• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文OA文献 >Sediment yield of the lower Tana River, Kenya, is insensitive to dam construction: sediment mobilization processes in a semi-arid tropical river system
【2h】

Sediment yield of the lower Tana River, Kenya, is insensitive to dam construction: sediment mobilization processes in a semi-arid tropical river system

机译：肯尼亚塔纳河下游的泥沙产量对水坝建设不敏感：半干旱热带河流系统中的泥沙动员过程

代理获取
本网站仅为用户提供外文OA文献查询和代理获取服务，本网站没有原文。下单后我们将采用程序或人工为您竭诚获取高质量的原文，但由于OA文献来源多样且变更频繁，仍可能出现获取不到、文献不完整或与标题不符等情况，如果获取不到我们将提供退款服务。请知悉。
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Dam construction in the 1960's to 1980's significantly modified sediment supply from the Kenyan uplands to the lower Tana River. To assess the effect on suspended sediment fluxes of the Tana River, we monitored the sediment load at high temporal resolution for one year and complemented our data with historical information. The relationship between sediment concentration and water discharge was complex: at the onset of the wet season, discharge peaks resulted in high sediment concentrations and counterclockwise hysteresis, while towards the end of the wet season, a sediment exhaustion effect led to low concentrations despite the high discharge. The total sediment flux at Garissa (ca. 250 km downstream of the lowermost dam) between June 2012 and June 2013 was 8.8 Mt yr−1. Comparison of current with historical fluxes indicated that dam construction had not greatly affected the annual sediment flux. We suggest that autogenic processes, namely river bed dynamics and bank erosion, mobilized large quantities of sediments stored in the alluvial plain downstream of the dams. Observations supporting the importance of autogenic processes included the absence of measurable activities of the fall-out radionuclides 7Be and 137Cs in the suspended sediment, the rapid lateral migration of the river course, and the seasonal changes in river cross-section. Given the large stock of sediment in the alluvial valley of the Tana River, it may take centuries before the effect of damming shows up as a quantitative reduction in the sediment flux at Garissa. Many models relate the sediment load of rivers to catchment characteristics, thereby implicitly assuming that alterations in the catchment induce changes in the sediment load. Our research confirms that the response of an alluvial river to external disturbances such as land use or climate change is often indirect or non-existent as autogenic processes overwhelm the changes in the input signal.
机译：1960年代至1980年代的大坝建设大大改变了从肯尼亚高地到塔那河下游的沉积物供应。为了评估对塔纳河悬浮泥沙通量的影响，我们在高分辨率下监测了一年的泥沙负荷，并用历史信息对我们的数据进行了补充。沉积物浓度与排水量之间的关系很复杂：在雨季开始时，排放峰值导致高的泥沙浓度和逆时针的滞后现象，而在雨季结束时，尽管雨季高，但泥沙排泄作用导致浓度低。排出。 2012年6月至2013年6月，加里萨（最低水坝下游约250 km）的总泥沙通量为8.8 Mt yr-1。当前流量与历史流量的比较表明，大坝的建设并没有很大地影响年输沙量。我们认为自生过程，即河床动力学和河岸侵蚀，动员了大坝下游冲积平原中存储的大量沉积物。支持自生过程重要性的观察结果包括悬浮泥沙中没有放射性放射性核素7Be和137Cs的可测量活动，河道的横向快速迁移以及河道横截面的季节性变化。考虑到塔纳河冲积河谷中大量的沉积物，可能需要几个世纪的时间才能将大坝的作用显示为对Garissa沉积物通量的定量减少。许多模型将河流的泥沙负荷与流域特征相关联，从而隐含地假设流域的变化引起泥沙负荷的变化。我们的研究证实，冲积河对外部干扰（如土地利用或气候变化）的响应通常是间接的或不存在的，因为自生过程压倒了输入信号的变化。

著录项

相似文献

  • 外文文献
  • 专利
代理获取

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