Browsing Hydrology & Water Resources Technical Reports by Subjects
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Deciding to RechargePublic water policy decision making tends to be too complex and dynamic to be described fully by traditional, rational models. Information intended to improve decisions often is rendered ineffective by a failure to understand the process. An alternative, holistic description of how such decisions actually are made is presented here and illustrated with a case study. The role of information in the process is highlighted. Development of a Regional Recharge Plan for Tucson, Arizona is analyzed as the case study. The description of how decisions are made is based on an image of public water policy decision making as 1) a structured, nested network of individuals and groups with connections to their environment through their senses, mediated by their knowledge; and 2) a nonlinear process in which decisions feed back to affect the preferences and intentions of the people involved, the structure of their interactions, and the environment in which they operate. The analytical components of this image are 1) the decision makers, 2) the relevant features of their environment, 3) the structure of their interactions, and 4) the products or outputs of their deliberations. Policy decisions analyzed by these components, in contrast to the traditional analysis, disclose a new set of relationships and suggest a new view of the uses of information. In context of information use, perhaps the most important output of the decision process is a shared interpretation of the policy issue. This interpretation sets the boundaries of the issue and the nature of issue-relevant information. Participants are unlikely to attend to information incompatible with the shared interpretation. Information is effective when used to shape the issue interpretation, fill specific gaps identified as issue-relevant during the process, rationalize choices, and reshape the issue interpretation as the issue environment evolves.
THE ESTIMATION AND SCALING OF LAND-SURFACE FLUXES OF LATENT AND SENSIBLE-HEAT WITH REMOTELY SENSED DATA OVER A GRASSLAND SITEThe overall topic of the research described in this dissertation was the partitioning of available energy at the Earth's surface into sensible and latent heat flux, with an emphasis on the development of techniques which utilize remotely sensed data. One of the major objectives was to investigate the modification of existing techniques, developed over agricultural surfaces, to "natural" ecosystems (i.e., non -agricultural vegetation types with variable and incomplete canopy cover). Ground -based measurements of surface fluxes, vegetation cover, and surface and root -zone soil moisture from the First ISLSCP (International Land Surface Climatology Program) Field Experiment (FIFE) were used to examine the factors controlling the partitioning of energy at ground stations with contrasting surface characteristics. Utilizing helicopter -based and satellite -based data acquired directly over ground -based flux stations at the FINE experimental area, relatively simple algorithms were developed for estimating the soil heat flux and sensible heat flux from remotely sensed data. The root mean square error (RMSE) between the sensible heat flux computed with the remotely sensed data and the sensible heat flux measured at the ground stations was 33 Wm 2. These algorithms were then applied on a pixel -by -pixel basis to data from a Landsat -TM (Thematic Mapper) scene acquired over the FIFE site on August 15, 1987 to produce spatially distributed surface energy- balance components for the FIFE site. A methodology for quantifying the effect of spatial scaling on parameters derived from remotely sensed data was presented. As an example of the utility of this approach, NDVI values for the 1,IFE experimental area were computed with input data of variable spatial resolution. The differences in the values of NDVI computed at different spatial resolutions were accurately predicted by an equation which quantified those differences in terms of variability in input observations.
THE HYDROLOGY AND RIPARIAN RESTORATION OF THE BILL WILLIAMS RIVER BASIN NEAR PARKER, ARIZONARiparian forests, which support rich biological diversity in the North American southwest, have experienced a sharp decline in the last century. The extent of this decline has been estimated to range from 70% to 95% across the southwest (Johnson and Haight, 1984). The principal components of riparian forests which sustain a broad spectrum of species and describe the overall health of a system are cottonwoods (sp. Populus) and willows (sp. Salix). The importance of cottonwoods is aptly described by Rood et al (1993): "....these trees provide the foundation of the riparian forest ecosystem in semi -arid areas of western North America. Unlike wetter areas to the east and west, a loss of cottonwoods in these riparian areas is not compensated through enrichment from other tree species. If the cottonwoods die, the entire forest ecosystem collapses." Cottonwood and willow species are adversely affected by anthropogenic influences ranging most prominently from the introduction of regulated flows via dams to agricultural clearing, water diversions, livestock grazing, and domestic settlement. These influences effectively alter the system hydrology that the forests rely upon. As the widespread destruction of these forests and the associated irreparable damage to endangered species habitat has come into clear view in the past decade, research efforts have focused upon identifying the ecological needs of riparian systems. The potential of modifying such systems to soften the human impact upon them, in effect presenting further alterations on a hydrologic system to return it to its natural regime, is another component of the research on riparian systems. The Bill Williams River riparian corridor, near Parker, Arizona (Figure 1.1), contains the last extensive native riparian habitat along the lower Colorado River (BWC Technical Committee, 1993). This unique resource was established as the Bill Williams River Management Unit, Havasu National Wildlife Refuge in 1941 and covers 6105 acres along the lower 12 miles of the Bill Williams River (Rivers West, 1990). The Bill Williams Unit is currently managed by the U.S. Fish and Wildlife Service of the U.S. Department of Interior. The U.S. Fish and Wildlife Service also funded this research effort. The lush vegetation corresponding to the wetland conditions along the valley floor sharply contrast with the Sonoran desert landscape of the upper valley walls creating a magnificent picture. The Management Unit terminates at Lake Havasu, which forms the confluence of the Bill Williams and Colorado Rivers. The system provides habitat for a wide variety of species, many of which are endangered or state- listed species, including habitat for neotropical migratory birds. This habitat has undergone serious degeneration during the past quarter century. The recruitment of cottonwood and willow trees has been fatally interrupted by anthropogenic encroachment in the form of the construction of Alamo Dam in 1969 at the head of the Bill Williams River and commercial development along the River.