Hydrology & Water Quality

Corrected Prediction Intervals for Change Detection in Paired Watershed Studies
Som, N.A., N.P. Zegre, L.M. Ganio, A.E. Skaugset

Autoregressive process pHydrological data may be temporally autocorrelated requiring autoregressive process parameters to be estimated. Current statistical methods for hydrological change detection in paired watershed studies rely on prediction intervals, but the current form of prediction intervals does not include all appropriate sources of variation. Corrected prediction intervals for the analysis of paired watershed study data that include variation associated with covariance and linear model parameter estimation are presented. We provide an example of their application to data from the Hinkle Creek Paired Watershed Study located in the western Cascade foothills of Southern Oregon, USA. Research implications of using the correct prediction limits and incorporating the estimation uncertainty of aarameters are discussed.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Journal Articles    TAGS: paired watershed study, generalized least squares, Prasad-Rao mean-squared error estimator, stream discharge, time series
The Effect of Timber Harvest on Summer Low Flows, Hinkle Creek, Oregon
Surfleet, C.G., A.E. Skaugset

Changes to summer low flows from forest harvesting were measured for a gauged fourth-order stream in the Hinkle Creek Paired Watershed Study. At the gauged stream, August streamflow increased an average of 1.9 mm/year (45%) for the three summers following forest harvest of 13% of a 1,084 ha watershed. Following a second harvest of an additional 13% of the watershed the August streamflow increased by 4.5 mm (106%) the first summer and 2.0 mm (47%) the second summer. Master recession curves were fit to the gauged watersheds and the resulting recession coefficients were used to predict low flows from small watersheds nested within the gauged watersheds. The estimated low flows were used to evaluate changes in summer low flows associated with forest harvest for the small watersheds. Using recession curve analysis, the estimated range of the increase for average August streamflow for the four small watersheds in the Hinkle Creek Paired Watershed Study was 1.7 mm to 4.4 mm the first summer following forest harvest. August streamflow in the small watersheds was not distinguishable from preharvest levels within 5 years for all but one watershed, which had the highest proportion of watershed area harvested.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Journal Articles    TAGS: low flow, recession curve, Forest management, water yield, Forest Hydrology
The Influence of Contemporary Forest Management on Stream Nutrient Concentrations in an Industrialized Forest in the Oregon Cascades
Meininger, W.S., K. Cromack, and A. Skaugset

Fertilizer was applied in 2004 and the response of the nutrient levels in the water was measured. Stream water samples were analyzed for nitrogen, phosphorus, calcium, sodium, potassium, magnesium, sulfate, chloride, and silicon as well as specific conductance, pH, and alkalinity. All treatment watersheds showed a statistically significant increase in NO3 + NO2 concentrations after clearcutting (p < 0.001). The slope of the streambed through the disturbance was a stronger predictor of the magnitude of the response than was the magnitude of disturbance. Ammonia and organic nitrogen displayed notable increases after harvest treatment, but these increases were attributed to increases in the control watersheds. Phosphorus showed a response to timber harvest in one headwater stream. The remaining nutrients showed a small decrease in the control and treatment watersheds for the period after harvest. The storm response results showed that NO3 + NO2 concentrations in stream water increase with discharge during small storms that occur after periods of negligible precipitation.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Presentations    TAGS: timber harvest, Nitrate Response, topography, clearcut
Local and Downstream Impacts of Contemporary Forest Practices on Sediment Yield
Skaugset A., N. Zègre, A. Simmons, and H. Owens

The hydrological impacts of forest management remains a primary concern to resources managers yet much of our understanding about these effects comes from historic paired watershed studies conducted up to four decades ago. While these early studies play a critical role in the development of current best management practices and forest harvesting practices, results do not necessarily reflect the effects of modern forest harvesting. In this presentation we show results of a study conducted at the decade-long Hinkle Creek Paired Watershed Study that examines the local and downstream impacts of forest harvesting on streamflow. Streamflow was measured at the outlet of six (4 treatment|2 reference) headwater catchments and two (1 treatment|1 reference) 3rd –order watersheds. Regression-based change detection models were developed between reference and treated catchments using mean monthly streamflow, instantaneous maximum peak flow, and storm quick flow. Contemporary forest harvesting practices, defined by the Oregon Forest Practice Rule, were used to clear-cut harvest trees in four experimental headwater catchments, while reference catchments remained untouched. Forest harvesting treatments were initiated in the experimental headwater catchments in 2005 (1st entry) removing trees from 13% to 65% of catchment area following a fifteen to eighteen month calibration period.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Presentations    TAGS: sediment yield, contemporary forest practices, Discharge
Herbicides in Needle Branch Streamwater
Louch, J., G. Allen, G. Ice, T. Garland, V. C. Hale, and J. McDonnell

Glyphosate, aminomethylphosphonic acid (AMPA), imazapyr, sulfometuron methyl, and metsulfuron methyl were measured in Needle Branch streamwater during and after application of herbicide(s). All herbicides were applied by helicopter in a single tank mix. Samples were collected at three sites: NBH (at the fish/no-fish interface in the middle of the harvest unit), NBU (at the bottom of the harvest unit), and NBL (well downstream). AMPA, imazapyr, sulfometuron methyl and metsulfuron methyl were not detected in any sample at 15 ng/L, 0.6 μg/L, 0.5 μg/L and 1 μg/L, respectively. However, a clear pulse of dissolved glyphosate manifested at NBH during the application (baseflow conditions).  Subsequent baseflow samples collected three days after treatment (DAT) showed ≈25 ng/L dissolved glyphosate at all three sites. Samples collected during the first storm event (8 DAT) showed a clear pulse of dissolved glyphosate at NBU, but not at NBH or NBL. The maximum concentration observed during this pulse at NBU was 115 ng/L, and the pulse persisted for about six hours. During the next storm event (10 DAT) a clear pulse of dissolved glyphosate manifested at NBH, but not at NBU or NBL. The maximum co centration observed was 42 ng/L, and this pulse persisted for about ten hours. Results from all subsequent storm events showed dissolved glyphosate at <20 ng/L in all samples. A limited number of analyses on suspended sediment (SS) showed that SS held de minimis masses of glyphosate and AMPA.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Presentations    TAGS: Glyphosate, herbicides, aerial application
Nutrient Response to Contemporary Forest Practices Regulations
Stednick J. D., V. C. Hale, G. Ice, D. Cook, T. Bousquet, and J. Light

