A two-dimensional, finite difference model was used to simulate the lowering of the water table below a floodplain in order to affect water conservation by reducing phreatophyte transpiration. Evapotranspiration capture percentages and unit water costs associated with alternative well network designs were calculated in order to determine those factors which are most important in designing an evapotranspiration capture project.

The Gila River Indian Reservation lies in the Sonoran Desert of south-central Arizona, with an elevation range from 941 to 4512 feet (287 to 1375 m). Three major desert streams (the Salt, Gila, and Santa Cruz Rivers) have their confluences on the reservation. The human occupancy of the Gila floodplain is believed to have been continuous for the past two millenia. In the past century loss of stream flow and deterioration of riparian and marsh habitats have resulted from drastic changes in hydrologic regimes of the major streams. Documentation of original habitat conditions is based on Hispanic accounts (1694-1821) and subsequent Anglo accounts, together with oral history from the Pima Indians. Riparian timber and emergent vegetation were gone by 1950 due to destructive floods and lowered water table. Irrigation run-off and Phoenix sewage effluent have reestablished locally riparian communities and marshes. Eleven major habitats occur today on the reservation. Their predominant vegetation is described. Field work on the reservation was conducted from 1963 to 1976. Modern distributional data are compared with evidence from archaeological, ethnographic, and historical sources. The total avifauna (all time horizons) consists of 232 species, of which 207 are supported by specimen evidence. At least 101 species are breeding or have bred in the past; five other species are probably breeding. On geographic grounds an additional seven species are suspected of having bred aboriginally. The taxonomy and migration are discussed in accounts of 46 species with two or more subspecies occurring on the study area. The Piman ethno-taxonomy of birds distinguishes 67 taxa, most of which correspond to Linnaean (biological) species. In the past 100 years 28 species (21 as breeding species) have been extirpated from the reservation. Of these 24 are directly related to loss of riparian woodlands or open water and marshes. Since 1958 at least 13 species have recolonized as a result of the redevelopment of riparian communities with willow, cottonwood, and cattail. The present reservation habitat and avifauna are contrasted with two modern analogs with perennial surface water and intact riparian communities. These are at similar elevations, less than 30 miles (48 km) from the reservation. Ten Neotropical species have colonized Arizona within the 20th century and an additional eight have extended their breeding ranges northward. Four Neotropical species have occupied the reservation during this period. Formerly allopatric subspecies of two species (Great-tailed Grackle, Quiscalus mexicanus, and Horned Lark, Eremophila alpestris) are now interbreeding on the reservation in areas of secondary intergradation. The northward movements are attributed to post- Pleistocene recolonizations, in part facilitated by human modifications of habitats. At least 15 wintering species are departing earlier in spring than they did at the turn of the century. This is attributed to habitat deterioration. The habitats with the greatest avifaunal diversity, both summer and winter, are the traditional Pima farms (rancherlas) and the recently redeveloped riparian communities along the Salt River. The least diversified and most disturbed habitats are the Gila River channel and the large-scale mechanized farms on lands leased to non-Indians. The future of both the natural habitats and the avifauna of the reservation is in the hands of tribal leaders.

Traditional flood-frequency techniques are based on the assumption that the observed flood record represents a sample that has been drawn from a single climatically homogeneous population of floods. A hydroclimatic approach was used to evaluate this assumption by identifying the circulation patterns and atmospheric flood-generating mechanisms which control the temporal and spatial variability of flooding. Mean monthly discharges and instantaneous peak flows of the partial duration series were analyzed for thirty gaging stations in the climatically sensitive, semiarid, Gila River basin for the period 1950 to 1980. Correlation fields and composite maps were constructed to define the relationship between 700 mb height circulation anomalies and mean monthly streamflow. Individual flood events were linked to climate by analyzing daily synoptic weather maps and classifying each flood event into one of eight hydroclimatic categories on the basis of the atmospheric mechanisms which generated each flow. The analysis demonstrated that floods and anomalously high streamflow in the Gila River basin originate from a variety of atmospheric processes which vary spatially, seasonally, and from year-to-year. The mechanisms most important for generating floods included winter fronts, cutoff lows, tropical storms, snowmelt, and widespread and localized summer monsoon-related circulation patterns. When flood discharges were grouped into hydroclimatically homogeneous categories, histogram plots of their frequency distributions exhibited means and variances that differed from those of the overall frequency distribution of the entire flood series. The means of the discharges generated by frontal precipitation and tropical storms tended to plot above the mean of the overall series, while the means of floods generated by snowmelt tended to plot below the overall mean. Flood estimates computed from a series containing mixed distributions were not the same as flood estimates computed from climatically homogeneous subsets of the same series. These results have implications for traditional flood-frequency analysis and other stochastic methods of analyzing hydrologic time series. The hydroclimatically-defined subgroups in the flood series of the Gila River basin indicate that nonhomogeneity and nonstationarity can be imparted to a hydrologic time series by differing atmospheric mechanisms alone.

