Centre for Hydrology Reports
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Browsing Centre for Hydrology Reports by Author "Pomeroy, John"
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Item Prairie Hydrological Model Study Progress Report, April 2008(Centre for Hydrology, University Saskatchewan, Saskatoon, Saskatchewan, 2008) Pomeroy, John; Westbrook, Cherie; Fang, Xing; Minke, Adam; Guo, XulinThis report is an update on the progress made over the first 12 months of the Prairie Hydrological Model Study and corresponds to Milestone #3. In summary, we have characterized the 2007-2008 Hydrological Year for modeling by installing weather, soil moisture, rainfall and pond level recording stations, observing summer evaporation, fall freeze-up and winter snowpack development to the start of melt. We have also made progress on wetland and basin characterization using remote sensing and other spatial information, and begun analysis of hydrometeorological data.Item Prairie Hydrological Model Study Progress Report, December 2008(Centre for Hydrology, University Saskatchewan, Saskatoon, Saskatchewan, 2009) Pomeroy, John; Westbrook, Cherie; Fang, Xing; Brown, Tom; Minke, Adam; Guo, XulinThis report is an update on progress made to the middle of December 2008, corresponding to “Milestone Month 20”. According to our study plan, at this milestone “we will have completed a wetland module and with evaluation on Smith Creek Research Basin and archival data available at the Centre for Hydrology (Objective 3, 4)”. More specifically, Objectives 3 and 4 are stated as: • Objective 3: A physically based, hydrological response unit-based hydrological model, (the Prairie Hydrological Model), will be developed that is suitable for multiple season simulation of the hydrology of the Canadian Prairie environment. The model will be capable of predicting water balance, soil moisture, snow cover, actual evaporation and streamflow on a daily time-step with minimal calibration of model parameters from streamflow records. The model will contain a wetland module that includes assigned variable drainage rates from the wetland. The intended basins would drain to a stream or internally drained lake/wetland, with basin size to be greater than ~1 km2 and less than ~250 km2. • Objective 4: The Prairie Hydrological Model will be evaluated at Smith Creek through hydrological simulation and quantitative analysis of multi-objective criteria, including streamflow and wetland extent. Whilst calibration will be minimised and limited to non-physical aspects of the model, certain parameters will be optimised from these comparisons. For streamflow, both annual and peak flows are parameters of interest. For wetlands, seasonal extent is the parameter of interest. Outlined below are the research activities regarding these two objectives, beginning with a description of the model created with the Cold Regions Hydrological Modelling Platform (CRHM), the CRHM-Prairie Hydrological Model, or CRHM-PHM, followed by a description of the addition of the wetland module, and concluding with preliminary results from CRHM-PHM evaluations at Smith Creek.Item A Review of Canadian Prairie Hydrology: Principles, Modelling and Response to Land Use and Drainage Change(Centre for Hydrology, University Saskatchewan, Saskatoon, Saskatchewan, 2007) Fang, Xing; Minke, Adam; Pomeroy, John; Brown, Tom; Westbrook, Cherie; Guo, Xulin; Guangul, SeifuThis report reviews research on the hydrological cycle, runoff generation, hydrological modelling and the influence of changes to land cover and wetlands on the same for the Canadian Prairies. The purpose of this report is to identify and examine the major processes that are responsible for prairie hydrology as well as the impacts of land cover change such as wetland drainage on water storage and on the streamflow hydrograph. The objective of this report is to propose hydrological modelling techniques; these techniques can contribute to the development of a predictive tool in the form of a prairie hydrological model. It is intent to utilize such a hydrological model to evaluate the impacts of wetland drainage and restoration as well as changes in the surrounding upland land use on downstream hydrology. Hydrology in the Canadian Prairie region is complex and highly varied. Only one third of annual precipitation occurs over the winter and the surface snow water equivalent distribution is highly heterogeneous due to wind redistribution of snow during blowing snow storms. Blowing snow can transport and sublimate as much as 75% of annual snowfall from open prairie fields. The formation of drifts from windblown snow lengthens the spring runoff season and modulates the peak spring flows. The frozen state of mineral soils results in rapid snowmelt runoff in the springtime, which produces 80% or more of annual local runoff. The prairie region is characterized by glacially-formed depressions; these depressions fill with water to form pothole sloughs and wetlands and are very important to prairie hydrology due to their surface storage capacity. A fill-and-spill runoff mechanism is identifiable in prairie basins that are dominated by these surface depressions where flow does not commence until all storage in the depressions is filled. This results in an episodic and rapid increase in contributing area during peak runoff events. However outside of these events much of the prairie landscape is non-contributing to streamflow and even in the most extreme runoff events, some prairie basins are internally drained and never contribute to streamflow. This fill and spill phenomenon is in contrast to forms of hydrological storage found in temperate regions in which the flow rate is proportional to storage. Because of depressional storage and poorly and internally drained basins, most surface runoff in the prairie region does not contribute to the major river systems. Hydrological processes in the prairie region are sensitive to the land cover and climate change. Wetlands can be completely dried out when surrounded by native grassland rather than agricultural fields. Droughts are frequent on the Canadian Prairies. Lower precipitation and higher air temperature are the common characteristics of droughts; surface snowmelt runoff is largely suppressed and can even completely cease when warmer (e.g. 5 ºC increase of temperature) or drier (e.g. 50% decrease of precipitation) conditions develop. The Cold Regions Hydrological Model platform (CRHM) is a “state-of-the-art” physically-based hydrological model designed for the prairie region. CRHM is based on a modular, object-oriented structure in which component modules represent basin descriptions, observations, or physically-based algorithms for calculating hydrological processes. Preliminary tests show reasonable performance of CRHM in simulating the water balance and streamflow hydrograph for prairie regions. The model also shows capabilities to simulate impact of land use change and climate change on hydrological processes and streamflow. Further work in CHRM will be development of surface storage and surface routing models that are suitable for modelling hydrology in the prairie wetland region.