The world is undergoing rapid changes and the future is uncertain. The changes are related to modification of the landscape due to human activities, such as large and small scale irrigation, afforestation and changes to the climate system. Understanding and predicting hydrologic change is one of the challenges facing hydrologists today. Part of this understanding can be developed from observed data, however, there often too few observations and those that are available are frequently affected by uncertainties. Hydrological models have become essential tools for understanding historical variations of catchment hydrology and for predicting future possible trends. However, most developing countries are faced with poor spatial distributions of rainfall and evaporation stations that provide the data used to force models, as well as stream flow gauging stations to provide the data for establishing models and for evaluating their success. Hydrological models are faced with a number of challenges which include poor input data (data quality and poorly quantified human activities on observed stream flow data), uncertainties associated with model complexity and structure, the methods used to quantify model parameters, together with the difficulties of understanding hydrological processes at the catchment or subbasin. Within hydrological modelling, there is currently a trend of dealing with equifinality through the evaluation of parameter identifiability and the quantification of uncertainty bands associated with the predictions of the model. Hydrological models should not only focus on reproducing the past behaviour of a basin, but also on evaluating the representativeness of the surface and subsurface model components and their ability to simulate reality for the correct reasons. Part of this modelling process therefore involves quantifying and including all the possible sources of uncertainty. Uncertainty analysis has become the standard approach to most hydrological modelling studies, but has yet to be effectively used in practical water resources assessment. This study applied a hydrological modelling approach for understanding the hydrology of a large Tanzanian drainage basin, the Great Ruaha River that has many areas that are ungauged and where the available data (climate, stream flow and existing water use) are subject to varying degrees of uncertainty. The Great Ruaha River (GRR) is an upstream tributary of the Rufiji River Basin within Tanzania and covers an area of 86 000 km2. The basin is drained by four main tributaries; the Upper Great Ruaha, the Kisigo, the Little Ruaha and the Lukosi. The majority of the runoff is generated from the Chunya escarpment, the Kipengere ranges and the Poroto Mountains. The runoff generated feeds the alluvial and seasonally flooded Usangu plains (including the Ihefu perennial swamp). The majority of the irrigation water use in the basin is located where headwater sub‐basins drain towards the Usangu plains. The overall objective was to establish uncertain but behavioural hydrological models that could be useful for future water resources assessments that are likely to include issues of land use change, changes in patterns of abstraction and water use, as well the possibility of change in future climates.

This study analyses the history of a large hydroelectric scheme – the Great Ruaha power project in Tanzania. The objective is to establish why and how this specific scheme came about, and as part of this to identify the key actors involved in the decision-making process, including the ideological contexts within which they acted. Although the Tanzanian actors and the World Bank (IBRD) are discussed, main focus is on the Swedish actors on project level.Kidatu, the first phase of the Great Ruaha power project (constructed between1970-1975), became the first large-scale hydropower station in Tanzania. As such, it paved the way for Tanzanian entrance into the Big Dam Era and significant changes within the Tanzanian landscape. As well as the dry river bed at Kidatu, and the small reservoir that precedes it, the Great Ruaha power project also involved the creation of a huge artificial lake, the Mtera reservoir. The Kidatu hydropower station was the first large undertaking within Swedish bilateral aid, and implied the takeover of control of hydropower construction in Tanzania by Swedish enterprises, replacing the enterprises of the former colonial power. A hydropower plant is a complex technoscientific artefact. The construction of a hydropower plant is preceded by a large number of technological choices, scientific prestudies and estimations of costs and revenues. A hydropower plant is also a complex social creation, and is as such filled with social actors engaged in conflicts, compromises and power structures. The decision to construct Kidatu hydropower station was a result of negotiations and activities within what is called “development assistance”. This brings in yet another dimension, the political one, involving export and import of technology, foreign capital, and foreign influence in decision-making processes, as well as ideas about how to bring development and progress to a people supposed to be living in “poverty and