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Item Uncertainty sources in climate change impact modelling of water resource systems(UniversityPublications.net, 2014) Oyebode, Oluwaseun Kunle; Adeyemo, Josiah; Otieno, Fredrick Alfred O.Modelling climate change impacts on water resources have been widely acknowledged to have various complexities. These complexities are due to the complex, dynamic and non-linear characteristics of the changes in atmospheric, climatological and hydrological processes. These changes are majorly as a result of human activities. Assessment of the potential impacts of these changes with the goal of planning adaptation strategies has given birth to numerous methodologies and approaches. However, uncertainty still occurs at almost every phase of the modelling process; from the development and downscaling of emission scenarios to the use of hydrological models. This paper reviews some of the current methods employed in hydrological modelling of climate change impacts and identifies the key sources of uncertainty inherent at each stage of the hydrological modelling process. Strategies that would incorporate of all sources of uncertainty while ensuring complementary modelling are suggested. These strategies would help in achieving meaningful progress with respect to the development of adaptive water resource systems, and also positively influence decision-making by relevant stakeholders.Item Use of remote sensing and geographical information system (GIS) for salinity assessment of Vaal-Harts irrigation scheme, South Africa(2013) Ochieng, George M.; Ojo, Olumuyiwa I.; Otieno, Fredrick Alfred O.; Mwaka, BeasonSoil salinity is a critical environmental problem in many countries around the world especially the arid and semi-arid countries like South Africa. The problem has great impact on soil fertility which in turns has a great effect on soil productivity. This paper addresses the use of remote sensing and GIS in the assessment of salinity using Landsat enhanced thematic mapper plus (ETM+) data of the Vaal-Harts irrigation scheme acquired with other field data sets and a topographical map to show the spectral classes and salt-affected areas for the years under assessment (1991 to 2005).Item A process-based model for fluidized bed in sand filled reservoirs(ASCE: American Society of Civil Engineers, 2011) Olufayo, O. A.; Ochieng, George M.; Ndambuki, Julius M.; Otieno, Fredrick Alfred O.Arid and semi-arid regions are prone to severe water inadequacies. They are characterized by little rainfall resulting in several seasonal rivers. Seasonal riverbeds provide opportunity for water to be stored in river’s sand-beds while their surfaces may appear dry. It is an important source of water in most rural areas under arid conditions. Several numerical models have been developed for solving sediment problems in alluvial rivers. However, rarely if ever were a model applied for sand filled reservoirs. This study presents a model to understand interacting factors through which physical water storage potential can be increased in sand filled reservoirs. Finite different method (FDM) has been applied to numerically solve mass balance continuity equation in sand filled reservoir. There were reasonable agreements between estimated results and experimental measurements from a laboratory setup. The study could provide economic and suitability data for increasing water supplies to a small community.Item One-dimensional finite difference approach for sedimentation process in sand filled reservoirs(Academic Journals, 2011-04-04) Olufayo, O. A.; Ochieng, George M.; Ndambuki, Julius M.; Otieno, Fredrick Alfred O.There have been continuing efforts to decrease silt deposits due to interstitial blockage in sand-filled reservoirs. However, estimating weir height to allow for deposition of required grain sizes is difficult. This paper presents a numerical process-imitating model aimed at improving water storage potential in sand filled reservoirs. The technique uses a finite difference (FD) numerical model to numerically solve mass balance continuity equation built upon the conservative laws of solid-fluid mixture hydrodynamics. Present investigation shows that barrier height used in sand-filled reservoirs determines the grade quality of deposited sands. The predictions of the model compared with laboratory measurements show agreement between computational and experimental results. The study could provide economic and suitability data for increasing water supplies to a small community through determination of appropriate weir height that will increase subsurface water storage potential.Item Sand water storage : unconventional methods to freshwater augmentation in isolated rural communities of South Africa(Academic Journals, 2010-10-20) Otieno, Fredrick Alfred O.; Olufayo, O. A.; Ochieng, George M.South Africa water resources are scarce in global terms with mean annual rainfall of about half world average of 860 mm a year. On the other hand, current economy development with resulting contamination of available water resources will further reduce water availability, if present patterns of water use continue unchanged. The conventional water resources (largely surface water) in the country have been fully exploited with little opportunity for further expansion. So therefore, new approaches are necessary by accessing alluvial aquifers of non-perennial rivers in forming additional water resources in this part of semi-arid region. High evaporative losses from surface storage, increasing costs of large dams and aridity conditions have hindered development of conventional water resources with increasing interest in using groundwater for rural water supply. Many South Africa rivers are non-perennial, therefore, development of unconventional sand water storage is appealing for freshwater augmentation in isolated rural communities. This paper presents overviews of South Africa water resources highlighting sand water storage options for potential application in rural water supply for isolated communities where groundwater potential is low.Item Making a case for systems thinking approach to integrated water resources management (IWRM)(Academic Journals, 2010-04-22) Dzwairo, Bloodless; Otieno, Fredrick