Thesis. 1976. M.S. cn--Massachusetts Institute of Technology. Dept. of Meteorology. / Microfiche copy available in Archives and Science. / Bibliography: leaves 113-116. / M.S.cn

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This thesis describes the use of a distrometer and two IBM-PC's to collect data in a large propagation experiment. The uses and methods of collecting drop size distribution are discussed as are the uses of IBM-PC's for both data collection and control. Methods of requiring the PC's to operate in real time are also included. / M.S.

Call number: LD2668 .T4 1956 S34 / Master of Science

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Distributed rainfall-runoff models are gaining widespread acceptance; yet, a fundamental issue that must be addressed by all users of these models is definition of an acceptable level of watershed discretization (geometric model complexity). The level of geometric model complexity is a function of basin and climatic scales as well as the availability of input and verification data. Equilibrium discharge storage is employed to develop a quantitative methodology to define a level of geometric model complexity commensurate with a specified level of model performance. Equilibrium storage ratios are used to define the transition from overland to channel-dominated flow response. The methodology is tested on four subcatchments in the USDA-ARS Walnut Gulch Experimental Watershed in southeastern Arizona. The catchments cover a range of basins scales of over three orders of magnitude. This enabled a unique assessment of watershed response behavior as a function of basin scale. High quality, distributed, rainfall-runoff data were used to verify the model (KINEROSR). Excellent calibration and verification results provided confidence in subsequent model interpretations regarding watershed response behavior. An average elementary channel support area of roughly 15% of the total basin area is shown to provide a watershed discretization level that maintains model performance for basins ranging in size from 1.5 to 631 hectares. Detailed examination of infiltration, including the role and impacts of incorporating small-scale infiltration variability in a distribution sense, into KINEROSR, over a range of soils and climatic scales was also addressed. The impacts of infiltration and channel losses on runoff response increase with increasing watershed scale as the relative influence of storms is diminished in a semi-arid environment such as Walnut Gulch. In this semi-arid environment, characterized by ephemeral streams, watershed runoff response does not become more linear with increasing watershed scale but appears to become more nonlinear.

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A Research Report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science. Johannesburg, October 2016. / Rainfall is a complex phenomenon, which has previously been explored by assessing rainfall patterns in time and space, typically using ground-based weather stations. Rainfall patterns in southern Africa tend to have a direct impact on vegetation growth and surface water availability, and an indirect impact on animal movement. This study investigated rainfall in Botswana by analysing changes in spatial and temporal patterns from 1998 to 2013, using satellite imagery. Tropical Rainfall Measuring Mission (TRMM) 3B43 dataset (1998-2013) was used to document monthly rainfall magnitude and variability over the 15-year period. Additionally, a GIS spatial analysis approach, the Anselin Local Moran’s I tool, was used to determine changes (i.e. persistence) of rainfall conditions on a year by year basis during the study period. WorldClim precipitation data (1950-2000) were utilised as a longer term average reference dataset against which TRMM data could be compared. This study found that the rainy season consisted of relatively high rainfall magnitudes and variability, while the post rainy season consisted of relatively lower rainfall magnitudes and variability across Botswana. Higher magnitudes persisted into April, indicating the occurrence of late summer rainfall during this observation period. From a regional perspective, the Okavango Delta remained a region of relatively higher rainfall magnitude and variability compared to surrounding regions, regardless of the season. The rainy season was associated with a high frequency of rainfall events above the long term WorldClim average, and the post rainy season with a high frequency of rainfall below the long term WorldClim average. The spatial analysis indicated an annual persistence of high rainfall clusters in northern Botswana, and a persistence of low rainfall clusters in southern Botswana throughout the 15-year analysis. In addition, a progressive drying trend towards the end of the time series was observed. These findings suggest that Botswana has experienced both wetter conditions and drier conditions within the 15-year analysis period, than have been historically documented. The progressive drying trend towards the end of the time series may be indicative of a changing climate in Botswana. However, due to the length of this analysis period it cannot be proven conclusively that the detected wetter and drier conditions, than historically documented, are a signal of climate change. This rainfall analysis provides a comprehensive understanding of recent spatial and temporal rainfall patterns and changes in Botswana. More specifically, this rainfall study fits into a bigger research project focused on herbivore conservation in Botswana. Together, these studies will collectively enable protected areas authorities to better manage herbivore migration, improving conservation in Botswana over time. Ultimately, this study stands to make a positive contribution towards the development of existing conservation practices in Botswana. / LG2017