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Archive for Lakes

Pollution Threats to Lake Mead, USA

36.1N 114.4W

June 12th, 2013 Category: Lakes MODISAqua

USA – June 9th, 2013

Two large artificial reservoirs can be seen in this image of arid Western USA: Lake Mead (left) and Lake Powell (right). This week, a mysterious brown foam found floating on the surface of Lake Mead, in its northern extension, the Overton Arm. The foam was seen extending about eight miles from near the mouth of the Virgin River to Echo Bay.

Although the Southern Nevada Water Authority is monitoring water quality at two intakes and so far hasn’t found anything problematic, hundreds of dead fish were seen floating in the water near the foam.

Climate Change and Water Temperature of Lake Baikal, Russia

53.1N 107.6E

June 11th, 2013 Category: Climate Change, Lakes VIIRSSuomi-NPP

Russia – June 10th, 2013

Lake Baikal, the world’s largest, oldest, and most biotically diverse lake, is responding strongly to climate change, according to recent analyses of water temperature and ice cover. By the end of this century, the climate of the Baikal region will be warmer and wetter, particularly in winter. As the climate changes, ice cover and transparency, water temperature, wind dynamics and mixing, and nutrient levels are the key abiotic variables that will shift, thus eliciting many biotic responses.

Among the abiotic variables, changes in ice cover will quite likely alter food-web structure and function most because of the diverse ways in which ice affects the lake’s dominant primary producers (endemic diatoms), the top predator (the world’s only freshwater seal), and other abiotic variables. Melting permafrost will probably exacerbate the effects of additional anthropogenic stressors (industrial pollution and cultural eutrophication) and could greatly affect ecosystem functioning (click here for more information).

Lake Balkhash and Climate Change’s Effects on Lakes in Central Asia – June 11th, 2013

42.8N 81.3E

June 11th, 2013 Category: Climate Change, Deserts, Image of the day, Lakes VIIRSSuomi-NPP

Kazakhstan and China – June 10th, 2013

Lakes in arid regions of Central Asia, such as Lake Balkhash, in Kazakhstan (upper left), northwest of China’s Taklamakan Desert (below), act as essential components of regional water cycles, providing sparse but valuable water resource for the fragile ecological environments and human lives.

Lakes in Central Asia are sensitive to climate change and human activities, and great changes have been found since 1960s. Mapping and monitoring these inland lakes can improve our understanding of mechanism of lake dynamics and climatic impacts. Satellite altimetry provides an efficient tool of continuously measuring lake levels in these poorly surveyed remote areas.

Scientists have shown that alpine lakes are increasing greatly in lake levels during 2003-2009 due to climate change, while open lakes with dams and plain endorheic lakes decrease dramatically in water levels due to human activities, which reveals the overexploitation of water resource in Central Asia (click here for more information).

Desertification, Water Loss and Temperature Changes in the Aral Sea – June 9th, 2013

45.2N 59.8E

June 9th, 2013 Category: Climate Change, Image of the day, Lakes MODISAqua

Aral Sea – June 9th, 2013

The primary effect of the Aral Sea desiccation has been the significant loss of water in the sea. The water level has dropped approximately 23 meters since the onset of its primary sources of water being diverted. Although the water level has fluctuated up to a few meters in the past due to natural variability in the water flow from the rivers, by 1970, the water loss exceeded the limit of natural water level variation that has occurred in the past.

The desiccation of the Aral Sea has been accompanied by the change in the Sea Surface Temperature. We see that the summer SSTs have been increasing, while winter SSTs have been decreasing. This is expected because as the sea loses volume, its heat capacity is reduced, therefore it can warm up and cool off faster than before. The day to night variations in SSTs, which are responsible for the sea breezes, have also increased.

In a sense, Aral sea has started to exhibit a monsoon climate, which is characterized by seasonal climate change due to warming and cooling of the sea. The desiccation period was also characterized by less ice covering of the sea. This can be explained by the fact that increased salt concentration lowers the freezing point of water; therefore the temperature would now need to be lower for the water to turn into ice (click here for more information).

Sensitivity of Great Salt Lake, USA, to Climate Change

41.0N 112.4W

June 6th, 2013 Category: Climate Change, Lakes MODISTerra

USA – June 5th, 2013

The Great Salt Lake Basin is a closed basin, meaning that it does not drain to an ocean. The Great Salt Lake (above center) stands out as a collector and integrator of signals from climatic and anthropogenically-induced hydrologic change. These changes are recorded in ancient lake terraces, accumulated sediments, short-term lake level changes, and recent changes in lake water chemistry.

The Great Salt Lake Basin is a snow-dominated hydrologic system, and, as such, it is highly sensitive to climate change. Changes in the volume of the Great Salt Lake, which have been recorded since 1847, represent the integrated effects of all of the major components of the hydrologic cycle.

The steep topography in the region provides short distances from catchment areas to the regional base level. Transects within the basin can span a range of geologies, elevations, climates, ecosystems, and land uses.

There is a high degree of interannual variability in precipitation within the Great Salt Lake Basin. In addition, the precipitation distribution is not normal, with bimodal tendencies toward wet or dry periods.
The three major watersheds to the east of the Great Salt Lake (the Bear River, Weber River, and Utah Lake Watersheds) provide the vast majority of water, sediment, and contaminant flux to the Great Salt Lake.