Stream temperature responses to forest harvest and debris flows in western Cascades, Oregon

2000 ◽  
Vol 57 (S2) ◽  
pp. 30-39 ◽  
Author(s):  
Sherri L Johnson ◽  
Julia A Jones
Keyword(s):  
Debris Flows ◽  
Riparian Vegetation ◽  
Stream Water ◽  
Stream Temperature ◽  
Early Summer ◽  
Temperature Data ◽  
Aquatic Biota ◽  
Clear Cutting ◽  
Study Sites ◽  
Temperature Responses

Stream temperature controls the rates of many biotic and abiotic processes and is influenced by changes in streamside land use practices. We compiled historic stream temperature data and reestablished study sites in three small basins in the H.J. Andrews Experimental Forest in the western Cascades, Oregon, to reexamine the effects on and recovery of stream temperatures following removal of riparian vegetation. Maximum stream temperatures increased 7°C and occurred earlier in the summer after clear-cutting and burning in one basin and after debris flows and patch-cutting in another. Diurnal fluctuations in June increased from approximately 2 to 8°C. Stream temperatures in both basins gradually returned to preharvest levels after 15 years. The influence of the primary factor controlling stream temperatures, shortwave solar radiation, was amplified following removal of riparian vegetation, and conduction between stream water and nearby soils or substrates also appeared to be an important factor. Shifts in the timing of summer maxima and greater increases in early summer stream temperatures could impact sensitive stages of aquatic biota.

scholarly journals Can riparian vegetation shade mitigate the expected rise in stream temperatures during heat waves in a pre-alpine river?

2016 ◽  
Author(s):  
Heidelinde Trimmel ◽  
Philipp Weihs ◽  
David Leidinger ◽  
Herbert Formayer ◽  
Gerda Kalny
Keyword(s):  
Climate Change ◽  
Return Period ◽  
Riparian Vegetation ◽  
Heat Waves ◽  
Stream Water ◽  
Turbulent Energy ◽  
Stream Temperature ◽  
Heat Event ◽  
Alpine River ◽  
Heat Events

Abstract. The influence of expected changes in heat wave intensity during the 21st century on the temperatures of an pre-alpine river are simulated and the mitigating effects of riparian vegetation shade on the radiant and turbulent energy fluxes analysed. Minor stream water temperature increases are modelled within the first half of the century, but a more significant increase is predicted for the period 2071–2100. The magnitude of maximum, mean and minimum stream temperature rises for a 20 year return period heat event was estimated to be in the region of 3 °C. Additional riparian vegetation is not able to fully mitigate the expected temperature rise caused by climate change, but can reduce maximum, mean and minimum stream temperatures by 1 to 2° C. Removal of existing vegetation amplifies stream temperature increases. Maximum stream temperatures could increase by more than 4 °C even in yearly heat events.

scholarly journals The temporally varying roles of rainfall, snowmelt and soil moisture for debris flow initiation in a snow-dominated system

2018 ◽  
Vol 22 (6) ◽  
pp. 3493-3513 ◽  
Author(s):  
Karin Mostbauer ◽  
Roland Kaitna ◽  
David Prenner ◽  
Markus Hrachowitz
Keyword(s):  
Soil Moisture ◽  
Debris Flow ◽  
High Intensity ◽  
Debris Flows ◽  
Regional Scale ◽  
Early Summer ◽  
Temporal Separation ◽  
Antecedent Soil Moisture ◽  
Trigger Mechanisms ◽  
Debris Flow Initiation

Abstract. Debris flows represent frequent hazards in mountain regions. Though significant effort has been made to predict such events, the trigger conditions as well as the hydrologic disposition of a watershed at the time of debris flow occurrence are not well understood. Traditional intensity-duration threshold techniques to establish trigger conditions generally do not account for distinct influences of rainfall, snowmelt, and antecedent moisture. To improve our knowledge on the connection between debris flow initiation and the hydrologic system at a regional scale, this study explores the use of a semi-distributed conceptual rainfall–runoff model, linking different system variables such as soil moisture, snowmelt, or runoff with documented debris flow events in the inner Pitztal watershed, Austria. The model was run on a daily basis between 1953 and 2012. Analysing a range of modelled system state and flux variables at days on which debris flows occurred, three distinct dominant trigger mechanisms could be clearly identified. While the results suggest that for 68 % (17 out of 25) of the observed debris flow events during the study period high-intensity rainfall was the dominant trigger, snowmelt was identified as the dominant trigger for 24 % (6 out of 25) of the observed debris flow events. In addition, 8 % (2 out of 25) of the debris flow events could be attributed to the combined effects of low-intensity, long-lasting rainfall and transient storage of this water, causing elevated antecedent soil moisture conditions. The results also suggest a relatively clear temporal separation between the distinct trigger mechanisms, with high-intensity rainfall as a trigger being limited to mid- and late summer. The dominant trigger in late spring/early summer is snowmelt. Based on the discrimination between different modelled system states and fluxes and, more specifically, their temporally varying importance relative to each other, this exploratory study demonstrates that already the use of a relatively simple hydrological model can prove useful to gain some more insight into the importance of distinct debris flow trigger mechanisms. This highlights in particular the relevance of snowmelt contributions and the switch between mechanisms during early to mid-summer in snow-dominated systems.

