Observations of Tidal Flat Sedimentation within a Native and an Exotic Spartina Species

Field measurements of bed elevation and related wave events were performed within a tidal marsh, on two cordgrass species, Spartina anglica (exotic) and Spartina maritima (native), in the Bay of Arcachon (SW France). Bed- and water-level time series were used to infer on the sediment behavior patterns from short to long term. A consistent response was found between the bed-level variation and the wave forcing, with erosion occurring during storms and accretion during low energy periods. Such behavior was observed within the two species, but the magnitude of bed-level variation was higher within the native than the exotic Spartina. These differences, in the order of millimeters, were explained by the opposite allocation of biomass of the two species. On the long term, the sedimentation/erosion patterns were dominated by episodic storm events. A general sediment deficit was observed on the site, suggested by an overall bed-level decrease registered within both species. However, further verification of within species variation needs to be considered when drawing conclusions. Despite possible qualitative limitations of the experimental design, due to single point survey, this work provides original and considerable field data to the understanding the different species ability to influence bed sediment stabilization and their potential to build marsh from the mudflat pioneer stage. Such information is valuable for coastal management in the context of global change.

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Spatial and temporal controls on overwash occurrence on a Great Lakes barrier spit

Canadian Journal of Earth Sciences ◽

10.1139/e92-011 ◽

1992 ◽

Vol 29 (1) ◽

pp. 102-117 ◽

Cited By ~ 24

Author(s):

Robin G. D. Davidson-Arnott ◽

John D. Fisher

Keyword(s):

Lake Level ◽

Field Measurements ◽

High Water ◽

Water Phase ◽

Storm Events ◽

North Shore ◽

The North ◽

High Lake Level ◽

Washover Fan

Field measurements from 1985 to 1990 and sequential aerial photography since 1945 show that overwash plays an extremely important role in the dynamics of Long Point, a large barrier spit on the north shore of Lake Erie. Overwash occurs primarily in the transgressive proximal and central zones of the spit, which together account for some 65% of the total shoreline length of 41 km. During periods of high lake level, over 50% of the shoreline in these zones may be overwashed. Washover morphology ranges from continuous washover terraces in areas of low foredunes to isolated washovers with narrow throats and distinct fans where breaching has occurred through high dunes. Individual overwash events commonly produce deposits on the fan surface 0.25–0.75 m or more in thickness. Washover-fan sediments are dominated by nearly horizontal planar bedding, with deposits near the fan margins often having foreset bedding, reflecting deposition in standing water of the bay or of interdune ponds.The frequency of overwash occurrence is strongly influenced by long-term lake-level fluctuations, which produce a distinct cycle of overwash activity. During the high-water phase more than 40% of the shoreline may consist of active washover fans or inlet breaches. Even storms with a return frequency of 1–2 per year can lead to significant overwash activity, and the washovers are generally reactivated several times in a 2 or 3 year period around the peak water level. During the low-water phase wider beaches offer protection against even extreme storm events, resulting in washover healing and restoration of a continuous foredune.

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Soil Erosion Estimates in Arid Region: A Case Study of the Koutine Catchment, Southeastern Tunisia

Applied Sciences ◽

10.3390/app11156763 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6763

Author(s):

Mongi Ben Zaied ◽

Seifeddine Jomaa ◽

Mohamed Ouessar

Keyword(s):

