Growth of riparian cottonwoods along regulated rivers can be limited by water availability. In this study we associate seasonal variation of environmental conditions and stream flows with water relations of a natural cottonwood grove located along a regulated river in southern Alberta. To link elements in the river-soil-plant-atmosphere continuum, river and groundwater levels and precipitation were monitored; sap flow was continuously measured with thermal dissipation probes in eight trees and stomatal conductance and leaf water potential were measured monthly; and weather conditions were monitored. From June through August, stomatal conductances at both leaf and canopy levels were increasingly limited by decreasing water availability. Artificially increasing the soil moisture in August resulted in an increase in sap flow and stomatal conductance at leaf and canopy levels. These responses can be attributed to seasonal changes in the water potential difference between soil and leaves or an alteration in hydraulic conductance, or a combination of both. / xiv, 135 leaves : ill. ; 29 cm

A characteristic of alpine drainage basins is the very sparse distribution of meteorological recording stations. This study models a contiguous distribution of microclimate and snowpack accumulation in the upper Oldman River basin. To accomplish this goal, gaps between weather recording stations are first filled using a modified MTCLIM climate simulation model in conjunction with the spatial analysis capabilities of the PAMAP geographic information system (GIS). The GIS provides terrain information such as elevation, slope, and aspect on a 100 metre grid as input into the microclimate simulator which, in turn, outputs daily meteorological conditions for a user-defined period of time. The estimation of snowpack accumaltion is achieved with another component of the model which makes use of the modelled microclimate to calculate daily accumulation and ablation on a grid point basis. Simulation results are returned to the GIS for display and spatial analysis. Discussion includes such thngs as the grouping of terrain variables and the derivation of an altitudinal precipitation profile, both of which are required for computational efficiency. While regression analysis indicates a very close relationship between observed and simulated temperature, precipitation is less successfully modelled at the daily time scale. Comparisons of simulated temperature with observed data resulted in an r2 + .94 and are therefore considered very reliable. Daily precipitation comparisons initially indicated a low correlation between observed and simulated data. However, when monthly totals are considered instead, r2 rises to 0.66. When snopack conditions are simulated for several snow pillows in the region, regression analysis with observed data producers r2 values as high as 0.896. / xi, 178 leaves : ill., maps ; 29 cm.

Freshwater and terrestrial ecosystems are connected through biomass exchanges such as the flow of predators, prey, nutrients and detritus between them. Emerging aquatic insects provide an alternate food source to riparian consumers often termed an allochthonous subsidy. Stable isotope analyses of naturally occurring carbon and nitrogen is effective for tracing energetic food sources to consumers. This thesis evaluated whether stable isotope analysis would be effective in the Oldman River Basin, Alberta. Aquatic and riparian primary consumers are distinct in their isotopic signatures and valid for to use in stable isotope analysis. Stable isotope modelling was then used to evaluate the proportional contribution of aquatic insects to riparian spider and beetle diets. Carbon analysis showed an overall aquatic insect contribution of 25 % and 18 % for spiders and beetles, respectively; while nitrogen analysis showed an overall contribution of 36 % and 20 %, respectively. The spatial extent of the aquatic insect contribution upland from the river was shown to decrease from 50 - 55 % at 1 m to 0 % at 30 m for both consumers using carbon, and from 35 - 40 % at 1 m to 0 % at 40 m using nitrogen. Finally, regression modelling of the size of a river and the spatial scale of an aquatic insect dietary contribution showed a significant relationship, indicating larger water bodies support higher production of aquatic insects. A meta-analysis of published literature applied to this model also indicated a significant relationship between the size of the river and the extent of an aquatic insect contribution. / xii, 126 leaves m ; 29 cm

In the northwestern prairies, the cottonwoods Populus deltoides Batr., P. balsamifera L., P. angustifolia James, and inerspecific hybrids, form the foundation of the riparian forest ecosystem. The present project characterized the phenotype and 391henology of each tree in a mature cottonwood grove (N=391) for the purposes of clone-delineation. In order of their utility, tree sex, general leaf-shape, six leaf dimensions, and phenology of flowering, leaf-flushing, senescence,and leaf-abscission were utilized. The population's 391 trunks represented only 115 individuals, 67 of which were clones which ranged from 2 to 58 trunks each. Thus, 88% of all trunks belonged to clones which ranged from 2 to 58 trunks each. Thus, 88% of all trunks belonged to clones, and this high clonal content reflects the senior age of the population. Clone structure explained the population's apparent spatial-clumping, female-skewed sex ratio, differential spatial distributions of the sexes and species, and complexity in trunk-size classes. Trends suggest that P. balsamifera and P. angustifolia are more strongly clonal than P. deltoides, partially explaining their differences in environmental preferences. The observed extent of asexual regeneration has implications for riparian resource management and analyses of cottonwood reproductive ecology. / xv, 201 leaves : ill. ; 28 cm.

