MODELING AND FORECASTING MONTHLY AVERAGE WATER LEVELS BASED ON THE ELLIPTIC ORBIT MODEL

2015 ◽  
Vol 28 (2) ◽  
pp. 109-132 ◽  
Author(s):  
ZONG-CHANG YANG
Keyword(s):  
Water Levels ◽  
Elliptic Orbit ◽  
Monthly Average ◽  
Modeling And Forecasting ◽  
Average Water ◽  
Elliptic Orbit Model ◽  
Orbit Model

Shift in wetland plant composition and biomass following low-level episodes in the St. Lawrence River: looking into the future

2004 ◽  
Vol 61 (4) ◽  
pp. 603-617 ◽  
Author(s):  
Christiane Hudon
Keyword(s):  
Plant Biomass ◽  
Lythrum Salicaria ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Terrestrial Plants ◽  
Hydrologic Variability ◽  
Najas Flexilis ◽  
Average Water ◽  
Similar Episode ◽  
St Lawrence River

The effects of a 1-m drop in average water levels in 1999 on species composition and biomass were documented for a St. Lawrence River wetland and compared with a similar episode in 1931. These observations highlight the manifold effects of past and future water level fluctuations on St. Lawrence River wetlands and faunal habitats, resulting from natural hydrologic variability, climate change, and (or) human intervention. In 1931 and 1999, waters were 2–3 °C warmer than the previous 10-year average. Low water levels markedly altered wetland vegetation: various Graminea (including Phalaris arundinacea and Phragmites australis) and facultative annual species invaded previously marshy areas. Submerged species previously found in shallow waters were replaced on dry ground by annual terrestrial plants; Alisma gramineum colonized emergent waterlogged mudflats. The low water levels of 1999 induced a spatially discontinuous plant biomass that was richer in terrestrial material than in previous years (1993–1994). In comparison with the 1930s, recent surveys indicate a decline of assemblages dominated by Equisetum spp. and Najas flexilis and a rise of those dominated by Lythrum salicaria, Potamogeton spp., and filamentous algae. These shifts reveal the additional effects of nutrient enrichment, alien species, and shoreline alteration accompanying a change from a mostly agricultural to a mostly urbanized and industrialized landscape.

scholarly journals Algal Boom Characteristics of Yeongsan River Based on Weir and Estuary Dam Operating Conditions Using EFDC-NIER Model

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2295
Author(s):  
Darae Kim ◽  
Changmin Shin
Keyword(s):  
Water Level ◽  
Algal Blooms ◽  
Water Security ◽  
Water Levels ◽  
Operating Conditions ◽  
The Yellow Sea ◽  
Management Level ◽  
Average Water ◽  
Reduced Water ◽  
Regional Water

A number of hydraulic structures have been installed along the Yeongsan River, including an estuary dam and two weirs (Seungchon and Juksan). While these structures aid in regional water security and use and reduce flooding, they reduce water flow in the summer, thereby frequently causing algal blooms. This study simulated algal bloom and water quality characteristics of sections of the Yeongsan River in South Korea under different weir and estuary dam operating conditions using the Environmental Fluid Dynamics Code—National Institute of Environment Research (EFDC-NIER) model. Results showed that when the management levels of the Juksan Weir and estuary dam were maintained, simulated water levels were EL. 3.7 m in the weir section and EL. −1.2 m (below average water level of the Yellow Sea) in the dam section. When both the weir and dam were open, the water levels varied with the tide; in contrast, when the Juksan Weir alone was open, the water level was between EL. −1.2 and −0.9 m, in line with the management level of the estuary dam. Opening the weir alone reduced algal blooms by 72–84% in the weir region, and opening the estuary dam alone reduced the algal blooms by 83% in the dam region. This improvement was attributed to the reduced water retention time and dilution due to seawater inflows.

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