A little data goes a long way: automating seismic phase arrival picking at Nabro Volcano with transfer learning

Supervised deep learning models have become a popular choice for seismic phase arrival detection. However, they do not always perform well on out-of-distribution data and require large training sets to aid generalization and prevent overfitting. This can present issues when using these models in new monitoring settings. In this work, we develop a deep learning model for automating phase arrival detection at Nabro volcano using a limited amount of training data (2,498 event waveforms recorded over 35 days) through a process known as transfer learning. We use the feature extraction layers of an existing, extensively trained seismic phase picking model to form the base of a new all-convolutional model, which we call U-GPD. We demonstrate that transfer learning reduces overfitting and model error relative to training the same model from scratch, particularly for small training sets (e.g., 500 waveforms). The new U-GPD model achieves greater classification accuracy and smaller arrival time residuals than off-the-shelf applications of two existing, extensively-trained baseline models for a test set of 800 event and noise waveforms from Nabro volcano. When applied to 14 months of continuous Nabro data, the new U-GPD model detects 31,387 events with at least four P-wave arrivals and one S-wave arrival, which is more than the original base model (26,808 events) and our existing manual catalog (2,926 events), with smaller location errors. The new model is also more efficient when applied as a sliding window, processing 14 months of data from seven stations in less than 4 h on a single graphics processing unit

Hydromorphological, hydraulic and ecological effects of restored wood: findings and reflections from an academic partnership approach

This is the peer reviewed version of the following article: Pinto, C. , Ing, R. , Browning, B. , Delboni, V. , Wilson, H. , Martyn, D. and Harvey, G. L. (2019), Hydromorphological, hydraulic and ecological effects of restored wood: findings and reflections from an academic partnership approach. Water and Environment Journal. doi:10.1111/wej.12457, which has been published in final form at https://doi.org/10.1111/wej.12457. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions© 2019 CIWEM Large wood (re)introduction can deliver multiple benefits in river restoration, but there is a dearth of the detailed and longer-term post-project monitoring and evaluation required for improving best practice. We present findings from an academic partnership approach to post-project evaluation, based on successive MSc research projects on restored large wood in the Loddon catchment, UK. Field and modelling data reveal: (i) key differences in large wood features between restored and natural reaches; (ii) increased hydraulic retention and changes to mesohabitats associated with large wood; (iii) differences in macroinvertebrate community composition around large wood but a lack of site-level effects; (iv) interactions between macrophytes and large wood that may be specific to restored reaches; (v) a need for further field and modelling studies to inform the accurate representation of large wood in hydraulic models. Some key challenges in partnership working are identified to aid planning and effectiveness of future collaborations

Drift induced by repeated hydropeaking waves in controlled conditions

Repeated hydropeaking events characterize most alpine rivers downstream of power plants fed by high elevation reservoirs. The effects of hydropeaking on the benthic communities are well known, and usually each hydropeaking wave causes an increase in tractive force and changes in temperature and water quality. Simulations of hydropeaking in artificial system can help to disentangle the direct effects of the modified flow regime from impacts associated with other associated physio-chemical changes, and with the effects of river regulation and land-use changes that often accompany water resource development. In September 2013 we conducted a set of controlled simulations in five steel flumes fed by an Alpine stream (Fersina stream, Adige River catchment, Trentino, Italy), where benthic invertebrates can freely colonize the flumes. One flume was used as control with no change in flow, in the other four flumes we simulated an hydropeaking wave lasting six hours, and repeated for five consecutive days. Flow was increased by twice baseflow in two flumes, and three times in the other two. We collected benthic samples before the beginning (morning of day 1) and after the end (afternoon of day 5) of the set of simulations to evaluate changes in the benthic communities due to induced drift migration. During each simulation, we collected drifting organisms at short time intervals to assess the responses to: 1) the initial discharge increase, 2) the persistence of high flows for several hours; 3) the decrease of discharge to the baseflow; 4) the change in drift with each successive day. Preliminary results indicate typical strong increases of catastrophic drift on the onset of each simulated hydropeaking, drift responses proportional to the absolute discharge increase, a decrease in the drift responses over successive days. Different taxa responded with different patterns: taxa which resist tractive force increased in drift only during the periods of baseflow that follow the habitat stress (behavioral drift) (e.g., Simuliidae, behavioral drift); other taxa which can not resist the increase in tractive force, drifted from the beginning of the simulation (e.g., Chironomidae, catastrophic drift)

