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Water in the 21st Century

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A Double-Edged Sword: Floods and Droughts

Floods and droughts have always been features of life on earth and have produced some of the worst natural disasters in recorded history. Due to inappropriate land use and land management practices, uncoordinated and rapid growth of urban areas, and loss of natural flood storage wetlands, floods are becoming more frequent. According to the Office of the United Nations Disaster Relief Coordinator, flooding is the hazard that affects more people than any other. Associated damage to property is escalating. Concurrently, destruction of forest cover has altered the hydrologic cycle and reduced water retention in forest soils. Accompanying soil erosion has permanently stripped fertile topsoil from vast areas, leading to further degradation of river basins and threatening the basis for sustainable natural resource management. Global climate change will have unpredictable but potentially devastating consequences for the hydrologic cycle by changing the total amount of precipitation, its annual and seasonal distribution, the onset of snowmelt, the frequency and severity of floods and droughts, and the reliability of existing water supply reservoirs. According to the Intergovernmental Panel on Climate Change, the frequency of droughts could rise by 50 percent in certain parts of the world by 2050.

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