Institute of Marine Sciences

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Browsing Institute of Marine Sciences by Author "Arthurton, Russell"

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    Beach Sand Supply and Transport at Kunduchi in Tanzania and Bamburi in Kenya
    (2012) Shaghude, Yohanna W.; Mburu, J. W.; Uku, Jacqueline; Arthurton, Russell; Nyandwi, Ntahondi; Onganda, H.; Magori, Charles; Sanga, Ignatio
    Beach-head erosion of sandy beach plains in eastern Africa threatens tourism-related infrastructure and the livelihoods of beach users. The nature and drivers of physical shoreline change at Kunduchi, Dar es Salaam, and Bamburi, Mombasa, are described with analyses of beach sand transport through the annual monsoon cycle and the provenance and sustainability of the beach sand supply. Time-series records of wind-vectors at Dar es Salaam and Mombasa show similar averaged patterns. Because of the contrasting alignments of these coasts, the net wind-wave driven longshore transport at Kunduchi (trending NNW) is northnorth-westwards, while at Bamburi (trending NNE) there is little net transport. At Bamburi, the beaches are recharged with reef/platform-derived calcium carbonate sand and siliciclastic sand discharged from the hinterland via tidal channels. At Kunduchi, recharge comprises mostly river-borne siliciclastic sand, but riverine sand mining threatens natural replenishment, jeopardising beach maintenance. Eroding beach plain deposits contribute siliciclastic sand at both sites.
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    Downstream and Coastal Impacts of Damming and Water Abstraction in Africa
    (Springer Science, 2007) Snoussi, Maria; Kitheka, Johnson; Shaghude, Yohanna W.; Kane, Alioune; Arthurton, Russell; Tissier, Martin; Virji, Hassan
    Abstract Anthropogenic factors associated with damming and water abstraction, and the resultant environmental pressures, are reviewed in six African river catchments using records and forecasts of climatic, demographic, and land-use change. Changes in the states of the flow regime through catchment drainage systems to the coastal sea are considered in conjunction with climate change and other humaninduced pressures. The impacts of these changes on downstream and coastal environments and their communities are described in past, present, and future perspectives. Linkages between the issues and the pressures of damming and water abstraction are appraised and scientific, policy, and management responses proposed aimed at remedying existing and perceived future negative impacts. The study proposes that there is a need to integrate catchment and coastal management to account for the whole water flow regime together with its human dimensions. Management priorities relating to the operation of existing damming and abstraction schemes and planning of future schemes include the following: consideration of ways in which water discharges could be adjusted to provide improvements in downstream and coastal environmental and socioeconomic conditions; addressing the problem of sediment trapping impacting on the sustainability of dam reservoirs; and assessment of downstream and coastal impacts of future schemes in the light of climate change forecasts.
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    Morphodynamics of the Manyema Tidal Delta at Kunduchi, Tanzania
    (WIOMSA, 2013) Nyandwi, Ntahondi; Shaghude, Yohanna W.; Mburu, J. W.; Dubi, Alfonse M.; Sanga, I.; Arthurton, Russell
    The prevailing northward longshore drift of beach sand on the northern part of Msasani Bay, north of Dar es Salaam, is interrupted at Kunduchi by the tidal flushing of Manyema Creek, a mangrove ecosystem partially developed for salt production. Shoreline changes around the creek mouth in recent decades have eroded coastal land and destroyed buildings, prompting stakeholders to construct protective groynes and revetments. Sand is transported across the delta by the interaction of two forcing processes – currents that flush the creek in response to tidal variation and, more generally, those generated by monsoonal wind-driven waves. A study of the sand morphology of the creek and delta platform together with time-series satellite imagery permitted demarcation of the respective sand transport pathways and morphodynamic changes in the delta over the last decade. The sand transport regime has promoted erosion of the shore to the south of the creek mouth, and has resulted in intermittent delivery of sand to beaches north of the channel. Attempts to stabilise the shore around the creek mouth are described and their effectiveness evaluated.
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    Shoreline Change in Tanzania and Kenya
    (Wiomsa, 2014) Shaghude, Yohanna W.; Mburu, J. W.; Arthurton, Russell
    Shoreline change is an ongoing issue affecting communities, their livelihoods and tourism development in the Western Indian Ocean (WIO) region. A particular concern has been the threat of coastal erosion to tourism infrastructure. Other concerns, arising both from coastal erosion and from efforts to control it, include habitat loss and the degradation of coastal amenities. In Tanzania and Kenya, the issue of shoreline change, and in particular the hazard of coastal erosion, has been the subject of regional and national reports, identifying a range of possible forcing factors. Despite these efforts, there is a lack of guidance on the methodologies for the assessment and mitigation of the risks from shoreline change, both to affected stakeholders and to the coastal environment. The WIOMSA MASMA programme has therefore sought to promote and facilitate the development of such guidance by supporting an intensive study of shoreline change, its causes, socio-economic and environmental consequences; and the management of the associated risks to coastal communities. This manual reflects the outcomes of this study. The fieldwork focused on two case-study sites; one in Kenya on Mombasa’s northern shore, and the other in Tanzania on the shore of Msasani Bay, on the northern outskirts of Dar es Salaam. The sites include many of the typical physical, ecological and socio-economic features of these countries’ shorelines. They were selected on the basis of known shoreline change issues of economic significance. The compilation of the manual has benefited greatly from many national and international publications dealing with coastal management and, specifically, shoreline change and its physical processes. The illustrations, figures and data relate mostly to the case-study sites. However, the issues addressed are common to most coastal areas of Tanzania and Kenya, and some of them to the coasts of the WIO region as a whole
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    Shoreline Change in Tanzania and Kenya: Manual for Assessment and Design of Mitigation Strategie
    (WIOMSA, 2015-01) Shaghude, Yohanna W.; Mburu, J. W.; Arthurton, Russell; Dubi, Alfonse M.; Gachuiri, S.; Kangwe, J.; Magori, C.; Msuya, Flower E.; Nyandwi, Ntahondi; Ochiewo, J.; Ong'anda, H.; Sallema, R.; Sanga, I.; Shalli, Mwanahija. S.; Uku, J.
    The aim of the manual is to raise awareness of the complex causes of, and the issues and risks associated with, shoreline change at local and national scales in Tanzania and Kenya, but also within the context of the WIO region. A greater awareness and application of shoreline planning and management can benefit coastal stakeholders, livelihoods, as well as local and national economies. The manual promotes the management of risks associated with shoreline change within the context of ICAM, with an emphasis on protecting the natural capital of the region’s coastal areas.