impacts arising from a water use system, can both be systematically studied to
identify the factors that affect the performance of the water use system.
The Modder River basin is located within the Upper Orange Water Management Area to
the west, north and east of the City of Bloemfontein (central South Africa). The irrigated
agriculture in the basin draws water mainly by pumping out of river pools and weirs. The
Krugersdrift Dam, which is located west of the City of Bloemfontein, acts as a buffer for
stabilising the water supply to the lower reaches of the Modder River. However, many of
the rural developing farmers rely on rain-fed agriculture for crop production. In the past
few years the Institute for Soil, Climate and Water (ISCW) of the Agricultural Research
Council (ARC) has been developing water harvesting techniques for small farmers in the
basin with objective of harnessing rainwater for crop production (Hensley et al., 2000).
They found that, with the use of the water harvesting technique developed at the centre
on an area of 1m2, the surface run-off was reduced to zero and that evaporation from the
soil surface was reduced considerably, resulting in a significant increase in crop yield
compared to conventional practices. Moreover, this practice was also reported to reduce
soil loss significantly, which otherwise would run into the river system. The researchers
expect that many developing farmers in the river basin with limited access to irrigation
water will be able to adapt this practice for crop production. The research question arising
from this scenario is: what will be the consequences of wider use of this practice on the
river water balance, and what will be the off-site impact of this practice on the
downstream of the river basin if used on a wider scale?
Based on some preliminary information, the present situation can be described as follows.
The total area of the Modder River basin is estimated to be 1.73 million ha, of which an
estimated area of 10% is reported to be suitable for rain water harvesting which is 173
000 ha. The current run-off coefficient is estimated at 5%. With mean annual rainfall of
500 mm in the area, it is estimated that an annual run-off amount of 25 mm can be
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generated, which gives 43.25x106 m3 of water annually from the areas suitable for water
harvesting techniques. Since food security is of primary importance in the area, an
important question is how much food can be produced with 43.25x106 m3 of water under
off-site conditions, compared to maintaining this water on the site to produce crops.
Comparison of food production under off-site and on-site use of rain water shows that,
with the assumption that 50% of the total runoff will actually reach the irrigated land, it
will be enough to irrigate 33 269 ha at 650 mm/ha/year. With a maize yield of 10t/ha
under irrigation, the total production could be 332 690 tons. Under on-site conditions it
has been reported that maize yield has increased from 1 t/ha to 2 t/ha by using the water
harvesting techniques (Hensley et al., 2000), which gives a total production of 346 000
tons (an increase of 173 000 tons) of maize if used on all suitable areas.
In the light of these preliminary calculations the hypothesis could be that the most
efficient use of rain water occurs when it is used where it falls. The value of this project is
that it will produce actual values for each of the assumptions and will, therefore, make a
valuable contribution to this and many other similar catchment areas. The socioeconomic benefits associated with on-site use of rain water are also of considerable
importance and further investigation into the economics of irrigation and rain-fed crop
production is required.
In fact, there are many activities that could possibly impact on the water balance of the
river basin, such as recreational activities, public water consumption, etc. It is not
possible to address of all these issues within the time frame and funding set for this
project, but they could be subjects for further investigation. An attempt will thus be made
to assess the possible scenario of the impact of the land use practices by developing
farmers on the river water balance.
GOAL
This study is intended to help improve the management of scarce water supplies available
for agriculture, within and responsive to a framework for Integrated Water Resources
Management in river basins.
PROJECT PURPOSE
The purpose of this project is to investigate possible scenarios or impact of land use
practices (aimed at harvesting rain water for crop production) on the Modder River water
balance and to improve the understanding of local communities in agricultural water
management.
OUTPUTS
The expected outputs are reports on the findings of the research consisting of
hydrological data of the Modder river basin, inventory of land use practices and their
impact on the river basin, and general information on the water use practices in the rural
area, such as the use of grey water. Moreover, problems will be identified for further
7
research. Further expected outputs are training of post-graduate students (M.Tech theses)
from previously disadvantaged communities in civil and agricultural engineering and in
the use of methodology for assessing water use by different sectors of a community.
These factors could influence water use and students will also learn how to include these
in water balance studies.
ACTIVITIES
The activities that are to be undertaken are visits to the regional offices of the
Departments of Agriculture and Land Affairs, and Water Affairs and Forestry.
Furthermore, direct observation, surveys using formal questionnaires and discussions
with small groups of farmers will be employed. The strategy to be adopted is the collation
of as much information as possible from both primary and secondary sources on the
hydrological data sets of the river basin.
Students, under the guidance of the principal investigators, will do the surveys. The
project will concentrate on using students from previously disadvantaged communities in
order to enhance their knowledge base, observation and interpretation skills.
