It is the purpose of this investigation to determine the amount of rain fall to be expected in various areas of the State of Florida. To date there are no published papers which are concerned with this aspect of rain fall in the state. Although this study is mainly concerned with the amount of rain fall which may be expected at ten per cent intervals throughout the state, it is probable that it has many ramifications which will be of value in other phases of water research. In speaking of the ten per cent intervals of time we are actually dealing with percentages of the total time. Hence, 25 years out of 50 years should not be construed to mean the next 25 years out of the next 50 years. / Typescript. / "August, 1949." / "Submitted to the Graduate Council of Florida State University in partial fulfillment of the requirements for the degree of Master of Science under Plan II." / Advisor: LeRoy Babcock, Professor Directing Paper. / Includes bibliographical references (leaf 58).

This study examines the relationship between gully erosion in channels, sidewalls, and interfluves, and precipitation parameters (duration, total accumulation, average intensity, and maximum intensity) annually and seasonally to determine seasonal drivers for precipitation-related erosion. Ordinary Least Square regression models of erosion using precipitation and antecedent precipitation at weekly lags of up to twelve weeks were developed for three erosion variables for each of three geomorphic areas: channels, interfluves, and sidewalls (nine models in total). Erosion was most pronounced in winter months, followed by spring, indicating the influence of high-intensity precipitation from frontal systems and repeated freeze-thaw cycles in winter; erosion in summer was driven by high-intensity precipitation from convectional storms. Annually, duration was the most important driver for erosion, however, during winter and summer months, precipitation intensity was dominant. Seasonal models retained average and maximum precipitation as drivers for erosion in winter months (dominated by frontal systems), and retained maximum precipitation intensity as a driver for erosion in summer months (dominated by convectional storms). In channels, precipitation duration was the dominant driver for erosion due to runoff-related erosion, while in sidewalls and interfluves intensity parameters were equally important as duration, likely related to rain splash erosion. These results show that the character of precipitation, which varies seasonally, is an important driver for gully erosion and that studies of precipitation-driven erosion should consider partitioning data by season to identify these drivers.

Mercury has been an element of great industrial importance since early times.This wide utilization of the element has led to pervasive mercury contamination in theglobal environment. Due to mercury's high toxicity, this is a matter of great concern. Anumber of methods, includ ing phytoremediation, filtration, and precipitation/chelation,have been investigated to remove mercury from the environment. Unfortunately, thesemethods are not entirely satisfactory for the in-situ remediation of mercury from aqueousenvironments.The hypothesis of this dissertation is that this can best be accomplished by theaddition of a large and flexible sulfur-based chelate, that will bind mercury in atetracoordinate and presumably tetrahedral environment, to mercury-contaminatedwaters. Although this proved difficult due to the tendency of these ligands to decomposeinto smaller, sulfur-containing rings, the synthesis and characterization of such a chelatewas achieved. Several potential mercury-binding ligands were eventually synthesizedsignificant amounts of mercury (91-100%) from the contaminated solutions, in one caselowering the mercury levels in the water to below the CVAF detection limits. Theresulting solids lost little (andlt;15 ppb) of their mercury during leaching studies.This work demonstrates the use of tetradentate chelates in precipating Hg2+ fromwater to produce stable mercury- ligand precipitates. A calculation for the quantification ofthe geometry of a four-coordinate compound was also developed and applied to aluminum,gallium, and mercury compounds. This calculation could also be applied to the mercurycompounds described in this thesis once X-ray structures become available

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No description available.

