In recent years, several attempts have been made to develop instrumentation to aid in the measurement of soil water electrical conductivity. Each of the instruments have specific limitations. This dissertation discusses the available methods of measuring this parameter and indicates the limitations of the transducers which have been described in the literature. Also, discussed are the basic theories of operation of these transducers and definitions related to soil salinity in general. The major objective of this research was to develop a new transducer which would be a significant improvement over existing types of instrumentation. It is believed that this research has led to the development of two transducers of different geometries which can assess the soil water conductivity over a wider range of matric potential just as rapidly and accurately as the next best unit. At the same time the new transducers incorporate automatic temperature compensation which has not been done by any other field instrumentation of its type. Also presented, is the application of heat transfer theories to the diffusion of ions from the transducer to the surrounding environment, Application of this theory allows one to predict how the transducer will respond to a step change in ion concentration in an unsaturated soil system where the only process involved is diffusion. Good agreement between experimental measurements and predicted response indicates that the model may also be useful in further refinements of the transducer.

Experiments were conducted at Tucson, Arizona during a 3-year period to determine the effect of water management on several characteristics in 'Mesa-Sirsa' alfalfa (Medicaqo sativa L.) grown under field conditions. Three water management treatments were imposed: (a) irrigating to field capacity when 50% of available soil moisture had been utilized to a depth of 1.2 m (high), (b) irrigating to field capacity when 100% of the available soil moisture had been utilized to the same depth (medium), and (o) irrigating similar to the high treatment on first and last harvests of the growing season, but withholding irrigation water during the balance of the growing season (low). Plants receiving medium and high water treatments were harvested at 25% bloom through the entire growing season while those receiving the low water treatment were harvested twice--at the first and last harvest for plants receiving medium and high water treatments. In plants grown under both the high and medium water treatments it was found that dry matter production, plant height at harvest, efficiency of water use, and total water utilization per growth period decreased during the summer months while the daily rate of water utilization increased. Treatments did not have an effect on any of these variables. When irrigation water was returned to plants grown under the low water treatments, dry matter production and plant height at the subsequent harvest were not significantly different from plants grown under the medium and high water treatments. Plant population per unit land area declined steadily during the three years of production. Neither stand decline nor root distribution was significantly influenced by water management over the 3-year period. Variation in root morphology among genotypes was observed. The majority of the variability was attributed to genetic expression. Water stress resulted in significant increased proline and decreased arginine content of root tissue. Sucrose content increased significantly in roots of plants subjected to water stress while fructose and glucose levels were not affected. Water insoluble N and water soluble protein levels were lower at midsummer when compared with the beginning and completion of the growing season. Total available carbohydrates (TAC) and water soluble protein levels decreased following forage harvest, while levels of water insoluble N, water soluble NI amino acid composition of proteins, and free sugar levels did not change during regrowth. TAC levels under the medium and high water treatments decreased during midsummer each of the 3 years of the study. The trend was not as evident during the initial production year as in subsequent years. Net carbohydrate utilization during the 2 weeks following harvest varied among years and harvests. Differences among harvests were attributed to climatic conditions as no treatment effect was observed. Variation among years may have resulted from root maturation and genotypic changes in the plant population. TAC levels of nonharvested summer-stressed plants in the low water treatment remained relatively constant unless rainfall occurred in sufficient magnitude to stimulate top growth, in which case a decrease in TAC levels was observed.

The purpose of this study was to develop a stochastic model of the snowfall, snow accumulation and ablation process. Snow storms occurring in a fixed interval were assumed to be a homogeneous Poisson process with intensity X. The snow storm magnitudes were assumed to be independent and identically distributed random variables. The magnitudes were independent of the number of storms and concentrated at the storm termination epochs. The snow water equivalent from all storms was a compound Poisson process. In the model, storms then occurred as positive jumps whose magnitudes equaled the storm amounts. Between storms, the snowpack ablated at a constant rate. Random variables characterizing this process were defined. The time to the occurrence of the first snowpack, generated by the first storm, was a random variable, the first snow-free period. The snowpack lasted for a random duration, the first snowpack duration. The alternating sequence of snow-free periods followed by snowpacks of random duration continued throughout the fixed interval. The snow-free periods were independent and identically distributed random variables as were the snowpack durations. The sum of each snow-free period and the immediately following snowpack duration formed another sequence of independent and identically distributed random variables, the snow-free, snow cycles. The snow-free, snow cycles represented the interarrival times between epochs of complete ablation, and thus defined a secondary renewal process. This process, called the snow renewal process, gave the number of times the snowpacks ablated in the interval. Distribution functions of the random variables were derived. The snow-free periods were exponentially distributed. The distribution function of the snowpack durations was obtained using some results from queueing theory. The distribution function of the first snow-free, snow cycle was derived by convoluting the density function of the first snowfree period and the first snowpack duration. The distribution of the sum of n snow-free, snow cycles was then the n-fold convolution of the first snow-free, snow cycle with itself. The probability mass function of the snow renewal process was evaluated numerically, from a known relationship with the sum of snow-free, snow cycles. The snowpack ablation rate was considered to be a random variable, constant within a season, but varying between seasons. The snowpack durations and snow-free, snow cycles were conditioned on the ablation rate, then unconditional distributions derived. An application of the model was made in the case where snow storm magnitudes were exponentially distributed. Specific expressions for the distribution functions of the random variables were obtained. These distributions were functions of the Poisson parameter X, the exponential parameter of storm magnitudes, Ne l, and the snowpack ablation rate. The snow model was compared with data from the climatological station at Flagstaff, Arizona. Snow storms were defined as sequences of days receiving 0.01 inch or more of snow water equivalent separated from other storms by one or more dry days. Snow storms occurred approximately as a homogeneous Poisson process. Storm magnitudes were exponentially distributed. Empirical distributions of snowpack ablation rates were obtained as the coefficients of a regression analysis of snowpack ablation. Two methods of estimating the Poisson parameter were used. The theoretical distribution functions were compared with the observed. The method of moments estimate generally gave more satisfactory results than the second estimate.

