Dr (Ms.) Tanuja Ariyananda (President, International Rainwater Catchment Systems Association) delivered the key note speech on “Rain Water Harvesting and Climate Change” at the 14th International Rainwater Catchment Systems Association (IRSCA) Conference held from 3rd to 6th August 2009. She said that;
Climate change and global warming has become the most concern of the 21st Centaury. Meteorological observations demonstrate that 11 of the past 12 years (1995-2006) are among the warmest years on record in terms of the average temperature of the Earth’s surface. And associated with increasing temperatures of the atmosphere and the oceans is a proportionate increase in the content of water vapor in the atmosphere (for each degree Celsius of this increase, the air can theoretically absorb about 7% more water vapor).
This causes numerous long-lasting climatic changes of regional and continental significance. Already world is recording the occurrence of extreme heat waves and intensive showers increased and it is predicted that this trend will continue. Serious dry spells (droughts) have affected vast regions of Europe, Asia, Canada, western and southern Africa and eastern Australia. The number of heavy floods (100-200 year floods) also increased significantly during the second half of the 20th century.
In the 20th century, however, humanity reached a degree of development that allowed it, knowingly or unknowingly, to change the water cycle to an unprecedented extent, and these changes, caused by human activities (along with many other factors) have clearly occurred and are still occurring. The old paradigm, which considered water as an eternally renewable resource, has failed, the truth being that water is only a renewable resource as long as the water cycle is functional. A new paradigm is therefore needed which will carefully protect the fragile equilibrium of this water cycle.
In the new water paradigm, the water balance at all levels—on the territory of individual communities, within cities, in forests, on agricultural land—is the central theme. The new water paradigm means developing, utilizing and supporting overland rainwater harvesting and conserving rainwater in watersheds so that ecosystems can “produce” enough good quality water for humanity, food and nature, can purify polluted water, can reduce the risk of natural disasters like floods, droughts and fires, can stabilize the climate and strengthen biodiversity and can become a component of economically sustainable development programs. What the new water paradigm offers is promotion and support for such a culture of land use which will permanently renew water in the water cycle through saturation of the soil with rainwater. The new water paradigm means a return to a natural responsibility for the state of water in one’s region, but can also bring a new dimension of solidarity and tolerance between people and communities in watersheds.