Search

Search Results

• 571. [Article] Precipitation characteristics for landslide hazard assessment for the central Oregon Coast Range

  Precipitation data from 1988-1995 for 13 rain gauges of the Department of Forest Engineering rain gauge network, and a longer precipitation record, 1976-1995, at Mapleton were analyzed. The objectives ...

  Citation × Citation Citation Abstract Copy Title: Precipitation characteristics for landslide hazard assessment for the central Oregon Coast Range Author: Surfleet, Christopher G. Precipitation data from 1988-1995 for 13 rain gauges of the Department of Forest Engineering rain gauge network, and a longer precipitation record, 1976-1995, at Mapleton were analyzed. The objectives were to assess the spatial and temporal distribution of precipitation intensity and antecedent precipitation, and understand the role of these characteristics for triggering debris slides from headwalls in the central Oregon Coast Range. Frequency distribution curves and recurrence intervals using a partial-duration series were calculated for the maximum 5-minute, 30 minute, 1 hour, 2 hour, 6 hour precipitation durations and antecedent precipitation index (API) for the rain gauge network and the maximum 1 hour and 2 hour precipitation durations for Mapleton. Isohyet lines showing selected 2-year precipitation intensities and API were used to characterize the spatial distribution of precipitation intensity and API across the central Oregon Coast Range. The effect of elevation on this spatial distribution was investigated. An attempt to quantify the occurrence of high intensity precipitation occurring with high antecedent precipitation, which is hypothesized to trigger debris slides, was done by testing if the highest precipitation intensities (greater than a 1 -year recurrence interval) occurred during the storms with the highest API. API and precipitation intensity were tested for correlation to discern if a particular precipitation duration could be used to predict API, thus make it possible to use a precipitation intensity based threshold to assess the general hazard of landslides. Precipitation intensities associated with selected recurrence intervals vary considerably over the study area. Precipitation values for selected durations and recurrence intervals could vary as much as 50% or larger for selected rain gauge locations. Precipitation intensities are higher in the central portion of the study area, centered around the ridges of the Siuslaw River watershed, with decreasing intensity toward the northern and southern boundaries possibly due to topographic influences. Higher API values are found more frequent where the high precipitation intensity spatial trends exists. Relationships between short duration precipitation intensities with elevation, and API with elevation, within the rain gauge network could not be determined. No single precipitation intensity, including total storm precipitation, showed a strong positive correlation with high API for the entire rain gauge network. It appears that any attempts to predict the precipitation characteristics which trigger headwall failure by a precipitation intensity threshold in the central Oregon Coast Range is not possible. Attempts to assess the risk of headwall failure by high API may be possible. High precipitation intensities occurred with high antecedent precipitation conditions and they occur at the highest antecedent precipitation conditions. Title: Precipitation characteristics for landslide hazard assessment for the central Oregon Coast Range Author: Surfleet, Christopher G. Precipitation data from 1988-1995 for 13 rain gauges of the Department of Forest Engineering rain gauge network, and a longer precipitation record, 1976-1995, at Mapleton were analyzed. The objectives were to assess the spatial and temporal distribution of precipitation intensity and antecedent precipitation, and understand the role of these characteristics for triggering debris slides from headwalls in the central Oregon Coast Range. Frequency distribution curves and recurrence intervals using a partial-duration series were calculated for the maximum 5-minute, 30 minute, 1 hour, 2 hour, 6 hour precipitation durations and antecedent precipitation index (API) for the rain gauge network and the maximum 1 hour and 2 hour precipitation durations for Mapleton. Isohyet lines showing selected 2-year precipitation intensities and API were used to characterize the spatial distribution of precipitation intensity and API across the central Oregon Coast Range. The effect of elevation on this spatial distribution was investigated. An attempt to quantify the occurrence of high intensity precipitation occurring with high antecedent precipitation, which is hypothesized to trigger debris slides, was done by testing if the highest precipitation intensities (greater than a 1 -year recurrence interval) occurred during the storms with the highest API. API and precipitation intensity were tested for correlation to discern if a particular precipitation duration could be used to predict API, thus make it possible to use a precipitation intensity based threshold to assess the general hazard of landslides. Precipitation intensities associated with selected recurrence intervals vary considerably over the study area. Precipitation values for selected durations and recurrence intervals could vary as much as 50% or larger for selected rain gauge locations. Precipitation intensities are higher in the central portion of the study area, centered around the ridges of the Siuslaw River watershed, with decreasing intensity toward the northern and southern boundaries possibly due to topographic influences. Higher API values are found more frequent where the high precipitation intensity spatial trends exists. Relationships between short duration precipitation intensities with elevation, and API with elevation, within the rain gauge network could not be determined. No single precipitation intensity, including total storm precipitation, showed a strong positive correlation with high API for the entire rain gauge network. It appears that any attempts to predict the precipitation characteristics which trigger headwall failure by a precipitation intensity threshold in the central Oregon Coast Range is not possible. Attempts to assess the risk of headwall failure by high API may be possible. High precipitation intensities occurred with high antecedent precipitation conditions and they occur at the highest antecedent precipitation conditions. Close

• 572. [Article] Distribution, abundance, and emigration of juvenile steelhead (Oncorhynchus mykiss), and analysis of stream habitat in the Steamboat Creek Basin, Oregon

  Snorkel dive estimates and an inventory of stream habitat of the juvenile steelhead (Oncorhynchus mykiss) population in the Steamboat Creek basin were made in the summers of 1987 and 1988. Emigration was monitored ...

