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首页> 外文期刊>Estuarine Coastal and Shelf Science >River discharge, sediment transport and exchange in the Tana Estuary, Kenya
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River discharge, sediment transport and exchange in the Tana Estuary, Kenya

机译：肯尼亚塔纳河口的河流排放，泥沙运输和交换

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This study focuses on sediment transport and exchange dynamics in the 27 km~2 Tana Estuary located at Kipini in the north Kenya coast. The estuary is drained by the Tana River, which contributes more than 50% of the total river discharges into the Kenyan sector of the Indian Ocean. The study involved measurement of river discharges, estuarine flood-ebb tidal discharges, total and particulate organic suspended sediment concentrations (TSSC, POSC) and fluxes, tidal water elevation, current velocities, temperature and salinity. The study was conducted between February 2001 and November 2003. The results of the study showed that the Tana River discharge ranged between 60 and 750 m~3 s~(-1). The maximum river discharges during the Southeast and Northeast monsoons were 750 and 350 m~3 s~(-1), respectively. The peak river discharges occurred in May and November. The total daily sediment load of the Tana River varied from 2796 tons day~(-1) during the dry season to 24,322 tons day~(-1) during the rainy season. The annual total sediment load is 6.8 x 10~6 tons yr~(-1), which is, however, smaller than that before the damming of the river in the Upper Tana Basin. Because of river discharge and occurrence of a wide mangrove wetland, the estuary is mainly ebb tide dominant. The peak ebb tide currents (0.87 m s~(-1)) were 30% larger than the peak flood tide currents (0.65 m s~(-1)). During spring tide, the estuary was partially well mixed. However, in neap tide, the estuary was stratified in the middle zone. The turbidity maximum zone with TSSC > 1.5 g l~(-1) was generated in spring tide by wave stirring of frontwater zone bed sediments and trapping of fine sediments at the toe of the salt wedge. The peak TSSC ranging from 1.5 to 5.0 g l~(-1) occurred at low tide due to river supply of sediment and resuspension of channel bed sediments by wind waves, particularly at the last stages of ebb tide and early stages of flood tide. Due to the influx of oceanic water into the estuary at flood tide TSSC decreased to < 0.2 g l~(-1) at high tide in the frontwater zone and was larger in the backwater zones of the estuary. The estuary exports sediments at a rate ranging from 0.02 to 0.08 kg m~(-2) tidal cycle~(-1). The net export of sediments causes a net denudation of the estuary at a rate ranging from 0.08 to 0.04 mm tidal cycle~(-1).
机译：这项研究的重点是位于肯尼亚北部海岸基皮尼（Kipini）的27 km〜2塔纳河口的沉积物迁移和交换动力学。河口被塔纳河排干，塔那河占印度洋肯尼亚河段总排放量的50％以上。该研究涉及河流流量，河口潮汐潮汐流量，有机悬浮物的总和颗粒悬浮物浓度（TSSC，POSC）和流量的测量，潮汐水位，流速，温度和盐度。该研究在2001年2月至2003年11月之间进行。研究结果表明，塔那河流量在60至750 m〜3 s〜（-1）之间。东南季风和东北季风期间的最大河流流量分别为750 m〜3 s〜（-1）。高峰流量发生在5月和11月。塔纳河的日总泥沙量从旱季的2796吨日〜（-1）到雨季的24322吨日〜（-1）不等。年总泥沙量为6.8 x 10〜6吨yr〜（-1），但比塔纳河上游河坝筑坝前的要少。由于河水排放和红树林湿地的出现，河口主要是潮汐主导。潮汐峰值电流（0.87 m s〜（-1））比潮汐峰值电流（0.65 m s〜（-1））大30％。在春季潮汐期间，河口部分混合。然而，在潮汐浪潮中，河口在中部被分层。 TSSC> 1.5 g l〜（-1）的最大浊度带是在春季潮汐时通过前水带床沉积物的波搅动和盐楔脚趾处细小沉积物的捕集而产生的。 TSSC的峰值在1.5到5.0 g l〜（-1）之间，发生在低潮时，这是由于河流的沉积物供应和风浪使河床底泥重新悬浮所致，特别是在退潮的最后阶段和洪水的早期。由于潮汐潮汐时海水流入河口，TSSC在高潮时在前水区下降至<0.2 g l〜（-1），而在河口回水区则更大。河口出口沉积物的速率为0.02至0.08 kg m〜（-2）潮汐周期〜（-1）。沉积物的净出口导致河口的净剥蚀，潮汐周期为（-1）的范围为0.08至0.04 mm。

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