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• 561. [Article] FishXing: evaluation of fish passage culvert model and comparision with Oregon Department of Forestry's compliance with fish passage and peak flow requirements at stream crossings

  FishXing (fish crossing), a computer aided stream crossing culvert model designed to analyze fish passage through culverts was compared with results of an Oregon Department of Forestry fish passage monitoring ...

  Citation × Citation Citation Abstract Copy Title: FishXing: evaluation of fish passage culvert model and comparision with Oregon Department of Forestry's compliance with fish passage and peak flow requirements at stream crossings Author: Morrissette, Brett A. FishXing (fish crossing), a computer aided stream crossing culvert model designed to analyze fish passage through culverts was compared with results of an Oregon Department of Forestry fish passage monitoring report. FishXing was created at Humboldt State University through sponsorship from the US Forest Service, USDA, Stream Team, Six Rivers National Forest, San Dimas Technology and Development Center, The Watershed Stewards Project, and the Federal Highway Administration. A comparison was made between results generated using FishXing with results found by ODF in the Oregon Department of Forestry (ODF): Compliance With Fish Passage and Peak Flow Requirements at Stream Crossings monitoring project. Stream crossing culvert data from the ODF fish passage study was used to run FishXing. The ODF monitoring project investigated 74 fish passage culvert installations that were constructed following approval of Written Plans filed with ODF in 1998. (An approved Written Plan is equivalent to a permit with ODF). Information about culvert installations was analyzed using FishXing. Four different trials were run for each culvert using both adult and juvenile Coho Salmon and Cutthroat trout using the FishXing software. Three trials used the default values for swimming abilities of adult and juvenile Coho salmon and adult Cutthroat trout. Juvenile Cutthroat trout were also included in the comparison; however, FishXing did not contain a default setting for them. Therefore, a velocity of 2 feet per second (fj,$), the current target velocity for stream crossings on fish 111 bearing streams in the state of Oregon, was used for juvenile Cutthroat trout (ODFW 2). After making comparisons with the preliminary ODF results, further study was done to assess the accuracy of the calculations carried out within FishXing. This was based on Manning's equation (V=1 .49/n*R2"3*Sh"2) and other formulas given in the "help" section of FishXing. Flow calculations were also compared with the Haestad Culvert Master program. The results produced using Manning's equation show no statistical difference from those generated using FishXing. Furthermore, there was an insignificant statistical difference found between FishXing-generated output and that of Culvert Master. Positive and negative attributes concerning FishXing are addressed at the end of the report. Title: FishXing: evaluation of fish passage culvert model and comparision with Oregon Department of Forestry's compliance with fish passage and peak flow requirements at stream crossings Author: Morrissette, Brett A. FishXing (fish crossing), a computer aided stream crossing culvert model designed to analyze fish passage through culverts was compared with results of an Oregon Department of Forestry fish passage monitoring report. FishXing was created at Humboldt State University through sponsorship from the US Forest Service, USDA, Stream Team, Six Rivers National Forest, San Dimas Technology and Development Center, The Watershed Stewards Project, and the Federal Highway Administration. A comparison was made between results generated using FishXing with results found by ODF in the Oregon Department of Forestry (ODF): Compliance With Fish Passage and Peak Flow Requirements at Stream Crossings monitoring project. Stream crossing culvert data from the ODF fish passage study was used to run FishXing. The ODF monitoring project investigated 74 fish passage culvert installations that were constructed following approval of Written Plans filed with ODF in 1998. (An approved Written Plan is equivalent to a permit with ODF). Information about culvert installations was analyzed using FishXing. Four different trials were run for each culvert using both adult and juvenile Coho Salmon and Cutthroat trout using the FishXing software. Three trials used the default values for swimming abilities of adult and juvenile Coho salmon and adult Cutthroat trout. Juvenile Cutthroat trout were also included in the comparison; however, FishXing did not contain a default setting for them. Therefore, a velocity of 2 feet per second (fj,$), the current target velocity for stream crossings on fish 111 bearing streams in the state of Oregon, was used for juvenile Cutthroat trout (ODFW 2). After making comparisons with the preliminary ODF results, further study was done to assess the accuracy of the calculations carried out within FishXing. This was based on Manning's equation (V=1 .49/n*R2"3*Sh"2) and other formulas given in the "help" section of FishXing. Flow calculations were also compared with the Haestad Culvert Master program. The results produced using Manning's equation show no statistical difference from those generated using FishXing. Furthermore, there was an insignificant statistical difference found between FishXing-generated output and that of Culvert Master. Positive and negative attributes concerning FishXing are addressed at the end of the report. Close

• 562. [Article] Spatial and temporal variability of freshwater discharge into the Gulf of Alaska

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://agupubs.onlinelibrary.wiley.com/agu/jgr/journal/10.1002/%28ISSN%292...

  Citation × Citation Citation Abstract Copy Title: Spatial and temporal variability of freshwater discharge into the Gulf of Alaska Author: Beamer, J., Bruhis, N., Arendt, A., Calos, S. E., Hill, D. F. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://agupubs.onlinelibrary.wiley.com/agu/jgr/journal/10.1002/%28ISSN%292169-9291/. Title: Spatial and temporal variability of freshwater discharge into the Gulf of Alaska Author: Beamer, J., Bruhis, N., Arendt, A., Calos, S. E., Hill, D. F. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://agupubs.onlinelibrary.wiley.com/agu/jgr/journal/10.1002/%28ISSN%292169-9291/. Close

• 563. [Article] A bioeconomic analysis of altering instream flows anadromous fish production and competing demands for water in the John Day River basin, Oregon

  The growing demand for water in the arid regions of the West increases the need for optimal allocation of water among competing uses. An efficient allocation of water between instream and out-of-stream uses ...