  Citation × Citation Citation Abstract Copy Title: Distribution, abundance, and emigration of juvenile steelhead (Oncorhynchus mykiss), and analysis of stream habitat in the Steamboat Creek Basin, Oregon Author: Dambacher, Jeffrey M. Snorkel dive estimates and an inventory of stream habitat of the juvenile steelhead (Oncorhynchus mykiss) population in the Steamboat Creek basin were made in the summers of 1987 and 1988. Emigration was monitored by fish trapping from spring through fall of 1988. Distribution, abundance, and habitat utilization of juvenile steelhead were affected by stream size and temperature. The majority (65%) of age >1 fish were in two mainstem channels, whereas numbers of age 0 fish were more evenly distributed throughout the basin. Age >1 fish significantly (P<O.005) increased their use of riffles with depth, and avoided shallow riffles. Where riffles were apparently too shallow, age >1 steelhead utilized pool habitat to a greater extent. Age >1 steelhead greatly avoided glides in all sizes of channels. Age 0 steelhead appeared to be less restricted in their choice of habitat than age >1 fish. Age 0 fish, presumably by virtue of a smaller body size, showed only slightly increased use of riffles with depth. Both age 0 and >1 steelhead increased their use of riffles in streams with higher temperature regimes. Densities of age >1 fish in channels with large boulder substrate increased significantly (p=O.02) with mean riffle depth, probably as a function of more wetted area being useable in streams with deep riffles, and more feeding microhabitats being afforded by rough channels. Densities of age 0 fish did not appear to be affected by the range of stream sizes studied, or by channel roughness, but were low in all channels with high stream temperatures. Compared to other steelhead producing streams, Steamboat Creek had low summer rearing densities, small smolts, and an exceptionally high proportion of fish emigrating as parr (considered to be at least one year away from development of smolt characteristics). Roughly 120,000 age 0 steelhead, 60,000 parr, and 4,100 steelhead smolts were estimated to have emigrated from the basin. Most parr emigrated in the spring when stream flows were high, whereas the majority of age 0 fish emigrated during summer base flow recession. I suggest that parr emigration from Steamboat Creek may be a life history adaptation that takes advantage of rearing conditions downstream in the North Umpqua River. Title: Distribution, abundance, and emigration of juvenile steelhead (Oncorhynchus mykiss), and analysis of stream habitat in the Steamboat Creek Basin, Oregon Author: Dambacher, Jeffrey M. Snorkel dive estimates and an inventory of stream habitat of the juvenile steelhead (Oncorhynchus mykiss) population in the Steamboat Creek basin were made in the summers of 1987 and 1988. Emigration was monitored by fish trapping from spring through fall of 1988. Distribution, abundance, and habitat utilization of juvenile steelhead were affected by stream size and temperature. The majority (65%) of age >1 fish were in two mainstem channels, whereas numbers of age 0 fish were more evenly distributed throughout the basin. Age >1 fish significantly (P<O.005) increased their use of riffles with depth, and avoided shallow riffles. Where riffles were apparently too shallow, age >1 steelhead utilized pool habitat to a greater extent. Age >1 steelhead greatly avoided glides in all sizes of channels. Age 0 steelhead appeared to be less restricted in their choice of habitat than age >1 fish. Age 0 fish, presumably by virtue of a smaller body size, showed only slightly increased use of riffles with depth. Both age 0 and >1 steelhead increased their use of riffles in streams with higher temperature regimes. Densities of age >1 fish in channels with large boulder substrate increased significantly (p=O.02) with mean riffle depth, probably as a function of more wetted area being useable in streams with deep riffles, and more feeding microhabitats being afforded by rough channels. Densities of age 0 fish did not appear to be affected by the range of stream sizes studied, or by channel roughness, but were low in all channels with high stream temperatures. Compared to other steelhead producing streams, Steamboat Creek had low summer rearing densities, small smolts, and an exceptionally high proportion of fish emigrating as parr (considered to be at least one year away from development of smolt characteristics). Roughly 120,000 age 0 steelhead, 60,000 parr, and 4,100 steelhead smolts were estimated to have emigrated from the basin. Most parr emigrated in the spring when stream flows were high, whereas the majority of age 0 fish emigrated during summer base flow recession. I suggest that parr emigration from Steamboat Creek may be a life history adaptation that takes advantage of rearing conditions downstream in the North Umpqua River. Close

• 573. [Article] Spatial patterns of fuel management activities and their effects on wildfire behavior

  Fuel management has been used as an effective local strategy to reduce the undesirable consequences of wildfires. Many efforts toward scheduling of fuel management activities across a broader landscape ...

