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Colorado River Delta

Colorado River Delta. SWES 574 Fall 2003 W.J. Ward. Rodriguez, C. A., Flessa, K. W., Tellez-Duarte, M. A., Dettman, D. L., and Avila-Serrano, G. A. (2001b). "Macrofaunal and isotopic estimates of the former extent of the Colorado River estuary,

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Colorado River Delta

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  1. Colorado River Delta SWES 574 Fall 2003 W.J. Ward

  2. Rodriguez, C. A., Flessa, K. W., Tellez-Duarte, M. A., Dettman, D. L., and Avila-Serrano, G. A. (2001b). "Macrofaunal and isotopic estimates of the former extent of the Colorado River estuary, upper Gulf of California, Mexico." Journal of Arid Environments, 49, 183-193.

  3. Outline Four Time Periods • Pre-Hover Dam (late 1800’s to 1932) • Post Hover Dam (1932 to 1996) • Current focus on Colorado Delta • Future

  4. Colorado River Factoids • Area drains over 242,000 square miles on its 1,450 mile course • Colorado flow rate max 7000 m3s-1 creating deposits 5 km thick in some areas. (average annual flow 60 year period (1906-65) is 15.09 million acre-feet • Colorado is saltiest carrying 9 million tons per year. Salinities were 32-35 l range now 35 – 45 l range • Flow irrigates over 1,000,000 acres in the United States and 500,000 acres in Mexico Source: Worster, 1985, & (Hoover Dam Web Site Hoover Dam Historyhttp://www.usbr.gov/lc/hooverdam/)

  5. Colorado Delta Factoids • Colorado river flowed into the Gulf of California forming a bay 50 miles wide. Each year the river deposited 140,000 acre feet of silt (214 sq. miles coved in 1 ft. of soil) • Colorado Delta was once 3000 sq. miles. Now ½ that size • The Salton Basin received flow from the Colorado river eight (8) times from 1824 to 1904 • 45 species in the United States segment of the Delta are now listed as endangered, threatened or sensitive (Hoover Dam Web Site Hoover Dam Historyhttp://www.usbr.gov/lc/hooverdam/)

  6. Aldo Leopold called the Delta “ a vast gallery forest of cottonwood, (Populus fremontii) and willow (Salix gooddingii) in the north interspersed with wetlands containing cattail (Typha domengensis) and common reed (Phragmites australis) in low areas and mesquite bosques (Prosopis glandulosa & Prospis pubescens) in higher terraces”. The endemic salt grass, Distichlis palmeri, dominated the estuarine zone. Beaver, jaguar and deer were in abundance and Egrets flocked in such numbers as to make the ground appear white in 1920. Glenn, E. P., Zamora-Arroyo, F., Nagler, P. L., Briggs, M., Shaw, W., and Flessa, K.(2001). "Ecology and conservation biology of the Colorado River Delta, Mexico." Journal of Arid Environments, 49, 5-15.

  7. Typical Colorado Delta Marsh – Early 1900’s

  8. Fort Yuma after Railroad Colorado river flooded town of Yuma in 1852, 1890, 1905, 1916, 1920. The river port of La Paz was left on high ground in 1868 by the Colorado river changing it’s course. Floods have occurred 1884, 1905, 1909, 1916, 1917, 1923, 1926, 1937, 1939, 1941, 1952, 1957, 1962, 1964, 1965, 1967. 1884 flood was 30.1 million acre-feet with discharge of 300,000 cubic feet per second. Interagency Committee (1970). "Lower Colorado Region Comprehensive Framework Study; app. 9, Flood Control." U. S. Pacific Southwest Inter-Agency Committee, 103.

  9. Sykes, 1937, Freshwater fish and saltwater fish at the mouth of the gulf were diminished in numbers as to almost be nonexistent. Bird life and many mammals such as raccoon and beaver were so diminished to have practically disappeared. (Sykes, 1937, The Colorado Delta.

  10. Zamora-Arroyo, F., Nagler, P. L., Briggs, M., Radtke, D., Rodriquez, H., Garcia, J., Valdes, C., Huete, A., and Glenn, E. P. (2001). "Regeneration of native trees in response to flood releases from the United States into the delta of the Colorado River, Mexico." Journal of Arid Environments, 49, 49-64.

