This thesis is comprised of four self contained chapters that report the results of a study on the stormflow hydrology of small forested watersheds in the Coast Mountains of southwestern British Columbia. The chapters discuss the general characteristics of the study watersheds and their instrumentation, the generation of stormflows from small forested watersheds, the stormflow (channel-phase) characteristics of one study watershed with steep topography, and the evaluation of initial changes in peak stormflow following logging of another study watershed. Chapter I. The characteristics of the study watersheds with respect to regional climate, physiography, soil hydrologic characteristics and forest cover were evaluated and summarized from available information. Emphasis is placed on the hydrologic characteristics of the watershed soils. The instrumentation of the study watersheds pertinent to the present study is also described. Due to the highly permeable nature of the watershed soils, the physical setting of the study watersheds favor a Rapid response of streamflow to rainstorms. On one study watershed this rapid response characteristic is reinforced by its steep topography and high drainage density. Chapter II. The problem of stormflow generation from small forested watersheds is dealt with by analyzing results from studies completed by the author and other workers in Jamieson Creek watershed and vicinity and by making field examinations in the same study area. A review is made of stormflow generation models, followed by analyses of rainfall intensity, saturated soil hydraulic conductivity and depression storage of the study area. These analyses revealed that overland flow rarely, if ever, occurs on coastal watersheds with hydro-logic environments similar to that of the study area. Instead, rain water takes alternate subsurface pathways through the soil to the stream channel. Observations made by the author in the study area and in other watersheds in this coastal region confirmed the existence of these alternate routes of water flow. Two types of subsurface stormflow pathways have been identified by earlier workers: (1) the matrix of forest floor and mineral soil beneath and (2) channels within or passing through the mineral soil. In the study area most soil channels were developed from dead or decaying roots. After passing through these two types of pathways, subsurface stormflows feed the expanding stream channel system laterally while rainfall is feeding the system from above. Subsurface stormflows are mainly in the form of saturated return flow from the ground and seepage flow through saturated stream banks. The stream channel system expansion during, and contraction after, a storm was measured in a small sub-watershed in the study area. It was found that the rate of stormflow from a watershed was closely related to the rate at which the stream channel expanded in response to the storm. From theestudy it is concluded that the model of subsurface stormflow from a variable source area is more appropriate than the other two models in describing stormflow generation in this coastal region. Chapter III. Stormflow characteristics of Jamieson Creek watershed, a small, steep, and forested watershed in the Coast Mountains of southwestern British Columbia, were evaluated by the analysis of 41 storm hydrographs from 1970-1974. During the study period, the rainfall amount per storm event varied from 5 to 330 mm, with the majority of the storm durations ranging from 20 to 60 hours. On the average, the fraction of storm rainfall that appeared as stormflow was 44 percent, varying from 2.5 to 81 percent. A significant number of major storms produced stormflow that accounted for more than 60 percent of the storm rainfall. Instantaneous peak flows varied considerably with storms, ranging from about 10 to 1,370 -1-2 1 s km and appeared to be mainly affected by the rainfall amount and distribution before the occurrence of the peak flow. Rising time (time to the peak) was short, usually within 30 hours, depending upon the rainfall distribution before the occurrence of the peak flow. Lag time was found to be relatively constant and short, ranging from 5 to 15 hours with an average of 8.5 hours. It is suggested that to derive lag time from characteristics of small watersheds, soil hydrologic properties should also be included with those parameters that are generally used. Stormflow amount was highly correlated with rainfall amount with 92 percent of its variance being accounted for. Antecedent base-flow rate was proposed as an index of watershed soil water storage prior to the storm hydrograph rise. One set of data from Jamieson Creek watershed and four additional data sets from two small steep watersheds in the Coweeta Hydrologic Laboratory were used to assess, through multiple regression analysis, the usefulness of antecedent baseflow rate in improving stormflow-rainfal1 relations. For all data sets, the inclusion of antecedent baseflow as a second independent variable significantly improved the stormflow estimate in comparison to that when rainfall amount was the only independent variable. Recession limbs of storm hydrographs varied with individual storms, depending on the degree of recharge to the watershed storage by the storm and the spatial distribution of such storage over the watershed. The stormflow characteristics of Jamieson Creek watershed reflect the influence of not only climatic conditions but also watershed characteristics: (1) shallow but highly permeable soils, (2) steep watershed slopes and stream channels, and (3) high drariinage density. The stormflow characteristics can be interpreted in terms of the generation of stormflow from a variable source area of the watershed. A comparison of the stormflow characteristics of Jamieson Creek watershed and the adjacent Elbow Creek watershed indicated that stormflow from the former usually has a sharper peak, higher peak flow ratio and steeper recession than stormflow from the latter, but both have very similar rising times. Differences in the streamflow response of the two watersheds could be caused by their differences in some topographical features. However, these differences also suggest that leakage from Elbow Creek, revealed in a preliminary field investigation, may deserve more detailed study. Chapter IV. This chapter provides the first quantitative Canadian information with respect to the impact of logging on peak stormflow. The paired-watershed technique was used to evaluate the initial changes in peak streamflow during storm periods following logging of a small watershed in the U.B.C. Research Forest, near Haney, B.C. Contrary to the majority of similar studies elsewhere, the analysis indicates that significant peak flow changes after logging occurred as follows: (1) an increase in the time to the peak, and (2) a decrease in the magnitude of the peak. The changes can be explained by (1) the degree of ground surface disturbance associated with the logging and (2) the stormflow generation mechanisms of the study area. Visual examination after the logging indicated that ground surface disturbance did not reduce the soil infiltration capacity to the extent that overland flow resulted. Workers in an earlier study speculated that forest floor disturbance could result in closure of some of the entrances to soil channels, thus increasing temporary water storage in the soil matrix. This, they further speculated, would result in reduced subsurface stormflow and, consequently, lower peak flow. The results of the present study tend to support the speculations, that the closure of some soil channel entrances is responsible for lower peak flow after logging. However, this study indicated that peak flow magnitude decreased mainly because of the flattening out of the hydrograph as a result of increased time to the peak (delayed peak rather than earlier hydrograph rise,). It is suggested that a lower rate of stormflow transmission through the soil matrix caused this increased time to the peak and, consequently, lower peak flow magnitude. Implications of this study for better water management are suggested. / Graduate and Postdoctoral Studies / Graduate

