Seed heteromorphism in a population ofSpergularia mediain relation to the ambient vegetation density

The effect of vegetation in hydraulic computations can be significant. This effect is important for flood computations. Today, the necessary terrain information for flood computations is obtained by airborne laser scanning techniques. The quality and density of the airborne laser scanning information allows for more extensive use of these data in flow computations. In this paper, known methods are improved and combined into a new simple and objective procedure to estimate the hydraulic resistance of vegetation on the flow in the field. State-of-the-art airborne laser scanner information is explored to estimate the vegetation density. The laser scanning information provides the base for the calculation of the vegetation density parameter ωp using the Beer–Lambert law. In a second step, the vegetation density is employed in a flow model to appropriately account for vegetation resistance. The use of this vegetation parameter is superior to the common method of accounting for the vegetation resistance in the bed resistance parameter for bed roughness. The proposed procedure utilizes newly available information and is demonstrated in an example. The obtained values fit very well with the values obtained in the literature. Moreover, the obtained information is very detailed. In the results, the effect of vegetation is estimated objectively without the assignment of typical values. Moreover, a more structured flow field is computed with the flood around denser vegetation, such as groups of bushes. A further thorough study based on observed flow resistance is needed.

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Attenuation of Wave Energy Due to Mangrove Vegetation off Mumbai, India

Energies ◽

10.3390/en12224286 ◽

2019 ◽

Vol 12 (22) ◽

pp. 4286 ◽

Cited By ~ 1

Author(s):

Samiksha S. V. ◽

P. Vethamony ◽

Prasad K. Bhaskaran ◽

P. Pednekar ◽

M. Jishad ◽

...

Keyword(s):

Climate Change ◽

Drag Coefficient ◽

Wave Energy ◽

Measured Data ◽

Stem Diameter ◽

Coastal Hazards ◽

Sensitivity Analyses ◽

Vegetation Density ◽

Mangrove Vegetation ◽

Set Up

Coastal regions of India are prone to sea level rise, cyclones, storm surges, and human-induced activities, resulting in flood, erosion, and inundation, and some of these impacts could be attributed to climate change. Mangroves play a very protective role against some of these coastal hazards. The primary aim of the study was to estimate wave energy attenuation by mangrove vegetation using modeling, and to validate the model results with measurements conducted off Mumbai coast, where a mangrove forest is present. Wave measurements were carried out from 5–8 August 2015 at three locations in a transect normal to the coast using surface-mounted pressure-level sensors in spring tide conditions. The measured data presented wave height attenuation of the order of 52%. Model set-up and sensitivity analyses were conducted to understand the model performance with respect to vegetation parameters. It was observed that wave attenuation increases with an increase in drag coefficient, vegetation density, and stem diameter. For a typical set-up in the Mumbai coastal region having a vegetation density of 0.175 per m2, stem diameter of 0.3 m, and drag coefficient varying from 0.4 to 1.5, the model reproduced attenuation ranging from 49% to 55%, which matches reasonably well with the measured data. Spectral analysis performed for the cases with and without vegetation very clearly portrays energy dissipation in the vegetation area. This study also highlights the importance of climate change and mangrove vegetation.

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Predator Presence and Vegetation Density Affect Capture Rates and Detectability of Litoria aurea Tadpoles: Wide-Ranging Implications for a Common Survey Technique

PLoS ONE ◽

10.1371/journal.pone.0143733 ◽

2015 ◽

Vol 10 (11) ◽

pp. e0143733 ◽

Cited By ~ 4

Author(s):

Madeleine R. Sanders ◽

Simon Clulow ◽

Deborah S. Bower ◽

John Clulow ◽

Michael J. Mahony

Keyword(s):

Vegetation Density ◽

Litoria Aurea ◽

Survey Technique ◽

Capture Rates

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A MODEL FOR ESTIMATING ACTUAL EVAPOTRANSPIRATION FROM POTENTIAL EVAPOTRANSPIRATION

Hydrology Research ◽

10.2166/nh.1975.0012 ◽

1975 ◽

Vol 6 (3) ◽

pp. 170-188 ◽

Cited By ~ 212

Author(s):

K. J. KRISTENSEN ◽

S. E. JENSEN

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Root Zone ◽

Potential Evapotranspiration ◽

Actual Evapotranspiration ◽

Vegetation Density ◽

Rainfall Distribution ◽

Sugar Beets

A model for calculating the daily actual evapotranspiration based on the potential one is presented. The potential evapotranspiration is reduced according to vegetation density, water content in the root zone, and the rainfall distribution. The model is tested by comparing measured (EAm) and calculated (EAc) evapotranspirations from barley, fodder sugar beets, and grass over a four year period. The measured and calculated values agree within 10 %. The model also yields information on soil water content and runoff from the root zone.