  Citation × Citation Citation Abstract Copy Title: A bioeconomic analysis of altering instream flows anadromous fish production and competing demands for water in the John Day River basin, Oregon Author: Johnson, Neal S. The growing demand for water in the arid regions of the West increases the need for optimal allocation of water among competing uses. An efficient allocation of water between instream and out-of-stream uses has been impeded by institutional constraints and the scarcity of information regarding instream flow benefits. The objectives of this thesis were to provide preliminary economic data on the value of instream water in "producing" recreational fishing and to examine the effect of forestry, agriculture, and livestock practices on temporal streamflow patterns and anadromous fish production. The steelhead trout (Salmo gairdneri) sport fishery within the John Day River basin in north-central Oregon provided the setting for this research. The interdisciplinary methodology employed in estimating the marginal value of water with respect to steelhead production consisted of two tasks. The first task involved valuing a marginal change in the quality of the steelhead recreational fishery. The contingent valuation method (CVM) was selected for this purpose. Both open- and closed-ended willingness-to-pay (WTP) questions were included in a questionnaire administered to John Day River steelhead anglers during the 1986/87 steelhead fishing season. Survey data were analyzed to arrive at individual and aggregate bid functions relating WTP to expected angling success rates. Results indicate that, under current conditions, the average angler is willing to pay approximately $7.20 to catch an additional steelhead. The second task of the instream water valuation methodology was directed at deriving a streamflow/steelhead production relationship. By including variables influencing steelhead production in a Ricker stock-recruitment model, it was possible to develop a model which could be estimated using linear regression techniques. Some difficulty arose, however, with interpretation of the model due to the unavailability of cohort escapement data and the subsequent use of standing crop data. While possibly masking the true magnitude of streamflow's effect on fish production, this drawback was not deemed limiting within the general context of the interdisciplinary methodology. Results of the biological model conformed to a priori expectations. Increases in summer and winter streamflows led to increased steelhead survival, whereas higher spring flows increased mortality levels. Other results indicate that the John Day Dam was responsible for a 31.5 percent decline in the population index for the 1969-1983 period. Combining the economic and biological results into one equation yielded an estimate of the marginal value of summer instream water in "producing" recreational steelhead angling. Similar equations were developed for winter and spring flows. The marginal value of water in producing recreational steelhead fishing within the John Day basin was estimated at $0.56 per acre-foot for summer flows, $0.046 for winter flows, and -$0.075 for spring flows. By including out-of-basin benefits, these values increased to $2.26, $0.19, and -$0.30, respectively. In comparison, water's value in irrigation within the John Day basin has been estimated at between $10 to $24 per acre-foot. However, nonuse values of steelhead, as well as the increased production of other fish species (such as spring chinook salmon) were not included in the instream water values. In addition, no attempt was made at valuing instream water's contribution to boating, camping, or other benefit-producing activities. A secondary objective of this thesis was to briefly examine the possible benefits accruing to other instream and out-of-stream users due to an alteration in streamflow patterns. In addition, the impact of activities by other resource users -- namely forestry, agriculture, and livestock production --on anadromous fish production was reviewed. Improper management practices by these activities can negatively impact the aquatic and riparian ecosystems. While no firm conclusions were drawn, it appears the quality of these ecosystems, as opposed to the amount of streamflow, has the largest marginal impact on anadromous fish populations. Title: A bioeconomic analysis of altering instream flows anadromous fish production and competing demands for water in the John Day River basin, Oregon Author: Johnson, Neal S. The growing demand for water in the arid regions of the West increases the need for optimal allocation of water among competing uses. An efficient allocation of water between instream and out-of-stream uses has been impeded by institutional constraints and the scarcity of information regarding instream flow benefits. The objectives of this thesis were to provide preliminary economic data on the value of instream water in "producing" recreational fishing and to examine the effect of forestry, agriculture, and livestock practices on temporal streamflow patterns and anadromous fish production. The steelhead trout (Salmo gairdneri) sport fishery within the John Day River basin in north-central Oregon provided the setting for this research. The interdisciplinary methodology employed in estimating the marginal value of water with respect to steelhead production consisted of two tasks. The first task involved valuing a marginal change in the quality of the steelhead recreational fishery. The contingent valuation method (CVM) was selected for this purpose. Both open- and closed-ended willingness-to-pay (WTP) questions were included in a questionnaire administered to John Day River steelhead anglers during the 1986/87 steelhead fishing season. Survey data were analyzed to arrive at individual and aggregate bid functions relating WTP to expected angling success rates. Results indicate that, under current conditions, the average angler is willing to pay approximately $7.20 to catch an additional steelhead. The second task of the instream water valuation methodology was directed at deriving a streamflow/steelhead production relationship. By including variables influencing steelhead production in a Ricker stock-recruitment model, it was possible to develop a model which could be estimated using linear regression techniques. Some difficulty arose, however, with interpretation of the model due to the unavailability of cohort escapement data and the subsequent use of standing crop data. While possibly masking the true magnitude of streamflow's effect on fish production, this drawback was not deemed limiting within the general context of the interdisciplinary methodology. Results of the biological model conformed to a priori expectations. Increases in summer and winter streamflows led to increased steelhead survival, whereas higher spring flows increased mortality levels. Other results indicate that the John Day Dam was responsible for a 31.5 percent decline in the population index for the 1969-1983 period. Combining the economic and biological results into one equation yielded an estimate of the marginal value of summer instream water in "producing" recreational steelhead angling. Similar equations were developed for winter and spring flows. The marginal value of water in producing recreational steelhead fishing within the John Day basin was estimated at $0.56 per acre-foot for summer flows, $0.046 for winter flows, and -$0.075 for spring flows. By including out-of-basin benefits, these values increased to $2.26, $0.19, and -$0.30, respectively. In comparison, water's value in irrigation within the John Day basin has been estimated at between $10 to $24 per acre-foot. However, nonuse values of steelhead, as well as the increased production of other fish species (such as spring chinook salmon) were not included in the instream water values. In addition, no attempt was made at valuing instream water's contribution to boating, camping, or other benefit-producing activities. A secondary objective of this thesis was to briefly examine the possible benefits accruing to other instream and out-of-stream users due to an alteration in streamflow patterns. In addition, the impact of activities by other resource users -- namely forestry, agriculture, and livestock production --on anadromous fish production was reviewed. Improper management practices by these activities can negatively impact the aquatic and riparian ecosystems. While no firm conclusions were drawn, it appears the quality of these ecosystems, as opposed to the amount of streamflow, has the largest marginal impact on anadromous fish populations. Close

• 564. [Article] The effect of the size and orientation of large wood on pool volume in two Oregon Coast Range streams

  This study was conducted to determine how the size and orientation of large wood placed in streams in combination with peak flows, substrate and channel gradient affect pool volume, surface area and maximum ...