misery”. The study is divided into three main parts. The first part analyses the context of Swedish development assistance in the support to the construction of hydropower plants. This part discusses Swedish state-supported hydropower exploitation of indigenous people’s territory within Sweden’s borders in the 20th century and the background of Swedish development assistance, from the 1950s to the early 1960s. The second part analyses the event of Swedish development assistance entering Tanzania and the Great Ruaha power project, with the main focus being on the period 1965 – 1970. The third part is an analysis of the technoscientific basis for the decisions taken to implement the Great Ruaha hydropower scheme. Main focus is on the period 1969-1974, discussed against the backdrop of precolonial and colonial studies. While focus is on the 1960s and 1970s, in both part two and three events in the 1980s and 1990s are discussed. The study shows that although Sweden was not a colonial power in Tanzania, colonial imagery, and relations to the colonial era, as well as Sweden’s background of internal colonialisation, exerted an influence on the decision-making process and the actors involved in the Great Ruaha power project.The study is mainly based on archival sources, complemented with oral sources from Tanzania and Sweden. Recognizing the complexity of large-scale hydropower and the attempts to control watercourses that large scale hydropower necessitates, in the specific context of decolonisation and development assistance that the decision-making process behind the Great Ruaha hydropower scheme reveals, the analysis of the actors involved is based on feminist and postcolonial perspectives. / QC 20100825

A Thesis Submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy May, 2015. / There is sufficient evidence supporting that climate change and variability are pervasive realities that are strongly impacting on smallholder farmers in the Great Ruaha River sub-Basin of Tanzania. This PhD study examines smallholder farmers’ vulnerability, coping and adaptation strategies to climate change and variability (including non-climatic stresses), and investigates how such coping and adaptation may be constrained or enhanced given climate variability and change. Both quantitative and qualitative data collection methods were used when engaging with smallholder farmers and government officials. Primary data collection was undertaken in two phases, with phase one using participatory tools (e.g. focus group discussions, wealth ranking, community mapping and transect walk, and historical time lines). Data collected include climatic and non-climatic extreme events, farmers’ perceptions, coping and adaptation strategies. Phase two involved detailed individual interviews (questionnaire surveys) and key informant interviews (case studies), so as to obtain in-depth information on issues of interest. Secondary data were collected from existing statistical sources, literature surveys in archives, libraries and documentation centres, and from governmental agencies (e.g. TMA). Demographic, agricultural production and livestock statistics, and rainfall and temperature records were collected. Results from selected meteorological stations and farmers’ perceptions (74%) indicate that there has been an increase in average maximum temperatures, and both dry and wet years with varying magnitudes during the past four decades. Other climatic stresses include delayed onset and later cessation of the rain seasons. The agreement between farmers’ perceptions and rainfall trends provides good evidence that the climate has become increasingly variable in the GRRB during the past four decades. Achieving sustainable livelihoods is further compounded by non-climatic stresses such as access to markets and coordinating institutions. Results indicate that vulnerability is a complex phenomenon that entails two approaches (end-point and starting-point perspectives). The end-point perspective views vulnerability as the net projected climate change impacts after adaptation has taken place, whilst the starting-point perspective looks at both the current and future multiple stresses and places much emphasis in improving the adaptive capacity. In the study villages, such a nuanced picture highlighted areas for enhanced adaptation strategies. Farmers respond by using various strategies to deal with droughts, floods and other stresses when they occur. During droughts, they mostly use irrigation (canal, pumping and cans), or plant short-term maturing crops. During food shortages, farmers use strategies such as buying food, borrowing money, temporary migration, working in other people’s farms for cash, and reducing consumption. Moreover, the farmers’ choice of adaptation and coping strategies is influenced by factors such as location, access to resources, education levels and institutions. This calls for a whole system approach, which entails defining vulnerability of smallholder farmers to climatic and non-climatic stresses and thus designing appropriate response strategies. For example, mainstreaming adaptation to such stresses when considering development plans, projects, programmes and policies at all scales.