Environmental models are important tools; however uncertainty is pervasive in the modeling process.   Current research has shown that under­standing and representing these uncertainties is critical when decisions are expected to be made from the modeling results.  One critical question has become: how focused should uncertainty intervals be with consideration of characteristics of uncertain input data, model equation representations, and output observations?   This thesis delves into this issue with applied research in four independent studies.  These studies developed a diverse array of simply-structured process models (catchment hydrology, soil carbon dynamics, wetland P cycling, stream rating); employed field data observations with wide ranging characteristics (e.g., spatial variability, suspected systematic error); and explored several variations of probabilistic and non-probabilistic uncertainty schemes for model calibrations.  A key focus has been on how the design of various schemes impacted the resulting uncertainty intervals, and more importantly the ability to justify conclusions.  In general, some uncertainty in uncertainty (u2) resulted in all studies, in various degrees.  Subjectivity was intrinsic in the non-probabilistic results.  One study illustrated that such subjectivity could be partly mitigated using a “limits of acceptability” scheme with posterior validation of errors.  u2 was also a factor from probabilistic calibration algorithms, as residual errors were not wholly stochastic.  Overall however, u2 was not a deterrent to drawing conclusions from each study. One insight on the value of data for modeling was that there can be substantial redundant information in some hydrological time series.  Several process insights resulted: there can be substantial fractions of relatively inert soil carbon in agricultural systems; the lowest achievable outflow phosphorus concentration in an engineered wetland seemed partly controlled by rapid turnover and decomposition of the specific vegetation in that system.  Additionally, consideration of uncertainties in a stage-discharge rating model enabled more confident detection of change in long-term river flow patterns. / <p>QC 20121105</p>

Wetlands water quality is influenced by the anthopogenic activities in the catchments’ areas. Wastewaters from the urban storm, agricultural runoff and sewage treatment often end up in wetlands before flowing to rivers, lakes and the sea. A lot of pollutants are readily transported in these wastewaters, thus subjecting the wetland ecosystem into a continuous resilience. Importantly, heavy metals like Cu, Zn, and Pb etc. are constituents of such pollutants in the wastewaters. The study has as a specific objective to investigate the effects of heavy metal Cu, Zn and Pb on denitrification, an important ecosystem process and service. In a wetland situation, denitrification is a permanent nitrogen removal process accounting for about 90% of the total nitrogen removal. The research was carried out in the laboratory and sediment samples were taken from a constructed wetland in Linkoping. We employed acetylene inhibition technique in obtaining N2O as a product resulting from nitrate reduction. The treatments (Cu, Zn and Pb) levels were 100 mg/kg, 250 mg/kg, 500 mg/kg and 1000 mg/kg of sediment, in three replicates and a control. Samplings of the assay were taken within 24hours. Gas chromatography was used to analyse and quantify N2O in the various samples. A linear regression analysis was carried out with Windows Excel and SPSS to compare the various treatments with the control at 95% confidence level. The results show that there were no inhibitions of denitrification at 100 mg/kg sediment treatment level for any of the element. Inhibition of denitrification was observed at treatment levels 500 mg/kg and 1000 mg/kg of sediment. The rate of nitrate reduction was compared from the slope of the regression curve. The rate for Cu at 500 mg and 1000 mg /kg of sediment was moderately related to that of the control, Zn shows a similar trend but a higher rate in some samples, while Pb shows more inhibition.

I evaluated the use of various wetlands by wintering ducks in the Tulare Lake Basin (TLB), California, during October 1982 - April 1983 and September 1983 - March 1984. Aerial waterfowl counts of the TLB were used to document spacial use patterns by ducks. Ground surveys on evaporation ponds in the Tulare Lake Drainage District (TLDD) were used to evaluate duck use of specific ponds with varying chemical and biological parameters. During mid-winter, up to 300,000 ducks used the TLB. The most abundant species (northern pintail (Anas acuta), northern shoveler (Anas clvoeata), and green-winged teal (Anas crecca)) were found on freshwater habitats. Ruddy ducks (Oxvura jamaicensis) were the only species to extensively use the evaporation ponds. With the exception of ruddy ducks, the evaporation ponds did not appear to be valuable for feeding areas, but provided sanctuary during the hunting season. The use of evaporation ponds by waterfowl may be heavier in years without the extensive floodwater that was present during this study. / Graduation date: 1991