Effects of repeated hydropeaking waves on benthic invertebrates: a flume study

In late summer 2013, we conducted a set of controlled simulations in five steel flumes directly fed by an Alpine stream (Fersina stream, left tributary to the Adige River, Trentino, Italy), where benthic invertebrates can freely colonize the flumes by downstream drift and egg deposition. We simulated a repetition of 5 daily hydropeaking events, lasting approximately 6 hours, of different intensities. We collected benthic samples before and after the set of simulations to determine changes in the benthic communities due to the depletive effect of repeated hydropeaking inducing the massive drift of invertebrates. During each simulation, we collected drifting organisms at short time intervals. We observed: 1) a strong increase in drift during the initial discharge increase; 2) drift responses proportional to the absolute discharge increase; 3) a decrease in the drift responses over successive days; 4) a decrease in benthic abundances at the end of the simulation

Effects of hydropeaking and substrate type on periphyton nutritional quality in an Alpine stream

Hydropeaking is well known for its direct, physical impact on river systems through the effect of scour causing catastrophic drift in aquatic communities. Moreover, river regulation with daily hydropeaking may persistently alter periphyton abundance and nutritional quality (e.g. nutrient ratios and essential fatty acids) compared to reference conditions, resulting in an indirect and potentially overlooked limiting effect on the aquatic communities in hydropower-impacted streams. Periphyton nutritional quality, especially fatty acids, have been suggested to be a fundamental limiting resource in aquatic systems, and have been demonstrated to be an important control on consumer growth rates, energy assimilation, reproduction, and other physiological responses. We simulated daily 8-hour hydropeak events over the course of 5 days in an in situ, open air, experimental flume system naturally fed by a pristine 2nd order Alpine stream. The effect of two different hydropeak magnitudes (2x and 3x baseflow) were examined on both wood and tile substrates in both spring and summer seasons. Hydropeaking resulted in decreased periphyton biomass growing on tiles, but there was no corresponding decrease in periphyton growing on wood. Changes in periphyton C:N stoichiometry, but not C:P, also varied with substrate type. We will also discuss the change in diatom and total algal species composition and total, polyunsaturated, and ω3/ω6 fatty acid composition. These results suggest that substrates respond differently to the scour effects of hydropeaking, and that the overall nutritional quality of periphyton downstream of hydropeaking dams may be dependent on the relative availability of wood substrates

Effects of experimental hydropeaking on periphyton nutritional quality in an Alpine stream

Hydropeaking has been shown to limit secondary production, most notably by causing catastrophic drift in downstream consumer communities. We hypothesized that rivers undergoing hydropeaking may also have suppressed periphyton biomass and especially nutritional quality (i.e. essential fatty acids) which may result in a secondary limitation on aquatic consumers. We further hypothesized that woody substrates, due to its effect on local hydraulic conditions, may react differently to hydropeaking than other hard substrates. We simulated daily 5-hour hydropeaks for 5 days in an in situ, open air, experimental flume system fed by a 2nd order stream in the Italian Alps. Hydropeaking resulted in decreased periphyton biomass on tile substrates, but there was no corresponding decrease in periphyton growing on wood. Essential polyunsaturated fatty acids and ω3:ω6 ratios decreased on both substrates, but there was less loss on wood. This suggests that hydropeaking may also limit production via depressing primary biomass and nutritional quality, and that the availability of wood substrates in the channel may mitigate this effec

