A model based on satellite altimetry and imagery to evaluate water volume changes in a reservoir in Brazil

Abstract. Lakes and reservoirs are crucial elements of the hydrological and biochemical cycle and are a valuable resource for hydropower, domestic and industrial water use and irrigation. Although their monitoring is crucial in times of increased pressure on water resources by both climate change and human interventions, publically available datasets of lakes and reservoir levels and volumes are scarce. Within this study, a time series of variation in lake and reservoir volume between 1984 and 2015 were analysed for 135 lakes over all continents by combining the JRC Global Surface Water (GSW) dataset and the satellite altimetry database DAHITI. The GSW dataset is a highly accurate surface water dataset at 30 m resolution compromising the whole L1T Landsat 5, 7 and 8 archive, which allowed for detailed lake area calculations globally over a very long time period using Google Earth Engine. Therefore, the estimates in water volume fluctuations using the GSW dataset are expected to improve compared to current techniques as they are not constrained by complex and computationally intensive classification procedures. Lake areas and water levels were combined in a regression to derive the hypsometry relationship (dh/dA) for all lakes. Nearly all lakes showed a linear regression, and 42 % of the lakes showed a strong linear relationship with an R2 > 0.8 and an average R2 of 0.91. For these lakes and for lakes with a nearly constant lake area (coefficient of variation

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THIRST RESPONSE TO POST-EXERCISE FLUID REPLACEMENT NEEDS AND CONTROLLED DRINKING

Pensar en Movimiento Revista de Ciencias del Ejercicio y la Salud ◽

10.15517/pensarmov.v14i2.25853 ◽

2016 ◽

Vol 14 (2) ◽

pp. 1-16

Author(s):

Catalina Capitán-Jiménez ◽

Luis Fernando Aragón-Vargas

Keyword(s):

Plasma Volume ◽

Repeated Measures ◽

Fluid Replacement ◽

Water Volume ◽

Volume Changes ◽

Physically Active ◽

Post Exercise ◽

Repeated Measures Design ◽

Controlled Drinking ◽

Before And After

Perceived thirst (TP) was evaluated as a dependent variable: can it distinguish among several levels of acute dehydration, is it reliable, and how does it respond to the ingestion of a fixed water volume post exercise? In a repeated-measures design, eight physically active students (24.5±3.6 years, mean±SD), reported to the laboratory on four non-consecutive days. They remained at rest or exercised at 32±3°C db and 65±6% rh to a randomly assigned dehydration equivalent to 1, 2, and 3% of body mass (BM). Following exercise, participants ingested a fixed water volume of 1.20% BM in 30 minutes; urine output, TP and plasma volume changes were assessed every 30 minutes over 3 hours. Post-exercise TP was not different before and after showering (p = 0.860), but it was significantly different among conditions (TP = 2.50 ± 0.45, 4.44 ± 0.72, 6.38 ± 0.82, and 8.63 ± 0.18 for 0, 1, 2, and 3% BM, p = 0.001). TP was associated with net fluid balance (rpart = -0.62, p < 0.0001) but, soon after drinking, TP was the same regardless of dehydration (p>0.05). Thirst perception is valid and reliable in the absence of drinking but it responds inappropriately to water intake.

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Constitutive relations for volume change in unsaturated soils

Canadian Geotechnical Journal ◽

10.1139/t76-029 ◽

1976 ◽

Vol 13 (3) ◽

pp. 261-276 ◽

Cited By ~ 138

Author(s):

D. G. Fredlund ◽

N. R. Morgenstern

Keyword(s):

