Gordon Putz

Plant growth simulation for landscape-scale hydrological modelling

Abstract Landscape-scale hydrological models can be improved by incorporating realistic, process-oriented plant models for simulating crops, perennial grasses and woody species. The objective of this project was to present some approaches for plant modelling applicable to daily time step hydrological transport models, such as SWAT. Accurate simulation of plant growth can improve the accuracy of simulations of hydrological and biogeochemical cycles. First, we describe some unique aspects of the general plant model ALMANAC. Next, we describe a modification of the original ALMANAC model used to simulate complex successional vegetation changes in the years following disturbance of a variety of different forest ecosystems, such as forest fires, clear cuts and insect infestations. Finally, we discuss alternative physiological and physical process simulation techniques of plant growth that could increase simulation accuracy in landscape-scale hydrological and transport models such as SWAT.

Comparison of Temperature-Index Snowmelt Models for Use within an Operational Water Quality Model.

The accurate prediction of snowmelt runoff is a critical component of integrated hydrological and water quality models in regions where snowfall constitutes a significant portion of the annual precipitation. In cold regions, the accumulation of a snowpack and the subsequent spring snowmelt generally constitutes a major proportion of the annual water yield. Furthermore, the snowmelt runoff transports significant quantities of sediment and nutrients to receiving streams and strongly influences downstream water quality. Temperature-index models are commonly used in operational hydrological and water quality models to predict snowmelt runoff. Due to their simplicity, computational efficiency, low data requirements, and ability to consistently achieve good results, numerous temperature-index models of varying complexity have been developed in the past few decades. The objective of this study was to determine how temperature-index models of varying complexity would affect the performance of the water quality model SWAT (a modified version of SWAT that was developed for watersheds dominated by boreal forest) for predicting runoff. Temperature-index models used by several operational hydrological models were incorporated into SWAT. Model performance was tested on five watersheds on the Canadian Boreal Plain whose hydrologic response is dominated by snowmelt runoff. The results of this study indicate that simpler temperature-index models can perform as well as more complex temperature-index models for predicting runoff from the study watersheds. The outcome of this study has important implications because the incorporation of simpler temperature-index snowmelt models into hydrological and water quality models can lead to a reduction in the number of parameters that need to be optimized without sacrificing predictive accuracy.

Hybrid modelling approach to prairie hydrology: fusing data-driven and process-based hydrological models

Abstract Much of the prairie region in North America is characterized by relatively flat terrain with many depressions on the landscape. The hydrological response (runoff) is a combination of the conventional runoff from the contributing areas and the occasional overflow from the non-contributing areas (depressions). In this study, we promote the use of a hybrid modelling structure to predict runoff generation from prairie landscapes. More specifically, the Soil and Water Assessment Tool (SWAT) is fused with artificial neural networks (ANNs), so that SWAT and the ANN module deal with the contributing and non-contributing areas, respectively. A detailed experimental study is performed to select the best set of inputs, training algorithms and hidden neurons. The results obtained in this study suggest that the fusion of process-based and data-driven models can provide improved modelling capabilities for representing the highly nonlinear nature of the hydrological processes in prairie landscapes. Editor D. Koutsoyiannis; Associate editor L. See

Sediment Export Modeling in Cold-Climate Prairie Watersheds

AbstractNonpoint source pollution is a critical problem in Canadian prairie watersheds. However, sediment mobilization and export are poorly represented in existing models for these watersheds. The poor representation is partly because the hydrology of the region is highly influenced by the existence of numerous dynamically-connected landscape depressions that vary in storage capacity and because of the complex freeze-thaw cycles in the region. The objective of this research was to improve sediment export simulation modeling in these cold-climate prairie watersheds by incorporating a probability distribution function of depression storage capacity and a seasonally varying soil erodibility factor into the soil and water assessment tool (SWAT) model. The probability distribution function is used to represent the variation in storage capacity of the numerous depressions, whereas the seasonally varied soil erodibility factor is used to account for changes in erodibility as the soil freezes and thaws. Results ...

Science and the industrial planning process in the western Canadian boreal forest: a case study

This investigation presents new and aggressive approaches to link the results of scientific endeavor to management of a portion of the Canadian boreal forest, within the framework of the detailed forest management plan (DFMP) process of a forestry company in the province of Alberta. The first component in the DFMP was landscape projection, whereby cumulative impacts of key natural and anthropogenic disturbance agents were modelled under current and altered climate conditions. The second component addressed two types of impact assessment. The Biodiversity Assessment Project (BAP) modelled ecosystem diversity at landscape and habitat levels, as well as developed habitat supply models, relative to changing vegetation composition, management practices, and stand age. Models were used during the development of a preferred forest management strategy to address undesirable ecological predictions. In the Forest Watershed and Riparian Disturbance (FORWARD) project, a variant of the soil and water assessment tool w...

Development of opinion-based generic reforestation regimes and their application in vegetation management and water modelling in the Upper and Lower Foothills of Alberta

The operational forestry practices employed by Millar Western Forest Products Ltd. in the Upper and Lower Foothills of Alberta, Canada integrate a broad range of tools to plan, implement, and manag...