scholarly journals Effect of aquatic vegetation on Manning´s roughness coefficient value – Case study at the Šúrsky channel

2020 ◽  
Vol 21 (1) ◽  
pp. 123-129
Author(s):  
Radoslav Schügerl ◽  
Yvetta Velísková ◽  
Valentín Sočuvka ◽  
Renáta Dulovičová
Keyword(s):  
Aquatic Vegetation ◽  
Roughness Coefficient

The Case Study in Zator, Poland

2013 ◽  
pp. 181-184
Author(s):  
Zenon Tederko
Keyword(s):  
Decision Support ◽  
Biodiversity Conservation ◽  
Aquatic Vegetation ◽  
Local Support

The mapping of aquatic vegetation in the 461 ha Przyreb fishpond complex at Zator, in Poland’s Carp Valley, was to help balance restoration of multifunctional aquaculture with biodiversity conservation. Strong local support has encouraged proposals for a geoportal to give map-linked decision support.

scholarly journals The role of patch size in ecosystem engineering capacity: a case study of aquatic vegetation

2019 ◽  
Vol 81 (3) ◽  
Author(s):  
Sofia Licci ◽  
Heidi Nepf ◽  
Cécile Delolme ◽  
Pierre Marmonier ◽  
Tjeerd J. Bouma ◽  
...  
Keyword(s):  
Patch Size ◽  
Aquatic Vegetation ◽  
Ecosystem Engineering

Economic valuation of ecosystem services, a case study for aquatic vegetation removal in the Nete catchment (Belgium)

2014 ◽  
Vol 7 ◽  
pp. 46-56 ◽  
Author(s):  
Annelies Boerema ◽  
Jonas Schoelynck ◽  
Kris Bal ◽  
Dirk Vrebos ◽  
Sander Jacobs ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Aquatic Vegetation ◽  
Economic Valuation ◽  
Vegetation Removal ◽  
Valuation Of Ecosystem Services

scholarly journals Object-based analysis of UAS imagery to map emergent and submerged invasive aquatic vegetation: a case study

2017 ◽  
Vol 5 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Dominique Chabot ◽  
Christopher Dillon ◽  
Oumer Ahmed ◽  
Adam Shemrock
Keyword(s):  
Image Analysis ◽  
Data Collection ◽  
Near Infrared ◽  
Aquatic Vegetation ◽  
Weather Conditions ◽  
Classification Performance ◽  
Unmanned Aircraft ◽  
Automated Image Analysis ◽  
Object Based

Small unmanned aircraft systems (UAS) combined with automated image analysis may provide an efficient alternative or complement to labour-intensive boat-based monitoring of invasive aquatic vegetation. A small mapping drone was assessed for collecting high-resolution (≤5 cm/pixel) true-colour and near-infrared imagery revealing the distribution of invasive water soldier (Stratiotes aloides) in the Trent–Severn Waterway, Ontario (Canada). We further evaluated the capacity of an object-based image analysis approach based on the Random Forests classification algorithm to map features in the imagery, chiefly emergent and submerged water soldier colonies. The imagery contained flaws and inconsistencies resulting from data collection in suboptimal weather conditions that likely negatively impacted classification performance. Nevertheless, our best-performing classification had a producer’s and user’s accuracy for water soldier of 81% and 74%, respectively, an overall accuracy of 78%, and a kappa value of 61%, indicating “substantial” accuracy. This trial provides an instructive case study on results achieved in a “real-world” application of a UAS for environmental monitoring, notably characterized by time constraints for data collection and analysis. Beyond avoiding data collection in unfavourable weather conditions, adaptations of the image segmentation process and use of a true discrete-band multispectral camera may help to improve classification accuracy, particularly of submerged vegetation.

scholarly journals Flow Resistance in Lowland Rivers Impacted with Distributed Aquatic Vegetation

2021 ◽  
Author(s):  
Saeid Okhravi ◽  
Radoslav Schügerl ◽  
Yvetta Velísková
Keyword(s):  
Cross Sections ◽  
Flow Resistance ◽  
Aquatic Vegetation ◽  
Roughness Coefficient ◽  
Sources Of Resistance ◽  
Lowland Rivers ◽  
Lowland Streams ◽  
Resistance Factors ◽  
Seasonal Flow ◽  
Bed Roughness

