scholarly journals Turbidity in the fluvial Gironde Estuary (S–W France) based on 10 year continuous monitoring: sensitivity to hydrological conditions

2015 ◽  
Vol 12 (3) ◽  
pp. 2843-2883 ◽  
Author(s):  
I. Jalón-Rojas ◽  
S. Schmidt ◽  
A. Sottolichio
Keyword(s):  
Continuous Monitoring ◽  
River Flow ◽  
Hysteresis Loops ◽  
Annual Runoff ◽  
Transitional Period ◽  
Hydrological Conditions ◽  
Frequency Monitoring ◽  
Turbidity Level ◽  
River Floods

Abstract. Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in the southwest France, the Gironde fluvial-estuarine systems has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and high-frequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low-water, inter-annual changes). Turbidity shows hysteresis loops at different time scales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the TMZ installation in the fluvial stations. Hydrological indicators of the persistence and turbidity level of the TMZ are also defined. The long-term evolution of these indicators confirms the influence of discharge decrease on the intensification of the TMZ in tidal rivers, and provides a tool to evaluate future scenarios.

scholarly journals Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

2015 ◽  
Vol 19 (6) ◽  
pp. 2805-2819 ◽  
Author(s):  
I. Jalón-Rojas ◽  
S. Schmidt ◽  
A. Sottolichio
Keyword(s):  
River Flow ◽  
Hysteresis Loops ◽  
Annual Runoff ◽  
Transitional Period ◽  
Estuarine System ◽  
Upstream Migration ◽  
Hydrological Conditions ◽  
Frequency Monitoring ◽  
Turbidity Level ◽  
River Floods

Abstract. Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in southwest France, the Gironde fluvial-estuarine system has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and high-frequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low discharge, interannual changes). Turbidity shows hysteresis loops at different timescales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the upstream migration of TMZ in the fluvial stations. Whereas the duration of the low discharge period mainly determines the TMZ persistence, the freshwater volume during high discharge periods explains the TMZ concentration at the following dry period. The evolution of these two hydrological indicators of TMZ persistence and turbidity level since 1960 confirms the effect of discharge decrease on the intensification of the TMZ in tidal rivers; both provide a tool to evaluate future scenarios.

Reactivity of southern Quebec aquifers to meteorological and hydrological conditions

2021 ◽  
Author(s):  
Trong Ahn Vu ◽  
Marie Larocque ◽  
Sylvain Gagné ◽  
Marc-André Bourgault
Keyword(s):  
Land Use ◽  
Groundwater Level ◽  
River Flow ◽  
Correlation Coefficients ◽  
Flow Rates ◽  
Groundwater Levels ◽  
Hydrological Conditions ◽  
Observation Network ◽  
Observation Wells

<p>Groundwater represents an important source of drinking water for 25% of the population in the province of Quebec (Canada) and for 80% of its rural population. The deployment of the Quebec Groundwater Observation Network (Réseau de suivi des eaux souterraines du Québec – RSESQ) since the start of the millennia provides important data on the dynamics of piezometric heads throughout southern Quebec. This study aims to use the wealth of available groundwater data available to better understand the resilience of groundwater resources to changes in meteorological and hydrological conditions. The study area is located between the St. Lawrence River and the Canada-USA border, and between the Quebec-Ontario border and Quebec City (36,000 km²). Available data consist of groundwater level time series from 81 observation wells (2000-2018; 43 in confined aquifers, 15 in semi-confined aquifers and 23 in unconfined aquifers), total flow rates from 179 hydrometric stations (1960-2017), and meteorological data from a spatially interpolated 10 km x 10 km grid (1960-2017). Statistical analyses (Mann Kendall and Sen’s slope) were used to understand if groundwater levels and flow rates are declining or rising, what is their short-, medium- and long-term memory and what are the geomorphological, land use, and climate controls of this reactivity. The results show that groundwater levels since 2007 exhibit statistically significant negative annual trends for most observation wells. Since 1960, river flow rates, total precipitation and air temperature all show significant increases. Trends calculated on five-year sliding windows confirm that groundwater levels and river flow rates are significantly correlated to the climate indices Southern Oscillation index (SOI), NINO-3 and Pacific Decadal Oscillation index (PDO). Autocorrelations of flow rates and groundwater level data indicate that rivers and aquifers have a short hydrological memory rarely extending beyond the hydrological year. Cross-correlations of flow rates and groundwater levels with temperature show high correlation coefficients with a lag of up to 60 days, indicating a season-long effect of temperature changes. As expected, cross-correlation analysis of the two data sets with precipitation shows smaller correlation coefficients and a shorter reaction time (10 days). Standard deviations of daily groundwater levels are significantly higher in shallower wells and in wells where groundwater levels are closer to the ground. This confirms the presence of highly dynamic shallow aquifers reacting rapidly to surface processes.  Analyses are under way to test if spatially distributed parameters (e.g., geological setting, slope, land use) and well-related parameters (e.g.: depth, confined or unconfined) are explaining factors of trends and variations in groundwater levels and flow rates. One key observation from this study is that the RSESQ is highly valuable to understand groundwater dynamics and should be maintained on a long-term horizon. This detailed analysis has allowed to identify external influences (e.g., pumping) on some observation wells that do not reflect natural conditions and could be removed from the observation network. Recommendations also include the need for new observation wells in specific locations to improve the representativity of groundwater flow conditions in the study area.</p>