Aquatic mercury (Hg) contamination caused by industrial Hg emissions, atmospheric transport and deposition to sensitive ecosystems is an ongoing concern in many parts of the world. Boreal ecosystems are particularly sensitive to Hg deposition, and large soil-Hg burdens in these regions may prolong recovery of Hg impacted surface waters for many decades. Four studies were undertaken to examine interactions between watershed characteristics, hydro-climatic variability and terrestrial-aquatic export of key chemical parameters linked to watershed Hg sensitivity. Two new quantitative techniques, hydrogeomorphic edge detection and characteristic morphology analysis, were developed to explicitly map and characterize the spatial distribution, geomorphic form and hydro-biogeochemical function of forested wetlands using airborne Light Detection and Ranging (LiDAR) surveys. The results demonstrate the critical contribution of forested wetlands and upland-wetland interactions to the production and mobilization of dissolved organic carbon (DOC) and methyl-mercury (MeHg) - respectively - to downstream surface waters. Results of strategic, event-based hydrochemical sampling also demonstrate the critical contribution of summer high-flow periods to terrestrial-aquatic MeHg export. Finally, an analysis of historical monitoring databases of streamflow volume, hydrochemistry and Hg concentrations in yearling perch in two contrasting headwater lake basins was conducted. The results indicate strong potential for short-term, hydrologically-driven shifts in terrestrial-aquatic coupling and watershed Hg sensitivity, but only for the wetland-dominated, humic lake that exhibited consistent, summertime hypolimnetic anoxia. These various findings suggest that accurate characterization of watershed structure can help researchers identify first-order limitations on whole-watershed methylation efficiency, particularly in relation to hydro-climatic drivers of terrestrial-aquatic coupling in Boreal headwater regions.

Graduation date: 1994

Soil moisture and ground thaw state are both indicative of a hillslopes ability to transfer water. In cold regions in particular, it is widely known that the wetness of surface soils and depth of ground thaw are important for runoff generation, but the diversity of interactions between surface soil moisture and ground thaw themselves has not been studied. To fill this knowledge gap, detailed shallow soil moisture and thaw depth surveys were conducted along systematic grids at the Baker Creek Basin, Northwest Territories. Multiple hillslopes were studied to determine how the interactions differed along a spectrum of topological, typological and topographic situations (T³ template). Results did not show a simple relationship between soil moisture and ground thaw as was expected. Instead, correlation was a function of wetness such that the correlation between soil moisture and ground thaw improved with site wetness. To understand why differences in soil moisture and ground thaw state arose, water and energy fluxes were examined for these subarctic study sites to discern the key processes controlling the patterns observed. Results showed that the key control in variable soil moisture and frost table interactions among the sites was the presence of surface water. At the peatland and wetland sites, accumulated water in depressions and flow paths maintained soil moisture for a longer duration than at the hummock tops. These wet areas were often locations of deepest thaw depth due to the transfer of latent heat accompanying lateral surface runoff. Although the peatland and wetland sites had large inundation extents, modified Péclet numbers indicated that the relative influence of external and internal hydrological processes at each site were different. Continuous inflow from an upstream lake into the wetland site caused advective and conductive thermal energies to be of equal importance to ground thaw. The absence of continuous surface flow at the peatland and valley sites led to the dominance of conductive thermal energy over advective energy for ground thaw. A quantitative explanation for the shallow soil moisture-ground thaw patterns was provided by linking hydrological processes and hillslope storage capacity with the calculated water and energy fluxes as well as the modified Péclet number. These results suggest that the T&#x00B3; template and the modified Péclet number could be very useful parameters for differentiating landscape components in modeling soil moisture and frost table heterogeneity in cold regions.

