Impacts of Climate Change on River Systems

Water.  The most abundant substance on Earth, covering approximately 70.9% of the Earth's surface (EPA, 2012). It is essential for life, and found in all living organisms and is essential for human survival (UN, 2010).  However, for as much water is present on Earth, very little is useable.  Of all the water on the Earth 96.5% is found in the oceans, as salt water, which is unusable, this leaves only 2.5% as useable freshwater (Shiklomanov, 1993). Of this 2.5%; 0.3% is surface water like rivers and streams, 30% is in groundwater, and 70% is in snow and ice which, unless melted, is also unusable (USGS, 2013).  Igor Shiklomanov presented a similar breakdown of the water on the planet in his chapter in "Water in Crisis: A Guide to the World's Fresh Water Resources".  This shows just how important the sources of useable freshwater are to human society.  Because these limited sources provide the water needed for many aspects of our society including irrigation, industry, and domestic use (UN WATER, 2012). A breakdown of water use reported by the UN Water shows that these three sectors compromise the total water use for society.  The most prevalent of these is irrigation at 70%; as the human population continues to grow it can be expected that the need for freshwater for both irrigation and domestic use will only grow.  And in fact UN Water estimated that by 2025 the amount of water withdrawals will increase by 50% in developing countries and 18% in developed countries.  To ensure that water is available for current and future use, efforts need to be taken to ensure the water systems are sustainable. One region in which these efforts will be needed are the river systems, only 0.0147% of the total water on the planet yet they play a vital role in our society.