Complete issue of the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / Throughout 1974 and 1975 the Department of Hydrology and Water Resources, University of Arizona, conducted a water quality study on Lake Havasu, Arizona, near the Central Arizona Project intake. This investigation was funded jointly by the Arizona Water Commission and the U.S. Bureau of Reclamation. The University study evaluated the hydrography and hydrology, sediments, turbidity, temperature, chemistry, dissolved oxygen (and biochemical oxygen demand), benthic invertebrates, phytoplankton, zooplankton, biomass analysis, and electrical conductivity to establish baseline data for the CAP intake area. The results showed weak stratification and generally good aeration in the lake and high turbidity in the Bill Williams River. Biological quality was good with low amounts of benthics and numerous zooplankton and phytoplankton species. The extensive data from chemical analysis generally conformed to public health standards.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / Lynx Lake Watershed consists of approximately 13,600 acres of the Agua Fria drainage. About 13 percent of the area is patented mining claims (mainly copper} with numerous mining shafts, waste dumps, and mill tailings. Lynx Creek itself was once mined for gold and the creek bed still shows the scars of the dredging operations. Drainage from the numerous old mining sites show a certain extent of toxic mineral and sediment pollution of the water resources in the area. Lynx Creek carries runoff which is slightly acidic in nature and has a high concentration of copper, manganese, iron, zinc, and sulfates. The Sheldon Mine complex is considered one of the major sources of pollution to the lake. Aquatic life and recreation potential of the watershed is greatly reduced by the water pollution problem. The pollutants from the abandoned mine sites enter into Lynx Lake, a trout fisheries lake, which was created by damming the creek in 1962 by the Arizona Game and Fish Department. The Sheldon Tailings pond was rehabilitated during the summer of 1975 as part of a reclamation study and demonstration project that is currently in progress and being sponsored by SEAM (Surface Environment and Mining}. The study is being conducted cooperatively by the School of Renewable Resources, University of Arizona, and the Prescott National Forest. An excellent vegetative cover is established on the site and studies are being conducted to measure the beneficial effects of the reclamation on water quality.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / The upper Gila River in Arizona and New Mexico contains extremely diverse geology and soils. One geological formation that is somewhat unique to the Southwest and the upper Gila drainage is the Gila Conglomerate formation. In New Mexico, this conglomerate is extensive on the main Gila River drainage, accounting for over 35 percent of the main basin area. A case study was done on the 22,580 hectare (55,793 acres) Lake Roberts Watershed to assess the current sedimentation problem and its sources. This study revealed interesting patterns of lake surface area changes with volume changes of the original 28.3 hectare (70 acres) man-made reservoir over the last 12 years. Surface area reduction (19%) has progressed at a rate over twice that for volume reduction (9%). The source of the problem stems primarily from soils derived from highly sensitive Gila Conglomerate. The watershed is not uncharacteristic of the unique geology and soils typical of the upper Gila drainage and may furnish insight into sediment production and sources for much of the Gila headwater drainage in New Mexico.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / Hydrographs of runoff from small watersheds in semiarid regions often have a sharp peak with a relatively short time of rise followed by a slower recession and a tail of low flow. This characteristic shape suggests the possible use of a double triangle unit hydrograph recently introduced to hydrology. The shape of this unit hydrograph is specified by four parameters, which may be estimated by an optimization procedure based on using the sum of absolute deviations or some other suitable criterion as an objective function. Rainfall and runoff data for a number of storm events on a small watershed in the Santa Rita Experimental Range in southeastern Arizona have been analyzed to test the above idea. Double triangle unit hydrographs were fitted to individual storm events. The differences in the shapes of individual unit hydrographs were found to be small so that they could be approximated by a single double triangle unit hydrograph.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / The University of Arizona Atterbury Experimental Watershed, located southeast of Tucson, Arizona has been instrumented for precipitation and runoff measurements since 1956. Early on the afternoon of July 16, 1975 an intense convective thunderstorm produced more than three inches of rainfall in less than 50 minutes as recorded in several rain gages located in the middle of one 8.1 square-mile desert subwatershed. Storm runoff from this rural subwatershed and an adjacent recently urbanized subwatershed filled the newly finished Lakeside Reservoir and topped the concrete flood spillway with a peak of greater than 3000 cfs, the greatest flow since monitoring began. An analysis of storm characteristics, along with previously available data from local urbanized watersheds, allows speculation on the effect of such an intensive storm in a highly urbanized area.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / The geomorphic threshold concept of landform evolution and its effect on hydrologic performance of drainage systems was investigated on small semiarid watersheds in Southeastern Arizona. Thresholds develop within a geomorphic system with time and can, when exceeded, cause drastic changes in the geomorphic features and in the hydrologic performance of the watershed. The slow continuous evolution of drainage characteristics can be suddenly altered with major readjustment of the landscape taking place. A new state of dynamic equilibrium will then prevail until the drainage system is again subjected to conditions which cause some geomorphic threshold to be exceeded. Areas of potential geomorphic readjustment can be identified from parameters such as channel slope, average land surface slope, drainage density, and mean length of first order streams and these data can be used as components in a calibrated kinematic-cascade model to determine the effects of various degrees of drainage system alteration. The influence on runoff from exceeding various geomorphic thresholds is tested and the resulting hydrologic modifications are simulated and discussed.