scholarly journals Domain randomization-enhanced deep learning models for bird detection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xin Mao ◽  
Jun Kang Chow ◽  
Pin Siang Tan ◽  
Kuan-fu Liu ◽  
Jimmy Wu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Continuous Monitoring ◽  
Bird Species ◽  
Training Data ◽  
Learning Models ◽  
Fine Grained ◽  
Bird Detection ◽  
Relationship Of ◽  
The Relationship

AbstractAutomatic bird detection in ornithological analyses is limited by the accuracy of existing models, due to the lack of training data and the difficulties in extracting the fine-grained features required to distinguish bird species. Here we apply the domain randomization strategy to enhance the accuracy of the deep learning models in bird detection. Trained with virtual birds of sufficient variations in different environments, the model tends to focus on the fine-grained features of birds and achieves higher accuracies. Based on the 100 terabytes of 2-month continuous monitoring data of egrets, our results cover the findings using conventional manual observations, e.g., vertical stratification of egrets according to body size, and also open up opportunities of long-term bird surveys requiring intensive monitoring that is impractical using conventional methods, e.g., the weather influences on egrets, and the relationship of the migration schedules between the great egrets and little egrets.

scholarly journals High Mountain Asian glacier response to climate revealed by multi-temporal satellite observations since the 1960s

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Atanu Bhattacharya ◽  
Tobias Bolch ◽  
Kriti Mukherjee ◽  
Owen King ◽  
Brian Menounos ◽  
...  
Keyword(s):  
Mass Loss ◽  
River Flow ◽  
Tien Shan ◽  
High Mountain ◽  
Glacier Mass Balance ◽  
Temperature And Precipitation ◽  
Multi Temporal ◽  
The 1960S ◽  
Northern Tien Shan

AbstractKnowledge about the long-term response of High Mountain Asian glaciers to climatic variations is paramount because of their important role in sustaining Asian river flow. Here, a satellite-based time series of glacier mass balance for seven climatically different regions across High Mountain Asia since the 1960s shows that glacier mass loss rates have persistently increased at most sites. Regional glacier mass budgets ranged from −0.40 ± 0.07 m w.e.a−1 in Central and Northern Tien Shan to −0.06 ± 0.07 m w.e.a−1 in Eastern Pamir, with considerable temporal and spatial variability. Highest rates of mass loss occurred in Central Himalaya and Northern Tien Shan after 2015 and even in regions where glaciers were previously in balance with climate, such as Eastern Pamir, mass losses prevailed in recent years. An increase in summer temperature explains the long-term trend in mass loss and now appears to drive mass loss even in regions formerly sensitive to both temperature and precipitation.

Long-term trajectories of decline in cognition and daily functioning before and after stroke

2021 ◽  
pp. jnnp-2021-326043
Author(s):  
Alis Heshmatollah ◽  
Lisanne J. Dommershuijsen ◽  
Lana Fani ◽  
Peter J. Koudstaal ◽  
M. Arfan Ikram ◽  
...  
Keyword(s):  
Continuous Monitoring ◽  
Mini Mental State Examination ◽  
Functional Decline ◽  
Population Based ◽  
Daily Functioning ◽  
Linear Mixed Effects ◽  
Before And After ◽  
State Examination

