INTEGRATED WATER RESOURCES MANAGEMENT STUDIES IN THE MBULUZI CATCHMENT, SWAZILAND DENNIS JABULANI MDUDUZI DLAMINI Submitted in partial ful:filment ofthe requirements ofthe degree of MScHydrology School ofBioresources Engineering and Environmental Hydrology University ofNatal Pietermaritzburg 2001 ABSTRACT Problems in the water sector range from degradation and depletion ofwater resources as a result of the impacts ofland based anthropogenic activities, to the impacts ofnatural hydrological disasters and floods, while inadequate availability ofwater is at the core ofmost water related disputes in arid and semi-arid areas at local, regional, national and international levels. In the past, finding practical solutions for these problems fell neatly within the traditional scope ofwater resources management, whichhinged almost entirelyoneconomic viability ofengineering orientedendeavors. However, a new set ofmanagement challenges has arisen following the high priority nowadays given to equity in water allocationandthe protectionofthe natural environment above other issues. These new challengeshave created a need for devising and adopting suitable management approaches, especially that would take social considerations into account. One ofthe approaches that provides promise relative to the new directions in dealing with contemporary water issues is integrated water resources management (IWRM). One objective ofthis study was to critically review the definitions and the fundamental principles of IWRM with the view of determining its applicability in developing countries and highlighting difficulties that may be faced regarding the adoption and implementation ofthis integrated approach. Swaziland is atypical example ofa developing country that is engulfed by the diverse water resources issues highlighted above and is currently engaged in updating water management legislation. Hence, Swaziland's experiences were used to put in perspective the key points and barriers regarding the adoption and implementation ofIWRM. The catchment, the recommended spatial unit of IWRM, poses the first practical barrier, as catchments oftencross bothpoliticaland administrative boundaries, therebycreating the need for many water management problems to be solved across catchments with international security issues, cultural issues, different levels ofdevelopment and different hydroclimatic regimes. The successful implementationofIWRMdepends oneffective participationofstakeholders. Lackofinformationflow betweenstakeholders ofdifferent backgrounds limits informed participation. Therefore, it is necessary to develop tools such as decision support systems (DSSs) that will foster easier multilateral information flow and aid decisionmaking. IWRMrequires informationwhich itselfshould be managed in an integrated manner and be readily accessible. This is not always the case in developing countries with shortage offunds for data collection, manipulation and storage as well as adequately trained and experienced staff With the shortage of sufficiently long and reliable hydrological data for water management, the alternative is to synthesize records throughhydrologicalmodelling. Anotherobjective ofthis study was to evaluate and test the suitability ofthe ACRUmodelling system, a daily time-step agrohydrological model, to simulate catchment level hydrological processes and land use impacts as part ofthe assessment studies whichform anintegralpart of integrated water resources management. ACRUwas set up for theMbuluzi, a 2958 km2 catchment in Swaziland. The catchment was subdivided into 40 subcatchments, after which the model was used for assessing both the impacts ofland use and management changes onrunoffyields and available water resources by evaluating present and future sectoral water demands, determining whether river flow from Swaziland into Mozambique meets the quantitative requirements of the international agreement existing between the two countries, and evaluating sediment yield and its spatial and temporal variation as well as its response to potential changes in land management. The physical-conceptual structure ofthe model, its multi-level adeptness regarding input information requirements, coupled with in-built decision support systems and generic default values make ACRU a suitable modelling tool in developing countries, as it makes it possible to obtain reasonable simulations for a range oflevels ofinput information. Togetherwiththe model's multi-purpose nature, the ability ofsimulating ''what ifscenarios", which was utilised in this study, makes it useful in the generation ofinformation for IWRM. Future research needs which were identified include finding means of encouraging effective communicationbetween scientists, water managers and other