An investigation into the mechanisms of stormflow generation on a glaciated hillslope in coastal British Columbia has been undertaken. The investigation included a controlled irrigation-runoff experiment on a 30 x 30 m hillslope plot in the U.B.C. Research Forest near Haney, B.C. Instrumentation included 12 rain gauges, 45 piezometers, and 2 outflow-tipping buckets. Piezometer slug tests to measure hydraulic conductivities and a geologic study to establish the representativeness of the experimental results were conducted to complement the irrigation experiment. The hydrogeologic units of the research plot consist of: A) 0.1 to 0.3 m of forest floor material consisting of organic material in various states of decay B) 0.3 to 0.8 m of heterogenous, red-brown B horizon containing many organic rich channels made up of live and decayed roots C) 0.5 to 2 m grey to grey-green Vashon till D) fractured to unfractured granodiorite bedrock The hydraulic conductivity of the till was approximately 10⁻⁷ m/s. A slightly higher value of 10⁻⁶ m/s was found for the lower B horizon matrix. A bulk conductivity for the lower B horizon was estimated at 10⁻⁴ m/s. The 2 to 3 order-of-magnitude difference is probably attributable to numerous, high conductivity root channels present throughout the lower B horizon. Stormflow was generated when the water table rose into the high conductivity B horizon. Outflow at the stream bank exited from the B horizon with most water flowing from high conductivity root channels. The rate of outflow was controlled by the position of the water table. Since the water table remained parallel to the overall hillslope, the hydraulic gradient remained approximately constant. Only the cross-sectional area available for flow varied. Once outflow had commenced, the rate of outflow was sensitive to variation in the rainfall rate. Input-outflow lag-times were as little as one hour. The time lag to initiation of outflow was 19 hours. Most of this lag was attributable to the filling of storage requirements after a two month period of no rain. The distribution of the hydrogeologic units in the research plot was found to be representative of the research area. Lag times were found to be in the range found in another similar B.C. mountain basin. It is concluded that the mechanism of stormflow generation operating in the research plot can be generalized to other similar basins. / Land and Food Systems, Faculty of / Graduate

No description available.

This research investigated human induced land use patterns, land cover change and hydrologic response in mountain watersheds. The hypothesis was that the spatial pattern of land use patches in a watershed influences runoff generating mechanisms, and thus affects peak flows and stream ecosystems. The goal was to increase the understanding of the influence of landscape pattern on environmental process, and thus provide a scientific basis for the design of urban development that maintains the structure and function of biological communities along a stream system. The study was a first attempt to apply the methods of landscape pattern analysis from landscape ecology to hydrology and stream response. Previous analyses in hydrology have not explicitly considered the spatial arrangement of land use/cover patterns in the watershed. Although statistical relationships between landscape pattern and stream discharge were not achieved because of limitations of the hydrological modelling, this study laid the groundwork for the realization of this goal. The geographic information system (GIS) software Maplnfo, and a hydrologic model based on the Rational Method, were used to investigate the relationships between land use patterns and their effect on the hydrology of four steep mountain stream systems in the Greater Vancouver region of British Columbia. Accepted land use/ cover categories and landscape metrics were used to quantify and characterise landscape change, across time (1946-1995) and between watersheds. Composite runoff coefficients ( Q were calculated for each land use, and a five-year peak stream discharge (Q) that took the changing landscape into consideration was modelled. Stream pattern, total impervious surface (TLA), and road networks were assessed as part of the description of the landscape. This thesis considered relationships between: discharge and percent land use area; discharge and total imperviouss area; discharge and landscape pattern; and percent land use area and landscape pattern. It was found that calculated discharge, percent impervious, and developed area increased across all watersheds across all time periods. The number of road crossings on the creek mainstem and total road length in the watersheds increased with percentage of developed area in the watersheds, and there was a linear relationship between C coefficient and the length of roads in the watershed. Development emerged in discrete patches, generally in the more accessible and flatter regions of the basin. Patch shape metrics followed an increasing trend with development levels between zero and twenty percent. However, between twenty and fifty percent developed the metrics scattered and did not have an apparent trend. This was likely due to a shift in the landscape matrix from forest cover to development. Increased development was associated with fragmentation of the landscape because more land use/cover categories were present in the watershed. This created a situation where average patch size decreased, patch diversity and density increased, and the watersheds had a fragmented appearance. Developed patches generally had a more complex shape than forest patches. The likelihood of finding a forest patch adjacent to a developed patch decreased as development increased.