Use of semiartificial flumes in stream ecology: an overview of simulations to assess anthropic impacts on alpine streams

The assessment of the ecological impacts of anthropic alteration of stream ecosystems is often difficult due to the presence of confounding and interacting factors. Starting in 2008, we have been using a set of five open-air, stream-side steel flumes, directly fed by a 2nd order gravel-bed Alpine stream (Trentino, NE Italy). The system diverts water directly from the river via a weir into a collecting tank, and the tank feeds five 30 cm wide, 20 m long U-frame metal flumes that contain a sluice gate at the upstream end to control discharge. Hence, periphyton and benthic invertebrates can colonize the substrate naturally and complete their life cycles in the flumes. We have been conducting sets of simulations to disentangle the effects on macroinvertebrates and periphyton of: 1) sudden changes in discharge (hydropeaking) caused by hydropower plant operations; 2) sudden changes of temperature (thermopeaking) associated to hydropeaking; 3) fine sediment waves caused by dam flushes; 4) light pollution; 5) flow intermittency; 6) minimum vital flows. We present the setting of the different simulations, and the main results achieved in terms of alterations of microbenthic communities abundances, composition, and functional groups; of periphytic communities biomass, composition, and nutritional quality

Contribution of large-scale mesocosm experiments in interdisciplinary river science: an overview of the SMART experimental activities

Assessing the ecological impacts of anthropic alteration of aquatic ecosystems is difficult due to the presence of confounding and interacting factors. Large-scale mesocosms enable experiments with greater complexity, e.g., by including different trophic levels, to be conducted and to separate effects of multiple stressors on whole ecosystems. Thus, results can be extrapolated to natural systems. Within the SMART programme, four PhD projects included interdisciplinary mesocosm experiments. Two different facilities were used: i) a set of five open-air, stream-side flumes, fed by a 2nd order gravel-bed Alpine stream (“Fersina flumes”, Trentino, NE Italy); ii) 24 large lake mesocosms (enclosures) reaching into the sediments (“LakeLab”, IGB, Lake Stechlin, Germany). The Fersina flumes were used by three SMART PhD students. The experiments aimed to disentangle the effects on macroinvertebrates and periphyton of: 1) HYDROPEAKING: we simulated daily 5-h hydropeaking events for five consecutive days in spring and autumn, and assessed the effects on periphyton biomass and nutritional quality, and on macroinvertebrates drift. For both biotic targets, we assessed the use of wood as a mitigation measure. 2) artificial light at night (ALAN): we simulated the light conditions of a light-polluted area in spring and autumn, and assessed the effects on periphyton growth by measuring biomass and community composition, and on zoobenthos by measuring density and composition and the induction of drift. The main findings were: 1) Repeated hydropeaking alter primary producers biomass and nutritional quality (fatty acids content), and zoobenthic communities densities and composition by inducing catastrophic drift, and availability of wood substrate may mitigate part of these effects; 2) ALAN alters biomass and composition of periphyton and potentially its nutritional quality in artificially-lit waters, and suppresses macroinvertebrates drift densities resulting in changes in benthic densities and composition. One SMART PhD student attended a LakeLab experiment within the ‘Illuminating Lake Ecosystems’ (ILES) project. This project aimed to elucidate the effects of increased levels of diffuse luminance of the night sky due to human presence and activity (i.e., skyglow) on lake ecosystem function. As part of this project, a large scale mesocosm experiment was carried out, simulating three skyglow conditions (no, low and high skyglow). Through the use of a mechanistic mathematical model and a stochastic calibration of model parameters in a Bayesian framework, metabolic rates were calculated: gross primary productivity, ecosystem respiration, and net ecosystem productivity. Interpretation of results will be supported by additional laboratory results still in preparation. This presentation will demonstrate the importance of mesocosm facilities in interdisciplinary research training and how this led to insights that would not have been possible otherwise