  Citation × Citation Citation Abstract Copy Title: Spatial patterns of fuel management activities and their effects on wildfire behavior Author: Kim, Young-Hwan Fuel management has been used as an effective local strategy to reduce the undesirable consequences of wildfires. Many efforts toward scheduling of fuel management activities across a broader landscape have been proposed, with the hope of achieving larger landscape-scale management effects. However, scheduling of fuel management treatments across the broader landscape is limited by understandings of how individual management activities aggregate to larger scales and how they affect the behavior of wildfires. Since full coverage of a landscape with fuels management treatments is unlikely, it is necessary to examine the effects of a spatial pattern of individual management activities at the landscape scale. In this research, four spatial patterns of fuel management activities – dispersed, clumped, random, and regular – were tested to investigate their potential for reducing the risk of severe wildfire. A new methodology was developed for optimizing fuel management patterns across a landscape based on a heuristic technique and GIS databases. To quantify the cumulative effects of fuel management patterns for disrupting the progress of wildfires, overall flame length, fireline intensity, and fire size were measured for simulated fires, using a fire growth simulation model, FARSITE. The management scenarios generated from the scheduling model presented a variety of dispersion and treatment sizes, but also evenly distributed the harvest volume through the multi-decade time horizon. The optimized spatial patterns were qualified through visual examination as well as a statistical assessment. Through this research, I have learned that the efficiency of fuels management activities for reducing severity of wildfire is primarily influenced by treatment size, type, and intensity. Most importantly, treatment types and intensity are the critical factor to disrupt human-caused wildfires. The regular pattern seemed to be the most acceptable for either random ignitions or hypothetical human-caused ignitions. It provided the highest frequency in which simulated fires could contact the treated units, and higher treatment intensity measured by amount of harvested volume from a unit area. To enhance the results of this research, we suggest that one should utilize more feasible management prescriptions for post-fire fuel conditions, and expand ignition sources to other type of human-caused ignitions or natural-caused ignitions. Title: Spatial patterns of fuel management activities and their effects on wildfire behavior Author: Kim, Young-Hwan Fuel management has been used as an effective local strategy to reduce the undesirable consequences of wildfires. Many efforts toward scheduling of fuel management activities across a broader landscape have been proposed, with the hope of achieving larger landscape-scale management effects. However, scheduling of fuel management treatments across the broader landscape is limited by understandings of how individual management activities aggregate to larger scales and how they affect the behavior of wildfires. Since full coverage of a landscape with fuels management treatments is unlikely, it is necessary to examine the effects of a spatial pattern of individual management activities at the landscape scale. In this research, four spatial patterns of fuel management activities – dispersed, clumped, random, and regular – were tested to investigate their potential for reducing the risk of severe wildfire. A new methodology was developed for optimizing fuel management patterns across a landscape based on a heuristic technique and GIS databases. To quantify the cumulative effects of fuel management patterns for disrupting the progress of wildfires, overall flame length, fireline intensity, and fire size were measured for simulated fires, using a fire growth simulation model, FARSITE. The management scenarios generated from the scheduling model presented a variety of dispersion and treatment sizes, but also evenly distributed the harvest volume through the multi-decade time horizon. The optimized spatial patterns were qualified through visual examination as well as a statistical assessment. Through this research, I have learned that the efficiency of fuels management activities for reducing severity of wildfire is primarily influenced by treatment size, type, and intensity. Most importantly, treatment types and intensity are the critical factor to disrupt human-caused wildfires. The regular pattern seemed to be the most acceptable for either random ignitions or hypothetical human-caused ignitions. It provided the highest frequency in which simulated fires could contact the treated units, and higher treatment intensity measured by amount of harvested volume from a unit area. To enhance the results of this research, we suggest that one should utilize more feasible management prescriptions for post-fire fuel conditions, and expand ignition sources to other type of human-caused ignitions or natural-caused ignitions. Close

• 574. [Article] Economic impact study for Detroit Lake and the Upper North Santiam Canyon

  Published May 2006. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog

  Citation × Citation Citation Abstract Copy Title: Economic impact study for Detroit Lake and the Upper North Santiam Canyon Author: Sorte, Bruce, Buerger, Chris, Oregon State University. Extension Service Published May 2006. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog Title: Economic impact study for Detroit Lake and the Upper North Santiam Canyon Author: Sorte, Bruce, Buerger, Chris, Oregon State University. Extension Service Published May 2006. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog Close

• 575. [Article] The effect of landscape topography and in-stream habitat on the distribution, growth, and survival of Lahontan cutthroat trout (Oncorhynchus clarki henshawi) in a high desert watershed

  Lahontan cutthroat trout (LCT) (Oncorhynchus clarki henshawi) are currently limited in their distribution to a patchwork of small isolated populations, the result of habitat degradation and natural variation ...