Volume Change ◽

Unsaturated Soils ◽

Soil Structure ◽

Constitutive Relations ◽

Water Volume ◽

Engineering Practice ◽

State Variables ◽

Volume Changes ◽

Stress Changes ◽

Measured Volume

Volume change constitutive relations for unsaturated soils are proposed from a semi-empirical standpoint. One equation describes the deformation of the soil structure and a second equation defines the volume of water present in the element. Each equation can be viewed as a three-dimensional surface with two independent stress state variables forming the abscissas.Uniqueness is tested by measuring volume changes resulting from stress changes in two orthogonal directions and comparing predicted and measured volume changes resulting from a stress change in a third direction. Samples of undisturbed Regina Clay and compacted kaolin showed good agreement between the predicted and measured volume changes for monotonic deformation of the soil structure. The agreement was not as close for the water phase. The variation was attributed to difficulties in measuring water volume changes over a long period of time. The laboratory results indicate that the proposed constitutive equations are of the appropriate form for use in engineering practice.

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Monitoring changes in the water volume of Hulun Lake by integrating satellite altimetry data and Landsat images between 1992 and 2010

Journal of Applied Remote Sensing ◽

10.1117/1.jrs.10.016029 ◽

2016 ◽

Vol 10 (1) ◽

pp. 016029 ◽

Cited By ~ 8

Author(s):

Jiajia Zheng ◽

Changqing Ke ◽

Zhude Shao ◽

Fei Li

Keyword(s):

Satellite Altimetry ◽

Water Volume ◽

Altimetry Data ◽

Landsat Images ◽

Hulun Lake ◽

Satellite Altimetry Data

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High Mountain Asia glacier elevation trends 2003–2008, lake volume changes 1990–2015, and their relation to precipitation changes

10.5194/tc-2018-238 ◽

2018 ◽

Cited By ~ 1

Author(s):

Désirée Treichler ◽

Andreas Kääb ◽

Nadine Salzmann ◽

Chong-Yu Xu

Keyword(s):

Reanalysis Data ◽

Tien Shan ◽

Water Volume ◽

High Mountain ◽

The Tibetan Plateau ◽

Volume Changes ◽

Spatially Resolved ◽

Lake Volume ◽

Precipitation Increase ◽

The Difference

Abstract. We present an updated, spatially resolved estimate of 2003–2008 glacier volume changes for entire High Mountain Asia (HMA) from ICESat laser altimetry data. The results reveal a diverse pattern that is driven by spatially greatly varying glacier sensitivity, in particular to precipitation availability and changes. We introduce a spatially resolved zonation where ICESat samples are grouped into units of similar glacier behaviour, glacier type, and topographic settings. In several regions, our new zonation reveals local differences and anomalies that have not been described previously. A step-increase in precipitation around 1997–2000 on the Tibetan Plateau (TP) caused thickening of glaciers in the Eastern Pamirs, Kunlun Shan and central TP by 0.1–0.7 m a−1. The thickening anomaly has a crisp boundary in the Eastern Pamir that continues just north of the central Karakoram. Glaciers in the south and east of the TP were thinning, with increasing rates towards southeast. The precipitation increase is reflected by growth of endorheic lakes in particular in the northern and eastern TP. We estimate lake volume changes through a combination of repeat lake extents from Landsat data and shoreline elevations from ICESat and the SRTM DEM for over 1300 lakes. The rise in water volume contained in the lakes corresponds to 4–25 m a−1, when distributed over entire catchments, for the areas where we see glacier thickening. The precipitation increase is also visible in sparse in-situ measurements and MERRA-2 climate reanalysis data, but less well in ERA Interim reanalysis data. Considering evaporation loss, the difference between average annual precipitation during the 1990s and 2000s suggested by these datasets is 34–100 m a−1, depending on region, which can fully explain both lake growth, and glacier thickening (Kunlun Shan) or glacier geometry changes (eastern TP). The precipitation increase reflected in these glacier changes possibly extended to the northern slopes of the Tarim Basin, where glaciers were nearly in balance in 2003–2008. Along the entire Himalaya, glaciers on the first orographic ridge, which are exposed to abundant precipitation, are thinning less than glaciers in the dryer climate of the inner ranges. Thinning rates in the Tien Shan vary spatially but are rather stronger than in other parts of HMA.

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