Indices of the status of freshwater resources for impact analyses

摘要

The sustainability of fresh-water use is increasingly becoming a topic of global concern. Adequate clean water is a fundamental necessity for human and ecological health. Indicators can be used to evaluate the vulnerability of freshwater systems. Thispaper reviews three freshwater indicators and their advantages and limitations. Simple indicators like the Falkenmark Index and the Water Scarcity Index are easy to use, but fail to delineate accurately a comprehensive picture of freshwater availability. In contrast, the Water Poverty Index covers wider aspects of freshwater availability and use. However, its complexity limits discrimination in international comparisons. The utility of indices depend on how well they assess the water demand and supplyof a country. It is understood that it is important to account for the water transferred due to traded goods. None of the indices considered here take this into account. The water footprint concept is based on consumption of water use which helps accounts for water traded in virtual form. The sustainability of water use depends upon the impact of water use and this varies spatially and temporally. The water footprint can be referenced to water resource indices for a better understanding of the impact ofwater use. For international comparisons to be valid they need to take into account the localized impact of water use. According to considered indicators of water availability, New Zealand is well endowed with freshwater resources compare to Australia,USA and Sri Lanka, but its high levels of water use reveal the need for vigilance to protect the country's valuable and renewable water resources.