  Citation × Citation Citation Abstract Copy Title: The effect of landscape topography and in-stream habitat on the distribution, growth, and survival of Lahontan cutthroat trout (Oncorhynchus clarki henshawi) in a high desert watershed Author: Boxall, George D. Lahontan cutthroat trout (LCT) (Oncorhynchus clarki henshawi) are currently limited in their distribution to a patchwork of small isolated populations, the result of habitat degradation and natural variation in landscape and in-stream conditions. The objectives of this study were to determine how landscape level topographic features influence LCT distribution patterns. The work was carried out in a sub-basin of the Quinn River system, McDermitt Creek, which drains the sagebrush desert of southeastern Oregon and northern Nevada. Headwater tributaries of this creek consist of alternating canyon-confined and valley bounded reaches and LCT within these systems are challenged by low discharge and high temperatures during the summer, and anchor ice during the winter. Contiguous whole stream surveys were used to look at trout distribution during the summer of 2003 and spring and fall of 2004. Our results showed that topography affected LCT distribution in all reaches. LCT numbers were highest in areas with greater numbers of nick-points (the transition zones between less confined and more confined valley segments) and greater valley confinement. Additionally, in the downstream portion of our headwater reaches, more LCT were found in nick-points than expected based on the availability of this habitat type. Our data suggest that hyporheic inputs may be high in such areas, thus providing LCT with shelter from warm water in the summer, anchor ice in the winter and shallow stream depths during all seasons. Spatial occurrence of these areas of refugia can be taken into consideration when planning land-use activities and restoration efforts. After almost 30 years of conservation effort, Lahontan cutthroat trout (LCT) (Oncorhynchus clarki henshawi) populations remain in peril throughout the Great Basin region of southeastern Oregon and northern Nevada. This is not surprising since very little research has been done on the ecology of LCT, and management has been carried out without essential information on this sub-species. The objectives of our study were to determine whether there are inter-stream or inter-reach differences in LCT habitat selection, and if those differences corresponded to differences in fish survival and growth. We relied upon contiguous whole stream surveys to look at fish distribution and in-stream habitat. The use of half duplex PIT tags allowed us to determine the growth, movement patterns, and survival rates of most adult (>100 mm) LCT within the system. We found greater trout growth (median daily change in biomass 0.46% vs. 0.07%), but lower survival (35% vs. 61% between July and November), in relatively warmer and more open reaches than in cooler reaches. Additionally, undercut banks (predation shelter) were more important to trout in cooler stream reaches than in warmer ones, where habitat choice responded first to cold water input (which was influenced by topography). Our results will be useful in identifying and describing areas of high quality LCT habitat in low order streams throughout the Great Basin, thus allowing informed management decisions to facilitate the recovery of the sub-species. Title: The effect of landscape topography and in-stream habitat on the distribution, growth, and survival of Lahontan cutthroat trout (Oncorhynchus clarki henshawi) in a high desert watershed Author: Boxall, George D. Lahontan cutthroat trout (LCT) (Oncorhynchus clarki henshawi) are currently limited in their distribution to a patchwork of small isolated populations, the result of habitat degradation and natural variation in landscape and in-stream conditions. The objectives of this study were to determine how landscape level topographic features influence LCT distribution patterns. The work was carried out in a sub-basin of the Quinn River system, McDermitt Creek, which drains the sagebrush desert of southeastern Oregon and northern Nevada. Headwater tributaries of this creek consist of alternating canyon-confined and valley bounded reaches and LCT within these systems are challenged by low discharge and high temperatures during the summer, and anchor ice during the winter. Contiguous whole stream surveys were used to look at trout distribution during the summer of 2003 and spring and fall of 2004. Our results showed that topography affected LCT distribution in all reaches. LCT numbers were highest in areas with greater numbers of nick-points (the transition zones between less confined and more confined valley segments) and greater valley confinement. Additionally, in the downstream portion of our headwater reaches, more LCT were found in nick-points than expected based on the availability of this habitat type. Our data suggest that hyporheic inputs may be high in such areas, thus providing LCT with shelter from warm water in the summer, anchor ice in the winter and shallow stream depths during all seasons. Spatial occurrence of these areas of refugia can be taken into consideration when planning land-use activities and restoration efforts. After almost 30 years of conservation effort, Lahontan cutthroat trout (LCT) (Oncorhynchus clarki henshawi) populations remain in peril throughout the Great Basin region of southeastern Oregon and northern Nevada. This is not surprising since very little research has been done on the ecology of LCT, and management has been carried out without essential information on this sub-species. The objectives of our study were to determine whether there are inter-stream or inter-reach differences in LCT habitat selection, and if those differences corresponded to differences in fish survival and growth. We relied upon contiguous whole stream surveys to look at fish distribution and in-stream habitat. The use of half duplex PIT tags allowed us to determine the growth, movement patterns, and survival rates of most adult (>100 mm) LCT within the system. We found greater trout growth (median daily change in biomass 0.46% vs. 0.07%), but lower survival (35% vs. 61% between July and November), in relatively warmer and more open reaches than in cooler reaches. Additionally, undercut banks (predation shelter) were more important to trout in cooler stream reaches than in warmer ones, where habitat choice responded first to cold water input (which was influenced by topography). Our results will be useful in identifying and describing areas of high quality LCT habitat in low order streams throughout the Great Basin, thus allowing informed management decisions to facilitate the recovery of the sub-species. Close