  Citation × Citation Citation Abstract Copy Title: The effect of the size and orientation of large wood on pool volume in two Oregon Coast Range streams Author: Lombard, Pamela This study was conducted to determine how the size and orientation of large wood placed in streams in combination with peak flows, substrate and channel gradient affect pool volume, surface area and maximum depth in two coastal Oregon streams. Eighteen Douglas-fir (Pseudotsuga menziesii) logs were placed in each of two streams, J-Line Creek and Preacher Creek, in the summer of 1989. Surveys were conducted annually from 1989-1996 at summer low flow using a total station electronic theodolite. The orientation of the introduced wood and the parameters of residual pools associated with the wood were determined from high resolution topographic maps made from the surveys. Residual pool volume associated with the introduced wood increased 2,500 percent over the seven years for J-Line Creek and 30 percent for Preacher Creek. Large spanners, logs placed perpendicular to the stream flow and flush with the stream bottom, had the greatest pool volume associated with them, however horizontal orientations shifted downstream over time. Large ramps, logs placed at a downstream orientation and angled up onto the bank, were the most stable treatment. Differences between the two watersheds and an interaction variable between the diameter of the introduced wood and the horizontal orientation of the introduced wood were the significant variables which entered the multiple linear regression model for residual pool volume. These variables, as well as the vertical orientation of the introduced wood, were significantly correlated to both residual pool surface area and maximum depth. The recurrence interval of the annual maximum instantaneous peak flow was not significantly associated with residual pool volume, surface area nor maximum depth. Multiple regression models explained, at most, twenty-eight percent of the variability in residual pool volume, maximum depth and surface area. Estimates of pool volume obtained with aquatic habitat inventories (Bisson et al., 1982) were compared with residual pool calculations determined from the topographic maps. Pool volume in a reach determined by aquatic habitat inventories explained 96 percent of the variability of residual pool volume in a reach, however estimates of individual pool volume explained only 40 percent of the variability in residual pool volume. Title: The effect of the size and orientation of large wood on pool volume in two Oregon Coast Range streams Author: Lombard, Pamela This study was conducted to determine how the size and orientation of large wood placed in streams in combination with peak flows, substrate and channel gradient affect pool volume, surface area and maximum depth in two coastal Oregon streams. Eighteen Douglas-fir (Pseudotsuga menziesii) logs were placed in each of two streams, J-Line Creek and Preacher Creek, in the summer of 1989. Surveys were conducted annually from 1989-1996 at summer low flow using a total station electronic theodolite. The orientation of the introduced wood and the parameters of residual pools associated with the wood were determined from high resolution topographic maps made from the surveys. Residual pool volume associated with the introduced wood increased 2,500 percent over the seven years for J-Line Creek and 30 percent for Preacher Creek. Large spanners, logs placed perpendicular to the stream flow and flush with the stream bottom, had the greatest pool volume associated with them, however horizontal orientations shifted downstream over time. Large ramps, logs placed at a downstream orientation and angled up onto the bank, were the most stable treatment. Differences between the two watersheds and an interaction variable between the diameter of the introduced wood and the horizontal orientation of the introduced wood were the significant variables which entered the multiple linear regression model for residual pool volume. These variables, as well as the vertical orientation of the introduced wood, were significantly correlated to both residual pool surface area and maximum depth. The recurrence interval of the annual maximum instantaneous peak flow was not significantly associated with residual pool volume, surface area nor maximum depth. Multiple regression models explained, at most, twenty-eight percent of the variability in residual pool volume, maximum depth and surface area. Estimates of pool volume obtained with aquatic habitat inventories (Bisson et al., 1982) were compared with residual pool calculations determined from the topographic maps. Pool volume in a reach determined by aquatic habitat inventories explained 96 percent of the variability of residual pool volume in a reach, however estimates of individual pool volume explained only 40 percent of the variability in residual pool volume. Close

• 565. [Article] Influence of cover crops on vine performance at two Willamette Valley vineyards

  It is estimated that 50-75% of Oregon vineyards cultivate at least every other alley in order to 1) reduce water stress 2) increase vineyard canopy temperatures and 3) increase nutrient availability. Because ...

  Citation × Citation Citation Abstract Copy Title: Influence of cover crops on vine performance at two Willamette Valley vineyards Author: Sweet, Rebecca Marie It is estimated that 50-75% of Oregon vineyards cultivate at least every other alley in order to 1) reduce water stress 2) increase vineyard canopy temperatures and 3) increase nutrient availability. Because many vineyards are situated on steep hillsides, frequent tillage could result in increased soil erosion, decreased soil quality and potential pollution of watersheds. Seven cover crop treatments were established at two commercial vineyards in the northern Willamette Valley in the fall of 2003 and monitored for establishment and their impact on grapevines in 2004 and 2005. Treatments were as follows: 1) winter annuals (oats, rye and vetch), 2) clover mix (subclovers, clovers and medic), 3) native grass mix (Willamette Valley upland prairie species), 4) native meadow mix (forbs plus grasses), 5) perennial grass mix (sheep fescue, dwarf perennial rye and hard fescue), 6) resident vegetation, and 7) a clean cultivated control. Each treatment was replicated four times at each of the vineyards in a randomized complete block design. Treatments were applied to four adjacent alleys flanking 8 or 10 vines in three vine rows with one clean cultivated boarder dividing blocks. Cover crop establishment was measured by destructively removing biomass during the growing season. Weeds were sorted from cover crops, and both were dried, weighed and measured for nitrogen (N) content. Over the course of the growing season, soil water was measured in the vine row and alleys with time domain reflectometry, and midday vine leaf water potential was measured with a pressure bomb. Shoot lengths were measured twice during the season. Vine leaf blades were collected at bloom and veraison for nutrient analysis (N,P,K, S, Ca, Mg, Mn, Cu, B, Zn and Fe). Root samples were taken at bloom and post harvest in the vine row and alley in three treatments (winter annuals, perennial grass mix and clean cultivated) and analyzed for colonization by arbuscular mycorrhizal fungi (AMF). At harvest, fruit yield was measured and fruit quality assessed by measuring soluble solids (BRIX), titratable acidity, pH and N content. Shoot prunings were collected and measured after vine dormancy. We expected to see 1) a higher amount of water in the soil, less vine water stress and more vigorous vine growth in the clean cultivated treatment compared to the others and 2) either an increase in vigor or concentration of N in vine tissues in response to the clover mix treatment. Biomass production and coverage of the soil by cover crops, as well as responses to treatments in the soil and vine often varied between sites. In general, cover crop treatments, including the clean cultivated control, had little effect on soil water content, vine water status, or vine vegetative growth. There was, however, a clear N affect from the clover mix treatment on vines, even without mechanical incorporation of cover crop residues. Vine leaf N and juice YANC both increased, and yield per vine and cluster weights both decreased in the clover mix treatment. However, the yield reductions were more pronounced in year two and only at one site. The increase in juice N was possibly an indirect effect of the lower yield, concentrating N in the remaining fruit. Results from this two year study indicate no apparent advantage to keeping the alleyways of established vineyards weed free with cultivation. Title: Influence of cover crops on vine performance at two Willamette Valley vineyards Author: Sweet, Rebecca Marie It is estimated that 50-75% of Oregon vineyards cultivate at least every other alley in order to 1) reduce water stress 2) increase vineyard canopy temperatures and 3) increase nutrient availability. Because many vineyards are situated on steep hillsides, frequent tillage could result in increased soil erosion, decreased soil quality and potential pollution of watersheds. Seven cover crop treatments were established at two commercial vineyards in the northern Willamette Valley in the fall of 2003 and monitored for establishment and their impact on grapevines in 2004 and 2005. Treatments were as follows: 1) winter annuals (oats, rye and vetch), 2) clover mix (subclovers, clovers and medic), 3) native grass mix (Willamette Valley upland prairie species), 4) native meadow mix (forbs plus grasses), 5) perennial grass mix (sheep fescue, dwarf perennial rye and hard fescue), 6) resident vegetation, and 7) a clean cultivated control. Each treatment was replicated four times at each of the vineyards in a randomized complete block design. Treatments were applied to four adjacent alleys flanking 8 or 10 vines in three vine rows with one clean cultivated boarder dividing blocks. Cover crop establishment was measured by destructively removing biomass during the growing season. Weeds were sorted from cover crops, and both were dried, weighed and measured for nitrogen (N) content. Over the course of the growing season, soil water was measured in the vine row and alleys with time domain reflectometry, and midday vine leaf water potential was measured with a pressure bomb. Shoot lengths were measured twice during the season. Vine leaf blades were collected at bloom and veraison for nutrient analysis (N,P,K, S, Ca, Mg, Mn, Cu, B, Zn and Fe). Root samples were taken at bloom and post harvest in the vine row and alley in three treatments (winter annuals, perennial grass mix and clean cultivated) and analyzed for colonization by arbuscular mycorrhizal fungi (AMF). At harvest, fruit yield was measured and fruit quality assessed by measuring soluble solids (BRIX), titratable acidity, pH and N content. Shoot prunings were collected and measured after vine dormancy. We expected to see 1) a higher amount of water in the soil, less vine water stress and more vigorous vine growth in the clean cultivated treatment compared to the others and 2) either an increase in vigor or concentration of N in vine tissues in response to the clover mix treatment. Biomass production and coverage of the soil by cover crops, as well as responses to treatments in the soil and vine often varied between sites. In general, cover crop treatments, including the clean cultivated control, had little effect on soil water content, vine water status, or vine vegetative growth. There was, however, a clear N affect from the clover mix treatment on vines, even without mechanical incorporation of cover crop residues. Vine leaf N and juice YANC both increased, and yield per vine and cluster weights both decreased in the clover mix treatment. However, the yield reductions were more pronounced in year two and only at one site. The increase in juice N was possibly an indirect effect of the lower yield, concentrating N in the remaining fruit. Results from this two year study indicate no apparent advantage to keeping the alleyways of established vineyards weed free with cultivation. Close

