scholarly journals Determination of ecological water-level in the eastern Lake Dongting with hydrological alterations

2013 ◽  
Vol 25 (3) ◽  
pp. 330-334 ◽  
Author(s):  
LIANG Jie ◽  
◽  
PENG Yeru ◽  
GUO Shenglian ◽  
LI Xiaodong ◽  
...  
Keyword(s):  
Water Level ◽  
Ecological Water Level

scholarly journals Simplified Lake Surface Area Method for the Minimum Ecological Water Level of Lakes and Wetlands

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1056 ◽  
Author(s):  
Songpu Shang ◽  
Songhao Shang
Keyword(s):  
Water Level ◽  
Surface Area ◽  
Lake Level ◽  
Lake Ecosystem ◽  
Lake Surface ◽  
Area Method ◽  
Ecosystem Protection ◽  
Lake Morphology ◽  
Lake Surface Area ◽  
Ecological Water Level

The determination of the rational minimum ecological water level is the base for the protection of ecosystems in shrinking lakes and wetlands. Based on the lake surface area method, a simplified lake surface area method was proposed to define the minimum ecological lake level from the lake level-logarithm of the surface area curve. The curve slope at the minimum ecological lake level is the ratio of the maximum lake storage to the maximum surface area. For most practical cases when the curve cannot be expressed as a simple analytical function, the minimum ecological lake level can be determined numerically using the weighted sum method for an equivalent multi-objective optimization model that balances ecosystem protection and water use. This method requires fewer data of lake morphology and is simple to compute. Therefore, it is more convenient to use this method in the assessment of the ecological lake level. The proposed method was used to determine the minimum ecological water level for one freshwater lake, one saltwater lake, and one wetland in China. The results can be used in the lake ecosystem protection planning and the rational use of water resources in the lake or wetland basins.

scholarly journals METHODOLOGY FOR HYDRAULIC CALCULATION OF RIVER REGULATION AND DETERMINATION OF DIKE PARAMETERS

2017 ◽  
Vol 16 (4) ◽  
pp. 298-303
Author(s):  
E. I. Mikhnevich
Keyword(s):  
Water Level ◽  
Water Flow Rate ◽  
Flood Plain ◽  
River Regulation ◽  
Hydraulic Calculation ◽  
Design Parameters ◽  
Flood Water ◽  
River Bed ◽  
Belt Width

Territory protection against flood water inundation and creation of polder systems are carried out with the help of protection dikes. One of the main requirements to the composition of polder systems in flood plains is a location of border dikes beyond meander belt in order to avoid their erosion when meander development occurs. Meander belt width can be determined on the basis of the analysis of multi-year land surveying pertaining top river-bed building and in the case when such data is not available this parameter is calculated in accordance with the Snishchenko formula. While banking-up a river bed a flooded area is decreasing and, consequently, water level in inter-dike space and rate of flood water are significantly increasing. For this reason it is necessary to locate dikes at a such distance from a river bed which will not cause rather high increase in water level and flow velocity in the inter-dike space. Methodology for hydraulic calculation of river regulation has been developed in order to substantiate design parameters for levee systems, creation of favourable hydraulic regime in these systems and provision of sustainability for dikes. Its main elements are calculations of pass-through capacity of the leveed channel and rise of water level in inter-dike space, and distance between dikes and their crest level. Peculiar feature of the proposed calculated formulae is an interaction consideration of channel and inundated flows. Their mass-exchanging process results in slowing-down of the channel flow and acceleration of the inundated flow. This occurrence is taken into account and coefficients of kinematic efficiency are introduced to the elements of water flow rate in the river channel and flood plain, respectively. The adduced dependencies for determination of a dike crest level (consequently their height) take into consideration a rise of water level in inter-dike space for two types of polder systems: non-inundable (winter) dikes with maximum spring flood rate and inundable (summer) dikes with summer-autumn flood rates. The proposed calculated formulae can be recommended for application at design organizations.