Abstract The study addresses the research concern that the employment of fixed value for bed roughness coefficient in lowland rivers (mostly ‌sand-bed rivers) is deemed practically questionable in the presence of a mobile bed and time-dependent changes in vegetation patches. To address this issue, we set up 45 cross-sections in four lowland streams to investigate seasonal flow resistance values within a year. The results first revealed that the significant sources of boundary resistance in lowland rivers with lower regime flow are bed forms and aquatic vegetation. Then, the study uses flow discharge as an influential variable reflecting the impacts of the above-mentioned sources of resistance to flow. The studied approach ended up with two new flow resistance predictors which simply connect dimensionless unit discharge with flow resistance factors, Darcy-Weisbach (f) and Manning (n) coefficients. A comparison between the computed and measured flow resistance values indicates that 87-89% of data sets were within the ±20% error bands. The flow resistance predictors are also verified against large independent sets of field and flume data. The obtained predictions using the developed predictors may overestimate flow resistance factors to about 40% for other lowland rivers. From a different view of this research, the findings on seasonal variation of vegetation abundance hint at the augmentation in flow resistance values, both f, and n, in low summer flows when the vegetation covers river bed and side banks. The highest amount of flow resistance was observed during the summer period, July-August.

scholarly journals Effects of Habitat Types on Macroinvertebrates Assemblages Structure: Case Study of Sun Island Bund Wetland

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Nagam Khudhair ◽  
Cai Yan ◽  
Manhong Liu ◽  
Hongxian Yu
Keyword(s):  
Aquatic Vegetation ◽  
Diversity Index ◽  
Vegetation Type ◽  
Habitat Type ◽  
Diversity Indices ◽  
Sediment Type ◽  
Habitat Types ◽  
Type Water ◽  
Richness Index

Sun Island Bund Wetland (SIBW) is a river floodplain wetland located at the south part of Heilongjiang Province in Northeast China. An investigation of the influence of habitat type on macroinvertebrates assemblages structure was conducted in July 2016. Nine (9) sampling sites were selected based on sediment type, water condition, and aquatic vegetation type. Macroinvertebrates attributes including density, biomass, and four diversity indices (Simpson diversity index, Margalef richness index, Shannon-Weiner index, and Pielou evenness index) were assessed. A total of 53 taxa were collected during the study period, with the highest density dominated being from aquatic insects and gastropods.Bellamya purificataandExopalaemon annandaleiwere the most dominant among all the species. The results showed that the assemblages structure of macroinvertebrates in different habitats was significantly different. Also, the results with PCA showed that the higher values of invertebrates density, biomass, diversity indices, and species richness had a greater association with the habitat types of silt-humus sediment, closed lentic area, and submerged-flouting-emergent vegetation.

Scale effect on the anisotropy characteristics of rock joint roughness

2021 ◽  
pp. qjegh2020-066
Author(s):  
Shi-Gui Du ◽  
Kai-Qian Du ◽  
Rui Yong ◽  
Jun Ye ◽  
Zhan-You Luo
Keyword(s):  
Scale Effect ◽  
Rock Joint ◽  
Rock Joints ◽  
Roughness Coefficient ◽  
Scale Dependency ◽  
Joint Roughness Coefficient ◽  
Local Anisotropy ◽  
Joint Roughness ◽  
Threshold Length

Accurate assessment of anisotropy and scale effect of rock joint roughness is essential for evaluating the mechanical behaviour of rock joints. However, in previous studies, how to quantify roughness anisotropy of rock joints remains largely unsolved, and the research about scale effect on roughness anisotropy is not conclusive. A statistical analysis on joint roughness coefficient of different sized profiles was implemented to investigate the scale-dependency of joint roughness. The scale effect on the roughness anisotropy were investigated based on class ratio transform approach. The roughness anisotropy was characterized by local anisotropy and global anisotropy. The global anisotropy tends to be almost constant when the sample size exceeds the stationarity threshold length of 70 cm. The result shows that the global anisotropy is scale-dependent. However, the scale effect on local anisotropy is less apparent. The case study indicates that the class ratio transform approach implies its superiority in roughness anisotropy investigation.

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