Soil Erosion ◽

Soil Loss ◽

Scientific Evidence ◽

Field Measurements ◽

Spatiotemporal Variability ◽

Soil Conditions ◽

Storm Events ◽

Erosion Processes ◽

Study Results ◽

Soil Losses

Soil erosion remains one of the principal environmental problems in arid regions. This study aims to assess and quantify the variability of soil erosion in the Koutine catchment using the RUSLE (Revised Universal Soil Loss Equation) model. The Koutine catchment is located in an arid area in southeastern Tunisia and is characterized by an annual mean precipitation of less than 200 mm. The model was used to examine the influence of topography, extreme rainstorm intensity and soil texture on soil loss. The data used for model validation were obtained from field measurements by monitoring deposited sediment in settlement basins of 25 cisterns (a traditional water harvesting and storage technique) over 4 years, from 2015 to 2018. Results showed that slope is the most controlling factor of soil loss. The average annual soil loss in monitoring sites varies between 0.01 and 12.5 t/ha/y. The storm events inducing the largest soil losses occurred in the upstream part of the Koutine catchment with a maximum value of 7.3 t/ha per event. Soil erosion is highly affected by initial and preceding soil conditions. The RUSLE model reasonably reproduced (R2 = 0.81) the spatiotemporal variability of measured soil losses in the study catchment during the observation period. This study revealed the importance of using the cisterns in the data-scarce dry areas as a substitute for the classic soil erosion monitoring fields. Besides, combining modeling of outputs and field measurements could improve our physical understanding of soil erosion processes and their controlling factors in an arid catchment. The study results are beneficial for decision-makers to evaluate the existing soil conservation and water management plans, which can be further adjusted using appropriate soil erosion mitigation options based on scientific evidence.

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Health and sustainability of glaciers in High Mountain Asia

Nature Communications ◽

10.1038/s41467-021-23073-4 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Evan Miles ◽

Michael McCarthy ◽

Amaury Dehecq ◽

Marin Kneib ◽

Stefan Fugger ◽

...

Keyword(s):

Current Knowledge ◽

Field Measurements ◽

Tien Shan ◽

High Mountain ◽

Specific Mass ◽

Ice Flow ◽

Ice Volume ◽

Mass Redistribution ◽

Glacier Ablation

AbstractGlaciers in High Mountain Asia generate meltwater that supports the water needs of 250 million people, but current knowledge of annual accumulation and ablation is limited to sparse field measurements biased in location and glacier size. Here, we present altitudinally-resolved specific mass balances (surface, internal, and basal combined) for 5527 glaciers in High Mountain Asia for 2000–2016, derived by correcting observed glacier thinning patterns for mass redistribution due to ice flow. We find that 41% of glaciers accumulated mass over less than 20% of their area, and only 60% ± 10% of regional annual ablation was compensated by accumulation. Even without 21st century warming, 21% ± 1% of ice volume will be lost by 2100 due to current climatic-geometric imbalance, representing a reduction in glacier ablation into rivers of 28% ± 1%. The ablation of glaciers in the Himalayas and Tien Shan was mostly unsustainable and ice volume in these regions will reduce by at least 30% by 2100. The most important and vulnerable glacier-fed river basins (Amu Darya, Indus, Syr Darya, Tarim Interior) were supplied with >50% sustainable glacier ablation but will see long-term reductions in ice mass and glacier meltwater supply regardless of the Karakoram Anomaly.

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Evaluating Simple Methodology for Piezoelectric Level Sensors Protection

Proceedings ◽

10.3390/ecws-4-06448 ◽

2019 ◽

Vol 48 (1) ◽

pp. 30

Author(s):

Luis Hamilton Pospissil Garbossa ◽

Argeu Vanz ◽

Matias Guilherme Boll ◽

Hamilton Justino Vieira

Keyword(s):

Water Level ◽

Flood Control ◽

Low Cost ◽

Solid Particles ◽

Storm Events ◽

Sewer Systems ◽

Continuous Monitor ◽

Level Monitoring ◽

Water Level Monitoring

The increasing frequency of extreme storm events has implications for the operation of sewer systems, storm water, flood control monitoring and tide level variations. Accurate and continuous monitor water level monitoring is demanded in different environments. Piezoelectric sensors are widely used for water level monitoring and work submerged in waters subject to the presence of solid particles, biological fouling and saltwater oxidation. This work aimed to develop a simple, low-cost methodology to protect sensors over long-term deployment. The results show that simple actions, costing less than 2 EUR, can protect and extend the lifecycle of equipment worth over 2000 EUR, ensuring continuous monitoring and maintaining quality measurements.