• 566. [Article] Economic comparison of alternative power resource development plans in the lower Mekong Basin

  In this thesis a system analysis compares power development plans for the 1980 decade in the Mekong countries i.e. Laos, Thailand Cambodia, and South Vietnam. Given the decision to invest in power development, ...

  Citation × Citation Citation Abstract Copy Title: Economic comparison of alternative power resource development plans in the lower Mekong Basin Author: Sookawesh, Pala In this thesis a system analysis compares power development plans for the 1980 decade in the Mekong countries i.e. Laos, Thailand Cambodia, and South Vietnam. Given the decision to invest in power development, an economic evaluation is made of complete system developments rather than just hydro or thermal plants. The power resources considered will adequately serve the Mekong countries from 1980 to 1990. Therefore it is assumed the benefits of the investment, however measured, are the same regardless of which system is developed. In this study, five alternative plans are evaluated. These include one all thermal system, two combined hydro-thermal systems, and two all hydro systems. Two large hydro projects along the main-stem of the Mekong river, i.e. Pa Mong and Sambor, are used in the hydro system alternatives. In each alternative the resources and the transmission systems are scheduled to meet the growing load over the period studied. Discounted cashflow is used as the basic method of analysis. A computer model is developed to perform the huge amount of calculations necessary to map out the year by year pattern of cashflow for each alternative extending over the study period. The present value of cost is also computed from the model at different discount rates. This permits drawing a curve showing the present value of cost of the different alternatives for all discount rates considered. The analysis of results shows that the hydro system alternatives are favored over thermal development at all discount rates up to 13 percent. This clearly supports a recommendation for the development of one of the hydro system alternatives in the Lower Mekong basin during the next decade. A sensitivity analysis is used in this study to show how much the rate of return on investment is affected by the variation of some important cost components of the system. The results of sensitivity analysis has shown that the investment cost of thermal plant is the most sensitive item; the next most critical item is the fuel expense and the least critical of those considered is the cost of dam and reservoir of Sambor project. In comparing the two hydro system alternatives, the system which proposes to interconnect the entire four country Mekong system load in the same year that Pa Mong project will start its initial operation is shown to be the best alternative at any discount rate greater than five percent. (This system has a rate of return on additional investment over thermal alternative of about 13 percent). However, the present value of cost of these two alternatives is shown to be only slightly different at discount rates ranging from 6 to 10 percent. Therefore, prior to any final decision it is recommended that cost components of the hydro system alternatives (i.e. transmission line Bangkok-Sambor and Sambor hydro-electric powerplant) be studied in detail. The results of this study are considered as one of the early steps needed in making a decision on early resource development, and the further application of this procedure will make a major contribution to the long-range resource development program of the Mekong Basin. Title: Economic comparison of alternative power resource development plans in the lower Mekong Basin Author: Sookawesh, Pala In this thesis a system analysis compares power development plans for the 1980 decade in the Mekong countries i.e. Laos, Thailand Cambodia, and South Vietnam. Given the decision to invest in power development, an economic evaluation is made of complete system developments rather than just hydro or thermal plants. The power resources considered will adequately serve the Mekong countries from 1980 to 1990. Therefore it is assumed the benefits of the investment, however measured, are the same regardless of which system is developed. In this study, five alternative plans are evaluated. These include one all thermal system, two combined hydro-thermal systems, and two all hydro systems. Two large hydro projects along the main-stem of the Mekong river, i.e. Pa Mong and Sambor, are used in the hydro system alternatives. In each alternative the resources and the transmission systems are scheduled to meet the growing load over the period studied. Discounted cashflow is used as the basic method of analysis. A computer model is developed to perform the huge amount of calculations necessary to map out the year by year pattern of cashflow for each alternative extending over the study period. The present value of cost is also computed from the model at different discount rates. This permits drawing a curve showing the present value of cost of the different alternatives for all discount rates considered. The analysis of results shows that the hydro system alternatives are favored over thermal development at all discount rates up to 13 percent. This clearly supports a recommendation for the development of one of the hydro system alternatives in the Lower Mekong basin during the next decade. A sensitivity analysis is used in this study to show how much the rate of return on investment is affected by the variation of some important cost components of the system. The results of sensitivity analysis has shown that the investment cost of thermal plant is the most sensitive item; the next most critical item is the fuel expense and the least critical of those considered is the cost of dam and reservoir of Sambor project. In comparing the two hydro system alternatives, the system which proposes to interconnect the entire four country Mekong system load in the same year that Pa Mong project will start its initial operation is shown to be the best alternative at any discount rate greater than five percent. (This system has a rate of return on additional investment over thermal alternative of about 13 percent). However, the present value of cost of these two alternatives is shown to be only slightly different at discount rates ranging from 6 to 10 percent. Therefore, prior to any final decision it is recommended that cost components of the hydro system alternatives (i.e. transmission line Bangkok-Sambor and Sambor hydro-electric powerplant) be studied in detail. The results of this study are considered as one of the early steps needed in making a decision on early resource development, and the further application of this procedure will make a major contribution to the long-range resource development program of the Mekong Basin. Close

• 567. [Article] Regional Scale Modeling of Climate, Cryosphere, and Freshwater Discharge in Changing Coastal Mountain Environments

  The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier ...

