Quantitative Impacts of Lake-Level Stabilization on Material Transfer between Water and Sediment in Newnans Lake, Florida

1993 ◽  
Vol 50 (8) ◽  
pp. 1610-1616 ◽  
Author(s):  
J. F. Gottgens ◽  
T. L. Crisman
Keyword(s):  
Water Level ◽  
Water Level Fluctuations ◽  
Accumulation Rates ◽  
Material Transfer ◽  
Short Term ◽  
Lake Productivity ◽  
Lake Volume ◽  
Water And Sediment ◽  
Kjeldahl Nitrogen

Spillways at lake outlets reduce water-level fluctuations but may accelerate sedimentation in the lake. In eutrophic Newnans Lake, Florida, a transect of sedimentary profiles, dated with 210Pb and 137Cs by γ-ray spectroscopy, showed threefold increases in accumulation rates of organic matter, total Kjeldahl nitrogen (TKN), and total phosphorus (TP) 1200 m lakeward of a spillway since its construction in 1967. Concentrations of TKN and TP increased 3.5 and 2.4 times, respectively, in sediments deposited since 1967. These increases were progressively less at stations farther from the spillway. Postspillway accumulation of TP was focused toward the dam whereas recent TKN deposition was similar lakewide. Flocculent sediment (> 90% water) accumulated at 1.4 cm/yr. Dams designed to reduce water-level fluctuations may provide short-term benefits for lake access and navigation but in the long-term may accelerate deposition of nutrient-rich detritus, reduce lake volume, cloud the water, alter plant communities, and change lake productivity.

scholarly journals Effects of Lake level changes on water quality and fisheries production of Lake Baringo, Kenya

2021 ◽  
Author(s):  
Jacques Walumona ◽  
Boaz Arara ◽  
Cyprian Ogombe ◽  
James Murakaru ◽  
Phillip Raburu ◽  
...  
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Fish Species ◽  
Lake Level ◽  
Water Level Fluctuations ◽  
Regression Analyses ◽  
Lake Level Fluctuations ◽  
Lake Level Changes ◽  
Over Time

The study was conducted in Lake Baringo and determined quantitative relationships between water level changes, water quality, and fishery production for informed lake basin management. Long-term (2008 to 2020) data on water level, water quality, and fisheries yields from Lake Baringo were analyzed using a combination of statistical methods. Linear and waveform regression analyses described patterns of lake level fluctuations over time while, Pearson’s correlation determined the concordance of lake level changes with water quality parameters, landings, and condition of fish species. PCA results grouped the study period into different years based on annual water quality variable levels. LOWESS analysis showed the decline of annual lake level amplitude over time with peak values in 1964 (8.6 m) and 2008 (9.4 m). The waveform regression significantly modeled lake level fluctuations as indexed by annual deviations from the long-term average (DLTM) and showed a 20-year oscillation between peak water levels in the lake. There were significant positive correlations of Water Level Fluctuations (WLFs) with water quality variables and water quality index (WQI) in Lake Baringo. Linear regression analyses showed a significant concordance (p < 0.05) between the annual fishery yield and the rising WLFs (r = 0.66). Overall, the results demonstrate that WLFs of Lake Baringo are a driver of fish species biomass and physico-chemical properties of the lake. We recommend the integration of fisheries yields, water quality assessment, and WLFs modeling at different temporal scales in the management of Afrotropical lake ecosystems

scholarly journals Deducing Thickness Changes Of An Ice Sheet From Radio-Echo And Other Measurements

1975 ◽  
Vol 14 (70) ◽  
pp. 49-56 ◽  
Author(s):  
J. F. Nye ◽  
H. H. Wills
Keyword(s):  
Ice Sheet ◽  
Accumulation Rates ◽  
Short Term ◽  
The Past ◽  
Long Term Changes ◽  
Rate Of Accumulation

The displacement of the surface of an ice sheet and of markers set in its top layers can be measured geodetically, and also, it is expected, by radio-echo methods. The paper discusses how such measurements could be interpreted as showing long-term changes in the thickness of the ice sheet; in particular it discusses how one might design an experiment so as to avoid unwanted effects due to short-term changes in rate of accumulation. The analysis is similar to that of Federer and others (1970), but it corrects an error, so that when applied to their results for central Greenland it gives a different result for the lowering of the surface. Federer and others have already concluded that the average accumulation rates during the past 100 years have been below those needed to keep in balance with the velocity of the ice sheet as a whole. Using a particular model, it is found that this has resulted in the surface lowering at a mean rate of 0.050 m a−1 between 1871 and 1968, and a mean rate of 0.140 m a−1 between 1959 and 1968.

Pollen- and Diatom-Inferred Climatic and Hydrological Changes in Sumxi Co Basin (Western Tibet) since 13,000 yr B.P.

1993 ◽  
Vol 39 (3) ◽  
pp. 300-313 ◽  
Author(s):  
Elise Van Campo ◽  
Francoise Gasse
Keyword(s):  
Younger Dryas ◽  
The Tibetan Plateau ◽  
Tropical Africa ◽  
Short Term ◽  
Lake Volume ◽  
Dry Spell ◽  
Climatic System ◽  
Long Term Trend ◽  
Local Hydrology

AbstractAlthough the Tibetan Plateau greatly influences the atmospheric circulation of the Nortbern Hemisphere, few continuous paleoclimatic records are available from the plateau. A 13,000-yr pollen and diatom record from the Sumxi-Longmu Co basin in western Tibet gives information on major changes both in regional vegetation and in local hydrology. After the basin first filled ca. 13,000 yr B.P., a dry spell occurred about 10,500 yr B.P. within the interval spanned by the European Younger Dryas chronozone. A major environmental change occurred suddenly at ≈10,000 yr B.P., with the establishment of wet conditions, and was followed by a long-term trend toward maximum aridity, which lasted approximately 6000 yr. Short-term oscillations are superimposed on this general climatic change with a major reversal event about 8000 yr B.P. and a second wet pulse leading to a maximum lake volume ca. 7500-6000 yr B.P. Maximum aridity occurred 4300 yr B.P. The major environmental fluctuations recorded at Sumxi-Longmu Co appear in phase with climatic changes recognized in north tropical Africa, suggesting that the 8000 to 7000-yr-B.P. event was caused by an abrupt disequilibrium in the climatic system, as was the Younger Dryas and possibly the 4300-yr-B.P. event.

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