Towards a better understanding of river dynamics in semi-urbanised areas: a machine learning analysis on time-series satellite images

2021 ◽  
Author(s):  
Alessio Cislaghi ◽  
Paolo Fogliata ◽  
Emanuele Morlotti ◽  
Gian Battista Bischetti
Keyword(s):  
Machine Learning ◽  
Time Series ◽  
Riparian Vegetation ◽  
Satellite Images ◽  
River Management ◽  
Machine Learning Algorithms ◽  
Flood Events ◽  
River Dynamics ◽  
Clear Cutting ◽  
Over Time

<p>River channels and floodplains have been highly modified over the last 70 years to mitigate flood risk and to gain lands for agricultural activities, settlements and soft infrastructures (e.g., cycle paths). River engineering measures simplified the geomorphologic complexity of river system, usually from braided or wandering channels to highly-confined single-thread channel. Meanwhile, rivers naturally adjust and self-organise the geomorphologic function as response of all the disturbances (e.g., flood events, river-bed degradation, narrowing, control works) altering sediment and water transfer, exacerbating bank erosion processes and streambank failures, and exposing bare sediment that can be subsequently colonized by pioneer species. In this context, river management has to address river dynamics planning sustainable practices with the aim to combine hydraulic safety, river functionality, and ecological/environmental quality. These actions require the detection of river processes by monitoring the geomorphological changes over time, both over the active riverbank and the close floodplains. Thus, remote sensing technology combined with machine learning algorithms offers a viable decision-making instrument (Piégay et al., 2020).</p><p>This study proposes a procedure that consists in applying image segmentation and classification algorithms (i.e., Random Forest and dendrogram-based method) over time-series high resolution RGB-NIR satellite-images, to identify the fluvial forms (bars and islands), the vegetation patches and the active riverbed. The study focuses on three different reaches of Oglio River (Valcamonica, North Italy), representative of the most common geomorphic changes in Alpine rivers.</p><p>The results clearly show the temporal evolution/dynamics of vegetated and non-vegetated bars and islands, as consequence of human and natural disturbances (flood events, riparian vegetation clear-cutting, and bank-protection works). Moreover, the procedure allows to distinguish two stages of riparian vegetation (i.e., pioneer and mature vegetated areas) and to quantify the timing of colonization and growth. Finally, the study proposes a practical application of the described methodology for river managers indicating which river management activity (including timing, intensity and economic costs) is more appropriate and sustainable for each studied reach.</p><p> </p><p>References: Piégay, H., Arnaud, F., Belletti, B., Bertrand, M., Bizzi, S., Carbonneau, P., Dufour, S., Liébault, F., Ruiz‐Villanueva, V. and Slater, L.: Remotely sensed rivers in the Anthropocene: state of the art and prospects, Earth Surf. Process. Landf., 45(1), 157–188, https://doi.org/10.1002/esp.4787, 2020.</p>

scholarly journals Debris flows on forested cones – reconstruction and comparison of frequencies in two catchments in Val Ferret, Switzerland

2007 ◽  
Vol 7 (2) ◽  
pp. 207-218 ◽  
Author(s):  
M. Bollschweiler ◽  
M. Stoffel
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Historical Knowledge ◽  
Study Region ◽  
Sampling Height ◽  
The Alps ◽  
Recurrence Intervals ◽  
Study Sites ◽  
Flow Activity ◽  
Different Characteristics

