Modification of running waters by humankind

• Published in: Stream Ecology pp. 305 - 342
• Main Author: Allan, J. David
• Format: Book Chapter
• Language: English; Japanese
• Published: Dordrecht Springer Netherlands 1995
• Subjects: Alien Species; Biotic Integrity; Instream Habitat; Large Woody Debris; Timber Harvest
• ISBN: 0412355302; 9780412355301
• DOI: 10.1007/978-94-011-0729-7_14

As Benjamin Franklin noted in 1772, ‘Rivers are ungovernable things, especially in hilly countries. Canals are quiet and very manageable.’ Perhaps no other ecosystems have been as significantly modified by human activity as have rivers and streams. From the dawn of agriculture we may presume that landscape changes due to farming, grazing and deforestation have influenced watershed characteristics direcdy and through effects on climate. Attempts to control the flow of rivers likewise date far back in time, and over human history there has been a continuous increase in the variety of ways and intensity with which humankind has modified the physical, chemical and biological nature of running waters. With our growing understanding of the tight coupling of the stream and its valley (Hynes, 1975), we now must recognize that our knowledge of pristine rivers is sparse, and most studies are of systems subject to varying degrees of modification from their ancestral state.