Objectives, methods, and environment--Gila River Phreatophyte Project, Graham County, Arizona

Abstract

PREFACEThis report is the first of a series of professional papers describing the hydrologic studies associated with the Gila Eiver Phreatophyte Project. The project plan is described in the report, including the details of observation. A sequence of fact finding, estimation, and decision is necessary in planning a project of this scope.First a study was made of the available information. Specific objectives were then denned, and the hydrologic problem was identified. Methods of measurement were investigated and a primary method was selected. The data requirements and statistical problems involved in the application of this method were then considered. A site was selected and the hydrologic characteristics investigated. Methods of data collection were determined and the project area was instrumented.The organization of this report follows the general sequence used in planning the project. A brief description of the facts considered and analyzed is presented to explain the reasons for making the planning decisions. The advice and assistance of many scientists were used in planning the project. The contributors to this report are the persons having the primary responsibility for making decisions concerning the planning and for subsequent reporting of results on the various phases of the project.

Fluvial processes and vegetation — Glimpses of the past, the present, and perhaps the future

“…can tap groundwater as deep as 15 m. In-depth investigations into the control on phreatophytes by groundwater levels were conducted by Culler (1970) for Tamarix pentandra (saltcedar) and other pheatophytes, by McQueen and Miller (1972) for saltcedar, willows, cottonwoods, and mesquites, and also for saltcedar by Van Hylckama (1974). Results of these studies showed that roots of T. pentandra can extend as deep as 10 m to saturated groundwater (Van Hylckama, 1974), and that stands of phreatophytes, particularly T. pentandra, can be quite dense in lowlands, thereby slowing the velocity of flood flows, reducing conveyance, increasing flood duration, and promoting sediment deposition (Culler, 1970). Later, Harner and Stanford (2003) related growth rates of bottomland cottonwood groves to interactions between shallow groundwater and surface water.…”

Subsurface hydraulics in the area of the Gila River Phreatophyte Project, Graham County, Arizona, with a section on aquifer tests

“…The primary objective of the Gila River Phreatophyte Project is to evaluate evapotranspiration from an analysis of all the significant components comprising the hydrologic system (Culler and others, 1970). Because ground water is a principal component in the hydrologic system, a relatively accurate evaluation of its amount and rate of movement through the project area is a prerequisite to making reliable estimates of evapotranspiration.…”

River responses to decadal-scale changes in discharge regime: the Gila River, SE Arizona

“…One of the most cited examples of such a change is that of the Gila River in SE Arizona, documented in detail by Burkham (1972). That study was part of a major US Geological Survey project on the hydrological effects of phreatophytes (Culler 1970). Burkham (1972) showed that the Gila River in Safford Valley, Arizona, had a narrow, stable, meandering channel in the late nineteenth/early twentieth century.…”