Browsing by Author "Westbrook, Cherie"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Improving and Testing the Prairie Hydrological Model at Smith Creek Research Basin(Centre for Hydrology, University of Saskatchewan, Saskatoon, Saskatchewan, 2014) Pomeroy, John W.; Shook, Kevin; Fang, Xing; Dumanski, Stacey; Westbrook, Cherie; Brown, TomThe 2010 Prairie Hydrological Model configuration of the Cold Regions Hydrological Model was developed to include improved snowmelt and evaporation physics and a hysteretic relationship between wetland storage and runoff contributing area. The revised model was used to simulate the snow regimes on and the streamflow runoff from the five sub-basins and main basin of Smith Creek, Saskatchewan for six years (2007-2013) with good performance when compared to field observations. Smith Creek measured streamflows over this period included the highest annual flow volume on record (2011) and high flows from heavy summer rains in 2012. Smith Creek basin has undergone substantial drainage from 1958 when it contained 96 km2 of wetlands covering 24% of the basin area to the existing (2008 measurement) 43 km2 covering 11% of the basin. The Prairie Hydrological Model was run over the 2007-2013 period for various wetland extent scenarios that included the 1958 historical maximum, measured extents in 2000 and 2008, a minimum extent that excluded drainage of conservation lands and an extreme minimum extent involving complete drainage of all wetlands in Smith Creek basin. Overall, Smith Creek total flow volumes over six years increase 55% due to drainage of wetlands from the current (2008) state, and decrease 26% with restoration to the 1958 state. This sensitivity in flow volume to wetland change is crucially important for the water balance of downstream water bodies such as Lake Winnipeg. Whilst the greatest proportional impacts on the peak daily flows are for dry years, substantial impacts on the peak daily discharge of record (2011) from wetland drainage (+78%) or restoration (-32%) are notable and important for infrastructure in and downstream of Smith Creek. For the flood of record (2011), the annual flow volume and the peak daily discharge are estimated to increase from 57,317 to 81,227 dam3 and from 19.5 to 27.5 m3 /s, respectively, due to wetland drainage that has already occurred in Smith Creek. Although Smith Creek is already heavily drained and its streamflows have been impacted, the annual flow volumes and peak daily discharge for the flood of record can still be strongly increased by complete drainage from the 2008 wetland state, rising to 103,669 dam3 and 49 m3 /s respectively. This model simulation exercise shows that wetland drainage can increase annual and peak daily flows substantially, and that notable increases to estimates of the annual volume and peak daily flow of the flood of record have derived from wetland drainage and will proceed with further wetland drainage.Item Prairie Hydrological Model Study Final Report(Centre for Hydrology, University Saskatchewan, Saskatoon, Saskatchewan, 2010) Pomeroy, John; Fang, Xing; Westbrook, Cherie; Minke, Adam; Guo, Xulin; Brown, TomThis report describes the development of the Prairie Hydrological Model (PHM), a model that is suitable for hydrological process simulations in the prairie pothole region of Western Canada. The model considers all major prairie hydrological cycle, wetland storage, and runoff generation mechanisms and is capable of addressing the influences of changing land use, wetland drainage and climate variability. The purpose of this report is to describe the model, examine the performance of the model, and to demonstrate the model as a predictive tool for prairie hydrology. This purpose is achieved by using the model to analyze the impacts of wetland drainage and restoration as well as changes in surrounding upland land use on downstream hydrology. This focus on wetland drainage impacts required the development and testing of a new volume-area-depth (v-a-h) method for estimating wetland volume in the prairie pothole region. The method was incorporated into the PHM and improved the model’s ability to estimate wetland volume. The Cold Regions Hydrological Model platform (CRHM) is a computational toolbox developed by the University of Saskatchewan to set up and run physically based, flexible, object oriented hydrological models. CRHM was used to create the PHM for Smith Creek Research Basin (~400 km2 ), Saskatchewan. Two types of PHM runs were performed to estimate the basin hydrology. The non-LiDAR (Light Detection and Ranging) runs used a photogrammetric based DEM (digital elevation model) to estimate drainage area and hydrograph calibration to determine maximum depressional storage. The LiDAR runs used a fine-scale LiDAR derived DEM to determine drainage area and maximum depressional storage; use of LiDAR information meant that calibration was not required to set any parameter value. In both cases all non-topographic parameters were determined from basin observations, remote sensing and field surveys. Both LiDAR and non-LiDAR model predictions of winter snow accumulation were very similar and compared quite well with the distributed snow survey results. The simulations were able to effectively capture the natural sequence of snow redistribution and relocate snow from ‘source’ areas (e.g. fallow and stubble fields) to ‘sink’ or ‘drift’ areas (e.g. tall vegetated wetland area and deeply incised channels). This is a vital process in controlling the water balance of prairie basins as most water in wetlands and prairie river channels is the result of redistribution of snow by wind and subsequent snowmelt runoff. Soil moisture status is an important factor in determining the spring surface runoff and in controlling agricultural productivity. Unfrozen soil moisture content at a point during melt was adequately simulated from both modelling approaches. Both modelling approaches were capable of matching the spring streamflow hydrographs with good accuracy; the non-LiDAR approach performed slightly better than the LiDAR approach because the streamflow hydrograph was calibrated, whereas no calibration was involved in the LiDAR simulation. However, the LiDAR approach to simulation shows promise for application to ungauged basins or to changing basins and demonstrates that prairie hydrology can be simulated based on our current understanding of physical principles and good basin data that provides “real” parameters. The approach uses a ii LiDAR DEM, SPOT 5 satellite images and involved automated basin parameters delineation techniques and a new wetland depth-area-volume calculation. The new wetland depth-area-volume calculation used a LiDAR-derived DEM to estimate maximum depressional storage, a substantial improvement over estimates generated