Rainstorms destroy, yet recharge water systems

Floods can destroy lives, urban infrastructure and pollute the environment, yet floods can recharge groundwater resources and make agricultural lands more fertile.

Floods can destroy lives, urban infrastructure and pollute the environment, yet floods can recharge groundwater resources and make agricultural lands more fertile. Too much rain in Europe is challenging government leaders, but annual floods and drought in India call for the widespread introduction of traditional rainwater harvesting to provide clean drinking water and recharge aquifers, according to the award-winning Centre for Science and Environment (CSE).

Floods and droughts are intensifying in Europe, while Atlantic hurricane forces have reached a ferocity that has left the US Gulf coast, particularly Louisiana, Mississippi, Alabama, devastated.

Extreme floods also wreaked havoc in the western states of Gujarat and Maharashtra, claiming more than 1,000 lives in July. On 26 July, 37.16 inches (944 mm) fell within a 24-hour period in western India, and yet the number of Indian villages suffering from drought is increasing yearly, according to the Conservation Science Institute.

More than ever, governments worldwide must take action to prevent floods and to reduce damages to life, property and infrastructure. Increasingly frequent and intense rainfall causes flash floods, erodes soil, overwhelms water and wastewater treatment plants, ruptures underground pipelines, damages water distribution systems, and contaminates water.

Global weather patterns are changing. Temperatures are rising. Warmer ocean temperatures are creating conditions that spawn hurricanes with far greater power in the Atlantic. Warmer temperatures in Europe are changing precipitation patterns, such that more rainfall instead of snowstorms are taking place in winter, resulting in immediate surface runoff. In typical winters, the slow meltdown of snow that occurs as spring approaches enables rivers to better handle the flow. Moreover, human activities such as deforestation, urban development on former flood plains, and even the “straightening” or canalization of rivers have increased the likelihood and severity of floods throughout the world.

This month’s cover article, “Climate change project produces tools to cope with increasing rainfall,” by Ken Farrer, the vice chairman of the global environmental consultancy MWH UK, discusses the results of a research project completed last year that predicted changes in future rainfall patterns in the UK. The project also developed ways to gain a better understanding of UK rainfall patterns in order to assess the impact on sewerage system performance. Researchers from MWH, HR Wallingford, the UK Meteorological Office and Imperial College (UK) predicted that summers are becoming drier, but less frequent rainstorms are likely to be more severe, with greater rainfall intensity, Farrer reports. This increase in rainfall will result in more flooding and overflows in combined sewage overflows.

More rain is coming, but constructive action is possible - upgrading sewers and drainage systems to handle larger volumes; designing more sustainable urban drainage systems; and even alternative solutions such as “using roads to divert flows rather than putting in bigger pipes,” according to Ian Noble of MWH UK.

The European Environment Agency reports several disturbing trends on the European continent that is prompting the governments of affected countries in central, northern and northeastern Europe to take concerted action on flood risk management. First, the EEA reports that annual precipitation increased over northern Europe by 10% to 40% during the period 1900 to 2000, while parts of southern Europe experienced a 20% decrease. The EEA also projects that “by 2070, river discharge is estimated to decrease by up to 50% in southern and eastern Europe, and to increase by up to 50% or more in many parts of northern or northeastern Europe.”

In contrast, droughts often follow floods in India, says Ms. Sunita Narain, the dynamic director of the Centre for Science and Environment (CSE), who contends that poor water management, not water scarcity, causes water supply shortages. Rain falls a total of 100 hours each year in India, Ms. Narain explained, so rainwater must be collected locally and stored for future use. The CSE was awarded the 2005 Stockholm Water Prize for successfully advocating new thinking on traditional water management systems, particularly rainwater harvesting, to solve severe water shortages. India can solve its water problems by creating a culture that emphasizes decentralization and democratic operations, while adopting traditional systems improved by efficient water use and reuse practices, Ms. Narain pointed out in her Stockholm Water Prize lecture during the World Water Week (22-26 August). Rainwater harvesting, practiced widely in different regions of India, captures rain in millions of storage systems - in tanks, ponds, stepwells and even rooftops - using it to recharge groundwater reserves for irrigation and drinking water needs.

Clearly, global weather patterns are changing, requiring countries to take serious steps to prevent future floods and reduce their impact - and to adopt sustainable systems where necessary to prepare for the inevitable cycle of drought and floods.

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