Transport phenomena in hydrologic systems are simulated with finite-state models (FSMs), which are similar to mixing cell models in that they utilize a mixing cell as their basic subdivision, yet are more flexible, capable of modeling more complex systems, and easier to manipulate than previous mixing cell models. The basic FSM equations are discrete, recursive forms of the continuity equation for mass transport and the storage equation for fluid transport. Different types of mixing and flow can be simulated by specifying appropriate algorithms for use in the basic equations. Finite-state models thus have a physical basis, although they avoid the use of differential equations. The FSM digital computer model can simulate systems in one, two, or three spatial dimensions with relative facility. In many important cases, transit number and age number distributions can be calculated. These distributions, and especially their means, are useful in determining fluid residence times in hydrologic systems. Two aquifer systems are modeled using finite-state models. In a portion of the Tucson Basin Aquifer of southern Arizona a three-dimensional, steady flow FSM is used to account for the observed carbon-14 age distribution in the aquifer without assuming piston flow in the aquifer and without evaluating dispersion parameters. This model provides a first approximation of the three-dimensional flow distribution, an estimate of the long-term average annual recharge, and fluid residence times in the aquifer. The second FSM, two-dimensional and non-steady flow, accounts for the transient distribution of tritium in the Edwards Limestone of south-central Texas. This aquifer is a highly anisotropic, nonhomogeneous karst aquifer that is difficult to model by traditional methods. In both models, first guesses for cell volumes and flow distributions were made on the basis of available hydrogeological data. Saturated, unsaturated, and open-channel flow also are examined. Flow algorithms for the basic FSM storage equation follow the theory of linear systems, although in certain regimes, especially those involving unsaturated flow, it may be necessary to develop nonlinear flow algorithms. This was not attempted. It is also shown that the finite-state model can simultaneously model the transport of mass and fluid in a hydrologic system. The FSM also has the potential for modeling heat transport, which may prove useful in simulating geothermal reservoirs as well as other systems involving heat transport.

Domestic waste water from toilets, showers, garbage grinding, and kitchens was characterized in terms of waste concentration and volume in order to formulate four representative synthetic domestic wastes. The synthetic waste formulations were used to simulate concentrated domestic wastes flowing from dwellings whose water use has been reduced by the use of water saving devices such as low flow toilets and showers. Biological treatment of wastes with Chemical Oxygen Demands (COD) of up to 1500 mg/1 using activated sludge was investigated with both bench scale batch and continuous processes. Specific items investigated as functions of waste concentration included substrate removal rates, oxygen uptake rates, aeration properties, sludge settling, sludge aeration time, and aeration tank turbulence. Substrate removal rates were not enhanced by increasing domestic waste concentrations although oxygen uptake rates did increase slightly due to possible differences in sludge yield. The minimum sludge aeration time was found to be between 12 and 16 hours per day. Increasing mixing intensity in the aeration tanks reduced sludge settling ability without significantly improving the substrate removal rate. Aeration properties of systems treating wastes at 1500 mg/1 COD were found to be inferior to those of systems treating wastes at 750 and 250 mg/1 COD. No significant differences were observed between systems treating 250 and 750 mg/I COD wastes. Results indicate that reducing the flow of water from domestic residences reduces treatment costs only so far as that afforded by the reduction in clarifier size and pumping costs.