from simpler area-volume methods. This was likely due to the inclusion of information on depression morphology when calculating volume. Further, the process to retrieve the coefficients from a LiDAR DEM was automated and wetland storage was estimated at a broad spatial scale. A GIS model was created that can automatically extract the elevation and area data necessary for use in the new depth-area-volume method. Using the Prairie Hydrological Model, PHM, a series of scenarios on changing land use and wetland and drainage conditions was created from 2007-08 meteorological data. The scenario simulations were used to calculate cumulative spring basin discharge, total winter snow accumulation, blowing snow transport and sublimation, cumulative infiltration, and spring surface depression storage status. From these simulations, spring streamflow volumes decreased by 2% with complete conversion to agriculture and by 79% with complete restoration of wetlands; conversely it increased by 41% with complete conversion to forest cover and by 117% with complete wetland drainage. The greatest sensitivity was to further drainage of wetlands which substantially increased streamflow. Additional sensitivity analysis of scenarios on basin streamflow using historical (29-year periods: 1965-82 and 1993-2005) meteorology and initial conditions and current land use was carried out. Results showed that the effects of land use change and wetland drainage alteration on cumulative basin spring discharge volume and peak daily spring discharge were highly variable from year to year and depended on the flow condition. For both forest conversion and agricultural conversion and wetland drainage scenarios increased the long-term average peak discharge from current conditions, whereas wetland restoration reduced it. Forest conversion, agricultural conversion and wetland drainage scenarios increased the long-term average spring discharge volume by 1%, 19%, and 36% respectively; whilst the wetland restoration scenario reduced volumes by 45%. Several recommendations were made regarding the modelling challenges faced by this study and value of local meteorological data collection and using a LiDAR generated DEM for Prairie hydrological modelling purposes. It is recommended that similar studies be conducted in other geographic areas of the prairies where climate, soils, wetland configuration and drainage may produce differing results.Item Progress Report: Land Use and Wetland Drainage Effects on Prairie Water Quality Study(Centre for Hydrology, University Saskatchewan, Saskatoon, Saskatchewan, 2009) Westbrook, Cherie; Brunet, Nathalie N.This report is an update on progress made to the end of December 2008. According to our study plan, we should have completed one summer worth of data collection and made progress in laboratory analytical work. Outlined in the report are data collection methods and progress to date made on our research objective of “determining changes in water quality of streams and impacts to ecosystem function associated with wetland drainage”. Considerable progress toward the research objective was achieved during the reporting period, and overall, the project is on schedule. Smith Creek was broken down into its tributaries (North Fork, South Fork and Thingvalla). Water samples at the outlet and tributaries of Smith Creek were taken on 35 occasions during the spring, summer and fall. Chemical analysis of these samples is 70% complete. The wetland for the drainage experiment was selected and instrumented with an electronic water level recorder and precipitation gauge. A bathymetry survey of the wetland was carried out and used to compute the volume of water stored in the wetland at different water levels. Water chemistry for the wetland was analyzed 29 times during the spring, summer and fall. Preliminary results show concentrations of DOC increased over the spring and early part of the summer as the wetland evaporated. Concentrations then fell to post-snowmelt values during the unusually wet late summer period. The wetland was drained this fall ahead of schedule due to the needs of the landowner. Once drained, the wetland lost 42% of its volume within 22 hours. Preliminary findings were that the drain was a source of TP during the first 2.5 hours and then transitioned to a sink. The Benthic Entomology (BENT Lab) of the Saskatchewan Watershed Authority (SWA) provided a preliminary assessment of the biotic health in the Smith Creek watershed. Sampling was conducted in spring 2008, and the progress of this assessment is as follows: a) Four sites were sampled in the watershed; b) 83% of all samples have been processed and identified; c) to date, a total of 9,669 individuals have been identified, representing 80 taxa; and d) of the samples processed, they are characterized primarily by pollution-tolerant fly larvae, and fast growing non-insect taxa typical of seasonal prairie streams. SWA is now preparing plans for additional assessment in 2009, and further evaluation of 2008 results using a reference condition approach and test site analysis in order to obtain robust measures of ecosystem health in the Smith Creek watershed.Item Snow Surveys and Hydrometeorology Data Collection in 2009 Winter Field Season at Smith Creek Basin(Centre for Hydrology, University Saskatchewan, Saskatoon, Saskatchewan, 2009) Pomeroy, John; Westbrook, Cherie; Fang, Xing; Minke, Adam; Guo, XulinThis report describes the data collection being conducted in 2009 winter field season at Smith Creek Basin. The data collection consists of two components: snow surveys and hydrometeorology. The following sections explain the procedures of collecting these data and how a comparison to the data from last winter field season.Item Wetland Drainage Effects on Prairie Water Quality : Final Report(Centre for Hydrology, University of Saskatchewan, Saskatoon, Saskatchewan, 2011) Westbrook, Cherie; Brunet, Nathalie; Philllips, Iain; Davies, John-MarkThis report describes factors influencing the spatial variation in wetland water quality and how drainage of wetlands affects downstream receiving waters in terms of their water quality and biotic health. The specific objectives of this work were to: 1) characterize the spatial and temporal variation in water quality of prairie potholes after snowmelt; 2) quantify solute export along a newly constructed wetland drainage ditch; 3) characterize solute export from drained pothole wetlands; 4) determine the extent to which stream water quality is influenced by wetland drainage; 5) contribute to the understanding of how wetland drainage affects ecosystem health. The research was conducted at the Smith Creek watershed, southeastern Saskatchewan, where there has been controversy over recent renewed efforts to drain wetlands to increase agricultural production.