Effects of changing freshwater ice regimes

淡水冰情变化的影响

• 批准号: RGPIN-2014-04021
• 负责人: Prowse, Terry
• 金额: $ 2.19万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=566246
• 关键词: Effects; changing; freshwater; ice; regimes

Climate Change/Variability and Freshwater-Ice Systems Freshwater ice is an integral component of cold-regions lakes and rivers and an important modifier of related physical, chemical and biological processes. Although repeated concerns have been expressed about the potential impacts of climate change on ice-covered systems (e.g., assessments for the Intergovernmental Panel on Climate Change and the Arctic Council (Arctic Climate Impact Assessment; Snow Water Ice Permafrost in the Arctic), our current knowledge base makes it difficult to predict the nature and magnitude of the effects of a changing climate on ice-covered systems. This project will focus on filling some of our most important knowledge gaps by addressing two major research themes: 1) extreme ice-induced hydrologic events on rivers (e.g., floods and droughts); and 2) the impact of changing ice-covers on lake water chemistry that controls biological production/diversity. The objective of the 1st theme is to establish the controlling characteristics and significance of extreme hydrologic events created by river ice in the major hydro-climatic regions of Canada. Although changes to extreme events are a major concern regarding future climate change, the importance of ice-induced extreme floods has never been fully quantified beyond a collection of disparate case studies. Previous research conducted by this researcher is leading to a multi-regional national classification of the seasonal/temporal trends in, and relative magnitude (compared to open-water events) of, spring break-up floods across Canada. Based on a unique data-archive assembled by this applicant, this research will: i) quantify temporal and spatial trends in river freeze-up levels across Canada, ii) evaluate their effect on subsequent break-up flooding; iii) quantify similar trends in ice-induced low flows, in the occurrence and magnitude of mid-winter break-up events. A related set of objectives is to define the hydro-climatic controls that have led to the historical trends in such ice-affected hydrologic events, and to project what changes will occur to these trends, under future climate change. Moreover, it will also indicate the regional locations and severity of projected future occurrences. Given the large economic effect that can occur from break-up flooding, the current and planned flow regulation of cold-regions rivers (e.g., for hydro-electric production), and the importance of winter water abstraction during the time of flows (e.g., for increasing industrial development), the results of this research will provide invaluable tools to be used in flow regulation, water-supply management, and flood forecasting. The 2nd project theme will focus on how a changing climate is affecting the composition of lake-ice covers, and specifically on ice-cover types important to lake ecology. Previous research by this applicant has quantified how lake-ice thickness across North America and the Northern Hemisphere will be altered under a future climate. This new research will extend the focus to the role of changes in hydro-climatic conditions that modify ice-cover composition, which affects underwater light regimes, thermal conditions, and dissolved oxygen levels. The numerical model MyLake used in the previous research will be modified to include key algorithms that model all such changes. Test data from multi-sensor lake buoys deployed at high-latitude sites (e.g., as part of Canada’s program to develop the Canadian High Arctic Research Station) will be used for model validation. This second theme will also make projections of future changes to ice-cover composition, water-quality conditions, related biological productivity, and their effect on key trace-gas fluxes (e.g., carbon and methane).

气候变化/变率与淡水-冰系统淡水冰是寒冷地区湖泊和河流的组成部分，是相关物理、化学和生物过程的重要调节剂。尽管人们一再关注气候变化对冰雪覆盖系统的潜在影响(例如，为政府间气候变化专门委员会和北极理事会进行的评估（北极气候影响评估；北极的雪水冰永久冻土），但我们目前的知识基础使我们难以预测气候变化对冰雪覆盖系统影响的性质和程度。该项目将通过解决两个主要研究主题来填补我们一些最重要的知识空白：1)极端冰诱导的河流水文事件（如洪水和干旱）；2)冰盖变化对控制生物生产/多样性的湖泊水化学的影响。第一个主题的目标是确定加拿大主要水文气候区由河冰造成的极端水文事件的控制特征和意义。尽管极端事件的变化是未来气候变化的主要关注点，但除了一系列不同的案例研究之外，冰引起的极端洪水的重要性从未得到充分量化。该研究人员之前进行的研究导致了加拿大各地春季破裂洪水的季节/时间趋势和相对强度（与开放水域事件相比）的多区域国家分类。基于该申请人收集的独特数据档案，本研究将：i)量化加拿大河流冻结水平的时空趋势，ii)评估其对随后的破裂洪水的影响；Iii)量化冰引起的低流量的类似趋势，在冬季中期破裂事件的发生和规模上。一组相关的目标是确定导致这种受冰影响的水文事件的历史趋势的水文气候控制，并预测在未来气候变化下这些趋势会发生什么变化。此外，它还将指出预测的未来灾害的区域位置和严重程度。考虑到破碎洪水可能产生的巨大经济影响，寒冷地区河流的当前和计划流量调节（例如，用于水力发电），以及在流量期间冬季取水的重要性（例如，用于增加工业发展），本研究的结果将为流量调节，供水管理和洪水预测提供宝贵的工具。第二个项目主题将关注气候变化如何影响湖泊冰盖的组成，特别是对湖泊生态重要的冰盖类型。该申请人之前的研究量化了在未来气候下北美和北半球的湖冰厚度将如何变化。这项新的研究将把重点扩展到水文气候条件变化的作用，这些变化会改变冰盖的组成，从而影响水下的光照状况、热条件和溶解氧水平。MyLake在之前的研究中使用的数值模型将被修改，以包括模拟所有这些变化的关键算法。部署在高纬度地点的多传感器湖泊浮标的测试数据（例如，作为加拿大开发加拿大高北极研究站计划的一部分）将用于模型验证。第二个主题还将预测未来冰盖组成、水质条件、相关生物生产力的变化及其对关键微量气体通量（例如碳和甲烷）的影响。