This study looks at land use allocation and wetland management on an agricultural landscape in the Canadas Prairie Pothole Region (PPR) within the context of social, ecological and economic factors. Policy considerations for the conservation of wetlands on an agricultural landscape are examined with a focus on financial incentive-based policy tools. Empirical research looks at the influences on wetland management and the potential for economic incentives in wetland policy. In addition, a spatial approach was employed to develop specific wetland conservation targeting scenarios for two case study farms in two distinct agricultural regions of Saskatchewan. Each targeting scenario was investigated to determine the potential effect on ecological goods and services, particularly carbon sequestration, as well as farm income over time. A hypothetical financial incentive-based wetland conservation program was developed looking at the potential of interplay with private carbon markets.<p>Land productivity, which is directly related to farm profitability, was the most important factor in predicting farmer participation in wetland conservation voluntarily (P<0.05). However, participation in the Environmental Farm Plan program, which provides financial incentives, was influenced by demographic factors such as age and farm size (P<0.01) while land productivity had no influence. This indicates that financial incentives may encourage farmers to participate in wetland conservation practices that otherwise would not. The spatial targeting scenarios indicated that trade-offs exist between economic and ecological optimization, the most effective strategies have the highest level of benefits relative to costs and will be readily adopted by farmers. Results also indicate that the publicly funded portion of wetland conservation program payments can be reduced by up to 20% when there is interplay with private carbon markets.

The lack of cost-effective, reliable sampling methods for many wetland characteristics hinders efforts to describe the structural and functional properties of wetlands. This study evaluated techniques for sampling the subsurface hydrology and invertebrates of freshwater wetlands. The depth of rusting on mild steel rods was compared with water well measurements to determine the reliability of rust depth as a predictor of subsurface water levels. An emergence trap and a benthic coring device were compared to determine the utility of each for sampling the invertebrate fauna of a wetland. Accuracy of the rods in estimating different water table measurements (average, lowest, most recent) and comparability of rod data (within sets of five rods) were investigated for different reference points on the rods, residence times, and wetland soils. The effect of the presence of vegetation in a soil low in organic matter on rod accuracy also was evaluated. The depth of lowest formation of a rust band on the rods predicted average and most recent water table depths in peat soil (r² for regressions of rust band depth on water table depth ranged from 0.71-0.95). Estimates of average water table depths were most precise for peat soil. Accuracy and precision were considerably lower in sand and clay soils, but significant relationships (P < 0.10) between depth of rust band formation and water table depth were found for all soils (r² values for sand and clay ranged from 0.13-0.55). The presence of vegetation had no effect on rod accuracy in the sand soil. Differences in rod performance between residence times were not apparent. However, a rod residence time of 4-6 weeks is recommended to balance the time necessary for adequate rust formation on the rods and to minimize the chance of exposure to large changes in water levels. A decrease in water table depth of approximately 40 cm in one month in the clay wetland caused a month lag time in rust formation. Differences in depth of rust band formation between the five rods within replicate sets were greatest for rods from clay (mean SD = ±7.9 cm). Variability of rust band measurements within replicate sets was lower in peat (mean SD = ±2.3 cm) and sand (mean SD = ±2.6 cm). The results indicated that the rusty rod technique has serious limitations and should be applied only in situations where the use of standard methods must be restricted. Emergence traps and a benthic coring device were used to sample the invertebrates of a freshwater, emergent wetland during late spring and summer, 1989. The fauna captured by each technique, disparities between the techniques in sampling certain taxa, and factors potentially affecting abundance estimates were examined. In addition, the efficiency of each technique, expressed as the number of samples required to achieve a desired level of precision, in estimating mean abundances of the dominant invertebrate group, the Chironomidae, was evaluated. Total and monthly estimates of insect family richness were higher for continuous sampling of emergence than for monthly core samples of the benthos. Emergence traps also caught a greater variety of the insect taxa inhabiting the wetland. The precision and efficiency of each technique in estimating abundances of the dominant group, the Chironomidae, varied between months and habitats (open water; vegetation). The variation was most likely due to the natural spatial and temporal variations inherent in invertebrate populations. The number of samples required (n[subscript r]) to estimate mean Chironomidae abundances for the entire summer, June-September, to a precision of D= 0.20 (equivalent to a standard error equal to 20% of the mean), varied between techniques. Fewer sampling stations would have been required to estimate mean adult abundances using emergence traps than would have been required for estimates of larval abundances using benthic core samples. Large numbers of benthic cores (27-208 individual cores per habitat) would have generally been required for both monthly and seasonal estimates of non-insect invertebrate abundances. Labor costs for processing emergence samples were about 30% of those for benthic samples. Subsampling of dominant groups in the emergence samples would have further reduced costs. Frequent sampling throughout a season, with several different techniques, is required to completely characterize the invertebrate community of a wetland. This study compared two quantitative techniques for sampling wetland insects. Continuous sampling with emergence traps provided higher estimates of insect family richness and more precise estimates of Chironomidae abundances at a lower cost per sample than monthly core samples of the benthos. / Graduation date: 1992