This research is conducted to develop an irrigation fee policy for the Upper Pampanga River Project in the Philippines. Project costs and benefits have been determined and benefit-cost ratios computed for the different phases of the project and for different combinations of phases. The different phases of the project include the Upper Pampanga River Project, the power phase, the Aurora-Perfaranda Irrigation Project, and the Tarlac Irrigation Systems Improvement Project. The internal rate of return has also been computed in some instances. In this analysis, the irrigation benefit has been evaluated based on the world market price of rice and expressed in terms of "freeon- board" (FOB) and "cost, insurance, and freight" (CIF). The power benefit, on the other hand, has been based on the cost of an alternative thermal plant. Costs are then allocated to various purposes of the project using the separable cost-remaining benefits method. Using the allocated costs, benefit-cost ratios are again determined for irrigation and power purposes. Allocated irrigation benefits have been expressed on a per hectare basis. The values obtained are used as bases for irrigation fee assessment. Another basis for irrigation fee assessment--the capability of the farmers to pay--turned out to be negative under 1975 circumstances. The farmer's capability to pay was based on a survey of more than 100 farmers for the two crop seasons in 1975. However, at full project development when the potential benefit has been realized, farmer-users should be able to pay all the irrigation costs. While the irrigation fee has just been increased to 300 kg of paddy/hectare/year, which at present is equivalent to 14330/hectare/year, the research indicates that the National Irrigation Administration should retain this assessment for about five years for the following reasons. 1. Additional irrigation fees should not be assessed the farmers since percentage of collection dropped as a result of the recent increase in charges. Further, on the basis of the farm budget analysis for 1975, the living expenses of a farm family are greater than the net farm income. 2. Increasing the irrigation fee at this stage is not compatible with the government program of self-sufficiency in food production. 3. Decreasing the irrigation fee is not a sound policy either, since at the present rate there is already a heavy government subsidy. If warranted, further subsidies and incentives could be better accomplished through agricultural reforms, agricultural extension programs, medical and health care, and other government programs. 4. Repayment of the foreign loan is approximately covered by the present irrigation fee charges if all the farmers pay their irrigation fees. The present percentage of collection rate leaves much to be desired. On this basis, several irrigation fee collection alternatives have been investigated. The alternatives that hold promise include the involvement of the Irrigators' Groups, the credit agencies, and the municipal treasury offices.

In the last 200 years the importance of wild animals to man has taken two distinct forms: the use of creatures that provide 'game" for sport hunting, and the existence of value for the scientific or aesthetic appreciation of wildlife. Further, the relative strength of these two uses has shifted over time. It appears that a recent, significant growth in the number of people who hold high value for nongame uses of wildlife has taken place. The traditional emphasis of state wildlife management agencies has been on the production of game species in response to the overwhelming financial support from sportsmen. It is often argued that game management contributes to the welfare of nongame species. The reverse is also true, and sportsmen's interests could be served by a wildlife program giving greater weight to nongame activities. Through a modest redefinition of objectives the Arizona Game and Fish Department could effect a political alignment of game (consumptive) and nongame (monconsumptive) wildlife interests. This study is based on a federally funded research project in which the nonconsumptive uses and values of wildlife are being assessed. In particular, the purpose of this study is two-phased: to estimate the economic benefits to nonconsumptive wildlife users from viewing, studying, and photographing wild animals, and to relate these benefits to the political process in which the Arizona Game and Fish Department obtains its funding and political support. A modification of the travel-cost technique was used in this study to estimate economic benefits obtained by nonconsumptive wildlife users. Importantly, an explicit measure of the monetary value of travel time is empirically derived, providing improved benefit estimates. Visitors to seven wildlife viewing locations in Southeast Arizona responded to a mailed questionnaire at a rate of 86 per cent to provide a voluntary sample of more than 600 wildlife enthusiasts. An array of social and economic data were gathered for individuals and households. Respondents can be generally characterized as highly educated, affluent, middle aged, metropolitan residents. Using multiple regression analysis, demand functions were estimated for each household visiting three representative sites. Consumers' surplus values were then estimated for each site, incorporating an explicit measure of the value of travel time. These values compare favorably to consumers' surplus values estimated for hunting and fishing activities in Arizona. The results of the economic analysis performed in this study are primarily methodological. They are suggestive, however, of considerable political influence regarding wildlife management in Arizona. Importantly, a method exists for measuring the economic value or social welfare of the nonconsumptive use of wildlife. Such measures, widely assessed, could permit the comparison of economic values between consumptive and nonconsumptive wildlife uses and the evaluation of the associated change in consumer welfare resulting from alternative management activities. Based on the estimates of the number of people for whom nonconsumptive wildlife appreciation is important, there is reason to expect that significant political involvement in wildlife management issues will occur. These findings portend a major opportunity for the Arizona Game and Fish Depar went in terms of operational budgets and continued wildlife management authority in the state. Several recommendations are made to the Arizona Game and Fish Department, including improvement in their public image and greater political involvement with nonconsumptive wildlife interest groups.