METHODOLOGY
The study will be conducted using a multitude of procedures. The map of the Modder
River basin will be used to delineate the catchments and sub-catchments, to the level of
quaternary catchments, so that the results of this study will be in line with the general
approach of water management as adopted by the Department of Water Affairs and
Forestry (Dept of Water Affairs and Forestry, 2002). Information on cultivated areas,
both by commercial and developing farmers, will be obtained from the Regional Office
of the Department of Agriculture. Hydrological information will be sought from the
Regional Office of the Department of Water Affairs and Forestry. On-site surveys will be
conducted in order to identify the different land use practices and the extent of use of
rainwater harvesting techniques by developing farmers. Other water use practices by the
rural community will also be assessed. Moreover, information on the use of grey water by
the rural community will be assessed using a survey technique.
BENEFICIARIES AND IMPACT
Localised benefit of water harvesting has been amply documented by Hensley et al.
(2000). While the advantages for the small farming community are clear, the studies on
water harvesting did not include the impact on lower lying and downstream small farmers
and communities. This study would indicate what effect water harvesting, if any, would
have on downstream farmers and communities, and would also indicate the boundaries
within which practices like water harvesting could take place and still ensure enough
water for use by downstream farmers and communities.
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The results of the study should also provide guidelines for future management of the
Modder River Basin by the Water Management Authority (to be implemented). Presently
the Department of Water Affairs and Forestry assumes this responsibility.
IMPLEMENTATION AND MANAGEMENT
 Lead coordinating agency: Technikon Free State
 Comparative advantage and respective roles of all collaborating institutions: Post
graduate students of the Technikon will be exposed to methodologies of water
balance determinations, interpretation of what they see in the target area and
interpretation of results against that background, field surveys, relevant computer
technology and hydrological system analysis.
 Location of different components of the work: On site surveys in the vicinity of
Thaba ’Nchu (a former “homeland” area), computer lab analysis at the Technikon.
 Policy and institutional environment within which the project will operate (demand
for the proposed research and the ability and willingness of partners to adopt research
findings): The research will be done within the policy framework as set out by the
Department of Water Affairs and Forestry in their strategy for future water
management. In this regard full cooperation of the Department has been indicated,
together with an indication that the to-be-implemented Water Management Authority
will implement the findings. South Africa is a country with a limited supply of water,
and any research that leads to an increased saving of water, including more optimal
water use, is welcomed by the department. The water harvesting project has shown a
rapid increase in adoption of that particular practice, and there is no reason to believe
that related projects would not be adopted by the local community. Communities that
could be affected by the outcome of this study will be fully informed about the
project, its goals and potential outcomes.
 Specific milestones: Month 1 - 2: Planning workshops by lead organization and its
investigators, representatives of communities that will be involved and
representatives of organizations/authorities in the target area. Project plan to be
finalized. Month 3 – 6: Literature study and on-site surveys. Month 7 – 9: Analysis
and interpretation of data. Month 10 – 12: Report writing.
 Work Plan or Activity Chart with time lines: See appendix 1
DISSEMINATION STRATEGY
Personnel of the Department of Water Affairs who have to implement the water
utilization strategy, extension personnel of the Department of Agriculture who act as
advisors to farmers affected or potentially affected by this study, researchers in this field.
Methodology for estimating (calculating/determining) will have been tested, published
and demonstrated to interested groups. Research results will be published as scientific
9
papers as well as in the popular media for general consumption. The researchers will also
be available to answer questions and to demonstrate developed methodologies to
interested parties. A user manual for use by local management organizations will be
published.
What other users in similar areas (agro-climatic, socio-economic, ecosystem) can benefit
from the results of this research? In which areas or countries?
All future Water Management Authorities would be interested as the management of
water in catchments will become their responsibility. In this regard, there is also a
potential for international application.
MONITORING: See the Log frame in appendix 2
Monthly evaluations against the targets indicated will be done during the course of the
project. The project leader will assume this responsibility. Progress reports to the funding
organization will be provided on a three monthly basis.
BUDGET SHEET
Name of Project Impact of Land Use on River Basin Water
Balance: Case Study of the Modder River
Basin, South Africa
Project Leader
Dr E. Pretorius
Theme
River basin study
Line Item (in US$)
Year 1
Researchers:
Dr. Y.E. Woyessa
Mr. P. Van Heerden
Dr. L.D. Van Rensburg
Dr. M. Hensley
National
- Agricultural Research Council
- University of the Free State
Consultants
Nat'l Staff Salaries & Benefits (staff expenses)
Office & Research Supplies
International Travel
Workshops
Fellowships
Publications & Disseminations
Contract Research
Contingency
Vehicles & Equipment (Computer)
Total
-----14 000.00
2 000.00
8 000.00
2 000.00
16 000.00
3 000.00
12 000.00
10 000.00
8 000.00
75 000.00
Requested by
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 Contribution by proposer and partners (both in terms of cash, kind and
complementary activities): The Technikon Free State (the proposing organization)
will cover the expenses amounting to US$14 000.00. Project and research leaders will
bring in expertise and supply locally developed computer programs for the estimation
of crop water use.
