The effects of climate and environmental change are likely to exacerbate water stress in Africa over the next five decades. It appears obvious, therefore, that large river basins with considerable total renewable water resources will play a prominent role in regional cooperation to alleviate the pressure of water scarcity within Africa. However, managing water resources in the large river basins of Africa involves problems of data paucity, lack of technical resources and the sheer scale of the problem. These river basins are located in regions that are characterized by poverty, low levels of economic development and little food security. The rivers provide multiple goods and services that include hydro-power, water supply, fisheries, agriculture, transportation, and maintenance of aquatic ecosystems. Sustainable water resources management is a critical issue, but there is almost always insufficient data available to formulate adequate management strategies. These basins therefore represent some of the best test cases for the practical application of the science associated with the Predictions in Ungauged Basins (PUB). The thesis presents the results of a process-based hydrological modelling study in the Congo Basin. One of the primary objectives of this study was to establish a hydrological model for the whole Congo Basin, using available historical data. The secondary objective of the study was to use the model and assess the impacts of future environmental change on water resources of the Congo Basin. Given the lack of adequate data on the basin physical characteristics, the preliminary work consisted of assessing available global datasets and building a database of the basin physical characteristics. The database was used for both assessing relationships of similarities between features of physiographic settings in the basin (Chapters 3 and 4), and establishing models that adequately represent the basin hydrology (Chapters 5, 6, and 7). The representative model of the Congo Basin hydrology was then used to assess the impacts of future environmental changes on water resources availability of the Congo Basin (Chapter 8). Through assessment of the physical characteristics of the basin, relationships of similarities were used to determine homogenous regions with regard to rainfall variability, physiographic settings, and hydrological responses. The first observation that comes from this study is that these three categories of regional groups of homogenous characteristics are sensible with regards to their geographical settings, but the overlap and apparent relationships between them are weak. An explanation of this observation is that there are insufficient data, particularly associated with defining sub-surface processes, and it is possible that additional data would have assisted in the discrimination of more homogenous groups and better links between the different datasets. The model application in this study consisted of two phases: model calibration, using a manual approach, and the application of a physically-based a priori parameter estimation approach. While the first approach was designed to assess the general applicability of the model and identify major errors with regard to input data and model structure, the second approach aimed to establish an understanding of the processes and identify useful relationships between the model parameters and the variations in real hydrological processes. The second approach was also designed to quantify the sensitivity of the model outputs to the parameters of the model and to encompass information sharing between the basin physical characteristics and quantifying the parameters of the model. Collectively, the study’s findings show that these two approaches work well and are appropriate to represent the real hydrological processes of Congo Basin. The secondary objective of this study was achieved by forcing the hydrological model developed for the Congo Basin with downscaled Global Climate Model (GCMs) data in order to assess scenarios of change and future possible impacts on water resources availability within the basin. The results provide useful lessons in terms of basin-wide adaptation measures to future climates. The lessons suggest that there is a risk of developing inappropriate adaptation measures to future climate change based on large scale hydrological response, as the response at small scales shows a completely different picture from that which is based on large scale predictions. While the study has concluded that the application of the hydrological model has been successful and can be used with some degree of confidence for enhanced decision making, there remain a number of uncertainties and opportunities to improve the methods used for water resources assessment within the basin. The focus of future activities from the perspective of practical application should be on improved access to data collection to increase confidence in model predictions, on dissemination of the knowledge generated by this study, and on training in the use of the developed water resources assessment techniques.

A large river system typically derives the majority of its biomass from production within the floodplain. The Neches River in the Big Thicket National Preserve is a large blackwater river that has an extensive forested floodplain. Organic carbon was analyzed within the floodplain waters and the river (upstream and downstream of the floodplain) to determine the amount of organic carbon from the floodplain that is contributing to the nutrient dynamics in the river. Dissolved organic carbon was significantly higher at downstream river locations during high discharge. Higher organic carbon levels in the floodplain contributed to increases in organic carbon within the Neches River downstream of the floodplain when Neches River discharges exceeded 10,000 cfs. Hurricane Rita passed through the Big Thicket National Preserve in September 2005. Dissolved organic carbon concentrations recorded after Hurricane Rita in the Neches River downstream of the floodplain were significantly higher than upstream of the floodplain. Dissolved organic carbon was twice as high after the hurricane than levels prior to the hurricane, with floodplain concentrations exceeding 50 ppm C. The increase in organic carbon was likely due to nutrients leached from leaves, which were swept from the floodplain trees prior to normal abscission in the fall. A continuum of leaf breakdown rates was observed in three common floodplain species of trees: Sapium sebiferum, Acer rubrum, and Quercus laurifolia. Leaves collected from blowdown as a result of Hurricane Rita did not break down significantly faster than leaves collected prior to abscission in the fall. Processing coefficients for leaf breakdown in a continuously wet area of the floodplain were significantly higher than processing coefficients for leaf breakdown on the floodplain floor. The forested floodplain of the Neches River is the main contributor of organic carbon. When flow is greater than 10,000 csf, the floodplain transports organic carbon directly to the river, providing a source of nutrition for riverine organisms and contributing to the overall health of the ecosystem.

