Reconstruction Of Paleo-Hydrologic Data For Vulnerability Assessment Of Water Resources Systems

Tree-ring chronologies are a rich source of information of past climate-driven non-stationarities in hydrologic variables. They are typically directly related to available water in respective years, thereby providing a basis for paleo-hydrology reconstruction. This study investigates the time series of tree-ring chronologies, with the objective of identifying the spatiotemporal patterns and extents of non-stationarities, which are essentially representations of past “climate changes”. This study also generates ensembles of moving-average streamflow time series for the centuries prior to the period of observational record. The major headwater tributaries of the Saskatchewan River basin (SaskRB), the main source of surface water in the Canadian Prairie Provinces, are used as the case study. This extended abstract gives a brief summary of the methodology and some examples of the results. The analyses and results show how the reconstruction of paleo-hydrology broadens the understanding of hydrologic characteristics of a basin beyond the limited observational records, and therefore, provides a basis for more reliable assessment and management of available water resources

A stochastic reconstruction framework for analysis of water resource system vulnerability to climate-induced changes in river flow regime

Assessments of potential impacts of climate change on water resources systems are generally based on the use of downscaled climate scenarios to force hydrological and water resource systems models and hence quantify potential changes in system response. This approach, however, has several limitations. The uncertainties in current climate and hydrological models can be large, such analyses are rapidly outdated as new scenarios become available, and limited insight into system response is obtained. Here, we propose an alternative methodology in which system vulnerability is analyzed directly as a function of the potential variations in flow characteristics. We develop a stochastic reconstruction framework that generates a large ensemble of perturbed flow series at the local scale to represent a range of potential flow responses to climate change. From a theoretical perspective, the proposed reconstruction scheme can be considered as an extension of both the conventional resampling and the simple delta-methods. By the use of a two-parameter representation of regime change (i.e., the shift in the timing of the annual peak and the shift in the annual flow volume), system vulnerability can be visualized in a two-dimensional map. The methodology is applied to the current water resource system in southern Alberta, Canada, to explore the system's vulnerability to potential changes in the streamflow regime. Our study shows that the system is vulnerable to the expected decrease in annual flow volume, particularly when it is combined with an earlier annual peak. Under such conditions, adaptation will be required to return the system to the feasible operational mode. © 2013. American Geophysical Union. All Rights Reserved

Recent climatic, cryospheric, and hydrological changes over the interior of western Canada: A review and synthesis

It is well established that the Earth's climate system has warmed significantly over the past several decades, and in association there have been widespread changes in various other Earth system components. This has been especially prevalent in the cold regions of the northern mid- to high latitudes. Examples of these changes can be found within the western and northern interior of Canada, a region that exemplifies the scientific and societal issues faced in many other similar parts of the world, and where impacts have global-scale consequences. This region has been the geographic focus of a large amount of previous research on changing climatic, cryospheric, and hydrological regimes in recent decades, while current initiatives such as the Changing Cold Regions Network (CCRN) introduced in this review seek to further develop the understanding and diagnosis of this change and hence improve the capacity to predict future change. This paper provides a comprehensive review of the observed changes in various Earth system components and a concise and up-to-date regional picture of some of the temporal trends over the interior of western Canada since the mid- or late 20th century. The focus is on air temperature, precipitation, seasonal snow cover, mountain glaciers, permafrost, freshwater ice cover, and river discharge. Important long-term observational networks and data sets are described, and qualitative linkages among the changing components are highlighted. Increases in air temperature are the most notable changes within the domain, rising on average 2°C throughout the western interior since 1950. This increase in air temperature is associated with hydrologically important changes to precipitation regimes and unambiguous declines in snow cover depth, persistence, and spatial extent. Consequences of warming air temperatures have caused mountain glaciers to recede at all latitudes, permafrost to thaw at its southern limit, and active layers over permafrost to thicken. Despite these changes, integrated effects on stream flow are complex and often offsetting. Following a review of the current literature, we provide insight from a network of northern research catchments and other sites detailing how climate change confounds hydrological responses at smaller scales, and we recommend several priority research areas that will be a focus of continued work in CCRN. Given the complex interactions and process responses to climate change, it is argued that further conceptual understanding and quantitative diagnosis of the mechanisms of change over a range of scales is required before projections of future change can be made with confidence

Diagnosis of Historical and Future Flow Regimes of the Bow River at Calgary Using a Dynamically Downscaled Climate Model and a Physically Based Land Surface Hydrological Model : Final Report

Final Report developed under Agreement #AP744 for the Natural Resources Canada Climate Change Adaptation Program.Developed under Agreement #AP744 for the Natural Resources Canada Climate Change Adaptation Program, with financial and in-kind assistance from Natural Resources Canada, Alberta Environment and Parks, the City of Calgary, Environment and Climate Change Canada and the Global Water Futures program.Non-Peer ReviewedThis report assesses the impacts of projected climate change on the hydrology, including the flood frequencies, of the Bow and Elbow Rivers above Calgary, Alberta. It reports on investigations of the effects of projected climate change on the runoff mechanisms for the Bow and Elbow River basins, which are important mountain headwaters in Alberta, Canada. The study developed a methodology and applied a case study for incorporating climate change into flood frequency estimates that can be applied to a variety of river basins across Canada