  Citation × Citation Citation Abstract Copy Title: Regional Scale Modeling of Climate, Cryosphere, and Freshwater Discharge in Changing Coastal Mountain Environments Author: Beamer, Jordan P. The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier cover change on regional hydrology. The region is data-sparse and contains a complex assemblage of topography and land cover, including a system of mountain glaciers that are retreating at some of the highest rates on Earth. The high rates of runoff from precipitation and glacial melt delivered by coastal rivers influence ocean circulation patterns, rates of global sea level rise, and provide spawning habitat for the large salmon populations. Physically-based hydrological modeling of the major water budget components of the GOA, driven using historical reanalysis weather data and land cover, reveals that the modeled water budget components, particularly precipitation input, vary widely between commonly-used weather products. The majority of the large freshwater flux into the GOA is derived from distributed coastal streams rather than the large inland rivers. The modeled seasonal aggregated GOA hydrograph is dominated by the spring and early summer snowmelt, and supplemented by late summer glacial ice melt. Model results demonstrate good agreement with NASA Gravity Recovery and Climate Experiment (GRACE) satellite data in terms of annual amplitudes and long term losses (ice loss), and suggest that existing GRACE solutions, previously reported to represent glacier mass balance alone, are actually measuring the full water budget of land and ice surfaces. An ensemble of climate models and future emissions scenarios were paired with systematically altered land cover to test the sensitivity of the hydrologic system to changes in regional climate patterns and glacier coverage representative of late twenty first century conditions. Compared with the hindcast simulations, the model results forced with increased regional air temperatures and precipitation inputs and reduced glacier cover produce an increase in the annual GOA freshwater discharge volume. The seasonal GOA hydrograph is flattened due to increased winter runoff from more winter rainfall and less snow accumulation, and lower levels of snowmelt and glacier ice contribution. Large uncertainties exist in the direction of change in the glacier runoff component, primarily due to uncertainties that exist in predicting glacier response to climate change. Hydrological modeling with high resolution and inclusion of relevant physical processes can produce significantly improved products that are of high value to and in demand by numerous other scientific communities. However, the value and accuracy of the output from the hydrologic model is highly dependent on the weather forcing quality. Given the considerable importance of quality weather forcing for hydrologic modeling, it is imperative to assess the suitability of multiple products by evaluating local and regional performance and accounting for uncertainty. Additional efforts should be made to improve the spatial resolution of the reanalysis through downscaling and to strategically increase the number of weather stations at high elevations and incorporate that data into weather forcing datasets. Title: Regional Scale Modeling of Climate, Cryosphere, and Freshwater Discharge in Changing Coastal Mountain Environments Author: Beamer, Jordan P. The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier cover change on regional hydrology. The region is data-sparse and contains a complex assemblage of topography and land cover, including a system of mountain glaciers that are retreating at some of the highest rates on Earth. The high rates of runoff from precipitation and glacial melt delivered by coastal rivers influence ocean circulation patterns, rates of global sea level rise, and provide spawning habitat for the large salmon populations. Physically-based hydrological modeling of the major water budget components of the GOA, driven using historical reanalysis weather data and land cover, reveals that the modeled water budget components, particularly precipitation input, vary widely between commonly-used weather products. The majority of the large freshwater flux into the GOA is derived from distributed coastal streams rather than the large inland rivers. The modeled seasonal aggregated GOA hydrograph is dominated by the spring and early summer snowmelt, and supplemented by late summer glacial ice melt. Model results demonstrate good agreement with NASA Gravity Recovery and Climate Experiment (GRACE) satellite data in terms of annual amplitudes and long term losses (ice loss), and suggest that existing GRACE solutions, previously reported to represent glacier mass balance alone, are actually measuring the full water budget of land and ice surfaces. An ensemble of climate models and future emissions scenarios were paired with systematically altered land cover to test the sensitivity of the hydrologic system to changes in regional climate patterns and glacier coverage representative of late twenty first century conditions. Compared with the hindcast simulations, the model results forced with increased regional air temperatures and precipitation inputs and reduced glacier cover produce an increase in the annual GOA freshwater discharge volume. The seasonal GOA hydrograph is flattened due to increased winter runoff from more winter rainfall and less snow accumulation, and lower levels of snowmelt and glacier ice contribution. Large uncertainties exist in the direction of change in the glacier runoff component, primarily due to uncertainties that exist in predicting glacier response to climate change. Hydrological modeling with high resolution and inclusion of relevant physical processes can produce significantly improved products that are of high value to and in demand by numerous other scientific communities. However, the value and accuracy of the output from the hydrologic model is highly dependent on the weather forcing quality. Given the considerable importance of quality weather forcing for hydrologic modeling, it is imperative to assess the suitability of multiple products by evaluating local and regional performance and accounting for uncertainty. Additional efforts should be made to improve the spatial resolution of the reanalysis through downscaling and to strategically increase the number of weather stations at high elevations and incorporate that data into weather forcing datasets. Close

• 568. [Article] The historic and contemporary ecology of western Cascade meadows : archeology, vegetation, and macromoth ecology

  Montane meadows in the western Cascades of Oregon occupy approximately 5% of the landscape, but contribute greatly to the region's biodiversity. Western Cascades meadows are dynamic parts of the landscape ...