Abstract. Debris flows represent a major threat to infrastructure in many regions of the Alps. Since systematic acquisition of data on debris-flow events in Switzerland only started after the events of 1987, there is a lack of historical knowledge on earlier debris-flow events for most torrents. It is therefore the aim of this study to reconstruct the debris-flow activity for the Reuse de Saleinaz and the La Fouly torrents in Val Ferret (Valais, Switzerland). In total, 556 increment cores from 278 heavily affected Larix decidua Mill., Picea abies (L.) Karst. and Pinus sylvestris L. trees were sampled. Trees on the cone of Reuse de Saleinaz show an average age of 123 years at sampling height, with the oldest tree aged 325 years. Two periods of intense colonization (the 1850s–1880s and the 1930s–1950s) are observed, probably following high-magnitude events that would have eliminated the former forest stand. Trees on the cone of Torrent de la Fouly indicate an average age of 119 years. As a whole, tree-ring analyses allowed assessment of 333 growth disturbances belonging to 69 debris-flow events. While the frequency for the Reuse de Saleinaz study site comprises 39 events between AD 1743 and 2003, 30 events could be reconstructed at the Torrent de la Fouly for the period 1862–2003. Even though the two study sites evince considerably different characteristics in geology, debris-flow material and catchment morphology, they apparently produce debris flows at similar recurrence intervals. We suppose that, in the study region, the triggering and occurrence of events is transport-limited rather than weathering-limited.

Influence of streamside buffers on stream temperature response following clear-cut harvesting in western Oregon

2013 ◽  
Vol 43 (11) ◽  
pp. 993-1005 ◽  
Author(s):  
Elizabeth Cole ◽  
Michael Newton
Keyword(s):  
Management Practice ◽  
Temperature Response ◽  
Stream Temperature ◽  
Forest Harvesting ◽  
Riparian Buffers ◽  
Daily Maximum ◽  
Clear Cut ◽  
Best Management ◽  
Temperature Trends ◽  
Temperature Responses

Determining the effectiveness of different riparian buffers for mitigating forest-harvesting impacts on stream temperatures continues to be of interest throughout the world. Four small, low or medium elevation streams in managed western Oregon forests were studied to determine how the arrangement and amount of streamside retention strips (buffers) in clear-cut units influenced stream temperatures. Buffers included (i) no tree, (ii) predominantly sun-sided 12 m wide partial, and (iii) two-sided (Best Management Practice, (BMP)) 15–30 m wide buffers. Harvested units alternated with uncut units along 1800–2600 m study reaches. Impacts of harvesting on stream temperatures were determined by time series comparisons of postharvest and preharvest regressions. Trends for daily maximum and mean stream temperature significantly increased after harvest in no tree buffer units. Partial buffers led to slight (<2 °C) or no increased warming. BMP units led to significantly increased warming, slight, or no increased warming. Temperature responses in uncut units appeared to be linked to responses in upstream harvested units. In many instances, when harvested units exhibited significantly higher postharvest trends, lower trends were observed in the uncut units downstream. Stream temperature trends of 7 day moving maxima indicated warming through the no tree buffer units and some of the BMP units. Peaks in maxima were not maintained in downstream units. Stream temperature responses were related to buffer implementation and stream features, relating to cooling and warming.

Communities of soil mites (Acarina) in planted birch stands compared with natural forests in central Finland

2003 ◽  
Vol 33 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Veikko Huhta ◽  
Ritva Niemi
Keyword(s):  
Betula Pendula ◽  
Soil Fauna ◽  
Deciduous Forests ◽  
Litter Layer ◽  
Natural Forests ◽  
Clear Cutting ◽  
Soil Mite ◽  
Spruce Stands ◽  
Study Sites ◽  
Mite Communities

The aim of the study was to compare the soil mite communities in anthropogenous birch stands of different origin with each other and with natural forests at the same latitude. Nine sites were investigated: three birch stands (Betula pendula Roth) planted ca. 30 years prior to the study after clear-cutting of spruce stands ("birch after spruce"), three birch stands planted ca. 30 years earlier on arable soil that had been under cultivation until reforestation ("birch after field"), and three natural deciduous forests. These were sampled twice, and microarthropods were extracted, counted, and identified. There were clear differences between birch stands established after spruce forest and after cultivation and between these and natural deciduous forests. The communities of birch after spruce were rather similar to those of natural spruce forests, but the population densities were lower. The populations in birch after field were generally very low. There were also conspicuous differences among replicates of the same kind of forests. All the dominant species in the study sites are common members of the forest soil fauna. The communities of birch after field could be characterized as impoverished forest communities. Soil pH and the removal of the litter layer by earthworms were regarded as the most important factors explaining the observed differences.

scholarly journals Improving representation of riparian vegetation shading in a regional stream temperature model using LiDAR data

2018 ◽  
Vol 624 ◽  
pp. 480-490 ◽  
Author(s):  
Pierre Loicq ◽  
Florentina Moatar ◽  
Yann Jullian ◽  
Stephen J. Dugdale ◽  
David M. Hannah
Keyword(s):  
Riparian Vegetation ◽  
Stream Temperature ◽  
Lidar Data ◽  
Temperature Model
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