• 576. [Article] Subsurface geology of the southeastern Cuyama Valley, southern Coast Ranges, California

  The southeastern Cuyama Valley is located in the southern Coast Ranges, west of Bakersfield, California. Subsurface geologic mapping using data from 62 prospect wells was integrated with surface mapping to ...

  Citation × Citation Citation Abstract Copy Title: Subsurface geology of the southeastern Cuyama Valley, southern Coast Ranges, California Author: Spitz, Herbert M. The southeastern Cuyama Valley is located in the southern Coast Ranges, west of Bakersfield, California. Subsurface geologic mapping using data from 62 prospect wells was integrated with surface mapping to determine the depositional and deformational history of this part of the Neogene Cuyama basin. The northwest-trending Russell fault system was active from late Oligocene to Pliocene time. Deformation along this major wrench system began during deposition of the late Oligocene to early Miocene Soda Lake Shale Member of the Vaqueros Formation and ended prior to deposition of the Plio-Pleistocene Morales Formation. The southern extension of this fault system remains uncertain, but it probably joins the Ozena fault southeast of the South Cuyama oil field. Removal of 16 to 18 miles of right-lateral offset on the Russell fault system restores the Ozena fault to a position directly east of the La Panza fault. These two faults were probably a single fault, designated the La Panza-Ozena fault, which was active, north-side down, during the Oligocene. Nonmarine conglomerates of the Simmler and lower Caliente formations were deposited north of this fault during the Oligocene, prior to the initiation of notion on the Russell fault system. Three major faults of the Cox fault zone on the west and the Lundstrom-Becker and Becker-Heller faults on the east define the margins of the Cox trough, a complex north- to northeast-trending graben north of the Russell fault which was active from Saucesian through Relizian time (early Miocene). The Saltos Shale Member of the Monterey Formation increases in thickness by 3 to 7 times across the margins of the trough. Growth faulting associated with the Cox trough ended prior to deposition of the middle Johnston sand on all faults except the Cox 46-5 fault, which was active through deposition of the Branch Canyon Sandstone. Post-Pliocene tectonism in the Cuyama basin was limited to folding and reverse-faulting in response to regional north-south compression. The Central Cuyama dome and associated north-dipping reverse faults formed during an early episode of this deformation. Subsequent deformation occurred on the Morales fault, the South Cuyama fault, and the rejuvenated Ozena fault. This Quaternary thrusting obscured the structures of the older wrench-tectonic regime and resulted in the formation of the Caliente and Sierra Madre Ranges and the present-day Cuyama Valley. Title: Subsurface geology of the southeastern Cuyama Valley, southern Coast Ranges, California Author: Spitz, Herbert M. The southeastern Cuyama Valley is located in the southern Coast Ranges, west of Bakersfield, California. Subsurface geologic mapping using data from 62 prospect wells was integrated with surface mapping to determine the depositional and deformational history of this part of the Neogene Cuyama basin. The northwest-trending Russell fault system was active from late Oligocene to Pliocene time. Deformation along this major wrench system began during deposition of the late Oligocene to early Miocene Soda Lake Shale Member of the Vaqueros Formation and ended prior to deposition of the Plio-Pleistocene Morales Formation. The southern extension of this fault system remains uncertain, but it probably joins the Ozena fault southeast of the South Cuyama oil field. Removal of 16 to 18 miles of right-lateral offset on the Russell fault system restores the Ozena fault to a position directly east of the La Panza fault. These two faults were probably a single fault, designated the La Panza-Ozena fault, which was active, north-side down, during the Oligocene. Nonmarine conglomerates of the Simmler and lower Caliente formations were deposited north of this fault during the Oligocene, prior to the initiation of notion on the Russell fault system. Three major faults of the Cox fault zone on the west and the Lundstrom-Becker and Becker-Heller faults on the east define the margins of the Cox trough, a complex north- to northeast-trending graben north of the Russell fault which was active from Saucesian through Relizian time (early Miocene). The Saltos Shale Member of the Monterey Formation increases in thickness by 3 to 7 times across the margins of the trough. Growth faulting associated with the Cox trough ended prior to deposition of the middle Johnston sand on all faults except the Cox 46-5 fault, which was active through deposition of the Branch Canyon Sandstone. Post-Pliocene tectonism in the Cuyama basin was limited to folding and reverse-faulting in response to regional north-south compression. The Central Cuyama dome and associated north-dipping reverse faults formed during an early episode of this deformation. Subsequent deformation occurred on the Morales fault, the South Cuyama fault, and the rejuvenated Ozena fault. This Quaternary thrusting obscured the structures of the older wrench-tectonic regime and resulted in the formation of the Caliente and Sierra Madre Ranges and the present-day Cuyama Valley. Close