  Citation × Citation Citation Abstract Copy Title: The historic and contemporary ecology of western Cascade meadows : archeology, vegetation, and macromoth ecology Author: Highland, Steven A. Montane meadows in the western Cascades of Oregon occupy approximately 5% of the landscape, but contribute greatly to the region's biodiversity. Western Cascades meadows are dynamic parts of the landscape and have contracted by over 50% in the past two hundred years in the HJ Andrews Experimental Forest (hereafter Andrews Forest). Many studies have linked the loss of meadows with local extirpation of species and loss of regional biodiversity, but these processes depend upon the factors that create and maintain meadows, and how species respond to meadow configuration. The prehistory of these meadows is poorly understood, as is the contemporary ecology. This study combined previously collected archeological and moth datasets, aerial photographs, and new plant, tree core, and moth data to investigate interactions between landforms, disturbance, vegetation, and moth abundance and diversity in montane meadows of the western Cascades of Oregon. Burning by prehistoric people may have created and maintained montane meadows, but relatively little evidence remains of the activities of prehistoric peoples in the western Cascades. This study assessed the extent to which prehistoric people preferentially used different landforms and vegetation types by inferring use from landscape distributions of archaeological sites. Descriptions of 359 previously recorded and four newly discovered archeological sites in the McKenzie River watershed of western Oregon were examined using GIS and chi-square analysis to determine how sites were distributed relative to classified vegetation and landforms of the 3700-km² McKenzie River watershed. The high ridges of the HJ Andrews Experimental Forest were analyzed using air photo change detection and archaeological field surveys to identify how archeological sites were distributed relative to landforms and vegetation communities, including meadows. The field surveys documented physical evidence (archeological sites) confirming Native American use of the meadows and surrounding open forests. The locations of these sites indicate that Native Americans utilized the edges between large open meadows and open forests, as well as gently sloping open meadows. The prior extent of meadows (before air photos) was estimated by dendrochronology of 220 trees along present-day and inferred past meadow edges. Forest age structure and the open-grown forms of Douglas fir suggests a much more open habitat, potentially due to fire, was present more than 200 years ago. Moths are major consumers of vegetation when in caterpillar stage and are food sources for many birds and mammals, and contribute greatly to the insect diversity in a region. Moth species richness and abundance may be associated with the distribution of vegetation communities and seasonal timing, and the conservation of rare moths may depend on the conservation of rare vegetation habitats. A dataset of moths sampled 10 times/year at 20 locations in the 64-km² Andrews Forest over the period 2004-2008 was analyzed using generalized linear mixed models (GLMM), non-metric multidimensional scaling (NMS), multi-response permutation procedure (MRPP), analysis of variance (ANOVA), and two tailed t-test to identify the overall patterns of rare and common moth distribution as well as moth community relationships to structurally and taxonomically derived vegetation classes and seasonality. Five hundred fourteen species and 69,168 macromoth individuals were identified. Moth species abundance and diversity were significantly higher in low elevation coniferous forests than in other vegetation types, according to the GLMM. Sixty-six rare moth species were significantly associated with high elevation open habitats. Species associated with meadows also were significantly more likely to be hardwood or herb-feeders than conifer-feeders as caterpillars, based on ANOVAs. The 26 most common moth species were significantly associated with low elevation coniferous forests and were more likely to be conifer-feeders as caterpillars, based on ANOVAs. Common moth species were significantly more likely to emerge earlier in warmer years than in cooler years, based on a two-tailed t-test. Managing the western Cascades landscape for moth biodiversity and for moth abundance requires maintenance and potentially expansion of rare upland habitats as well as lowland coniferous forests. Montane meadows in the Andrews Forest are contracting in size, but it is not known how these changes have affected moth and plant biodiversity. The rate and pattern of meadow contraction from 1949 to 2005 along the high ridges of the Andrews Forest were analyzed using air photo change detection. Overall meadows contracted by nearly 50% from 1949 to 2005, but rates of meadow loss were much higher for the largest meadow complexes. Plant community diversity in seventeen meadows and the diversity, abundance, and community structure of moths at 98 locations sampled in the summers of 2008, 2009, and 2010 were related to measures of meadow size, isolation, and other variables using cluster analysis (CLA), MRPP, NMS, and generalized additive models (GAMs). Plant diversity in meadows was significantly positively related to meadow area in 1949 and the distance of the meadow from the road, based on GAM analysis. Plant community structure was most closely correlated with meadow area in 1949 and slope, based on CLA, MRPP, and NMS analysis. Calendar day explained the most variation in moth species richness, abundance, and community structure, but the next most important explanatory variables differed according to feeding guild, based on GAMs. Richness, abundance, and community structure of herb-feeding moths was related to meadow area in 1949 and elevation. For angiosperm-feeding moths, area-perimeter ratio in 2005 explained the most variation in richness, abundance, and community structure after calendar day. For gymnosperm-feeding moths, meadow area change from 1949-2005, a variable measuring the amount of increase in coniferous tree cover, explained the most variation in richness, abundance, and community structure after calendar day. The abundance and diversity of herb-feeding moths and meadow plants exhibited a lagged response to habitat loss, which may indicate an extinction debt. In contrast, angiosperm-and gymnosperm-feeding moths responded quickly (within 50 years) to increases in their habitat. Managing for the conservation of biodiversity in the upper elevations of the Andrews Forest will require targeted management strategies for different groups of organisms. Herb-feeding moths and meadow plants will benefit from expansion of open meadow habitat, while angiosperm and gymnosperm-feeders will require the maintenance of edge environments and coniferous forests. Title: The historic and contemporary ecology of western Cascade meadows : archeology, vegetation, and macromoth ecology Author: Highland, Steven A. Montane meadows in the western Cascades of Oregon occupy approximately 5% of the landscape, but contribute greatly to the region's biodiversity. Western Cascades meadows are dynamic parts of the landscape and have contracted by over 50% in the past two hundred years in the HJ Andrews Experimental Forest (hereafter Andrews Forest). Many studies have linked the loss of meadows with local extirpation of species and loss of regional biodiversity, but these processes depend upon the factors that create and maintain meadows, and how species respond to meadow configuration. The prehistory of these meadows is poorly understood, as is the contemporary ecology. This study combined previously collected archeological and moth datasets, aerial photographs, and new plant, tree core, and moth data to investigate interactions between landforms, disturbance, vegetation, and moth abundance and diversity in montane meadows of the western Cascades of Oregon. Burning by prehistoric people may have created and maintained montane meadows, but relatively little evidence remains of the activities of prehistoric peoples in the western Cascades. This study assessed the extent to which prehistoric people preferentially used different landforms and vegetation types by inferring use from landscape distributions of archaeological sites. Descriptions of 359 previously recorded and four newly discovered archeological sites in the McKenzie River watershed of western Oregon were examined using GIS and chi-square analysis to determine how sites were distributed relative to classified vegetation and landforms of the 3700-km² McKenzie River watershed. The high ridges of the HJ Andrews Experimental Forest were analyzed using air photo change detection and archaeological field surveys to identify how archeological sites were distributed relative to landforms and vegetation communities, including meadows. The field surveys documented physical evidence (archeological sites) confirming Native American use of the meadows and surrounding open forests. The locations of these sites indicate that Native Americans utilized the edges between large open meadows and open forests, as well as gently sloping open meadows. The prior extent of meadows (before air photos) was estimated by dendrochronology of 220 trees along present-day and inferred past meadow edges. Forest age structure and the open-grown forms of Douglas fir suggests a much more open habitat, potentially due to fire, was present more than 200 years ago. Moths are major consumers of vegetation when in caterpillar stage and are food sources for many birds and mammals, and contribute greatly to the insect diversity in a region. Moth species richness and abundance may be associated with the distribution of vegetation communities and seasonal timing, and the conservation of rare moths may depend on the conservation of rare vegetation habitats. A dataset of moths sampled 10 times/year at 20 locations in the 64-km² Andrews Forest over the period 2004-2008 was analyzed using generalized linear mixed models (GLMM), non-metric multidimensional scaling (NMS), multi-response permutation procedure (MRPP), analysis of variance (ANOVA), and two tailed t-test to identify the overall patterns of rare and common moth distribution as well as moth community relationships to structurally and taxonomically derived vegetation classes and seasonality. Five hundred fourteen species and 69,168 macromoth individuals were identified. Moth species abundance and diversity were significantly higher in low elevation coniferous forests than in other vegetation types, according to the GLMM. Sixty-six rare moth species were significantly associated with high elevation open habitats. Species associated with meadows also were significantly more likely to be hardwood or herb-feeders than conifer-feeders as caterpillars, based on ANOVAs. The 26 most common moth species were significantly associated with low elevation coniferous forests and were more likely to be conifer-feeders as caterpillars, based on ANOVAs. Common moth species were significantly more likely to emerge earlier in warmer years than in cooler years, based on a two-tailed t-test. Managing the western Cascades landscape for moth biodiversity and for moth abundance requires maintenance and potentially expansion of rare upland habitats as well as lowland coniferous forests. Montane meadows in the Andrews Forest are contracting in size, but it is not known how these changes have affected moth and plant biodiversity. The rate and pattern of meadow contraction from 1949 to 2005 along the high ridges of the Andrews Forest were analyzed using air photo change detection. Overall meadows contracted by nearly 50% from 1949 to 2005, but rates of meadow loss were much higher for the largest meadow complexes. Plant community diversity in seventeen meadows and the diversity, abundance, and community structure of moths at 98 locations sampled in the summers of 2008, 2009, and 2010 were related to measures of meadow size, isolation, and other variables using cluster analysis (CLA), MRPP, NMS, and generalized additive models (GAMs). Plant diversity in meadows was significantly positively related to meadow area in 1949 and the distance of the meadow from the road, based on GAM analysis. Plant community structure was most closely correlated with meadow area in 1949 and slope, based on CLA, MRPP, and NMS analysis. Calendar day explained the most variation in moth species richness, abundance, and community structure, but the next most important explanatory variables differed according to feeding guild, based on GAMs. Richness, abundance, and community structure of herb-feeding moths was related to meadow area in 1949 and elevation. For angiosperm-feeding moths, area-perimeter ratio in 2005 explained the most variation in richness, abundance, and community structure after calendar day. For gymnosperm-feeding moths, meadow area change from 1949-2005, a variable measuring the amount of increase in coniferous tree cover, explained the most variation in richness, abundance, and community structure after calendar day. The abundance and diversity of herb-feeding moths and meadow plants exhibited a lagged response to habitat loss, which may indicate an extinction debt. In contrast, angiosperm-and gymnosperm-feeding moths responded quickly (within 50 years) to increases in their habitat. Managing for the conservation of biodiversity in the upper elevations of the Andrews Forest will require targeted management strategies for different groups of organisms. Herb-feeding moths and meadow plants will benefit from expansion of open meadow habitat, while angiosperm and gymnosperm-feeders will require the maintenance of edge environments and coniferous forests. Close

