Runoff Problem: Water Wasted

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By: Zhi Chang Joo Hu

A lot has been discussed on the effects that global warming may have on the earth’s climate and its population, specially considering that one of the most affected resources is also one of the most important for human beings: fresh water. This resource takes more importance once considering the scarcity of fresh water in a place with water scarcity and dry climate as Los Angeles, a place on which most of the water has to be imported rather than being local. According to the Urban Water Management Plan from 2010 of the Los Angeles Department of Water and Power (LADWP) an astonishing 86% of LA’s water is imported, with the Los Angeles Aqueduct providing on average 36% of the city’s water supply and the Metropolitan Water District providing around 50%. Furthermore, of the remaining 14% local groundwater accounts on average for 12% and recycled water is only marginal –around 1-2%- annually (5-6).

As global warming creates changes in rain patterns and accelerate snowpack melting seasons, the water supply in southern California is compromised. Furthermore, the transportation of water over such long distances does not only mean that we are destroying local habitats on the water extraction places, but also wasting enormous amounts of energy for transportation. Needless to say, water also evaporates while it is being transported, evaporation that reduces the sustainability of water transportation even further.The actual situation is not sustainable anymore, something needs to change. It should be logical that the solution is to have a higher percentage of local water sources and  to use the water more efficiently -a topic that is discussed in another entry-.

Los Angeles Aqueduct, One of the many sources of LA's water. Source: Wikipedia (http://upload.wikimedia.org/wikipedia/commons/thumb/a/ac/First_Los_Angeles_Aqueduct_Cascades,_Sylmar.jpg/250px-First_Los_Angeles_Aqueduct_Cascades,_Sylmar.jpg)
Los Angeles Aqueduct, One of the many sources of LA’s water. Source: Wikipedia

It is necessary then to consider some ways on how to capture and reuse most of the water that is already on Los Angeles. One of the easiest ways to do this is by capturing most of the water that arrives in the form of rain. However, most of the water that comes into the LA area is not saved, but rather creates runoff, -or drainage of water to the ocean- as most of LA surface is impermeable. To make matters worse, runoff also brings most of the pollutants that are found in the street to the ocean, transforming it into “largest source of pollution to Southern California’s coastal waters.” (“Urban Runoff”) and causing up to 1.8  million cases of gastroenteritis per year (Los Angeles County: clean water, clean beaches measure 2).It is then necessary to implement solutions that will not only capture runoff pollution but also refill the underground aquifers, as otherwise more than 200 billion gallons of runoff water would be reaching the oceans (Los angeles County: clean water, clean beaches measure 1).

Water run off in Culver City. Note that all this water could be used instead for human purpouses instead of being wasted. Source: Universal Image Group
Water run off in Culver City. Note that all this water could be used instead for human purpouses instead of being wasted. Source: Universal Image Group

The second stage of this plan would be to recycle most of the used water in order to depend less on imported water sources. Some ways on which this idea can be done is in the form of grey water -water that is used, but that can be reused in other activities such as watering plants- or through wastewater treatment facilities. Although some people may argue that recycling water should be a priority given its ability to process more water, it is also a more expensive and difficult to implement -as they also have political implications-. As a result, runoff water capture should be a priority, not only because it will quickly supply water to LA, but will also stop runoff pollution to the oceans, its easier to implement in the short term and communities can be given incentives to cooperate.

Recycling water: One of the projects on the long run. Source: Department of Water Resources
Recycling water: One of the projects on the long run. Note that water could be used several times before reaching the ocean, and thus less water would be needed from external sources. Graph Source: Department of Water Resources
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