Botswana is a water scarce country. Rainfall is highly variable, leading to limited surface and groundwater resources. Due to persistently dry conditions most rivers found in Botswana are ephemeral. The Boteti River sub-Basin is one of the numerous ephemeral river sub-Basins, in Botswana. Key environmental challenges, resulting from human activities, in the sub-Basin are: increased pressure on local resources due to overstocking, overgrazing and over-harvesting; reductions in wildlife numbers; denudation of vegetation and the resultant exposure of the soil to wind erosion. As a major step, to pilot implementation of river basin management in the ephemeral river basins in southern Africa, the Boteti River sub-Basin is one of the key areas identified for study under the Ephemeral River Basins in the Southern African Development Community SADC (ERBSADC) Project. This study was initiated, as part of the ERB-SADC project and its aim is to investigate the socio-economic status of the Boteti River sub-Basin and determine the potential for developing integrated management of water and land resources in the sub- Basin. Its key objectives are to identify and assess types and patterns of water use; to identify and assess key livelihood activities; and to critically assess community participation in water resources management in the sub-Basin. A questionnaire was administered to 293 households, a focus group discussion was held with twelve community representatives of six villages in the sub-Basin, six traditional leaders and five local government officers were interviewed as key informants, and informal discussions were held with three local farmers. Results from the study indicate low livelihood levels based on livestock and arable agriculture, high dependence on natural resources and low participation of communities in water management. The study concludes that a livelihood approach to integrated water resources management can help deal with environmental challenges and enhance community participation. / Environmental Sciences / Thesis (M.A. (Environmental Science))

Botswana is a water scarce country. Rainfall is highly variable, leading to limited surface and groundwater resources. Due to persistently dry conditions most rivers found in Botswana are ephemeral. The Boteti River sub-Basin is one of the numerous ephemeral river sub-Basins, in Botswana. Key environmental challenges, resulting from human activities, in the sub-Basin are: increased pressure on local resources due to overstocking, overgrazing and over-harvesting; reductions in wildlife numbers; denudation of vegetation and the resultant exposure of the soil to wind erosion. As a major step, to pilot implementation of river basin management in the ephemeral river basins in southern Africa, the Boteti River sub-Basin is one of the key areas identified for study under the Ephemeral River Basins in the Southern African Development Community SADC (ERBSADC) Project. This study was initiated, as part of the ERB-SADC project and its aim is to investigate the socio-economic status of the Boteti River sub-Basin and determine the potential for developing integrated management of water and land resources in the sub- Basin. Its key objectives are to identify and assess types and patterns of water use; to identify and assess key livelihood activities; and to critically assess community participation in water resources management in the sub-Basin. A questionnaire was administered to 293 households, a focus group discussion was held with twelve community representatives of six villages in the sub-Basin, six traditional leaders and five local government officers were interviewed as key informants, and informal discussions were held with three local farmers. Results from the study indicate low livelihood levels based on livestock and arable agriculture, high dependence on natural resources and low participation of communities in water management. The study concludes that a livelihood approach to integrated water resources management can help deal with environmental challenges and enhance community participation. / Environmental Sciences / Thesis (M.A. (Environmental Science))

This study describes macroinvertebrate community structure and assesses its potential in detecting point and non-point sources of disturbance associated with rural and urban areas in the Upper Trinity River Basin. Geospatial techniques were used to quantify landuse within the watershed in a GIS. At rural sites near the headwaters of the Trinity River, collector-gathering burrowers that are adapted to minimal flow comprised the majority of taxa. Destinies of taxa compositions at downstream sites increased and shifted toward psammophilic and rheophilic invertebrates, including primarily collector-filtering clingers, that are characteristic of shifting sand habitats in large prairie rivers. Benthic community structure generally benefited from point source impacts including wastewater treatment plant effluents that maintained higher flow. Community indices were negatively associated with forest landuse and positively associated with urban landuse. Partial CCA determined that flow and landuse contributed equally to species dispersions. Comparisons with historical biomonitoring studies in upper Trinity River Basin indicate improved watershed health.

