Colonia Solana neighborhood in Tucson, Arizona was designed in 1928 by landscape architect Stephen Child. The use of native plants and topography as the basis for the site plan was unusual in 1928, and also has applicability today as the basis for an ecologically sound, self-sustaining landscape. Factors influencing Tucson's early development were examined as the background of this subdivision. Thus Colonia Solana neighborhood, the last work known to have been designed by Child prior to his death in 1936, became the starting point for inqueries into the life and other works of the landscape architect. It was discovered that Stephen Child (1866-1936) was not only a landscape architect, and one of the early advocates for the use of native plants; he was also a charter member of the American City Planning Institute in 1917. His works in Boston, Santa Barbara, San Francisco, and Tucson were documented.

The status of the Palmer's agave (Agave palmeri) population at Coronado National Memorial was determined by studying recruitment, herbivory and flowering. Data was collected during the summers of 1995 and 1996. Baseline information was found that will aide in comparisons about the population in the future. The population structure was found to have a large number of younger individuals with a high mortality rate. The older age classes had a much lower mortality rate. The affect of grazing was examined as one of the possible impacts to this specific population. There were no significant differences in recruitment, flowering or herbivory between areas exposed to grazing versus areas not exposed to grazing. Palmer's agave is a long-lived species that will require several years of monitoring its population to get a better understanding of the factors that determine its population dynamics.

As our southwestern cities continue to grow in essentially uncontrolled and sprawling patterns it becomes increasingly apparent that new planning approaches and design guidelines must be generated to rectify past and combat future problems. Today, many community developments focus decision making principles on purely economic gain at the expense of addressing the socio-cultural, aesthetic, functional, economic, and environmental issues. In an attempt to address these issues, we employed both qualitative and quantitative methods of research. The qualitative methods included: a case study analysis of past, present and future communities; a literature review of past communities and new theoretical movements; structured interviews with real estate developers in the southwest; and participant observation encompassing peer dialogue and design reviews. The quantitative methods included statistical analysis of questionnaires given to designers and developers practicing in the southwest. A series of design and planning guidelines were distilled from this research. They were then tested by applying them to the design of a new community in the southwestern United States.

The error associated with the Revised Universal Soil Loss Equation (RUSLE) was determined by utilizing data from 21 U.S. sites representing 1704 years of measurements from 206 plots. RUSLE estimates were compared to the measured values for each year and the average value for each plot duration. The model efficiency coefficient on an annual basis was (.58) and on an average annual basis was (.73). The RUSLE was consistent with a previous study of the USLE which tended to over predict on plots with low erosion rates and under predict on plots with high erosion rates. Also the Topographic Factor (LS) value and the Cover and Management Factor (C) value had the most influence on model efficiency. The basis for this study was to compare the RUSLE with the USLE and to compare RUSLE simulations with observed data that was not a part of its critical development.

The Endangered Species Act of 1973 (ESA) reflects society's concern over the rate of species extinction and aims to halt or reverse this trend. Several policies of the ESA protect listed species over resource development projects. Due to this protection, several listed species have recently experienced a recovery. Two have been removed, or delisted, from the federal Endangered Species list. Once a recovered species becomes delisted, the majority of these protections are removed. This paper analyzes the political implications of such delistings utilizing formal interviews, personal experiences, and a literature search. Through analysis, it is found that two specific policies seem to protect delisted species. It is concluded that a quantitative analysis may be premature at this time due to the small number of recovered species and that these policies must be effected to their fullest potential to ensure the long-term success of the federal endangered species program.

A comparative hydrology approach was proposed to analyze the hydrological behavior of small mediterranean shrubland watersheds and provide a potential basis for regionalization studies. Four simple regressiontype models were used to describe the behavior of nine mediterranean shrubland watersheds from France, California and South Africa. The values of the models' paramaters were found significantly different. To explain the differences, a set of morphometric and climatic variables was selected, and a stepwise regression analysis was done. The results show that most of the variability encountered among the parameters was the effect of the watersheds' morphometry and of the summer rainfall amount in each region. Additional watershed data is needed to validate the parameters' explanatory equations. However, the approach proposed here seems to present valuable opportunities for the comparative study of other vegetation types, the regionalization of hydrological models parameters, and the study of the effects of watershed management practices.

A conceptual and experimental analysis of rainfall-runoff hydraulics on a natural microcatchment was conducted in the Negev Desert, Israel. The kinematic wave equations were utilized as a physically-based, hydrodynamic model because they can mathematically describe the simultaneous processes of rainfall, infiltration, and runoff. Model inputs are rainfall and infiltration rates, catchment response time, and flow velocity. A series of experiments was conducted over a range of rainfall intensities using a rainfall simulator. The slope of the infiltration curve, time when runoff begins, time to peak, and peak discharge were found to be dependent on rainfall intensity. Owing to its effects on infiltration, the highest rainfall intensity did not produce the largest water yield. Velocity was found to be independent of flow depth and a linear function of rainfall intensity. The concept of constant velocity linearized the kinematic wave equation and enabled analytic solutions to be developed. These solutions are not unique; graphical fitting or multiple regression should be used to identify optimal parameter values. Model equations can be used to calculate the catchment size necessary to supply the water requirements of a given tree species and can be applied in regions where computer use is not feasible.