How Does a Climate Change Influence Water Resources?

Topics: Hydrology, Water, Water management Pages: 10 (3145 words) Published: November 30, 2008
How does a climate change influence water resources?

Climate change is the biggest challenge that we face in the world today. It is already leading to significant changes in the world’s physical environment. Extreme weather events are becoming more frequent. Glaciers are melting. Sea ice and snow cover are declining. Animals and plants are responding to earlier seasons. Global warming has already driven up mean sea levels by 110-20 centimetres during the last 100 years, and this is forecast to rise by up to another 88 centimetres by 2100. In this essay I will discuss how climate change influences water resources and how the impact of climate change on hydrology can be minimised.

Water is essential to human life and many of life’s activities, from direct issues such as drinking water and agriculture, to other essential modern activates such as industry and power generation. Consequently, there have been a number of studies into the potential effects climate change can have on hydrology and water resources. These studies are usually estimated by constructing scenarios for changes in climatic inputs to a hydrological model from the output of general circulation models (G.C.M’s). The main motive for creating such a model is to better understand how climate changes affect hydrology so it is paramount that these models are appropriate for measuring the impact on water quantity and quality.

Such research over time is vital, as it will help predict future changes and in particular seasonal flow predictions. As sea levels rise due to increases in global temperatures the risks of flooding are much higher and therefore a greater emphases on water management based on the minimisation and adaptation to these changes in capacity must be made (I.E. flood defences). Also as climate change affects the quality and quantity of water, supply strategies must adapt. These practices will have a major impact on how climate change will affect the water sector and in some countries water managers regard climate change exclusively, as S. Subak explains:

2In the UK, water supply companies were required by regulators in 1997 to “consider” climate change in estimating their future resource.

A major concern with climate change is the possibility of changes in the hydrologic cycle. The hydrologic cycle (or the water cycle), describes the continuous movement of water on, and below the surface of the Earth And any changes to the cycle can be disastrous. The variation of water is mainly influenced by precipitation and changes can have devastating effects on hydrology and therefore water resources, such as the frequency of which floods and droughts occur. Effects have been observed showing in general that the Northern hemisphere has had more rainfall and the tropics and subtropics less rainfall than in previous years. Along with this, 3T. J Osborn monitored that the occurrence of intense rainfall has risen in the United Kingdom and 4HadCM2 experiments show a rise in the relative inconsistency of seasonal and annual precipitation levels as a result of climate change.

With the increase in droughts agriculture will suffer, as the amount of water held in the ground is vital to the growth of vegetation. Simulations of soil moisture conducted by 5Gregory et al show that with an increase in greenhouse gases is directly linked with lower levels of soil moisture in the Northern Hemisphere. It is also thought that climate change may affect the capacity of water that soil can hold as Boix-Fayos et al. explains:

6‘Infiltration and water-holding capacity of soils on limestone are greater with increased frost activity’.

This shows that if temperatures increase and freezing is less frequent then typical moisture may not be absorbed by the soil. Therefore during the increased winter rainfall (rather than snow or hail), the amount of effective rainfall, which would be absorbed and consequently recharge the soil, will decrease, as the soil can no longer...

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2Subak, S., 2000: Climate change adaptation in the U.K
3Osborn, T.J., M. Hulme, P.D. Jones, and T.A. Basnet, 2000: Observed trends in the daily intensity of United Kingdom precipitation. International Journal of Climatology, 20, 347–364
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5Arnell, N.W., 1999b: Climate change and global water resources. Global Environmental Change, 9, S31–S49
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