• 577. [Article] Homeowner Association Resident’s Perceptions on Stormwater Retention Ponds and Clean Drinking Water: (Montgomery West Homeowners Association (MWHOA) Gaithersburg, Maryland).

  Graduation date: 2015

  Citation × Citation Citation Abstract Copy Title: Homeowner Association Resident’s Perceptions on Stormwater Retention Ponds and Clean Drinking Water: (Montgomery West Homeowners Association (MWHOA) Gaithersburg, Maryland). Author: Roberts, William Hadyn Jr Graduation date: 2015 Title: Homeowner Association Resident’s Perceptions on Stormwater Retention Ponds and Clean Drinking Water: (Montgomery West Homeowners Association (MWHOA) Gaithersburg, Maryland). Author: Roberts, William Hadyn Jr Graduation date: 2015 Close

• 578. [Article] The influence of climate change and restoration on stream temperature

  Water temperature is an essential property of a stream. Temperature regulates physical and biochemical processes in aquatic habitats. Various factors related to climatic conditions, landscape characteristics, ...

  Citation × Citation Citation Abstract Copy Title: The influence of climate change and restoration on stream temperature Author: Diabat, Mousa Water temperature is an essential property of a stream. Temperature regulates physical and biochemical processes in aquatic habitats. Various factors related to climatic conditions, landscape characteristics, and channel structure directly influence stream temperature. Numerous studies indicate that increased average air temperature during the past century has led to stream warming across the world. The trend of stream warming was also present in spring-fed watersheds, where summer flow has decreased. In addition, anthropogenic practices that alter the natural landscape and channel structure, such as forest management, agriculture, and mining contributed to stream warming. For example, deforested and unshaded stream reaches or dredged channels were warmer than shaded reaches and meandering streams. Stream temperatures in North American lotic habitats are of a specific concern due to their significant economic, cultural, and ecological value. With climate projections indicating that air temperature will only continue to rise throughout the 21st century, cold- or cool-water organisms, especially fishes, will be affected. Therefore, there is a strong need to better understand the impacts of changing climate, riparian landscape, and channel structure on a stream's heat budget. This may assist in restoring the historic thermal regime in impacted sites and mitigating the impacts of future climate change. This study looks into the relative influences of the different factors on a stream's heat budget with three manuscripts: one on stream temperature response to diel timing of air warming, one on stream temperature response to changes in air temperature, flow, and riparian vegetation, and one on stream temperature response to air warming and channel reconstruction. I used the software Heat Source version 8.05 to simulate stream temperature for all three analyses along the Middle Fork John Day River, Oregon USA. Two of the manuscripts were applied to an upper 37 km section of the Middle Fork John Day River (presented in chapter 2 and 3), where the third manuscript was applied to a 1.5-km section. The sensitivity analysis of stream temperature response to diel timing of air warming (Chapter 2: Diel Timing of Warmer Air under Climate Change Affects Magnitude, Timing, and Duration of Stream Temperature Change) was based on scenarios representing uniform air warming over the diel period, daytime warming, and nighttime warming. Uniform warming of air temperature is a simple representation of increases in the average daily or monthly temperatures generated by the 'delta method'. The delta method relies on adding a constant value to the air temperature time-series data. This constant value is the difference (delta) between base case average air temperatures and the projected one. Scenarios of daytime or nighttime warming represent conditions under which most of the warming of the air occurs during the daytime or the nighttime, respectively. I simulated the stream temperature response to warmer air conditions of +2 °C and +4 °C in daily average for all three cases of air warming conditions. The three cases of different diel distributions of air warming generated 7-day average daily maximum stream temperature (7DADM) increases of approximately +1.8 °C ± 0.1 °C at the downstream end of the study section relative to the base case. In most parts of the reach, the three distributions of air warming generated different ranges of stream temperatures, different 7DADM values, different durations of stream temperature changes, and different average daily temperatures. Changes of stream temperature were out of phase with imposed changes of air temperature. Therefore, nighttime warming of air temperatures would cause the greatest increase in maximum daily stream temperature, which typically occurs during the daytime. The sensitivity analysis of the relative influences of changes in air temperature, stream flow, and riparian vegetation on stream temperature (Chapter 3: Assessing Stream Temperature Response to Cumulative Influence of Changing Air Temperature, Flow, and Riparian Vegetation). This study summarized stream temperature simulation in 36 scenarios representing possible manifestations of 21st century climate conditions and land management strategies. In addition to existing conditions (base case) of flow, air temperature, and riparian vegetation, scenarios consisted of: two air temperature increases of 2 °C and 4 °C, two stream flow variations of +30% and -30%, three spatially uniform riparian vegetation conditions that create