Aquatic mercury (Hg) contamination caused by industrial Hg emissions, atmospheric transport and deposition to sensitive ecosystems is an ongoing concern in many parts of the world. Boreal ecosystems are particularly sensitive to Hg deposition, and large soil-Hg burdens in these regions may prolong recovery of Hg impacted surface waters for many decades. Four studies were undertaken to examine interactions between watershed characteristics, hydro-climatic variability and terrestrial-aquatic export of key chemical parameters linked to watershed Hg sensitivity. Two new quantitative techniques, hydrogeomorphic edge detection and characteristic morphology analysis, were developed to explicitly map and characterize the spatial distribution, geomorphic form and hydro-biogeochemical function of forested wetlands using airborne Light Detection and Ranging (LiDAR) surveys. The results demonstrate the critical contribution of forested wetlands and upland-wetland interactions to the production and mobilization of dissolved organic carbon (DOC) and methyl-mercury (MeHg) - respectively - to downstream surface waters. Results of strategic, event-based hydrochemical sampling also demonstrate the critical contribution of summer high-flow periods to terrestrial-aquatic MeHg export. Finally, an analysis of historical monitoring databases of streamflow volume, hydrochemistry and Hg concentrations in yearling perch in two contrasting headwater lake basins was conducted. The results indicate strong potential for short-term, hydrologically-driven shifts in terrestrial-aquatic coupling and watershed Hg sensitivity, but only for the wetland-dominated, humic lake that exhibited consistent, summertime hypolimnetic anoxia. These various findings suggest that accurate characterization of watershed structure can help researchers identify first-order limitations on whole-watershed methylation efficiency, particularly in relation to hydro-climatic drivers of terrestrial-aquatic coupling in Boreal headwater regions.

The Long Point wetland complex is one of the most significant coastal wetland systems in the Great Lakes, containing a diverse mosaic of wetland vegetation communities that have developed in response to water level fluctuations due to natural climate variability. Natural short-term water level variations are important for promoting wetland productivity and diversity, but long-term water level changes resulting from human-induced climate change can have serious and long-term consequences on the integrity and health of wetlands. The historical response of the wetland to water level fluctuations was quantified and modelled to provide an indication of how the wetland may respond to future projected water level changes - water level fluctuations are used as a surrogate for climate change. A spatiotemporal trend analysis was conducted within a geographic information system (GIS) to determine the effects of water level conditions on wetland vegetation and land cover at the wetland complex at Long Point, Ontario for seven years from 1945 to 1999. The spatiotemporal trend analysis documented changes in the structure and composition of the wetland complex in response to declining and rising water level conditions. During drier periods, there were significant increases in the amount of drier emergent and meadow vegetation, especially within the Inner Bay and northern portion of the outer peninsula. There was less fragmentation and complexity in the wetland as these drier communities expanded forming larger continuous patches of vegetation. During wetter periods, open water increased and there was a predominance of wetter emergent and meadow communities in the wetland. Drier vegetation communities became interspersed with water creating a more fragmented convoluted wetland landscape. The historical response of the wetland vegetation and land cover to water level fluctuations was then simulated with three different wetland models developed in the GIS. A rule-based model, a probability model, and a transition model were developed to assess wetland response to future water level changes. The models were evaluated using simple statistical methods. The transition and rule-based models performed the best and were successful in predicting over 80 % of the wetland vegetation distribution correctly. The probability model was the least successful, predicting only 55 % of the response correctly. The GIS proved successful in documenting wetland response to historical water level fluctuations and providing insight into the potential impacts of future climate change though water level fluctuations on the Long Point coastal wetland complex. The spatiotemporal analysis and wetland modelling advance the role of GIS in wetland management and analysis. They are practical methods within a GIS that can be used to assess the impacts of climate change on wetland systems and to document and model wetland change in other coastal wetlands of the Great Lakes.