Summary and synthesis of Changing Cold Regions Network (CCRN) research in the interior of western Canada – Part 2: Future change in cryosphere, vegetation, and hydrology

CCRN from the Natural Sciences and Engineering Research Council of Canada (NSERC) through their Climate Change and Atmospheric Research (CCAR) programPeer ReviewedThe interior of western Canada, like many similar cold mid- to high-latitude regions worldwide, is undergoing extensive and rapid climate and environmental change, which may accelerate in the coming decades. Understanding and predicting changes in coupled climate–land– hydrological systems are crucial to society yet limited by lack of understanding of changes in cold-region process responses and interactions, along with their representation in most current-generation land-surface and hydrological models. It is essential to consider the underlying processes and base predictive models on the proper physics, especially under conditions of non-stationarity where the past is no longer a reliable guide to the future and system trajectories can be unexpected. These challenges were forefront in the recently completed Changing Cold Regions Network (CCRN), which assembled and focused a wide range of multi-disciplinary expertise to improve the understanding, diagnosis, and prediction of change over the cold interior of western Canada. CCRN advanced knowledge of fundamental cold-region ecological and hydrological processes through observation and experimentation across a network of highly instrumented research basins and other sites. Significant efforts were made to improve the functionality and process representation, based on this improved understanding, within the fine-scale Cold Regions Hydrological Modelling (CRHM) platform and the large-scale Modélisation Environmentale Communautaire (MEC) – Surface and Hydrology (MESH) model. These models were, and continue to be, applied under past and projected future climates and under current and expected future land and vegetation cover configurations to diagnose historical change and predict possible future hydrological responses. This second of two articles synthesizes the nature and understanding of cold-region processes and Earth system responses to future climate, as advanced by CCRN. These include changing precipitation and moisture feedbacks to the atmosphere; altered snow regimes, changing balance of snowfall and rainfall, and glacier loss; vegetation responses to climate and the loss of ecosystem resilience to wildfire and disturbance; thawing permafrost and its influence on landscapes and hydrology; groundwater storage and cycling and its connections to surface water; and stream and river discharge as influenced by the various drivers of hydrological change. Collective insights, expert elicitation, and model application are used to provide a synthesis of this change over the CCRN region for the late 21st century

Developing interdisciplinary science for integrated catchment management : the UK lowland catchment research (LOCAR) programme

Across the European Union, the Water Framework Directive is a major driver for change in river basin management. However, its focus on integrated management and, in particular, on ecological quality raises major scientific and technical questions. In the UK, the focus of experimental hydrology has been on the uplands, and at small catchment scale (< 10 km2), whereas major management pressures lie in the lowlands, and for catchment management units of about 300-400 km2. Particular problems arise for permeable lowland catchments: the scientific understanding of the major UK aquifers (the Chalk and the Triassic Sandstone) is poor, and tools for the integrated modelling of surface water-groundwater interactions are limited. In response to these factors, the LOwland CAtchment Research programme (LOCAR) was conceived. A major objective of the programme is to develop new interdisciplinary science and improved modelling tools to meet the challenges of integrated catchment management. The paper describes the research programme and addresses the issues raised in designing and implementing a major interdisciplinary research initiative

The role of the riparian zone in complex Chalk aquifer-stream systems

Hydrological and hydrogeological processes in Chalk catchments can show a significant degree of spatial variability. Riparian wetlands found within these catchments have been found to act as biogeochemical cycling hotspots, with the potential to transform and attenuate the nutrient and geochemistry signal from the catchment. As part of a larger programme of lowland catchment research in the UK, we have investigated a sub-catchment of the River Lambourn in southern England, encompassing a reach of the river and a riparian wetland. We have used an array of hydrogeochemical and geophysical techniques to further understand surface water-groundwater interactions within this system. This multi-disciplinary approach has demonstrated that there are a number of pathways and a number of water sources which give rise to large spatial and temporal variations in nutrients in the river corridor. Gravels in the river corridor indicate a mixture of at least three source terms that include Chalk groundwater from upslope, recent local recharge and river water. The river component is present beneath the gravels in the Chalk down to at least 20 metres with better connection between the Chalk and the river than the gravels and the river. The system is also dynamic with varying proportions of these sources mixing at different times of the year. We suggest that surface water-groundwater interactions are governed not only by Chalk/river connectivity but that the superficial geology and its hydrogeological nature fundamentally determines these interactions. Major connections with the groundwater component occur in the dry valleys. In addition, the river corridor acts as a linear aquifer/river system and this system is very heterogeneous. Consequently much of the nutrient transformation capacity of the riparian zone can be by-passed to a variable extent because of the geological and hydrogeological complexity