• 569. [Article] Reach scale sampling metrics and longitudinal pattern adjustments of small streams

  Several types of channel morphology measurement parameters used to characterize fish habitat of small streams are refined, developed and evaluated in terms of their accuracy, precision, and sensitivity ...

  Citation × Citation Citation Abstract Copy Title: Reach scale sampling metrics and longitudinal pattern adjustments of small streams Author: Robison, E. George Several types of channel morphology measurement parameters used to characterize fish habitat of small streams are refined, developed and evaluated in terms of their accuracy, precision, and sensitivity to disturbance. Data for 74 stream reaches in Oregon and Alaska are used in analysis. Over half the reaches are from a pre-pilot study funded by EPA's Environmental Monitoring and Assessment Program (EMAP). A new methodology for determining residual pools is developed (termed the Longitudinal Streambed Simulation Method). This new method and an older method are compared with a more rigorous time consuming method for determining residual pools. Results indicate a generally close correspondence. For instance, the absolute percent departure of longitudinal residual pool area was typically within 10% and always less than 25% for streams with wetted widths greater than 3.5 meters. Precision is evaluated for three data sets containing replicated stream reach measurements. Directly measured parameters like standard deviation depth are demonstrated as precise and repeatable. In contrast, visual scoring systems and visual determinations of riffles versus pools have low precision. Adequate reach length for determining various channel characteristics is evaluated by using classic sample size statistics, time series, and short versus long reach comparisons. Results suggest that reach lengths of 30-40 channel widths with 2-3 measurements per wetted channel width seem to provide adequate coverage to determine residual pools. However, simple determinations of mean depth or width can be spaced as wide as two channel widths apart without significant accuracy loss. While many relationships regarding pool formation versus riparian and watershed characteristics are evaluated, probably the most intriguing result is the influence roughness (large woody debris) has on the formation of residual pools and in increasing variation in systematically placed depth measurements along the stream. The results also suggest a range of channel slope in which variability in these depth measurements is maximized (0.5-6.0% slope). These results provide valuable information for anyone attempting to develop, implement, or analyze data from a monitoring protocol that evaluates channel morphology or morphological fish habitat. Information on the residual pool concept and how to use it in monitoring is also provided. Title: Reach scale sampling metrics and longitudinal pattern adjustments of small streams Author: Robison, E. George Several types of channel morphology measurement parameters used to characterize fish habitat of small streams are refined, developed and evaluated in terms of their accuracy, precision, and sensitivity to disturbance. Data for 74 stream reaches in Oregon and Alaska are used in analysis. Over half the reaches are from a pre-pilot study funded by EPA's Environmental Monitoring and Assessment Program (EMAP). A new methodology for determining residual pools is developed (termed the Longitudinal Streambed Simulation Method). This new method and an older method are compared with a more rigorous time consuming method for determining residual pools. Results indicate a generally close correspondence. For instance, the absolute percent departure of longitudinal residual pool area was typically within 10% and always less than 25% for streams with wetted widths greater than 3.5 meters. Precision is evaluated for three data sets containing replicated stream reach measurements. Directly measured parameters like standard deviation depth are demonstrated as precise and repeatable. In contrast, visual scoring systems and visual determinations of riffles versus pools have low precision. Adequate reach length for determining various channel characteristics is evaluated by using classic sample size statistics, time series, and short versus long reach comparisons. Results suggest that reach lengths of 30-40 channel widths with 2-3 measurements per wetted channel width seem to provide adequate coverage to determine residual pools. However, simple determinations of mean depth or width can be spaced as wide as two channel widths apart without significant accuracy loss. While many relationships regarding pool formation versus riparian and watershed characteristics are evaluated, probably the most intriguing result is the influence roughness (large woody debris) has on the formation of residual pools and in increasing variation in systematically placed depth measurements along the stream. The results also suggest a range of channel slope in which variability in these depth measurements is maximized (0.5-6.0% slope). These results provide valuable information for anyone attempting to develop, implement, or analyze data from a monitoring protocol that evaluates channel morphology or morphological fish habitat. Information on the residual pool concept and how to use it in monitoring is also provided. Close

• 570. [Article] Hydrologic properties of soil and subsoil on a steep, forested slope

  The purpose of this study was to examine certain hydrologic properties of the soil and subsoil on a steep forested slope and relate these -rceTties to the movement of water via subsurface routes. The hydrologic ...

