Edited by Douglas S. Kenney and Robert Wilkinson
2. Energy, water and the natural environment Melinda Kassen and Jack E. Williams INTRODUCTION: THE IMPORTANCE OF RIVERINE HABITATS TO THE NATURAL ENVIRONMENT 2.1. Flowing water shapes the world we live in. Rivers and streams carve canyons and build valleys. They provide us with sustenance and a place to recreate. They are a source of aesthetic pleasure and can even serve as a source of spiritual inspiration. However, most of the products and services that we realize from rivers and streams are largely taken for granted. When viewed in context with their riparian habitats, floodplains and watersheds, the benefits provided by river systems substantially increase. These systems not only provide drinking water, they purify it. They can moderate the impact of floods and lessen the severity of droughts. They slow runoff and erosion, recharge aquifers and maintain at least minimal baseflows in rivers, even during dry summers. Additionally, rivers and streams in North America support a wealth and diversity of living things, including over 1000 native, freshwater fish species (Williams and Miller, 1990), and more than 600 mayfly species (Hafele and Hughes, 2004). The ability of rivers and streams to provide these benefits is influenced profoundly by their health. The health of flowing waters can be determined by examining them for increases in rates of erosion, changes in flow regimes, resistance and resilience to disturbances such as floods and droughts, the loss of native species and the presence of invasive, nonnative species. In degraded or highly modified watersheds, precipitation is...
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