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Mutations in Phytoene Desaturase Gene in Fluridone-Resistant Hydrilla (Hydrilla verticillata) Biotypes in Florida

Weed Science ◽

10.1614/ws-07-011.1 ◽

2007 ◽

Vol 55 (5) ◽

pp. 412-420 ◽

Cited By ~ 8

Author(s):

Atul Puri ◽

Gregory E. MacDonald ◽

Fredy Altpeter ◽

William T. Haller

Keyword(s):

Herbicide Resistance ◽

Single Point ◽

Hydrilla Verticillata ◽

The United States ◽

Phytoene Desaturase ◽

Day Length ◽

Single Point Mutation ◽

Aquatic Weed ◽

Systemic Control

Hydrilla is one of the most serious aquatic weed problems in the United States, and fluridone is the only U.S. Environment Protection Agency (USEPA)–approved herbicide that provides relatively long-term systemic control. Recently, hydrilla biotypes with varying levels of fluridone resistance have been documented in Florida. One susceptible and five fluridone-resistant biotypes of hydrilla varying in resistance levels were maintained in 950-L tanks under ambient sunlight and day-length conditions from September 2004 to September 2005 in absence of fluridone. Because fluridone is an inhibitor of the enzyme phytoene desaturase (PDS), the gene for PDS (pds) was cloned from fluridone-susceptible and -resistant hydrilla biotypes. Somatic mutations in amino acid 304 of hydrilla PDS are known to confer herbicide resistance. We determinedpdssequence from these hydrilla biotypes at planting and 12-mo after planting. Two independent mutations at the arginine 304 codon ofpdswere found in the resistant hydrilla plants. The codon usage for arginine 304 is CGT, and a single point mutation yielding either serine (AGT) or histidine (CAT) was identified in different resistant hydrilla biotypes. There were no differences at codon 304 in the PDS protein of any hydrilla biotype 12-mo after planting. Several other mutations were also found in resistantpdsalleles, though their possible role in herbicide resistance is unclear.

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Assessing dry weather flow contribution in TSS and COD storm events loads in combined sewer systems

Water Science & Technology ◽

10.2166/wst.2011.185 ◽

2011 ◽

Vol 63 (12) ◽

pp. 2983-2991 ◽

Cited By ~ 9

Author(s):

M. Métadier ◽

J. L. Bertrand-Krajewski

Keyword(s):

Time Series ◽

Oxygen Demand ◽

Seasonal Effect ◽

Storm Events ◽

Combined System ◽

Time Step ◽

Urban Catchment ◽

Sewer Systems ◽

Continuous Discharge

Continuous high resolution long term turbidity measurements along with continuous discharge measurements are now recognised as an appropriate technique for the estimation of in sewer total suspended solids (TSS) and Chemical Oxygen Demand (COD) loads during storm events. In the combined system of the Ecully urban catchment (Lyon, France), this technique is implemented since 2003, with more than 200 storm events monitored. This paper presents a method for the estimation of the dry weather (DW) contribution to measured total TSS and COD event loads with special attention devoted to uncertainties assessment. The method accounts for the dynamics of both discharge and turbidity time series at two minutes time step. The study is based on 180 DW days monitored in 2007–2008. Three distinct classes of DW days were evidenced. Variability analysis and quantification showed that no seasonal effect and no trend over the year were detectable. The law of propagation of uncertainties is applicable for uncertainties estimation. The method has then been applied to all measured storm events. This study confirms the interest of long term continuous discharge and turbidity time series in sewer systems, especially in the perspective of wet weather quality modelling.

