Browsing by Author "Mwaipopo, O. U."

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    Hydrodynamics of Chwaka Bay, a Shallow Mangrove-Fringed Tropical Embayment, Tanzania
    (Elsevier, 2000) Nyandwi, Ntahondi; Mwaipopo, O. U.
    Time-series data of currents, sea levels and temperatures from Chwaka Bay,Zanzibar were analysed with the view of understanding the water circulation of the bay. The analyses show that there is a tidal asymmetry in the bay, with peak ebb tidal currents in the deep channels (45 cm s−1) being stronger than flood tidal currents (35 cm s−1), and ebb periods (7 hours) being longer than flood periods (5 hours). The velocity and time asymmetry as well as the asymmetry in the current direction are controlled by the morphological variations of the tidal basin. It was found that, as the water flows from the inner bay during the ebbing tide, it first drains towards the main tidal creek which leads to concentrated but delayed flows. The temperature variations in the inner part of the bay are predominantly diurnal, whereas at the mouth of the bay they are semi-diurnal. There is a general temperature gradient between the inner bay and the mouth, the highest temperatures being recorded in the inner bay (30.14°C). This indicates high residence times of the bay waters, presumably resulting from entrapment.
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    Sediment Characteristics and Hydrodynamic Setting of Reef Platform Sediments of Kunduchi, North Of Dar es Salaam Harbour
    (2006) Shaghude, Yohanna W.; Nyandwi, Ntahondi; Muzuka, A. N. N.; Dubi, Alfonse M.; Mwaipopo, O. U.
    Sediment grain size distribution, carbonate content and current velocities for the Kunduchi area are used to determine its hydrodynamic setting and sediment characteristics. The sediment mean grain size generally decreases northward. The sediments consist of medium to coarse sand south of the Tegeta River and fine sand further north. The sediment sorting values, which lack a northsouth trend, vary from moderately well sorted to poorly sorted. The skewness of the sediment vary from near-symmetrical to very negatively skewed while the peakedness (kurtosis) varies from platykurtic to leptokurtic. The carbonate content increases with distance offshore, whereas the siliciclastic component decreases with distance offshore. The siliciclastic/carbonate transition of the investigated area is characterized by a narrow transition with no inter-fingering of the two facies. The lack of inter-fingering of the two facies suggests that there is a limited offshore transport of land-derived sediments. This is further supported by the drogue experiment results, which shows that the predominant surface current flows northward irrespective of the tidal phase