  11. Current Colorado River Flow Today much of the area between channels is a vast monoculture of Tamarix ramosissima

  12. Bivalue mollusk Mulinia coloradoensis reduced to only small areas where they can still be found. Total living clams reduced by 95 % due to increased salinity and lower nutrients from sediment flows. Salinities were 32-35 l range now 35 – 45 l range. Rodriguez, C. A., Flessa, K. W., and Dettman, D. L.(2001a). "Effects of Upstream Diversion of Colorado River Water on the Estuarine Bivalve Mollusc Mulinia coloradoensis.“ Conservation Biology, 15(1), 249-258 .

  13. Changes in downstream water total flows, seasonal timing of flows, short-term fluctuations in flows, extreme high and low flows, & water quality such as temperature, nutrient load, turbidity, and dissolved gases, can dramatically change biodiversity.

  14. Biodiversity Changes • Meander cutting and abandonment of river channels leads to a geomorphologically diverse floodplain, and consequently the development of highly complex forest. • Channel incision or lowering the channel bed causing water table to decline greater than 1.5 m can greatly impact cottonwood trees. • Populus fremontii survived 1 cm sediment deposit by the time it reached 2 cm tall (approx. 2 weeks); Tamarix ramosissima at 4-6 cm tall (approx. 5 weeks). However, Tamarix ramosissima exhibited some survival after complete burial of 1-2 cm.

  15. Future Focus • 80-120 m3s-1 flow rates on the 140 km stretch between Morelos Dam and the Gulf is sufficient to bring the river out of its existing cannel and inundate the floodplain. A 3- month spring release is sufficient to germinate tree seedlings. Native trees, once established, can survive at least 4 years between floods by utilizing alluvial water tables that are 1-2 m below the surface along this stretch of the riparian corridor. Zamora-Arroyo, F., Nagler, P. L., Briggs, M., Radtke, D., Rodriquez, H., Garcia, J., Valdes, C., Huete, A., and Glenn, E. P. (2001). "Regeneration of native trees in response to flood releases from the United States into the delta of the Colorado River, Mexico.“ Journal of Arid Environments, 49, 49-64.

  16. References • Cohen MJ, Henges-Jeck C, Castillo-Moreno G, “A preliminary water balance for the Colorado River delta, 1992-1998”, J Arid Environ 49 (1): 35-48 Sep 2001 • Garcia-Hernandez J, Hinojosa-Huerta O, Gerhart V, et al.,”Willow flycatcher (Empidonax traillii) surveys in the Colorado River delta: implications for management”, J Arid Environ 49 (1): 161-169 Sep 2001 • Glenn EP, Zamora-Arroyo F, Nagler PL, et al., “Ecology and conservation biology of the Colorado River delta, Mexico”, J Arid Environ 49 (1): 5-15 Sep 2001 • Hayes, Rachel, “The Colorado River Delta: Bordering on a Sustainable Future”, Borderlines 38, vol. 5, no. 8, Aug. 1997 • Kowalewski M, Avila Serrano GE, Flessa KW, Goodfriend GA, “Dead delta's former productivity: Two trillion shells at the mouth of the Colorado River”, Geology; December 2000; v.28 no.12 p.1059-1062 • Pitt J, Luecke DF, Cohen MJ, et al.,”Two nations, one river: Managing ecosystem conservation in the Colorado River delta”, Nat Resour J 40 (4): 819-864 Fall 2000 • Stromberg JC,”Restoration of riparian vegetation in the south-western United States: importance of flow regimes and fluvial dynamism”, J Arid Environ 49 (1): 17-34 Sep 2001 • Vandersande MW, Glenn EP, Walworth JL,”Tolerance of five riparian plants from the lower Colorado River to salinity drought and inundation”, Journal of Arid Environments (2001) 49: 147-159 • Varady RG, Hankins KB, Kaus A, et al.,.”.. to the Sea of Cortes: nature, water, culture, and livelihood in the Lower Colorado River basin and delta – an overview of issues, policies, and approaches to environmental restoration”, J Arid Environ 49 (1): 195-209 Sep 2001

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