Alfred O.; Ochieng, George M.While definite benefits could be gained from integrating the management of natural and human systems, taking into account the effects of human activities on the environment, the task of operationalising and implementing this approach in practice represents an enormous challenge. Some limitations highlighted include the definition of integrated water resources management (IWRM) itself, where it appears to be broad, all-encompassing and impressive but contains ‘‘lofty phrases’’ that have little practical importance for either present or future water management practices. This paper makes recommendations to uptake and incorporate the systems thinking approach (STA) in IWRM decision making processes, an approach envisaged to be more participatory and also process-oriented. Incorporation of socio-economic dynamics is also recommended, with a suggestion that the biophysical relationships like interactions in a basin between water, the human population and settlements should be analysed to the extent possible.Item Towards a more sustainable surface raw water tariff structure in the Vaal basin : a situational analysis(Academic Journals, 2011-04-18) Dzwairo, Bloodless; Otieno, Fredrick Alfred O.; Ochieng, George M.With an increasingly urbanised population, further study was necessary to determine if water could be used more efficiently by applying efficient tariff structures in combination with decision support tools in the form of models. This paper highlighted challenges towards establishing a sustainable surface raw water tariff structure. Limitations of using the pollute-pays principle for setting a surface raw water tariff structure within a highly urbanised environment were noted. A tariff structure in the Upper and Middle Vaal Water management Areas which are part of the Vaal basin in South Africa was shown to promote inequity such that a downstream user paid more for using more polluted water. Recommendations specific to the Vaal basin included adopting a user-pays principle and also use of a model that incorporated variability in surface raw water quality for tariff setting and also for purposes of predicting potable water treatment costs.Item Ecological functionality of the Upper and Middle Vaal Water Management areas(2012-12-05) Dzwairo, Bloodless; Otieno, Fredrick Alfred O.; Ochieng, George M.A harmonised in-stream water quality guideline was constructed for the Upper and Middle Vaal Water Management Areas (WMAs) using ideal catchment background values for the sub-catchments; Vaal dam, Vaal barrage, Klip River and Blesbokspruit/Suikerbosrant Rivers. Data for years 2003 to 2009 was interpolated to a daily time-step for 2526 days at 21 monitoring sites covering both WMAs. Conductivity was used as a surrogate to capture the variability in water quality. This provided an ecological functionality model of the study area, coded for ranges 10-18, 19-45, 46-80, 80< and 81-100 mS/m. The Upper and Middle Vaal basin is currently extremely vulnerable to changes in water quality, uncertainty about changes which it can tolerate, and the fact that there are very limited options for mitigating effects of poor water quality in the basin, overall. Thus a precautionary approach is being proposed in this paper, in order to protect the ecological functionality of the aquatic ecosystem. The proposed harmonised guideline presents a crucial model to pre-determine the ecological functionality for any water point in the study area, in order to provide upstream-downstream pollution trading and other decision support processes towards sustainable basin managementItem The impact of pricing of raw water on cost of treatment and ultimately on the cost of potable water(2012-11-19) Otieno, Fredrick Alfred O.; Dzwairo, BloodlessThe Department of Water Affairs and Forestry (DWAF) sells raw water to water boards, generally at a fixed price determined annually. The cost of this water does generally not take into account the quality that the water boards receive. Water boards are then expected to treat this water to a certain specified standard for distribution to local authorities which then supply consumers. Consumers are charged based on the volume they consume, presumably a charge that would recover the cost of treatment and other associated overheads, which are agreed upon in advance. The result of this could be one of two things, namely that the consumers in different parts of the country pay different rates or that the water boards may be operating at a loss. Based on recent and ongoing research in the Vaal River system, this paper looks at the implications of this on the final cost of treatment and ultimately on the cost to consumers and suggests ways in which raw water could be priced to ensure fairness and spread of burden to the consumers based on quality requirements.Item Water demand management and losses in Garankuwa and Mabopane, South Africa(2012-11-19) Mhlongo, Ntombie Thandazile; Otieno, Fredrick Alfred O.; Ochieng, George M.This study attempted to address possible solutions to water demand management for the improvement of efficient use of a given volume of water while increasing water access to new users; application of water demand management tools both at the utility and end-user sides; and managing water losses in the distribution network which is a critical aspect of water demand management. The research was conducted in Garankuwa and Mabopane supplied by ODI Water Services in South Africa. This paper describes water resources in South Africa, water demand management tools in place and water supply to the ODI Water Services. It further presents data for the total purchases of water from Rand water and the final billed water at the utility, and water consumption patterns during the period of July to December 2009. This included attempts made to identify and quantify water losses in Garankuwa and Mabopane during the same period. Suggestions were made on how water losses can be reduced. In Garankuwa and Mabopane it was discovered that human perceptions on water demand management and water wastage through unaccounted-for-water together with the indigenous knowledge systems for the management of natural resources need to be altered as the country is water stressed.