The ecologically and culturally rich Amazonian border zones are increasingly targeted for development and the exploitation of natural resources, even as these zones often double as existing or proposed sites for the conservation of biodiversity and protection of indigenous lands. Governmental and Non-Governmental Organizations alike project their goals from central offices onto borderland landscapes assumed to be empty of local people but full of valuable resources, biodiversity or development potential. Simultaneously, loggers, miners, drug traffickers, and others operate illegally or quasi-legally within these border zones and, in the absence of a strong governmental presence, cultivate the borderland's reputation as a violent hinterland. Within this complex borderland reality, the local people (indigenous and non-indigenous), largely invisible to authorities, struggle to survive with subsistence strategies while either negotiating with illegal interlopers to supplement their income or resisting them for their very survival. The resulting landscape is a tangle of overlapping and competing concessions, conservation units, and indigenous territories whose contestation and resulting confusion advances the agenda of illegal extractivists and drug traffickers. This study highlights the continued importance of fieldwork in geography. Here, field-based research provides insight into the poorly understood borderlands of Peru and Brazil. Research used a combination of participatory methods, Geographic Information Systems, ethnography, document research, and remote sensing to analyze mapping, logging, and coca cultivation within four borderland watersheds. These data were combined with regional data on coca eradication, resource concessions, conservation units, and indigenous territories from both Brazil and Peru. Field-based results demonstrate these borderlands to be highly contested and poorly mapped with an exploitative and poorly managed timber industry and a dynamic front of coca cultivation contributing to social disruption and environmental degradation. More fieldwork is needed to generate the geographic information necessary for sustainable development and conservation planning and to help local people defend their territory from illegal operators and the imposition of state resource concessions. Ecological Economic Zoning is recommended as a participatory policy framework to improve geographic information and long term planning. / text

Traditional peoples are often described as "stewards of agricultural diversity", yet little research has been conducted on the determinants of agrodiversity. This thesis focuses on agrodiversity and how peasant farmers build and maintain cultivated plant diversity in home gardens found in three distinct traditional communities along the Maranon river in the Peruvian Amazon---an upland mixed agricultural village, a lowland agricultural village, and a lowland fishing village. Data were gathered through household surveys (n = 192) and in-depth interviews (n = 112). Substantial variation in cultivated plant diversity was found among and within villages. Residents with the highest home garden agrodiversity tend to be among the wealthier households, and are more likely to have both established their own garden, and tended it for longer periods. Complex planting material exchange networks underlie the establishment and maintenance of home garden agrodiversity. The results underscore the importance of studying local variations in agricultural diversity, and exchange networks that bring agricultural planting stock to peasant farmers.