Eighty years of chlorine atomic weight measurements revealed no variation of the stable isotope ratio, 37C1/ 35C1 (with precision up to 1.0%.) in natural materials. This result is not surprising because chlorine occurs in relatively few compounds, has a strong affinity for the liquid phase, occurs mostly in the -1 oxidation state and organisms don't discriminate between chlorine isotopes. Chlorine isotopes have been found to fractionate in the laboratory during kinetic reactions, equilibrium between phases and diffusion. This dissertation examined chlorine isotope composition of chloride from sea water halite, hydrothermal water samples and ground-water samples where chloride was likely moving by diffusion. The measurement method was mass spectrometry of methyl chloride gas prepared by quantitative precipitation of AgC1 from solution, and reaction of the AgC1 with methyl iodide. The precision of the technique is 0.24%. Results from sea water indicate that isotope ratios in sea water do not vary beyond measured uncertainty, thus sea water became the designated standard called SMOC (Standard mean ocean chloride). Many of the samples measured in this study vary significantly, though most are within 1.0%, of SMOC. All halite and hydrothermal samples are heavier than SMOC. Halite results may indicate isotope effects durina precipitation or time dependent variations of sea water. Hydrothermal samples may indicate source differences and/or fractionation mechanisms. Milk River aquifer samples indicate that chloride in the same aquifer may vary due to dual filtration or differina sources. Samples from a Canadian glacial clay show a total chloride variation of 2.4%,, linearly distributed with depth. chloride in the clay is known to be diffusing against ground-water movement. The isotope distribution can be approximated with a counter-current column equation. Samples from Texas and Louisiana contain an isotope range of about 1.8%, linearly distributed with depths from 6,000 to 14,000 feet. The distribution can be approximated with a simple diffusion equation. As a tracing tool, chlorine isotope measurements showed that halite AO kilometers from the ocean in south Africa probably did not precipitate from sea water mist, and that oil field brines adiacent to the Weeks Island salt dome (Louisiana) probably did not receive substantial quantities dome chloride.

Cryptosporidium is a protozoan parasite that causes gastroenteritis in man and animals. One mode of transmission of cryptosporidiosis is by the fecal-oral route. A method was developed for the concentration and detection of Cryptosporidium oocysts in water to study this organism's occurrence in the environment and its potential for waterborne disease transmission. Oocysts from an infected calf were used in experiments and monoclonal antibody labeled with fluorescein isothiocyanate was used for oocyst detection. A concentration method was developed using spun polypropylene cartridge filters. Optimal conditions for concentration, filter elution, filter porosity, and detection were determined by passage of 20-L volumes of tapwater seeded with 10⁵-10⁶ oocysts through the filters. The best method incorporated a 1-μm filter; 2 L eluent containing 0.1% Tween 80; backflush of eluent through filter; cutting the filter; mechanically shaking filter and eluate; and for 378-L volumes, three successive washings of filter material. Modifications were made when attempting to recover 10²-10³ oocysts in 378-L volurnes. These included addition of 1% Tween 80 and 1% sodium dodecyl sulfate (both made in distilled water) to the pellet, followed by homogenization, sonication, Sheather's flotation, and examination of the entire final preparation using a slide antibody test. To distinguish oocysts from other organisms such as yeast which may cross-react with the antibody, crystal violet and acid-fast stains were used. Cryptosporidium oocysts were isolated from secondarily treated sewage and identified on the basis of size, shape, reaction with antibody, acid-fastness, and inability to take up crystal violet. Limited studies with hepatitis A virus (HAV), a cause of waterborne disease, were performed using the HAS-15 strain of HAV and the FRhk-4 cell line. Four procedures used for concentration and detection of HAV in water were developed. They were radioimmunoassay for detection of viral antigen, production of HAV stocks, radioimmunofocus assay for quantitation of infective virus, and inhibition of certain strains of enteroviruses other than HAV, by guanidine.

A mathematical model was developed to integrate the physical concepts needed to predict the concentration of tebuthiuron in runoff and soil water. The model is based on a mass balance equation combined with a hydraulic routing equation and a solute transport equation in soil water. These equations are linked by a diffusion-controlled release of solutes from soil water to runoff. Field experiments were conducted on the Walnut Gulch Experimental Watershed in southeastern Arizona. A rotating-boom rainfall simulator was used to apply simulated rainfall to paired 3 x 11 m plots. The model was tested using rainfall simulator data after the application of tebuthiuron on a dry and on a wet soil. Rainfall, runoff, sediment and soil moisture content were sampled along with tebuthiuron concentration in soil, runoff and sediment. The results showed that the model represented the observations found in the field, though tebuthiuron concentrations in runoff were overestimated in the early stages of the runoff events.