...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Urban and Environmental Engineering >A STUDY ON THE EFFECTS OF TIDE ON SEDIMENTATION IN ESTUARIES OF THE NIGER DELTA, NIGERIA
【24h】

A STUDY ON THE EFFECTS OF TIDE ON SEDIMENTATION IN ESTUARIES OF THE NIGER DELTA, NIGERIA

机译：潮汐对尼日尔三角洲河口沉积物影响的研究

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Estuaries in the Niger Delta-Nigeria are influenced by tidal currents and wave actions due to their proximity to the Atlantic Ocean. Tidal current provides the energy required to move sediments in and out of the estuaries from the seashores, while wave actions curtails the deposition of sediments at the bottom of the estuaries as the bed get shallower, resulting in the modification and long-term regulation of siltation through erosion or accretion. The interaction between estuaries bathymetric shapes, tidal currents and wave actions can only be fully understood through analytical or mathematical relationships. Analytical methods are less accurate in predicting future tides, while none of the existing mathematical relationships can accurately predict tidal behavior in the Niger Delta region due to the fact that parameters governing tidal actions vary from region to region, hence the need for this study. This study shows the behavior of the estuaries in response to variation in tidal heights, currents and wave actions through mathematical modeling, a knowledge which is useful in planning and timing of marine activities that requires pre-knowledge of tidal levels, direction and current velocities. The models were formulated and calibrated using parameters generated from the hydrographic, hydraulics and geotechnical investigation, including local field observations and measurements conducted within the study area. Soil samples taken from the area are composed of peat, organic clays, silty clays and sand. Peat constitutes the dominant soil which is locally known as 'chikoko' with high compressibility and color ranging from dark brown to dark gray and texture from soft to firm. Typical bed material size (D50) is approximately 0.2mm. Tides in the region are mostly semidiurnal with tidal prism ranging from 0.4 to 1.5m. The tidal strength is strongest at the inlets and decreases with distance inland. The depth of the estuaries is controlled by the strength of the tidal currents. Areas very close to the ocean with stronger tidal effect are very deep; while shallow canals and creeks predominates the hub of the estuaries. The results obtained using the present models compared favorably with the field measurements. Average correlation coefficients of 0.9 were obtained in some cases. The results showed that the estuaries erodes, accretes, or remain stable, depending on the rate at which sediment is supplied or removed from them.
机译：尼日尔三角洲和尼日利亚的河口由于靠近大西洋而受到潮流和波浪作用的影响。潮汐流提供了将沉积物从海岸移入和移出河口所需的能量，而随着床层变浅，波浪作用会限制沉积物在河口底部的沉积，从而导致泥沙淤积的改变和长期调控通过侵蚀或吸积。河口测深形状，潮流和波浪作用之间的相互作用只能通过分析或数学关系来完全理解。分析方法预测未来潮汐的准确性较差，但由于控制潮汐作用的参数因地区而异，因此现有的数学关系均无法准确预测尼日尔三角洲地区的潮汐行为，因此需要进行此项研究。这项研究通过数学模型显示了河口对潮汐高度，洋流和波浪作用变化的响应，这对于需要事先了解潮汐水平，方向和水流速度的海洋活动的规划和时间安排很有用。使用从水文，水力和岩土研究中产生的参数（包括在研究区域内进行的局部现场观测和测量）生成的参数来制定和校准模型。从该地区采集的土壤样品包括泥炭，有机粘土，粉质粘土和沙子。泥炭构成主要土壤，在当地被称为“ chikoko”，其可压缩性高，颜色范围从深棕色到深灰色，质地从软到硬。典型的床身材料尺寸（D50）约为0.2mm。该地区的潮汐大多为半昼间，潮汐棱镜的范围为0.4至1.5m。潮汐强度在进口处最强，并随着距离内陆而减小。河口的深度由潮流强度控制。靠近海洋且具有更强潮汐作用的区域非常深;而浅水渠和小溪则是河口的枢纽。使用本模型获得的结果与现场测量结果相比具有优势。在某些情况下，平均相关系数为0.9。结果表明，河口侵蚀，增生或保持稳定，这取决于沉积物的供应或清除速度。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号