ObjectiveAlthough knowledge on poststroke cognitive and functional decline is increasing, little is known about the possible decline of these functions before stroke. We determined the long-term trajectories of cognition and daily functioning before and after stroke.MethodsBetween 1990 and 2016, we repeatedly assessed cognition (Mini-Mental State Examination (MMSE), 15-Word Learning, Letter–Digit Substitution, Stroop, Verbal Fluency, Purdue Pegboard) and basic and instrumental activities of daily living (BADL and IADL) in 14 712 participants within the population-based Rotterdam Study. Incident stroke was assessed through continuous monitoring of medical records until 2018. We matched participants with incident stroke to stroke-free participants (1:3) based on sex and birth year. Trajectories of cognition and daily functioning of patients who had a stroke 10 years before and 10 years after stroke and the corresponding trajectories of stroke-free individuals were constructed using adjusted linear mixed effects models.ResultsDuring a mean follow-up of 12.5±6.8 years, a total of 1662 participants suffered a first-ever stroke. Patients who had a stroke deviated from stroke-free controls up to 10 years before stroke diagnosis in cognition and daily functioning. Significant deviations before stroke were seen in scores of MMSE (6.4 years), Stroop (5.7 years), Purdue Pegboard (3.8 years) and BADL and IADL (2.2 and 3.0 years, respectively).ConclusionPatients who had a stroke have steeper declines in cognition and daily functioning up to 10 years before their first-ever stroke compared with stroke-free individuals. Our findings suggest that accumulating intracerebral pathology already has a clinical impact before stroke.

To the problem of uncertainty in interpolation of annual runoff

2012 ◽  
Vol 43 (6) ◽  
pp. 833-850 ◽  
Author(s):  
Ziqi Yan ◽  
Lars Gottschalk ◽  
Irina Krasovskaia ◽  
Jun Xia
Keyword(s):  
Cross Validation ◽  
Drainage Basin ◽  
Annual Runoff ◽  
Mean Value ◽  
Regular Grid ◽  
Main River ◽  
Average Annual Runoff ◽  
The One ◽  
Better Than

The long-term mean value of runoff is the basic descriptor of available water resources. This paper focuses on the accuracy that can be achieved when mapping this variable across space and along main rivers for a given stream gauging network. Three stochastic interpolation schemes for estimating average annual runoff across space are evaluated and compared. Two of the schemes firstly interpolate runoff to a regular grid net and then integrate the grid values along rivers. One of these schemes includes a constraint to account for the lateral water balance along the rivers. The third scheme interpolates runoff directly to points along rivers. A drainage basin in China with 20 gauging sites is used as a test area. In general, all three approaches reproduce the sample discharges along rivers with postdiction errors along main river branches around 10%. Using more objective cross-validation results, it was found that the two schemes based on basin integration, and especially the one with a constraint, performed significantly better than the one with direct interpolation to points along rivers. The analysis did not allow identification of possible influence of surface water use.

Long-term continuous monitoring of the dissolved CO2 performed by using a new device in groundwater of the Mt. Etna (southern Italy)

2011 ◽  
Vol 45 (9) ◽  
pp. 3005-3011 ◽  
Author(s):  
Sofia De Gregorio ◽  
Marco Camarda ◽  
Manfredi Longo ◽  
Santo Cappuzzo ◽  
Gaetano Giudice ◽  
...  
Keyword(s):  
Continuous Monitoring ◽  
Southern Italy ◽  
New Device ◽  
Mt Etna

scholarly journals Longer Growing Seasons Cause Hydrological Regime Shifts in Central European Forests

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1656
Author(s):  
Petr Kupec ◽  
Jan Deutscher ◽  
Martyn Futter
Keyword(s):  
Regime Shift ◽  
Hydrological Regime ◽  
Annual Runoff ◽  
Order Effects ◽  
Runoff Generation ◽  
Central European ◽  
European Forests ◽  
Water Limitation ◽  
Growing Seasons

In this study, we present evidence for a hydrological regime shift in upland central European forests. Using a combination of long-term data, detailed field measurements and modelling, we show that there is a prolonged and persistent decline in annual runoff: precipitation ratios that is most likely linked to longer growing seasons. We performed a long term (1950–2018) water balance simulation for a Czech upland forest headwater catchment calibrated against measured streamflow and transpiration from deciduous and coniferous stands. Simulations were corroborated by long-term (1965–2018) borehole measurements and historical drought reports. A regime shift from positive to negative catchment water balances likely occurred in the early part of this century. Since 2007, annual runoff: precipitation ratios have been below the long-term average. Annual average temperatures have increased, but there have been no notable long term trends in precipitation. Since 1980, there has been a pronounced April warming, likely leading to earlier leaf out and higher annual transpiration, making water unavailable for runoff generation and/or soil moisture recharge. Our results suggest a regime shift due to second order effects of climate change where increased transpiration associated with a longer growing season leads to a shift from light to water limitation in central European forests. This will require new approaches to managing forests where water limitation has previously not been a problem.

Sign in / Sign up

Export Citation Format

Share Document