stakeholders, who may be "laypeople". There is a need to conduct research that will lead to equipping ACR U with sediment routing and deposition algorithms, as well as routines to account more explicitly for dam operating rules and ecological issues, which would render its output even more useful in IWRM than the model's present structure allows. I wishto certify that the work reported in this dissertation in my original and unaided work except where specific acknowledgment is made. Signed: L D. J. M. Dlamini ACKNO~EDGMENTS The author wishes to express his most sincere gratitude and appreciation for the assistance given by the following: Professor R. E. Schulze, Professor ofHydrology, School ofBioresources Engineering and Environmental Hydrology, University of Nata~ for his support and supervision of this research; Professor J. I. Matondo, Associate Professor ofHydrology, University ofSwaziland, for believing in my capabilities, his advice, co-supervision and for making this study possible; MrA. Pike, ResearchHydrologist, School ofBioresources Engineering and Environmental Hydrology, University ofNatal, for his kind advice and co-supervision ofthis study; Professor P. W. L. Lyne, Head, School ofBioresources Engineering and Environmental Hydrology, University ofNat~ for making this study possible through this School; Mr M. J. C. Horan, GIS Programmer, School of Bioresources Engineering and Environmental Hydrology, University ofNatal, for his assistance; MrJ. S. Hallowes, CPHwater, for allowing that his Fortranprograms be modified and used to aggregate model output; Computing Centre for Water Research, for the provision ofcomputing facilities; The staffofthe Computing Centre for WaterResearch in particular the late Mr A. Kure, Messrs R. De Vos, R. Nundall, J. Thorpe and S. Moodley for their friendly advice and assistance, as well as All my fellow post-graduate students of1999 and 2000, particularly Ms A. Roelofsen, Ms L. A. Perks, Mr N. R. Sihlophe, Ms V. A. Taylor, MrJ. Surendorff, Mr A. J. Pott, Mr A. Butler, Ms C. Kedge and Mr G. Ascough for being patient with my then seemingly endless questions and making me feel at home. The work leading to this dissertation was supported financially through the University of Swaziland by a European Union funded project with an abbreviated title "Integrated Water Resources Management Systems". TABLE OF CONTENTS Page LIST OF FIGURES v LIST OF TABLES ix 1. INTRODUCTION 1 2. ASPECTS OFINTEGRATED CATCHMENTMANAGEMENT (ICM) AND INTEGRATED WATER RESOURCES MANAGEMENT (IWRM) 5 2.1 Definitions 5 2.2 The Catchment as a Water Resources Management Unit 6 2.2.1 Benefits ofadopting the catchment as a management unit 7 2.2.2 Shortcomings ofthe catchment as a management unit 8 2.3 The Concept ofIntegration in Water Resources Management 8 ,-~o/2.3.1 Social issues in water resources management 10 / ," 2.3.2 Integrating catchment information management 11 , '- 2.3.3 Barriers to integrated information management 13 2.4 Sustainability of Water Resources Development and Management 14 ~ 2.5 Stakeholder Participation in Water Resources Management 15 2.6 Types, concerns a..d Roles ofStakeholders Common in Developing countries 15 2.6.1 The Government 16 2.6.2 Agricultural water users 16 2.6.3 Industrial water users 17 2.6.4 Public interest groups 18 2.6.5 Indigenous communities 18 2.6.6 Downstream international obligations 19 2.7 A Review ofWater Resources Management in Swaziland 20 2.7.1 Existing institution framework 21 1 2.7.2 Proposed institutional structure 23 2.7.3 The Water Resources Master Plan 23 .>,2.8 Hydrological Modelling for Integrated Water Resources Management 25 '/,. 2.9 Modelling Problems in Developing Countries 27 3. DESCRIPTION OF THE STUDY AREA 29 3.1 Geographical Location 29 3.2 Physiography, Geology and Relief 29 3.3 Climate 34 3.4 Soils 34 3.5 Natural Vegetation 37 3.6 Present Land and Water Use in the Catchment 37 4. METHODOLOGY 42 4.1 Introduction 42 4.2 The ACRU Agrohydrological Modelling System 42 4.3 Applications ofthe ACRUModel 45 4.4 Modelling the Hydrology ofthe Mbuluzi Catchment 46 4.4.1 Layout and configuration of the Mbuluzi catchment simulation system 46 4.4.2 Preparation of model input 50 4.4.2.1 Rainfall information 51 4.4.2.2 Potential evaporation and temperature information 56 4.4.2.3 Soils information 56 4.4.2.4 Land cover and land use information 60 4.4.2.4.1 Land cover under assumed baseline conditions 61 4.4.2.4.2 Land use under present conditions 61 4.4.2.5 Irrigation information 62 II 4.4.2.6 Information on Dams 69 4.4.2.7 Abstraction ofwater from the stream channels other than for irrigation 70 4.4.2.7.1 Estimation of rural water demands 70 4.4.2.7.2 Estimation of municipal water demands 71 4.4.2.7.3 Estimation of livestock water demands 72 4.4.2.8 Inter-catchment