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Soil respiration and N2O emission in croplands under different ploughing practices: a case study in south-east China

Soil Research ◽

10.1071/sr07225 ◽

2009 ◽

Vol 47 (2) ◽

pp. 198 ◽

Cited By ~ 8

Author(s):

Shutao Chen ◽

Yao Huang

Keyword(s):

Soil Respiration ◽

Soil Temperature ◽

Agricultural Soils ◽

Field Measurements ◽

Triticum Aestivum L ◽

N2o Emission ◽

Cropping Season ◽

Significant Difference

Studies on the CO2 and N2O emission patterns of agricultural soils under different ploughing practices may provide an insight into the potential and magnitude of CO2 and N2O mitigation in highly managed farmland soils. In this study, field measurements of soil respiration and N2O flux with different ploughing depths were performed in the 2003–04 wheat (Triticum aestivum L.), 2004 maize (Zea mays L.), and 2004–05 wheat seasons. Soil temperature and moisture were simultaneously measured. Results showed that, in each cropping season, the seasonal variation in soil respiration developed with a similar pattern for different treatments, which was primarily regulated by soil temperature. This work demonstrates that ploughing depth can influence long-term loss of carbon from soil, but this was contingent on preceding cropping types. Given the same preceding cropping practice, no significant difference in N2O emission was found among different ploughing depths in each cropping season.

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FIELD MEASUREMENTS AND MODELLING OF NEARSHORE CURRENTS AT A HIGH-ENERGY GEOLOGICALLY-CONSTRAINED BEACH

Coastal Engineering Proceedings ◽

10.9753/icce.v36v.currents.18 ◽

2020 ◽

pp. 18

Author(s):

Arthur Mouragues ◽

Philippe Bonneton ◽

Bruno Castelle ◽

Vincent Marieu

Keyword(s):

Surf Zone ◽

Low Frequency ◽

Field Measurements ◽

High Energy ◽

Oblique Wave ◽

Wave Forcing ◽

Circulation Patterns ◽

Wave Conditions ◽

Nearshore Currents ◽

Set Up

We present field measurements of nearshore currents at a high-energy mesotidal beach with the presence of a 500-m headland and a submerged reef. Small changes in wave forcing and tide elevation were found to largely impact circulation patterns. In particular, under 4-m oblique wave conditions, our measurements indicate the presence of an intense low-frequency fluctuating deflection rip flowing against the headland and extending well beyond the surf zone. An XBeach model is further set up to hindcast such flow patterns.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/EiqnjBIkWJE

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Data Correction Method of The Persistent Scatterer Interferometric Synthetic Aperture Radar Technique in Landslide Surface Monitoring

Mining Scince ◽

10.37190/msc192607 ◽

2019 ◽

Vol 26 ◽

Author(s):

Mowen Xie ◽

Fuxia Lv ◽

Liwei Wang

Keyword(s):

Synthetic Aperture Radar ◽

Single Point ◽

Synthetic Aperture ◽

Hydropower Station ◽

Landslide Monitoring ◽

Interferometric Synthetic Aperture Radar ◽

Reservoir Area ◽

Radar Technique ◽

Aperture Radar

Landslides generally cause more damage than first predicted. Currently, many methods are available for monitoring landslides occurrence. Conventional methods are mainly based on single-point monitoring, which omits the aspect of variation in large-scale landslides. Due to the development of radar satellites, the differential interferometric synthetic aperture radar technique has been widely used for landslide monitoring. In this study, an experimental region in the Wudongde Hydropower Station reservoir area was studied using archived spaceborne synthetic aperture radar (SAR) data collected over many years. As the permanent scatterer interferometric SAR (PS-InSAR) technique is an advanced technology, it could be suitably used to overcome the time discontinuity in long time series. However, the accuracy of date processing obtained using the PS-InSAR technique is lower than that obtained using the single-point monitoring method. The monitoring results of the PS-InSAR technique only demonstrate the moving trend of landslides and do not present the actual displacement. The Advanced Land Observation Satellite and a high-precision total station were used for long-term landslide monitoring of the Jinpingzi landslide at the Wudongde Hydropower Station reservoir area. Based on a relationship analysis between the data obtained using the PS-InSAR technique and the total station, a revised method was proposed to reduce the errors in the PS-InSAR monitoring results. The method can not only enhance the monitoring precision of the PS-InSAR technology but also achieve long-term monitoring of landslide displacement from a bird’s-eye view.

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