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Controls on Reach Scale Hydrologic Response in Urban Streams and Implications for Restoration Design.

机译：城市河流水域响应规模控制及其对恢复设计的意义。

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摘要

This dissertation explored the nature of hydraulic controls on flow paths and residence times in the channel and riparian zone in two highly urban and two suburban 2nd-3rd order streams in the Baltimore metropolitan region. The influence of urban development and in-stream infrastructure on flow patterns across the flow frequency spectrum were compared to natural features in the channel and riparian zone that have similar effects on flow patterns. This work was motivated by the recognition that the "urban stream syndrome" paradigm of simplified channel geometry associated with extremes of low and high flow does not account for the full range of interactions between urban watershed hydrology, riparian zone morphology, and urban infrastructure.;First, to overcome technical obstacles associated with measuring discharge in flashy urban streams, an innovative methodology is presented in Chapter 2 for extrapolating the high end of discharge rating curves in four urban streams, the results of which were used to more accurately quantify the hydrologic response of the watersheds subsequently studied in this dissertation. In Chapter 3, the goal was to assess how a spectrum of channel and riparian zone morphologies affect the behavior of floodwaves generated from an urban landscape. A degraded urban non-alluvial headwater stream experienced almost pure floodwave translation under existing conditions and also when routed through a planned restoration design intended to improve connectivity with the adjacent riparian zone. Even in a third scenario where the upland corridor was removed and the floodplain was widened to an extreme extent there was little change in the hydrograph routed through the restoration reach. Only in an extremely unrealistic scenario in which the water was stored without release was there a significant change to the hydrographs. For these designs, simply increasing floodplain connectivity did not significantly alter the hydrographs. Next, the effects of a long, broad alluvial riparian zone in a suburban watershed on the properties of floodwaves were assessed. Floods that occur naturally in this watershed overwhelmed the storage capacity of the floodplain and experienced translation, while significant attenuation was observed when hydrographs with large peaks and narrow time bases from a highly impervious headwater urban watershed were routed through this alluvial valley. In Chapter 4, the relationships between longitudinal channel geometries, urban infrastructure, channel-spanning blockages, and mean hydraulic residence times under base flow conditions were also explored. Results show that road crossings create abrupt, non-erodible knickpoints in the channel which exert a strong effect on the distribution of elevation drops in water surface, similar to the controlling influence of channel blockages on channel forming processes. Modeling results across the spectrum of base flows indicate that these urban structures can play a role in controlling flow patterns and residence time, and that channel-spanning blockages and other restoration structures have a significant influence on estimates of in-channel residence time. This work is an important contribution to our understanding of the mechanisms controlling the propagation and storage of surface waters in urban stream networks and adjacent riparian zones, and helps to better define the efficacy of stream restoration practices.
机译：本文探讨了巴尔的摩都会区两个高度城市化和两个郊区二，三阶水流中河道和河岸带水流路径和停留时间的水力控制性质。将城市发展和河内基础设施对整个流量频谱中流量模式的影响与河道和河岸带中对流量模式具有相似影响的自然特征进行了比较。这项工作的动机是认识到，简化的河道几何形态与低流量和高流量的极端现象相关的“城市流综合症”范式并不能说明城市流域水文学，河岸带形态和城市基础设施之间的相互作用。首先，为克服与测量浮华城市溪流流量相关的技术障碍，第2章介绍了一种创新方法，用于推断四个城市溪流的流量等级曲线的高端，其结果用于更准确地量化水文响应本文随后对流域进行了研究。在第3章中，目标是评估河道和河岸带形态的频谱如何影响城市景观产生的洪水波的行为。在现有条件下，退化的城市非冲积源头水流几乎经历了洪水波的平移，并且在经过规划的修复设计以改善与相邻河岸带的连通性时也经历了这种洪水。即使在第三种情况下，高地走廊被拆除，洪泛区被扩大到一个极端的程度，经过修复河段的水文地形几乎没有变化。只有在极其不切实际的情况下，水被储存而没有释放，水位图才发生重大变化。对于这些设计，仅增加洪泛区连通性并不会显着改变水文图。接下来，评估了郊区分水岭上一个长而宽的冲积河岸带对洪水波特性的影响。在该流域自然发生的洪水淹没了漫滩的储水能力，并经历了平移，而当高度不透水的城市流域的高峰和窄时基的水文图通过该冲积河谷时，观察到了明显的衰减。在第4章中，还探讨了纵向水渠的几何形状，城市基础设施，水渠跨度的堵塞以及基流条件下平均水力停留时间之间的关系。结果表明，人行横道在河道中形成了一个不可侵蚀的突变点，这对水面高程下降的分布产生了很大的影响，类似于河道堵塞对河道形成过程的控制作用。在基础流量范围内的建模结果表明，这些城市结构可以在控制流量模式和停留时间方面发挥作用，而跨河阻塞和其他恢复结构对通道内停留时间的估计有重要影响。这项工作为我们对控制城市河网和邻近河岸带中地表水的传播和存储机制的理解做出了重要贡献，并有助于更好地定义河道修复实践的有效性。

著录项

  • 作者

    Lindner, Garth.;

  • 作者单位

    University of Maryland, Baltimore County.;

  • 授予单位 University of Maryland, Baltimore County.;
  • 学科 Hydrology.;Geography.;Environmental Sciences.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 185 p.
  • 总页数 185
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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