Determination of Survey Boat “Heave” Motion with the Use of RTS Technique

2017 ◽  
Author(s):  
Dariusz Popielarczyk
Keyword(s):  
Water Level ◽  
Vertical Movement ◽  
Bathymetric Survey ◽  
Total Station ◽  
Vistula River ◽  
Level Data ◽  
Water Level Data ◽  
Hydroacoustic Measurements ◽  
Heave Motion

The paper presents analysis of determination of vertical movement of the surveying boat called “heave” with the use of Robotized Total Station (RTS) technique. The classical geodetic Total Station was used for sub-centimeter calculation of water level changes during hydroacoustic measurements on the fragment of Vistula river behind the dam and hydropower in Włocławek in Poland. The power station work causes up to 1.7 m movement of vertical reference water surface in aspect of local bathymetric survey. The experimental, hydrographic surveys on the river were conducted where the water level was changing significantly over time depending on the operational schedule of the power plant. Verified hydrographic data had to be brought to the common water level. To determine the final water level, data on the height of the Robotized Total Station prism positioned on the boat during sounding was considered. The RTS technique with 0.02–0.05 m vertical accuracy proved to be very useful and essential in engineering inland bathymetric measurements.

scholarly journals Influence of water level fluctuation on the mortality and aboveground biomass of the aquatic macrophyte Eleocharis interstincta (VAHL) roemer et schults

2004 ◽  
Vol 47 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Anderson Medeiros dos Santos ◽  
Francisco de Assis Esteves
Keyword(s):  
Water Level ◽  
Aboveground Biomass ◽  
Aquatic Macrophyte ◽  
Sampling Period ◽  
Water Level Fluctuations ◽  
Northern Coast ◽  
Significant Difference ◽  
Influence Of Water ◽  
Response To Water

The goal of this study was to study the biometric alterations of Eleocharis interstincta in response to water level fluctuations in Cabiúnas Lagoon, located on the northern coast of the state of Rio de Janeiro, in the municipality of Macaé. Three quadrats of 0.0625 m² were harvested every two weeks from June/1997 to June/1998; samples were separated into stems, dead stems (detritus) and rhizome; lenghted, dried and weighted. The water level fluctuated seasonally in the macrophyte stand with two periods of drawdown. The first period occurred naturally at the end of winter and beginning of spring, when rainfall in the area was normally lowest. The second period of drawdown was the result of an artificial breaching of the sandbar that isolate the lagoon from the sea. The breach was made in the summer, at the time of highest rainfall, when the water level in the lagoon reached the maximum value recorded during the study (1.35 m). There was a strongly positive correlation of the water level with stems mean height and aboveground biomass, indicating that water level played an important role in the determination of these parameters. There was a significant difference between stem height (ANOVA; p < 0.001) and biomass (ANOVA; p < 0.001) in each sampling period, ranging from 143.9 cm and 338.8 g dry wt.m-2, before the sandbar opening, to 16.3 cm and 20.2 g dry wt.m-2 respectively after the sandbar breaching. The drastic variation of the water level, leading mass mortality of the stems, together with the lowest mean biomass/stem (0.057 g dry wt.individual-1), recorded after the sandbar breaching, did not represent a strong disturbance for E. interstincta, since the resilience time estimated for this population was about 30 days.

scholarly journals Determination of Dynamic Under Keel Clearance of Maneuvering Ship

2008 ◽  
Vol 8 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Wiesław Galor
Keyword(s):  
Water Level ◽  
Economic Benefit ◽  
Water Level Change ◽  
Ship Manoeuvring ◽  
Level Change ◽  
Wave Response

Determination of Dynamic Under Keel Clearance of Maneuvering Ship The safety of navigation of a ship manoeuvring within port waters mainly depends on its under keel clearance (UKC). Mainly UKC depends on water level change, squatting of moving ship and heeling and wave response. The effect of these components will be determined currently than such UKC is called as dynamic under keel clearance. The paper presents an analysis of certain components of UKC to maximise of ship draft and thus to achieve the economic benefit to port and ships owner.

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