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Did
you know?
Reverse osmosis is the finest water filtration method known. This process will
allow the removal of particles as small as ions from a solution. It is used
to purify water and remove salts and other impurities in order to improve the
color, taste or properties of the fluid. R.O. uses a membrane that is semi-permeable,
allowing the fluid that is being purified to pass through it, while rejecting
other ions and contaminants from passing.
This technology uses a process
known as crossflow to allow the r.o. membrane to continually clean itself. This
is the reason of why an r.o. element can last many years before clogging or
need replacement. This
water purification process requires a driving force to push the fluid through
the membrane, and the most common force is household water pressure or pressure
from a booster pump. The higher the pressure, the larger the driving force and
efficiency.
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Climate
change and the water.
The
overwhelming scientific consensus is that global warming - the rise in
global temperatures caused by the buildup of carbon dioxide and other
emissions in the atmosphere that trap the sun's heat like a blanket -
poses a significant threat to our health, our economy, and our environment.
Read on to learn what global warming means for our rivers and water supply
- and what steps we can take to meet the challenges ahead. Climate change
is likely to have significant impacts on the availability of fresh water.
Already in short supply throughout many parts of the world, water for
human consumption, agriculture, and industry will be a major factor in
economic growth, ecological sustainability, and global conflict.
Research
was undertaken to make initial assessments of potential impacts of climate
change on stream flow and water balance in the western United States-a
region characterized by the shortage of water. Additionally, research
was conducted to address the need for models, which account for the spatial
magnitude and extent of hydrologic processes. The models need to handle
key parameters such as precipitation, soil moisture, and evaporation,
in response to changing climatic conditions. The models must account for
vegetation interactions with soil moisture. This is particularly important
for simulating regional vegetation response to climate change since vegetation
distribution is controlled in large part by the availability of soil moisture.
Research focused on developing and refining detailed watershed scale hydrology
models to address stream dynamics and water storage. Regional-scale modeling
research was directed toward developing physically and mechanically-based
water balance models, which can be spatially distributed at watershed,
regional, and continental scales. The research effort contributed to developing
methods for spatially distributing climatic data at scales appropriate
for the models, and providing these data bases to the climate change research
community. This ORD project has been completed; extensions of this research
are continuing within the US Geological Survey.
So
what does all this data and modeling mean? The increasing demand for water
by population and industrial growth is creating chronic water shortages
throughout the world (Revenga 2000). Add to this the potential impacts
of global climate change on water supplies and chronic shortages could
reach crisis levels. Throughout much of the western United States the
supply of water for human consumption, agriculture, and industry depends
on snow pack and reservoir storage. Most global climate warming scenarios
suggest warmer winters with more rainfall and less snowfall for much of
the western United States, which would substantially reduce snow accumulation
and shift the high flow season for many rivers from the spring to the
winter (Lettenmaier et. al. 1992).
A
substantial amount of the natural storage of winter precipitation that
presently occurs in the snow pack would be lost resulting in increased
spills in the winter and lower reservoir levels in the summer and fall
(Lettenmaier and Sheer 1991). A significant increase in flood hazard in
the western US could result from climate change, primarily due to an increase
in rain-on-snow events (Lettenmaier and Gan Water 2 1990). Such events
occur when warm, wet storms move over existing snow pack. Rapid melting
of the snow pack is the result of a combination of warm air temperature,
high wind and high humidity, which cause significant condensation on the
snow, and is particularly severe in forest openings and forest clear-cuts
(Marks et al. 1998). This research suggests that some mitigation of the
adverse effects of global climate change may be achieved by adapting land
and water management practices to changes in runoff patterns and maximizing
the protective effects of natural vegetation.
Global
climate changes are expected to be regional in nature, and affect land
cover and land use. Key to understanding such regional effects on water
supplies is the response of vegetation. Plant communities play a significant
role in regional energy and water balance. While hydrologic models designed
to simulate large river systems are good for operating reservoirs systems,
they are not adequate for predicting changes to regional water balance
and, hence, changes in regional vegetation (Marks et al.1993). Dolph et
al. (1991) developed a spatially distributed regional water balance model
to evaluate the sensitivity of large river basins to climate change. The
model was exercised for the Columbia River Basin. This research demonstrated
that the existing Historic Climate Network of climate monitoring stations
underestimate precipitation primarily because mountainous areas are underrepresented.
With climate warming, the model predicted increased evaporative loss,
decreased runoff and soil moisture.
These
conditions could have profound effects on vegetation distribution and
subsequently regional water resources. The ability to predict changes
in regional vegetation is necessary to evaluate the effects of climate
change on forest resources, agriculture, and water supplies. Changes in
soil moisture and evapo-transpiration resulting from climate will have
large impacts on water and vegetation. If changes in the regional water
balance are significant, major shifts in vegetation patterns and condition
are a likely (Marks et al. 1993). Neilson and Marks (1994) incorporated
a distributed water balance model with a vegetation model to produce a
biogeographic model, MAPSS (Mapped Atmosphere-Plant-Soil System). This
model was used to predict changes in vegetation leaf area index, site
water balance and runoff as well as changes in biome boundaries.
When
applied to potential climate change scenarios, two areas exhibiting among
the greatest sensitivity to drought- induced forest decline were determined
to be eastern North America and Eastern Europe to western Russia. How
will global warming affect rivers in these and other areas? Global warming
is projected to have far-ranging effects on rivers across the United States
and worldwide. Although these changes will vary from region to region,
scientists expect higher average global temperatures over the next century
to cause higher river temperatures, resulting in harm to freshwater fish
like salmon and bass and significant changes in aquatic plant and animal
habitat.
In
addition, rainfall patterns will shift -some areas will get more precipitation,
some less. Higher temperatures will cause mountain snow pack to melt earlier
in the year, causing significant changes to river flow patterns - with
less water available during the warmer and drier summer months. Changing
water levels in our rivers poses greater challenges for farming, manufacturing,
drinking water supplies and wildlife habitat. The supply of and demand
for water will be affected dramatically by these changes, as regions of
the country that currently have wet climates are expected to become drier
and vice versa.
Some
places may experience prolonged periods of drought, while others could
see a dramatic increase in rainfall and more frequent flooding. These
changes will have significant implications for a wide range of water uses,
including agriculture, industry, energy production, recreation, water
infrastructure/storage, waste disposal, and of course, healthy watershed
functions.
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