Sustainable Built Environments Senior Capstone Project / For over a century, Pima Indians living just south of Phoenix, Arizona on the Gila River Indian Reservation have suffered from an epidemic of type 2 Diabetes Mellitus. Over half of the Pima population living on the reservation is diagnosed with diabetes while the socioeconomic conditions of the tribal community are in an unstable and dilapidated state (Unnatural Causes 2008). Fifty percent of the Pimas living on the Gila River Indian Community live below the poverty level (Unnatural Causes 2008). Displacement from traditional customs and neglect from the U.S. federal government are just some of the detrimental impacts the people have faced over the last century (Unnatural Causes 2008). The discussions within this paper will attempt to address how and why the Pima Indians have experienced such severe changes in lifestyle and economy over the last century and what affect this has had on the physical health of the people in the community. By addressing these overarching issues, one should find that socioeconomics and conditions of physical health are strongly connected. Looking even closer though, specifically at the epidemic of type 2 diabetes and the contributing risk factors that this population suffers from, one will begin to question how within just a matter of 3 decades the number of diagnosed cases of type 2 diabetes doubled among the Pima and how the rates are some of the highest recorded in the entire world. Moreover, the underlying issue is not simply a cause of poor diet, change in activity levels and unfavorable genetics, rather - being robbed of a critical natural resource, forced to adapt to unfavorable economic changes and in the end, the U.S. government failure to intervene – are truly the underlying causes that have impacted the health of the Pima Indians of Southern Arizona. The Pimas are people of their natural environment. Having a long history of living along the Gila River, the Pima were water irrigation engineers (Unnatural Causes 2008). Cultivating local crops, living off the land and providing for themselves using waters of the Gila River in an arid climate is as much a part of their culture as is their ancestral bloodline. The research presented in these discussions will look at the identical ancestry of Pima Indians living in Southwestern Sonora, Mexico in the Sierra Madre Mountains of Maycoba in order to evaluate the Pima tribe’s predisposition to the disease. The significance of looking at these groups is that their genetic history is the same based upon linguistic and genealogy studies (Schulz, Bennett, Ravussin, Kidd, Kidd, Esparza, Valencia, 2006). However, the Pima living in Sonora have not seen the same ever-increasing rates of type 2 diabetes or even obesity, as their northern counterparts have. Notably, the Mexican Pima have not experienced the same environmental changes (i.e. drought) either. Subsequently, the Pima of Sonora have been able to continue their traditional ways of life including subsistence farming and healthy diet and exercise. A historical background of the Arizona Pimas will be provided, from their cultural traditions as irrigation engineers to their participation in federal subsidy programs and their current economic state. In-depth historical accounts will also be made for the history of water law in the Southwestern United States, including what drove white settlers’ demand for water west of the Mississippi over the course of two centuries, to the attempts to mitigate the severity of drought on Native American reservations through multiple legislative acts. Information regarding the Mexican Pima’s current economy, levels of physical activity and typical diet will be presented in comparison to the present health and economic conditions of the Arizona Pima.

No description available.

No description available.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1989. / Includes bibliographical references (leaves 96-99).

Thesis (Ph. D. - Geology)--University of Arizona. / Part of illustrative material fold. in pocket. Bibliography: leaves 243-249.

abstract: ABSTRACT The Phoenix Four Rivers Flora is an inventory of all the vascular plants growing along the Salt, Gila, New and Agua Fria Rivers, and their tributaries in the Phoenix Metropolitan Area during the years of the study (2009-2011). This floristic inventory documents the plant species and habitats that exist currently in the project area, which has changed dramatically from previous times. The data gathered by the flora project thus not only documents how the current flora has been altered by urbanization, but also will provide a baseline for future ecological studies. The Phoenix Metropolitan Area is a large urbanized region in the Sonoran Desert of Central Arizona, and its rivers are important for the region for many uses including flood control, waste water management, recreation, and gravel mining. The flora of the rivers and tributaries within the project area is extremely diverse; the heterogeneity of the systems being caused by urbanization, stream modification for flood control, gravel mining, and escaped exotic species. Hydrological changes include increased runoff in some areas because of impermeable surfaces (e.g. paved streets) and decreased runoff in other areas due to flood retention basins. The landscaping trade has introduced exotic plant species that have escaped into urban washes and riparian areas. Many of these have established with native species to form novel plant associations. / Dissertation/Thesis / M.S. Plant Biology 2011

abstract: ABSTRACT The Sentinel-Arlington Volcanic Field (SAVF) is the Sentinel Plains lava field and associated volcanic edifices of late Cenozoic alkali olivine basaltic lava flows and minor tephra deposits near the Gila Bend and Painted Rock Mountains, 65 km-100km southwest of Phoenix, Arizona. The SAVF covers ~600 km2 and consists of 21+ volcanic centers, primarily low shield volcanoes ranging from 4-6 km in diameter and 30-200 m in height. The SAVF represents plains-style volcanism, an emplacement style and effusion rate intermediate between flood volcanism and large shield-building volcanism. Because of these characteristics, SAVF is a good analogue to small-volume effusive volcanic centers on Mars, such as those seen the southern flank of Pavonis Mons and in the Tempe Terra region of Mars. The eruptive history of the volcanic field is established through detailed geologic map supplemented by geochemical, paleomagnetic, and geochronological analysis. Paleomagnetic analyses were completed on 473 oriented core samples from 58 sites. Mean inclination and declination directions were calculated from 8-12 samples at each site. Fifty sites revealed well-grouped natural remanent magnetization vectors after applying alternating field demagnetization. Thirty-nine sites had reversed polarity, eleven had normal polarity. Fifteen unique paleosecular variation inclination and declination directions were identified, six were represented by more than one site with resultant vectors that correlated within a 95% confidence interval. Four reversed sites were radiometrically dated to the Matuyama Chron with ages ranging from 1.08 ± 0.15 Ma to 2.37 ± 0.02 Ma; and one normal polarity site was dated to the Olduvai normal excursion at 1.91 ± 0.59 Ma. Paleomagnetic correlations within a 95% confidence interval were used to extrapolate radiogenic dates. Results reveal 3-5 eruptive stages over ~1.5 Ma in the early Pleistocene and that the SAVF dammed and possibly diverted the lower Gila River multiple times. Preliminary modeling of the median clast size of the terrace deposits suggests a maximum discharge of ~11300 cms (~400,000 cfs) was necessary to transport observed sediment load, which is larger than the historically recorded discharge of the modern Gila River. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2015