Pressures on braided river systems in New Zealand are increasing due to anthropogenic stresses such as demand for irrigation water, braidplain conversion to farmland and invasive vegetation, as well as extreme natural events associated with earthquakes and climate change. These pressures create issues around preserving braided river physical environments and associated ecosystems, and managing hazards such as floods, aggradation and erosion. A need for more robust understanding and quantification of braided river morphodynamic processes underpins many of these issues. Here, we present eight morphodynamic research challenges to service this need. The first four research challenges relate to managing aggradation‐related flooding hazards; the last four address issues stem largely from recent dairy expansion, which has created huge pressure to take land and irrigation water from the alp‐fed braided rivers and to alter flow regimes at their mouths. Hāpua, the freshwater lagoons found where most braided rivers meet the coast, show complex morphodynamic behaviour in response to the interplay of river and coastal processes, and their special ecosystems are sensitive to river flow and sediment load changes. We discuss how physical laboratory experiments and novel numerical modelling can help to understand the morphological processes braided rivers undergo, and we show how those research advances could inform planning and legal decisions to regulate land rights and irrigation water allocation on New Zealand's braidplains. We illustrate these environmental and engineering issues and research challenges with examples from the Kowhai, Waiho, Waiau, Rangitata and Hurunui Rivers. © 2020 John Wiley & Sons, Ltd.

中文翻译：

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辫状河流环境的形态动力学研究挑战：来自新西兰标志性案例的经验教训

由于对人为的压力，例如对灌溉水的需求，将辫状平原转变成农田和侵入性植被，以及与地震和气候变化有关的极端自然事件，对辫状河系统的压力正在增加。这些压力围绕维护辫状河流的物理环境和相关的生态系统，以及管理洪水，积水和侵蚀等灾害产生了问题。对编织河的形态动力学过程需要更深入的了解和量化，这些都是许多问题的基础。在这里，我们提出了八个形态动力学研究挑战来满足这一需求。前四个研究挑战与管理与积水有关的洪水灾害有关；后四个解决问题的主要原因是最近的乳制品扩张，这给从辫状河流中吸取土地和灌溉水以及改变河口的水流状况造成了巨大压力。哈普阿（Hāpua）是大多数辫状河流与海岸相遇的淡水泻湖，响应河流与沿海过程的相互作用，表现出复杂的形态动力学行为，其特殊的生态系统对河流流量和沉积物负荷变化敏感。我们讨论了物理实验室实验和新颖的数值模型如何帮助理解辫状河流所经历的形态过程，并展示了这些研究进展如何为规划和法律决策提供信息，以规范新西兰辫状平原的土地权和灌溉用水分配。我们以Kowhai，Waiho，Waiau，朗伊塔塔河和胡鲁努伊河。分级为4 +©2020 John Wiley＆Sons，Ltd.