Forest disturbances significantly affect snowmelt dominated watersheds. Given that snowmelt from mountain regions provides up to 80% of the annual stream ow in the North American west, disturbances in these watersheds will impact water availability for downstream users. This study used eld data from stand-scale studies to represent forest disturbances in a hydrological model in order to quantify the potential snow hydrology response to varying spatial extent of disturbance. The sensitivity of snow accumulation and ablation response increased with disturbance severity and extent of disturbance. Results may provide water resource management with a greater understanding of the potential impact on post-disturbance snowmelt runo ff. / xii, 135 leaves : ill. ; 29 cm

The research reported here constitutes an investigation into features of internal ordering of stories narrated in natural conversation. Following the work of Sacks, Schegloff and other sociological analysts of conversational structure, this report focuses on methodical ways in which utterances are interpretable by reference to, e.g., sequential placement. An existing literature on the social organization of the telling of jokes and stories suggests that slots designed for utterance-types can be analytically identified. The present study aims to show that there is an identifiable position, story closing, which provides for orderly expectations concerning the items that may be found in such a location. The report argues that there are two independently describeable organizations which structure naturally occuring stories: the course-of-action framework and an organization oriented to giving a grounding identity to the story's teller. The former is concerned with the series of connected, temporally unfolding events, marked by beginning and end, which the story proposes to represent by a sequence of utterances. In that story-tellers exhibit selectivity and coherence, it is evident that such stories are formulated from the point of view of the character that teller allocates to self within the narration. The latter organization provides for the story's recipients a "members adequate sociological explanation" of the teller's character's point of view. It does so by assigning to teller's character a social identity which is the locus of commonly known, socially organized motives and attitudes. The story closing is a sequential position that closes off the course-of-action from the teller's character's point of view. The expectation that such an item will fill that slot can be used by the story's recipients to decide among different possible interpretations of a story's last utterance. / Arts, Faculty of / Sociology, Department of / Graduate

This research investigated human induced land use patterns, land cover change and hydrologic response in mountain watersheds. The hypothesis was that the spatial pattern of land use patches in a watershed influences runoff generating mechanisms, and thus affects peak flows and stream ecosystems. The goal was to increase the understanding of the influence of landscape pattern on environmental process, and thus provide a scientific basis for the design of urban development that maintains the structure and function of biological communities along a stream system. The study was a first attempt to apply the methods of landscape pattern analysis from landscape ecology to hydrology and stream response. Previous analyses in hydrology have not explicitly considered the spatial arrangement of land use/cover patterns in the watershed. Although statistical relationships between landscape pattern and stream discharge were not achieved because of limitations of the hydrological modelling, this study laid the groundwork for the realization of this goal. The geographic information system (GIS) software Maplnfo, and a hydrologic model based on the Rational Method, were used to investigate the relationships between land use patterns and their effect on the hydrology of four steep mountain stream systems in the Greater Vancouver region of British Columbia. Accepted land use/ cover categories and landscape metrics were used to quantify and characterise landscape change, across time (1946-1995) and between watersheds. Composite runoff coefficients ( Q were calculated for each land use, and a five-year peak stream discharge (Q) that took the changing landscape into consideration was modelled. Stream pattern, total impervious surface (TLA), and road networks were assessed as part of the description of the landscape. This thesis considered relationships between: discharge and percent land use area; discharge and total imperviouss area; discharge and landscape pattern; and percent land use area and landscape pattern. It was found that calculated discharge, percent impervious, and developed area increased across all watersheds across all time periods. The number of road crossings on the creek mainstem and total road length in the watersheds increased with percentage of developed area in the watersheds, and there was a linear relationship between C coefficient and the length of roads in the watershed. Development emerged in discrete patches, generally in the more accessible and flatter regions of the basin. Patch shape metrics followed an increasing trend with development levels between zero and twenty percent. However, between twenty and fifty percent developed the metrics scattered and did not have an apparent trend. This was likely due to a shift in the landscape matrix from forest cover to development. Increased development was associated with fragmentation of the landscape because more land use/cover categories were present in the watershed. This created a situation where average patch size decreased, patch diversity and density increased, and the watersheds had a fragmented appearance. Developed patches generally had a more complex shape than forest patches. The likelihood of finding a forest patch adjacent to a developed patch decreased as development increased. / Applied Science, Faculty of / Architecture and Landscape Architecture (SALA), School of / Graduate