averages of effective shade 7%, 34%, and 79%, in addition to 14% for base case conditions. Results suggest that variation in riparian vegetation was the dominant factor influencing stream temperature because it regulates incoming shortwave radiation, the largest heat input to the stream, while variation in stream flow has a negligible influence. Results indicated that increasing the effective shade along the study section, particularly in the currently unshaded sections, could mitigate the influence of increasing air temperature, and would reduce stream temperature maxima below current values even under future climate conditions of warmer air. With the small influence it had, increasing stream flow reduced the 7DADM under low shade conditions. However, increasing stream flow showed counterintuitive results as it contributed to increasing stream temperature maxima when the stream was heavily shaded. The applied study examined the stream temperature response to restoration practices and their potential to mitigate the influence of warmer air conditions (Chapter 4: Estimating Stream Temperature Response to Restoring Channel and Riparian Vegetation and the Potential to Mitigate Warmer Air Conditions). This study focused on a 1.5 km section along the upper part of the Middle Fork John Day River that was modified due to past anthropogenic activities of mining for gold and timber harvest. Currently, the riparian vegetation of the study site is mostly shrubs and stands of short trees. Restoration designs call for the restoration of both the channel structure and replanting the riparian vegetation. Simulation results showed that the 7DADM was higher in the restored channel than the existing channel with both conditions of low and high effective shade conditions. However, a combined restoration practice of channel reconstruction and medium effective shade conditions reduced stream temperature maxima more than restoring riparian vegetation alone. In addition, results showed that restoring riparian vegetation was sufficient to mitigate the influence of warmer air on stream temperature, while restoring the channel alone is not. Heat budget analysis showed that heat accumulation during the daytime increased in the restored channel, which was longer, narrower, and deeper than the existing channel. It is important to emphasize that stream temperature is one of many goals that restoration activities aim to improve. Furthermore, differences in 7DADM among the different scenarios of restoration are negligible. Such small differences could hardly be measure. While this study examined a short section of 1.5 km, longer stream sections may increase the differences in 7DADM. Primary conclusions of this study are: 1) daily maxima of stream temperature will increase in response to increased air temperature regardless of the distribution of air warming during the diel cycle; 2) nighttime air warming caused a greater increase in stream temperature maximum than daytime warming; 3) riparian vegetation was the dominant factor on stream's heat budget, more than air temperature or stream flow; 4) restoring riparian vegetation mitigated the influence of warmer air; 5) restoring channel structure alone was not sufficient to lower temperature maxima; and 6) restoration project was most successful in improving degraded stream temperature when combined with channel reconstruction and improved riparian shade. Title: The influence of climate change and restoration on stream temperature Author: Diabat, Mousa Water temperature is an essential property of a stream. Temperature regulates physical and biochemical processes in aquatic habitats. Various factors related to climatic conditions, landscape characteristics, and channel structure directly influence stream temperature. Numerous studies indicate that increased average air temperature during the past century has led to stream warming across the world. The trend of stream warming was also present in spring-fed watersheds, where summer flow has decreased. In addition, anthropogenic practices that alter the natural landscape and channel structure, such as forest management, agriculture, and mining contributed to stream warming. For example, deforested and unshaded stream reaches or dredged channels were warmer than shaded reaches and meandering streams. Stream temperatures in North American lotic habitats are of a specific concern due to their significant economic, cultural, and ecological value. With climate projections indicating that air temperature will only continue to rise throughout the 21st century, cold- or cool-water organisms, especially fishes, will be affected. Therefore, there is a strong need to better understand the impacts of changing climate, riparian landscape, and channel structure on a stream's heat budget. This may assist in restoring the historic thermal regime in impacted sites and mitigating the impacts of future climate change. This study looks into the relative influences of the different factors on a stream's heat budget with three manuscripts: one on stream temperature response to diel timing of air warming, one on stream temperature response to changes in air temperature, flow, and riparian vegetation, and one on stream temperature response to air warming and channel reconstruction. I used the software Heat Source version 8.05 to simulate stream temperature for all three analyses along the Middle Fork John Day River, Oregon USA. Two of the manuscripts were applied to an upper 37 km section of the Middle Fork John Day River (presented in chapter 2 and 3), where the third manuscript was applied to a 1.5-km section. The sensitivity analysis of stream temperature response to diel timing of air warming (Chapter 2: Diel Timing of Warmer Air