Impact of land use on river basin water balance: Case study of Modder River

PAGE 5

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

PROJECT TITLE

IMPACT OF LAND USE ON RIVER BASIN WATER BALANCE: A CASE STUDY OF THE MODDER RIVER BASIN, SOUTH AFRICA

SUMMARYPROJECT MANAGER

Dr. E. PretoriusHead, School of Civil Engineering and Built Environment, Technikon Free StatePrivate Bag X20539, Bloemfontein 9300, South AfricaEmail: lpretori@tfs.ac.zaPRINCIPAL 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 AfricaEmail: ywoyessa@tfs.ac.za2. 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.zaCOLLABORATORS & 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.zaDr 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.zaDr 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 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.

TOTAL COST OF PROJECT: US$75 000, AMOUNT REQUESTED FOR THE PROJECT: US$61 000DURATION 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 water-related 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 basins 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 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 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 socio-economic 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 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.

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 1DISSEMINATION 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 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 ProjectImpact of Land Use on River Basin Water Balance: Case Study of the Modder River Basin, South Africa

Project LeaderDr E. Pretorius

ThemeRiver 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)14 000.00

Office & Research Supplies2 000.00

International Travel8 000.00

Workshops2 000.00

Fellowships16 000.00

Publications & Disseminations3 000.00

Contract Research12 000.00

Contingency10 000.00

Vehicles & Equipment (Computer)8 000.00

Total75 000.00

Requested by

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$61 000.00REFERENCES

1. Bandaragoda, D. J. 2001. A Framework for Institutional Analysis for Water-Resources 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 activitiesTime frame

Planning workshop and finalizing project plan

Literature study and secondary data collection

On-site surveys and primary data collection

Data analysis and interpretation

Report writingJan. 2004 Feb. 2004

Mar. 2004 Apr. 2004

May 2004 Jun. 2004

Jul. 2004 Sep. 2004

Oct. 2004 Dec. 2004

Appendix 2: Log frameNarrative SummaryObjectively verifiable indicatorsMeans of verificationImportant (critical) assumptions

Goal

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 basinsSuitable water management practices are applied- Observation of the application

of good water management

practices

- Reliable agricultural water use

statistics will be availableWater management association structures for river basins will be implemented

Purpose

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.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

Outputs

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

trained in analysis and

interpretation of river basin water

balance and agricultural water

management- 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 publicationsSufficient funds will be made available for the conduct of the study and for graduate students involved in the project

Activities

- 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 budgetSufficient funds will be made available for the conduct of the study and for graduate students involved in the project