This study investigated the influence of geomorphic context and flow regulation on cottonwood (Populus) age structure, stand size, recruitment rates, and annual radial growth patterns along the Oldman River in southern Alberta. Dendrochronological techniques were used to age trees, establish population structures, and measure annual radial growth on three reaches in differing geomorphic contexts. Cottonwoods within a narrow, 'constrained' reach were more negatively impacted by partial dewatering of the river, but responded more favorably to increased late-summer flows combined with suitable recruitment conditions than the trees within a wide, 'alluvial' reach. A positive linear relationship between early-summer peak discharge and annual radial growth was found only on the alluvial reach. However, these trees also had the slowest growth rates, likely due to competition between trees because alluvial reaches often support large, dense stands of cottonwoods. This study demonstrates the need to consider the geomorphic context when studying cottonwood responses to river regulation. / xvi, 141 leaves : ill. ; 29 cm.

Grid-based digital elevation models (DEMs) are used to simulate overland flow paths in hydrological models. The accuracy of these drainage patterns are dependent upon how well the DEM represents the terrain features that control runoff patterns. Often regional DEMs are not produced at scales small enough to represent rural infrastructure. The scale of runoff patterns that can be accurately modeled is, therefore, restricted, particularly when the terrain is relatively flat. The RIDEM (Rural Infrastructure Digital Elevation Model) model is presented that utilizes commonly available ancillary data to downscale grid-based runoff patterns. The resulting drainage patterns reflect drainage modifications imposed by rural infrastructure including: roads, ditches, culverts, and irrigation canals. Downscaling runoff patterns enables the completion of runoff studies at smaller scales. The model was implemented with the Oldman River watershed, Alberta, Canada to determine the spatial patterns of potential runoff contributing areas in three agricultural watersheds regularly contaminated by pathogens. / vii, 170 leaves : ill. (some col.) ; 29 cm.

Limited freshwater supply is the most important challenge in water resources management, particularly in arid and semi-arid basins. However, other variations in a basin, including climate change, population growth, and economic development intensify this threat to water security. The Oldman River Basin (OMRB), located in southern Alberta, Canada, is a semi-arid basin and encompasses several water challenges, including uncertain water supply as well as increasing, uncertain water demands (consumptive irrigation, municipal, and industrial demands, and non-consumptive hydropower generation, and environmental demands). Reservoirs, of which the Oldman River Reservoir is the largest in the basin, are responsible for meeting most of demands, and, protecting the basin’s economy. The OMRB has also faced extreme natural events, floods and droughts, in the past, which reservoir management plays a critical role to adapt to. The complexity of the climate, hydrology, and water resource system and water governance escalates the challenges in the basin. These factors are highly interconnected and establish dynamic, non-linear behavior, which requires an integrated, feedback-based tool to investigate. Integrated water resources (IWRM) modelling using system dynamics (SD) is such an approach to tackle the different water challenges and understand their non-linear, dynamic pattern. In this research study the Sustainability-oriented Water Allocation, Management, and Planning (SWAMPOM) model for the Oldman River Basin is developed. SWAMPOM comprises a water allocation model, dynamic irrigation demand, instream flow needs (IFN), and economic evaluation sub-models. The water allocation model allocates water to all the above-mentioned demands at a weekly time step from 1928 to 2001, and under different water availability scenarios. Meeting irrigation demands relies on the crop water requirement (CWR), which is calculated under different climatic conditions by the dynamic irrigation demand sub-model. This sub-model estimates the weekly irrigation demand for main crops planted in the basin. SWAMPOM also computes environmental demands or instream flow need (IFN) for the Oldman River, and allocates water to rivers to meet IFN under different policy scenarios and uncertain water supply. Finally, the major water-related economic benefit in the basin, earned by agriculture and hydropower generation, is computed by the economic evaluation sub-model. The results show that SWAMPOM could reasonably satisfy the demands at a weekly time step and provide an adequate estimation of the crop water requirement under different hydrometeorological conditions. Based on the SWAMPOM’s results, the average annual irrigation demand is 306 mm over the historical time period from 1928 to 2001 in the main irrigation districts. The average weekly instream flow need of the Oldman River is calculated to be approximately 20.5 m3/s, which can be met in more than 97% of weeks in the historical time period. Average annual water-related economic benefit was computed to be 192.5 M$ in the OMRB. It decreased to 82.8 M$ in very dry years, and increased up to 328.6 M$ in very wet years. This research also developed different sets of Oldman Reservoir’s operation zones, resulting in trade-offs between the optimal economic benefit, water allocated to the ecosystem, minimum floodwater and minimum flood frequency. This helps decision makers to decide how much water should be stored in the reservoir to meet a specific objective while not sacrificing others. A multi-objective performance assessment, Pareto curve approach, is applied to identify the optimal trade-offs between the four objective functions (OFs), and 18 different optimal, or close to optimal sets of operating zones are provided. The decision regarding the operating zones depends on decision makers’ preference for higher economic benefit, water allocated to IFN, or flood security. However, the set of operating zones with minimum floodwater causes 11 less flood events; the operating zones with maximum economic benefits result in 4.1% more financial gain; and the zones with maximum water allocated to IFN lead to 10.1% more ecosystem protection in the whole 74 years, compared to current zones.