The original Alsea Watershed Study measured water quality before and after logging. For Deer Creek with patchcuts and streamside vegetation buffers, there were no changes in water quality post-harvesting. Needle Branch was harvested without streamside buffers and the slash burned. Nitrate concentrations increased from 0.70 to a maximum of 2.10 mg/L, and returned to pretreatment levels by the 6th year after logging. The loss of nitrogen was negligible when compared to the nitrogen capital (soils and vegetation) and loss of terrestrial productivity was not anticipated. Additional water quality monitoring in the study watersheds identified spatial and temporal variations instream water quality. Of particular note is the influence of landscape elements including vegetation, soils, slope, and hydraulic conductivity as related to water quality, particularly nitrogen. Also the first significant fall storm flushes oxidized nitrogen from the soil profile and results in higher stream water nitrate concentrations. The Alsea Watershed Study Revisited (AWSR) provides an assessment of water quality response to contemporary forest practices. Nested watersheds in Needle Branch, including immediately below the harvest unit (NBU) and the original gauge (NBL) were compared for water quality changes. During the pre-treatment monitoring, nutrient concentrations at NBU were generally higher but paralleled concentrations at NBL.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Presentations    TAGS: Nitrate concentration, ammonia, phosphorus
Dissolved Oxygen Response to Forest Management in the Alsea Watershed Study Revisited
Ice G., V. C. Hale, T. Bousquet, A. Simmons, G. Brown, and D. Lee

The original Alsea Watershed Study found dissolved oxygen (DO) concentrations at or near saturation in the control (Flynn Creek) and patchcut and buffered (Deer Creek) watersheds. DO concentrations in some reaches of the clearcut and unbuffered watershed (Needle Branch) were found to be substantially below saturation following the 1966 harvest. The depressed concentrations were thought to result from a combination of increased biochemical oxygen demand, reduced solubility due to stream heating, increased biological activity, and reduced reaeration. The Alsea Watershed Study Revisited (AWSR) returns to the same watersheds and provides an assessment of physical, chemical, and biological response to contemporary forest practices. During the pre-treatment phase of the AWRS low DO concentrations were observed in Needle Branch in the summer and fall. These low concentrations coincided with low flow periods. At these times flow becomes “discontinuously perennial” and portions of the stream network go subsurface. We now believe that despite having some of the highest reaeration rates ever measured, certain reaches of Needle Branch are prone to depressed DO concentrations. For some reaches, surface flow during critical late season periods is largely composed of recently emerged groundwater or hyporheic water. Both original study and AWSR findings show high spatial variability in DO concentrations.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Presentations    TAGS: Dissolved Oxygen, fish distribution, perennially-flowing, groundwater, discontinuously perennial
The Alsea Paired Watershed - Revisited: Harvest Effects on Stream Temperatures
Light J., G. Ice, V. C. Hale, J. McDonnell, and M. Teply

This project explores the effects of harvesting on the temperature of the fish bearing streams. It also draws comparisons to the historical effects of the old best management practices in comparison to contemporary beast management practices. Some warming was found but significantly less than what had been found in old projects.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Presentations    TAGS:
Alsea Watershed Study Revisited: Hydrologic Response to First Harvest
Hale V. C., G. Ice, J. Stednick, J. Light, and N. Zègre

The hydraulic response of the Alsea watershed study to the first harvest produced results to in the streamflow of Needle Branch creek. Deer creek was shown to be a suitable control and that Upper and Lower Needle Branch respond similarly. There is still a lot of work to be done and suspended sediment analysis to complete.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Presentations    TAGS:
Alsea Watershed Study and Alsea Watershed Study Revisited
Brown G.

The original Alsea Basin Logging and Aquatic Resources Study (1959-1973) was established in response to public and legislative concerns about the impact of timber harvesting and road construction on salmon. It was the first paired watershed study in North America to document these impacts. The study design utilized one watershed (Flynn Creek) as an untreated control for the duration of the study. Deer Creek was roaded and harvested with three small patch clearcuts covering about 25% of the basin. Harvest boundaries were kept 50 feet or more from the stream banks. The small clearcuts received a light slash fire following logging. Needle Branch was roaded and completely clearcut without stream protection buffers and, following logging, was burned with a very hot slash fire and channel cleaned of debris, which typified the logging practices of the day. Before and after treatments, streamflow, water quality and aquatic resources were carefully monitored on all three watersheds. Changes in streamflow, water quality and aquatic resource populations were small after road construction and logging in Deer Creek, even with the very narrow stream protection buffers. Large changes in water quality and suspended sediment were recorded after clearcutting without stream protection and the hot slash fire in Needle Branch. Temperature and suspended sediment levels returned to pretreatment levels within five years. Cutthroat trout numbers decreased significantly.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Presentations    TAGS:


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