  Citation × Citation Citation Abstract Copy Title: Hydrologic properties of soil and subsoil on a steep, forested slope Author: Ranken, Darrel Wesley The purpose of this study was to examine certain hydrologic properties of the soil and subsoil on a steep forested slope and relate these -rceTties to the movement of water via subsurface routes. The hydrologic properties examined were bulk density, soil texture, total porosity, pore size distribution, saturated hydraulic conductivity, - and soil moisture-tension relationships. Soil samples were taken from a 2. 5 ha study slope on watershed 10 of the H. S. Andrews Experimental Forest near Blue River, Oregon. Eleven soil pits were excavated and six soil core samples were taken at depths of 10, 30, 70, 110, 130, 150, and 200 cm where soil conditions permitted. Laboratory analyses were conducted to determine the hydrologic properties of each sample. The extreme permeability and high porosities of the samples necessitated the use of specially designed apparatus to measure the saturated weights and hydraulic conductivities. Particle size distribution changed only slightly with depth. The A and B horizons were predominately clay barns and the C horizons were classified as clays. Total porosities also varied little with depth. The porosity of the soil (A and B horizons) averaged nearly 65% while the porosity of the subsoil (C horizons) averaged nearly 55%. Bulk density also varied little with depth. Soil bulk densities averaged 825 gm/cm3 and subsoil bulk densities averaged 1. 180 gm/cm3. The hydraulic conductivity and pore size distribution of the soil and subsoil were well. correlated and changed considerably with depth. Significant decreases in the hydraulic conductivities occurred between the 30 cm and 70 cm depths as well as between the 110 cm and 130 cm depths in some of the soil pits. At most soil pits the surface soil had conductivities greater than 400 cm/hr while the soil at the 70 cm and 110 cm depths had conductivities near 200 cm/hr. Subsoils had much lower conductivities, less than 60 cm/hr in most soil pits and less than 10 cm/hr in some pits. A power curve regression analysis was 'S. used to relate the hydraulic conductivity (Y) and the mean percentage of pores greater than . 294 mm in diameter (X) according to the equa- Y 10, 040X2997 . The resulting r2 was .945. The percentage of pores greater than . 294 mm in diameter was also found to change abruptly between the 30 cm and 70 cm depths in most soil pits and between the 110 cm and 130 cm depths in some soil pits. The hydrologic properties were used to discuss the possible nature of water movement through the soil and subsoil of the study slope. The soil hydrologic properties and antecedent moisture conditions were predicted to be conducive to vertical unsaturated translatory flow. A zone of saturation was predicted to occur during winter rainfall events above the subsoil horizon having extremely low conductivity rates (above the 130 cm depth near soil pit 1). This zone of saturation was predicted to be the most probable zone of lateral water movement in the form of saturated translatory flow. Data from a soil pit known to have saturated flow over the subsoil and from tensiometers installed near the soil pits were presented as evidence that a zone of saturation does exist within the subsoil during some rainfall events and that the soil and subsoil moisture conditions are conducive to translatory flow during the winter rainy season. Title: Hydrologic properties of soil and subsoil on a steep, forested slope Author: Ranken, Darrel Wesley The purpose of this study was to examine certain hydrologic properties of the soil and subsoil on a steep forested slope and relate these -rceTties to the movement of water via subsurface routes. The hydrologic properties examined were bulk density, soil texture, total porosity, pore size distribution, saturated hydraulic conductivity, - and soil moisture-tension relationships. Soil samples were taken from a 2. 5 ha study slope on watershed 10 of the H. S. Andrews Experimental Forest near Blue River, Oregon. Eleven soil pits were excavated and six soil core samples were taken at depths of 10, 30, 70, 110, 130, 150, and 200 cm where soil conditions permitted. Laboratory analyses were conducted to determine the hydrologic properties of each sample. The extreme permeability and high porosities of the samples necessitated the use of specially designed apparatus to measure the saturated weights and hydraulic conductivities. Particle size distribution changed only slightly with depth. The A and B horizons were predominately clay barns and the C horizons were classified as clays. Total porosities also varied little with depth. The porosity of the soil (A and B horizons) averaged nearly 65% while the porosity of the subsoil (C horizons) averaged nearly 55%. Bulk density also varied little with depth. Soil bulk densities averaged 825 gm/cm3 and subsoil bulk densities averaged 1. 180 gm/cm3. The hydraulic conductivity and pore size distribution of the soil and subsoil were well. correlated and changed considerably with depth. Significant decreases in the hydraulic conductivities occurred between the 30 cm and 70 cm depths as well as between the 110 cm and 130 cm depths in some of the soil pits. At most soil pits the surface soil had conductivities greater than 400 cm/hr while the soil at the 70 cm and 110 cm depths had conductivities near 200 cm/hr. Subsoils had much lower conductivities, less than 60 cm/hr in most soil pits and less than 10 cm/hr in some pits. A power curve regression analysis was 'S. used to relate the hydraulic conductivity (Y) and the mean percentage of pores greater than . 294 mm in diameter (X) according to the equa- Y 10, 040X2997 . The resulting r2 was .945. The percentage of pores greater than . 294 mm in diameter was also found to change abruptly between the 30 cm and 70 cm depths in most soil pits and between the 110 cm and 130 cm depths in some soil pits. The hydrologic properties were used to discuss the possible nature of water movement through the soil and subsoil of the study slope. The soil hydrologic properties and antecedent moisture conditions were predicted to be conducive to vertical unsaturated translatory flow. A zone of saturation was predicted to occur during winter rainfall events above the subsoil horizon having extremely low conductivity rates (above the 130 cm depth near soil pit 1). This zone of saturation was predicted to be the most probable zone of lateral water movement in the form of saturated translatory flow. Data from a soil pit known to have saturated flow over the subsoil and from tensiometers installed near the soil pits were presented as evidence that a zone of saturation does exist within the subsoil during some rainfall events and that the soil and subsoil moisture conditions are conducive to translatory flow during the winter rainy season. Close