 Contribution requested from the Comprehensive Assessment Competitive Research
Grant Scheme: Funding the project with an amount of US$61 000.00
REFERENCES
1.
Bandaragoda, D. J. 2001. A Framework for Institutional Analysis for WaterResources Management in a River Basin Context. In D.J. BryanBruns, and M.S.
Bandaragoda (eds), Proceedings of the Regional Workshop, Malang, Indonesia,
January 15-19, 2001.
2.
Dept of Water Affairs and Forestry, 2002. Proposed National Water Resources
Strategy. Government Gazette. Pretoria.
3.
Hensley, M., Botha, J.J., Anderson, J.J. Van Staden, P.P., du Toit, A., 2000.
Optimizing rainfall use efficiency for developing farmers with limited access to
irrigation water. WRC Report No. 878/1/00
4.
Saleth, Maria R., and Ariel Dinar. 1999. Water challenge and institutional response:
A cross-country perspective. Policy Research Working Paper 2045. Washington D.C.:
The World Bank.
5. Sunaryo TM, 2001. Integrated Water Resources Management in a River-Basin
Context: The Brantas River Basin, Indonesia. In D.J. BryanBruns, and M.S.
Bandaragoda (eds), Proceedings of the Regional Workshop, Malang, Indonesia,
January 15-19, 2001.
Appendix 1: Work Plan or Activity Chart with time lines
Type of activities
Planning workshop and finalizing project plan
Time frame
Jan. 2004 – Feb. 2004
Literature study and secondary data collection
Mar. 2004 – Apr. 2004
On-site surveys and primary data collection
May 2004 – Jun. 2004
Data analysis and interpretation
Jul. 2004 – Sep. 2004
Report writing
Oct. 2004 – Dec. 2004
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Appendix 2: Log frame
Narrative Summary
Goal
Purpose
Outputs
To help improve the management
of scarce water supplies available
for agriculture, within and
responsive to a framework for
Integrated Water Resources
Management in river basins
To investigate possible scenarios
or impact of land use practices
(aimed at harvesting rain water for
crop production) on the Modder
River water balance and to
improve the understanding of local
communities in agricultural water
management.
Determine crop and irrigation
water use
- cropping pattern information in
the area
- data on irrigation versus rain-fed
crops
- information on irrigation systems
and system efficiencies
Impact of water harvesting
techniques
- The extent of use of water
harvesting techniques
- The total impact on run-off
- The potential suitable area for
water harvesting techniques
Capacity building
- Informed local communities
regarding agricultural water use
- Students from previously
disadvantaged communities
Objectively verifiable
indicators
Suitable water management
practices are applied
Means of verification
Suitable water management
practices are applied for the
Modder River and on a local
community level
For the Modder River:
- Observation of the application
of good water management
practices
- Reliable agricultural water use
statistics will be available
Water management
structures for the Modder
River basins will be
implemented
- Reliable crop and irrigation
water use information will
have been determined and
disseminated
- The impact of water harvesting
techniques will have been
determined reliably and
disseminated
- Local communities will have
been informed on efficient
crop water use
- Students will have trained at
Masters level in Agricultural
Water Management
- Reports with relevant data
tabled and/or published
- Number of workshops held
- Number of Masters degrees
obtained in Agricultural Water
Management
- Popular publications
Sufficient funds will be
made available for the
conduct of the study and for
graduate students involved
in the project
- Observation of the application
of good water management
practices
- Reliable agricultural water use
statistics will be available
Important (critical)
assumptions
Water management
association structures for
river basins will be
implemented
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Activities
trained in analysis and
interpretation of river basin water
balance and agricultural water
management
- Characterize and delineate the
sub-catchment.
- Collate survey data from the
research area and secondary data
from DWAF, Departments of
Agriculture and Statistics and
other relevant sources.
- Application of SAPWAT model
to determine crop water
requirements
- Analyze land type data to
determine extent of land
suitability for water harvesting
- Organize information workshops
for local communities
- Identify and train students from
previously disadvantaged
communities at Masters level in
agricultural water management
Inputs
Refer to the attached budget
Sufficient funds will be
made available for the
conduct of the study and for
graduate students involved
in the project