Quantifying climatological precipitation and soil moisture as well as interannual variability and trends requires extensive observation. This work focuses on the analysis of available precipitation and soil moisture data and the development of new ways to estimate these quantities. Precipitation and soil moisture characteristics are highly dependent on the spatial and temporal scales. We begin at the point scale, examining hourly precipitation and soil moisture at individual gauges. First, we focus on the Walnut Gulch Experimental Watershed (WGEW), a 150 km² area in southern Arizona. The watershed has been measuring rainfall since 1956 with a very high density network of approximately 0.6 gauges per km². Additionally, there are 19 soil moisture probes at 5 cm depth with data starting in 2002. In order to extend the measurement period, we have developed a water balance model which estimates monsoon season (Jul-Sep) soil moisture using only precipitation for input, and calibrated so that the modeled soil moisture fits best with the soil moisture measured by each of the 19 probes from 2002-2012. This observationally constrained soil moisture is highly correlated with the collocated probes (R=0.88), and extends the measurement period from 10 to 56 years and the number of gauges from 19 to 88. Then, we focus on the spatiotemporal variability within the watershed and the ability to estimate area averaged quantities. Spatially averaged precipitation and observationally constrained soil moisture from the 88 gauges is then used to evaluate various gridded datasets. We find that gauge-based precipitation products perform best followed by reanalyses and then satellite-based products. Coupled Model Intercomparison Project Phase 5 (CMIP5) models perform the worst and overestimate cold season precipitation while offsetting the monsoon peak precipitation forward or backward by a month. Satellite-based soil moisture is the best followed by land data assimilation systems and reanalyses. We show that while WGEW is small compared to the grid size of many of the evaluated products, unlike scaling from point to area, the effect of scaling from smaller to larger area is small. Finally, we focus on global precipitation. Global monthly gauge based precipitation data has become widely available in recent years and is necessary for analyzing the climatological and anomaly precipitation fields as well as for calibrating and evaluating other gridded products such as satellite-based and modeled precipitation. However, frequency and intensity of precipitation are also important in the partitioning of water and energy fluxes. Therefore, because daily and sub-daily observed precipitation is limited to recent years, the number of raining days per month (N) is needed. We show that the only currently available long-term N product, developed by the Climate Research Unit (CRU), is deficient in certain areas, particularly where CRU gauge data is sparse. We then develop a new global 110-year N product, which shows significant improvement over CRU using three regional daily precipitation products with far more gauges than are used in CRU.

In this thesis we propose an automated process for the removal of non-precipitation echoes present in weather radar signals and accurate detection of rainfall. The process employs multifractal analysis using directional Gabor wavelets for accurate detection of the rain events. An optoelectronic joint transform correlator is proposed to provide ultra fast processing and wavelet analysis. Computer simulations of the proposed system show that the proposed algorithm is successful in the detecting rainfall accurately in radar images. The accuracy of the algorithms proposed are compared to accurate results that were generated under expert supervision. Results of the proposed system are also compared to results of QC algorithm for the ground validation software (GVS) used by TRMM ground validity Project and a previous QC algorithm. Several statistical measures computed for different reflectivity ranges show that the proposed algorithm gives accuracy as high as 98.95%, which exceed the 97.46% maximum accuracy for the GVS results. Also, the minimum error rate obtained by the proposed algorithm for different dB ranges decreases to 1.09% whereas the GVS results show a minimum error rate of 1.80%. The rain rate accumulation confirms the success of the proposed algorithm in the accurate removal of nonprecipitation echoes and a higher precision in rain accumulation estimates.

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Silica is detrimental to the recovery of zinc from zinc bearing siliceous materials. The difficulties involved in the hydrometallurgical processing of silica are well documented, the major problem being the formation of gels. These are extremely difficult to separate from solution, creating serious problems. This work investigates the mechanism of the formation of granular silica precipitates and how this differs from the mechanism of formation of the gels.Batch precipitation studies of silica from sulfuric acid solutions have revealed valuable information about the processes occurring. A solution of monosilicic acid (Si(OH)4(subscript)) was produced by leaching synthetic zinc orthosilicate (Zn2SiO4) in sulfuric acid. Precipitation was monitored by measuring the turbidity and silica concentration in solution at regular intervals. Electron microscopy was used to examine the precipitate morphology. Variables known to influence silica precipitation are supersaturation, temperature, seeding and the concentrations of sulfuric and hydrofluoric acids and zinc, iron (III) and aluminium sulfates. These were investigated by comparing their effects on precipitation with those of a control experiment. The evaluation criteria used were induction time, precipitation rate, precipitation time, product morphology and filterability. The results of this work define conditions that yield a granular silica precipitate in preference to a gel, low supersaturation being the most important condition. The product morphology is insensitive to precipitation rate over the range of conditions studied.A laboratory scale continuous crystalliser was designed and constructed and used to carry out a series of experiments to determine the operating conditions for suitable processing of natural zinc orthosilicate ore to remove the silica impurity in an easily separable form. The variables examined were ++ / supersaturation as well as mixing and product removal conditions. The relationship between supersaturation and morphology discovered during the batch experiments was confirmed to also occur when employing a continuous basis. This finding has not been previously reported in the literature. The use of classified stirring and classified product removal led to the formation of the highest quality silica product with a reasonable residence time. The most important quality criterion being the filtration rate.Insight into the mechanism of silica precipitation has been gained by analysing information from both batch and continuous experiments. Under the strongly acidic conditions studied, colloidal silica particles are initially formed. At low supersaturation (S </= 2.9) the colloidal particles aggregate and cement together to form solid particles, while at higher supersaturation (S>/= 4.3) the colloidal particles aggregate to form a gel.