This study involves the application of the ACRU Agrohydrological Model to a selected study catchment in the Lower Mgeni Catchment, and its discretized subcatchments, immediately downstream of the Inanda Dam. This study was initiated on the assumption that the Inanda Dam, which came into operation in 1989, would have significant impacts on the downstream (Lower Mgeni) hydrology, geomorphology and ecology. The overall aim of this study, to set up and run the ACRU model for the delimited study catchment, was successfully accomplished. This aspect of the study involved firstly, the setting up of an input database for each distributed catchment within the catchment; secondly, the processes and techniques used to translate data into hydrological information; and finally the "running" of the hydrological model, which in turn "drives" the system and simulates the catchment hydrology. Specific objectives of the study entailed the simulation of hydrology, which focussed on simulated runoff and streamflow; and sediment yield responses of the subcatchments and the total study catchment of the Lower Mgeni, with respect to gross volumes and sediment yield rates produced. The streamflow results reported indicated a season of "Iow" flow, with a monthly flowrate ranging from 1155m3s-1 to 2735m3s-1 , from April to September; and is identified and distinguished from the period of "high" flowrate, ranging from approximately 483m3s-1 to 1747m3s-1 , for the remaining months of the year. The mean annual volume for the delimited subcatchment is 22 278.5 million m3 , exceeding the annual volume required to maintain riverine and estuarine ecology, which according to DWAF (1990) is 18.5 million m3 . The simulated results of sediment yield indicate that Subcatchment 3 and 4 have the lowest sediment yield rates of 32.3 t km-2 a-1 and 32.6 t km-2 a-1 , respectively. Subcatchment 2 has the highest yield rate at the value of 617 t km-2 a-1 , while subcatchment 1 has a rate of 53.2 t km-2 a-1 . Annual sediment production in the Lower Mgeni subcatchment is 10 855.1 tons per annum with respect to gross mass, resulting in a sediment yield rate of 73.8 t km-2 a-1 . The outcomes of this study compare very favourably with other studies conducted on hydrology and sediment yield, especially those undertaken within this geographical area. It may be assumed therefore, that the results produced herein can be applied with confidence to enable appropriate planning and management of resources within this catchment. Modelling of hydrology in the Lower Mgeni is expected to contribute significantly towards meeting riverine and estuarine ecological and geomorphological streamflow requirements. It would facilitate the development of an appropriate management and dam release strategy of Inanda Dam, in order to meet these requirements. The modelling of sediment yield is expected to contribute to the development of a sustainable sandwinning policy and strategy for the Lower Mgeni, as current extraction rates exceed the annual sediment production. Once the model has been applied to a selected catchment, it has the ability to consider different scenarios, providing an invaluable tool for planning. Based on the results of this study, the ACRU model may be applied, with confidence, to other similar ungauged catchments. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

Metals are naturally found in ecosystems but can also enter via human activity such as fossil fuel combustion, and disposal of metal products. Copper, lead, and iron have frequently been detected throughout Indiana freshwaters based on historical samples. Since microbial activity is a holistic measure of ecosystem function, changes in microbial activity in response to metals may indicate potential areas of concern. Metal concentrations in seven streams of the Upper White River watershed of central Indiana were measured during spring (May) and summer (August) in conjunction with measurement of sediment nitrification rates using the nitrapyrin-inhibition technique. Additionally, the influence of copper, lead, and iron on microbial nitrification was studied using in vitro mesocosms inoculated with stream sediment from selected sites. Copper, lead, and iron concentrations in stream sediment and water varied among sites with sediment concentrations ranging 654 – 1985 mg Fe/kg sediment and 1.00 - 2.91 mg Cu/kg sediment. Water concentrations ranged from below detection to 0.10 mg Fe /L, and 0.01 – 0.02 mg Cu/L. Lead concentrations were below detection at all sites except in May at one site (Pleasant Run Creek 0.47 mg Pb/kg sediment) and in August at one site (Mud Creek 0.38 mg Pb/ kg sediment). Stream sediment nitrification rates were positively correlated to stream sediment copper concentration (r = 0.78, p = 0.001). There was no significant correlation between sediment nitrification rates and stream sediment iron, pH, dissolved iron, or total dissolved solids (TDS; p > 0.05). Positive correlations were found between nitrification response rates and total Fe (r = 0.61, p = 0.02) and Cu (r = 0.74, p = 0.002) concentrations. Experimental mesocosms indicate metal addition of 127 mg/L may reduce stream sediment nitrification rates though stream physiochemical characteristics and history of metal exposure likely dictate microbial response. Further, metal concentrations in the stream sediment may have more of an influence on nitrifying microbes than dissolved metal in the water column. / Department of Biology

Agrobiodiversity constitutes an essential resource for traditional rural populations. Home gardens are "hotspots" of agrobiodiversity and important loci of in situ conservation efforts. This study seeks to understand the factors affecting gardeners' choices and to assess the accessibility of planting material in rural communities of the Peruvian Amazon. Household surveys and garden inventories conducted in 15 villages of the Corrientes river (n = 300), and case studies in three of these villages (n = 89), allowed to describe the local and regional patterns of garden agrobiodiversity and the structure of planting material exchange networks. Analyses reveal a strong link between species diversity and both household cultural and socioeconomic characteristics, and village ethnicity and size. Planting material flows primarily through matrilineal bonds, from advice-givers to advice-seekers, from old to young and from rich to poor. Farmers with exceptional species diversity, propensity to give and/or expertise are identified and their role in the conservation of cultivated plants is assessed. Expertise is not found to be as closely related to high species diversity as expected, but knowledge and planting stock dissemination go hand-in-hand.