under Climate Change Affects Magnitude, Timing, and Duration of Stream Temperature Change) was based on scenarios representing uniform air warming over the diel period, daytime warming, and nighttime warming. Uniform warming of air temperature is a simple representation of increases in the average daily or monthly temperatures generated by the 'delta method'. The delta method relies on adding a constant value to the air temperature time-series data. This constant value is the difference (delta) between base case average air temperatures and the projected one. Scenarios of daytime or nighttime warming represent conditions under which most of the warming of the air occurs during the daytime or the nighttime, respectively. I simulated the stream temperature response to warmer air conditions of +2 °C and +4 °C in daily average for all three cases of air warming conditions. The three cases of different diel distributions of air warming generated 7-day average daily maximum stream temperature (7DADM) increases of approximately +1.8 °C ± 0.1 °C at the downstream end of the study section relative to the base case. In most parts of the reach, the three distributions of air warming generated different ranges of stream temperatures, different 7DADM values, different durations of stream temperature changes, and different average daily temperatures. Changes of stream temperature were out of phase with imposed changes of air temperature. Therefore, nighttime warming of air temperatures would cause the greatest increase in maximum daily stream temperature, which typically occurs during the daytime. The sensitivity analysis of the relative influences of changes in air temperature, stream flow, and riparian vegetation on stream temperature (Chapter 3: Assessing Stream Temperature Response to Cumulative Influence of Changing Air Temperature, Flow, and Riparian Vegetation). This study summarized stream temperature simulation in 36 scenarios representing possible manifestations of 21st century climate conditions and land management strategies. In addition to existing conditions (base case) of flow, air temperature, and riparian vegetation, scenarios consisted of: two air temperature increases of 2 °C and 4 °C, two stream flow variations of +30% and -30%, three spatially uniform riparian vegetation conditions that create averages of effective shade 7%, 34%, and 79%, in addition to 14% for base case conditions. Results suggest that variation in riparian vegetation was the dominant factor influencing stream temperature because it regulates incoming shortwave radiation, the largest heat input to the stream, while variation in stream flow has a negligible influence. Results indicated that increasing the effective shade along the study section, particularly in the currently unshaded sections, could mitigate the influence of increasing air temperature, and would reduce stream temperature maxima below current values even under future climate conditions of warmer air. With the small influence it had, increasing stream flow reduced the 7DADM under low shade conditions. However, increasing stream flow showed counterintuitive results as it contributed to increasing stream temperature maxima when the stream was heavily shaded. The applied study examined the stream temperature response to restoration practices and their potential to mitigate the influence of warmer air conditions (Chapter 4: Estimating Stream Temperature Response to Restoring Channel and Riparian Vegetation and the Potential to Mitigate Warmer Air Conditions). This study focused on a 1.5 km section along the upper part of the Middle Fork John Day River that was modified due to past anthropogenic activities of mining for gold and timber harvest. Currently, the riparian vegetation of the study site is mostly shrubs and stands of short trees. Restoration designs call for the restoration of both the channel structure and replanting the riparian vegetation. Simulation results showed that the 7DADM was higher in the restored channel than the existing channel with both conditions of low and high effective shade conditions. However, a combined restoration practice of channel reconstruction and medium effective shade conditions reduced stream temperature maxima more than restoring riparian vegetation alone. In addition, results showed that restoring riparian vegetation was sufficient to mitigate the influence of warmer air on stream temperature, while restoring the channel alone is not. Heat budget analysis showed that heat accumulation during the daytime increased in the restored channel, which was longer, narrower, and deeper than the existing channel. It is important to emphasize that stream temperature is one of many goals that restoration activities aim to improve. Furthermore, differences in 7DADM among the different scenarios of restoration are negligible. Such small differences could hardly be measure. While this study examined a short section of 1.5 km, longer stream sections may increase the differences in 7DADM. Primary conclusions of this study are: 1) daily maxima of stream temperature will increase in response to increased air temperature regardless of the distribution of air warming during the diel cycle; 2) nighttime air warming caused a greater increase in stream temperature maximum than daytime warming; 3) riparian vegetation was the dominant factor on stream's heat budget, more than air temperature or stream flow; 4) restoring riparian vegetation mitigated the influence of warmer air; 5) restoring channel structure alone was not sufficient to lower temperature maxima; and 6) restoration project was most successful in improving degraded stream temperature when combined with channel reconstruction and improved riparian shade. Close