The Colorado River transects the Colorado Plateau. The Colorado River is ranked the fifth largest river in the United States, and is often referred to as the Nile of North America. This nickname describes its arid location and the vast human population that relies upon it (Kammerer, 2005). Despite its size, fluctuations in Colorado River stream flow are sensitive to the seasonal and annual changes in precipitation and temperature typical in arid systems. Long periods of below-average precipitation and large diurnal changes in temperature place high evaporative demand on the river. Additionally, the Colorado River supplies water to over 33 million people (Environmental Defense Fund, 2013). It is the most over-allocated river in the world
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Average flow at the mouth of the Colorado River today is less than one-fifth its original flow 100 years ago (Krammerer, 2005). Low annual precipitation totals on the Colorado Plateau are punctuated by single high-precipitation events that often cause flooding along the river. Back-to-back extremely wet and extremely dry years shape the Colorado River corridor as well as the Colorado Plateau at large. The problem of too much water some years can eclipse the threat of having too little. For example, the 40-year period from 1964-2004 included the two lowest annual flows (1977, 2002) and the two highest annual flows (1983, 1984) on instrumental record. In 1983, the inflows to Lake Powell were so great that the outlet tunnels at Glen Canyon Dam were severely damaged. The same 40-yr period saw two multi-year wet periods sandwiching a 5-year drought, followed by the most severe multi-year drought in the entire record (Lukas, 2009). During flooding events, dramatic geomorphological changes may occur in the river channel. Cycles of erosion and deposition from flooding events rearrange erosion and depositional features within the channel and …show more content…
Drought, or prolonged dry conditions, is a natural part of life on the Colorado Plateau and more broadly in the Southwest. Tree-ring records have revealed that drought is a persistent feature in the region over centuries. Droughts of long duration, such as a 60-year event that occurred during the 1100’s, are present in the long-term tree-ring reconstructions. The most recent drought, which continues today, began in late 1999. The mostly wet conditions across the Plateau during the 1990’s yielded to more than a decade of below average precipitation. Impacts of the drought were felt almost immediately in 2000 and 2001 when stream flow measurements were only 74% and 73% of the long-term average respectively. The drought worsened in 2002, with only 41% of the average flow in the Colorado, the second-worst year on record (Lukas, 2009). The drought continued in 2003 and 2004, with flows into Lake Powell well below average. In April 2005 Lake Powell dropped to only 33% of capacity. Just last year because of dry soils and low precipitation, July flows in the Colorado River were 13% of “normal” (Lukas,
Average flow at the mouth of the Colorado River today is less than one-fifth its original flow 100 years ago (Krammerer, 2005). Low annual precipitation totals on the Colorado Plateau are punctuated by single high-precipitation events that often cause flooding along the river. Back-to-back extremely wet and extremely dry years shape the Colorado River corridor as well as the Colorado Plateau at large. The problem of too much water some years can eclipse the threat of having too little. For example, the 40-year period from 1964-2004 included the two lowest annual flows (1977, 2002) and the two highest annual flows (1983, 1984) on instrumental record. In 1983, the inflows to Lake Powell were so great that the outlet tunnels at Glen Canyon Dam were severely damaged. The same 40-yr period saw two multi-year wet periods sandwiching a 5-year drought, followed by the most severe multi-year drought in the entire record (Lukas, 2009). During flooding events, dramatic geomorphological changes may occur in the river channel. Cycles of erosion and deposition from flooding events rearrange erosion and depositional features within the channel and …show more content…
Drought, or prolonged dry conditions, is a natural part of life on the Colorado Plateau and more broadly in the Southwest. Tree-ring records have revealed that drought is a persistent feature in the region over centuries. Droughts of long duration, such as a 60-year event that occurred during the 1100’s, are present in the long-term tree-ring reconstructions. The most recent drought, which continues today, began in late 1999. The mostly wet conditions across the Plateau during the 1990’s yielded to more than a decade of below average precipitation. Impacts of the drought were felt almost immediately in 2000 and 2001 when stream flow measurements were only 74% and 73% of the long-term average respectively. The drought worsened in 2002, with only 41% of the average flow in the Colorado, the second-worst year on record (Lukas, 2009). The drought continued in 2003 and 2004, with flows into Lake Powell well below average. In April 2005 Lake Powell dropped to only 33% of capacity. Just last year because of dry soils and low precipitation, July flows in the Colorado River were 13% of “normal” (Lukas,