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Numerical Study on Wave Attenuation of Tsunami-Like Wave by Emergent Rigid Vegetation

Journal of Earthquake and Tsunami ◽

10.1142/s1793431121500287 ◽

2021 ◽

pp. 1-28

Author(s):

K. Qu ◽

G. Y. Lan ◽

S. Kraatz ◽

W. Y. Sun ◽

B. Deng ◽

...

Keyword(s):

Solitary Waves ◽

Wave Energy ◽

Wave Attenuation ◽

Tsunami Wave ◽

Numerical Study ◽

Wave Model ◽

Indian Ocean Tsunami ◽

Vegetation Density ◽

Rigid Vegetation ◽

Total Wave

The extreme surges and waves generated in tsunamis can cause devastating damages to coastal infrastructures and threaten the intactness of coastal communities. After the 2004 Indian Ocean tsunami, extensive physical experiments and numerical simulations have been conducted to understand the wave attenuation of tsunami waves due to coastal forests. Nearly all prior works used solitary waves as the tsunami wave model, but the spatial-temporal scales of realistic tsunamis differ drastically from that of solitary waves in both wave period and wavelength. More recent work has questioned the applicability of solitary waves and been looking towards more realistic tsunami wave models. Therefore, aiming to achieve more realistic and accurate results, this study will use a parameterized tsunami-like wave based on wave observations during the 2011 Japan tsunami to study the wave attenuation of a tsunami wave by emergent rigid vegetation. This study uses a high-resolution numerical wave tank based on the non-hydrostatic wave model (NHWAVE). This work examines effects of prominent factors, such as wave height, water depth, vegetation density and width, on the wave attenuation efficiency of emergent rigid vegetation. Results indicate that the vegetation patch can dissipate a considerable amount of the total wave energy of the tsunami-like wave. However, the tsunami-like wave has a higher total wave energy, but also a lower wave energy dissipation rate. Results show that using a solitary instead of a tsunami-like wave profile can overestimate the wave attenuation efficiency of the coastal forest.

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Wave energy dissipation in the mangrove vegetation off Mumbai, India

10.5194/os-2017-49 ◽

2017 ◽

Author(s):

Samiksha S. Volvaiker ◽

Ponnumony Vethamony ◽

Prasad K. Bhaskaran ◽

Premanand Pednekar ◽

MHamsa Jishad ◽

...

Keyword(s):

Energy Dissipation ◽

Drag Coefficient ◽

Wave Height ◽

Wave Attenuation ◽

Coastal Region ◽

Measured Data ◽

Vegetation Density ◽

Mangrove Vegetation ◽

Wave Height Attenuation ◽

Set Up

Abstract. Coastal regions of India are prone to sea level rise, cyclones, storm surges and human induced activities, resulting in flood, erosion, and inundation. The primary aim of the study is to estimate wave attenuation by mangrove vegetation using SWAN model in standalone mode, as well as SWAN nested with WW3 model for the Mumbai coastal region. To substantiate the model results, wave measurements were carried out during 5–8 August 2015 at 3 locations in a transect normal to the coast using surface mounted pressure level sensors under spring tide conditions. The measured data presents wave height attenuation of the order of 52 %. The study shows a linear relationship between wave height attenuation and gradual changes in water level in the nearshore region, in phase with the tides. Model set-up and sensitivity analyses were conducted to understand the model performance to vegetation parameters. It was observed that wave attenuation increased with an increase in drag coefficient (Cd), vegetation density, and stem diameter. For a typical set-up for Mumbai coastal region having vegetation density of 0.175 per m2, stem diameter of 0.3 m and drag coefficient varying from 0.4 to 1.5, the model reproduced attenuation, ranging from 49 to 55 %, which matches well with the measured data. Spectral analysis performed for the cases with and without vegetation very clearly portrays energy dissipation in the vegetation area as well as spectral changes. This study has the potential of improving the quality of wave prediction in vegetation areas, especially during monsoon season and extreme weather events.

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