Thesis (M.S. - Agricultural Economics)--University of Arizona, 1986. / Includes bibliographical references (leaves 172-177).

Thesis (Ph. D. - Soil and Water Science)--University of Arizona, 1992. / Includes bibliographical references (leaves 240-246).

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1968. / Includes bibliographical references (leaves 63-65).

Thesis (M.S.)--University of Nevada, Reno, 2007. / Includes bibliographical references (p. 301-309). Also available via the Internet.

Thesis (Ph.D.)(Agricultural Economics)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

The pervious pavement system has been identified as an effective source control device capable of removing urban stormwater pollution by trapping pollutants within the system and biodegradation. Recent studies have further demonstrated that the pervious pavement system could be used as a source of renewable energy capable of reducing household energy bill by about 80%. In view of ever increasing demand for water and the continued reduction in available fresh water resources in the world, stormwater has been recognized as a potential valuable source of water which could be harnessed. The overall aim of this multi disciplinary research was to evaluate the suitability of a modified pervious pavement system (PPS) for water harvesting and re-use, particularly focussing on potential third world applications and taking advantage of the latest developments in materials that are available for such applications. The aim was a holistic one in which water re-use was examined in terms of both the potential advantages from an irrigation point of view without ignoring the very important public health concerns that are often of concern when water is stored in circumstances which do not fit the normally used criteria for potable supplies. The results of this study confirmed the pollution control capability of the porous pavement system as earlier determined by previous studies. Also, a novel experimental rig was designed to reproducibly create very high and realistic rainfall events over model pavement structures. Furthermore, the performance of a new geotextile, Inbitex Composite® in the pervious pavement system was determined for the first time. Furthermore, this study also tested for the first time, the performance of a pervious pavement system modified by the incorporation of Inbitex Composite® geotextile with slits and made prescriptions as to how this new geotextile could be best installed in a modified pervious pavement system in order to achieve high infiltration without compromising pollution control. This study tested the practical use of the pervious pavement system for water harvesting and storage for reuse in irrigation. In order to achieve this, the author took what could be considered as a holistic approach to water quality issues and determined the chemical, electrochemical and microbiological quality of water stored in the system as well as investigated the public health concern of the potential of pathogenic organisms in waters stored in unconventional water storage system as the pervious pavement system. It also determined that the pervious pavement system have the capability to recycle water with physical, chemical and microbiological qualities that will meet international standards for irrigation and that the system does not offer a conducive environment for potential pathogenic organisms if contamination incident occurs from adjoining areas. This study also became the first to practically relate Sustainable Urban Drainage System (SUDS) to agricultural benefit by demonstrating how a SUDS device (pervious pavement system) could be used in addition to its urban drainage control role, as a source of supply of high quality irrigation water to cultivate crops fit for human and animal consumption despite high application of pollutants. This study determined contrary to the observation of earlier studies that the use of slow-release iv fertilizer could lead to eutrophication problems in cases where the water is channeled to natural water courses. Furthermore, active response of potential pathogenic bacteria to the presence of slow-release fertilizer was observed in this study. This raises a huge question on the need to add fertilizer to the pervious pavement system. Coupe, (2004) had demonstrated that oil degrading microbes would respond positively to food sources in the system and hence, there was no significant need for simulation by nutrient addition, the author concluded in the study presented here that fertilizer addition should only be conducted if the waters are to be used for irrigation where the nutrients would be beneficial to the plants and that even in this case, the microbiological water quality should be constantly monitored and the addition suspended if the risk of contamination from adjoining areas is high.

A obstrução de emissores por causas químicas, em sistemas de irrigação localizada, é um problema crucial enfrentado pelos irrigantes, que em muitos casos, dependendo da gravidade, são obrigados a substituir o sistema existente. Isso se deve à presença de íons específicos, que em determinadas condições precipitam, provocando a obstrução dos emissores e tubulações. No entanto, pode-se intervir nas condições propícias a esse processo, de modo a preveni-lo. Uma forma de intervenção é a injeção de ácido, uma vez que este processo ocorre com maior proporção quando a água de irrigação apresenta valores de pH acima de 7. Neste contexto, objetivou-se com este trabalho desenvolver um dispositivo eletrônico de controle do pH da água para irrigação localizada. O trabalho foi desenvolvido no Laboratório de Hidráulica do Departamento de Engenharia de Biossistemas (LEB) da Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP). O sistema de controle apresenta de um dispositivo de injeção de ácido (atuadores) controlado através de uma válvula solenóide, comandada por pulsos elétricos, enviados pelo processador, que está associado a um circuito de leitura de um sensor, que detecta o pH da água em tempo real. A lógica de controle é baseada na diferença entre as entradas e as saídas do controlador, de modo que, as decisões futuras são baseadas nas respostas proporcionadas pelas ações anteriores. O ciclo de cada ação sobre os atuadores tem uma duração média de 3 s, que compreende o tempo entre 2 leituras consecutivas do pH e injeção de ácido na água. O sistema foi testado em águas de diferentes valores iniciais de pH (variando de 6,2 a 9,2) sob vazão constante (264 L h-1) e variável. Além disso, foi instalada uma linha lateral de irrigação com comprimento de 44 m, composta de microtubos (emissores) espaçados de 1 m, aonde foi verificado os valores de pH da água na saída dos emissores ao longo da linha lateral (início, 1/3, 2/3 e fim) e em diferentes intervalos de tempos a partir do início dos testes. Os resultados obtidos comprovam a eficiência do dispositivo em manter o pH da água na faixa desejada, tanto para a condição de vazão constante, quanto variável. Em relação ao pH da água medido na saída dos emissores, não foi verificado variações significativas, tanto temporal quanto espacial, sempre se mantendo dentro da faixa desejada. / The clogging of emitters by chemical causes, in drip irrigation systems, is a crucial problem faced by the irrigators that in many cases, depending of the gravity, are ordered to replace the existent system. This is occurring due to the presence of the specific ions, which it precipitates in determined conditions, causing the clogging of emitters and pipes. However, it can intervene in the conditions for these processes to prevent them. A way of intervention is the acid injection, since this process occurs in major proportion, when the irrigation water shows values of pH above 7. In this context, the aim of this work was to develop an electronic device of control of the pH water for irrigation drip. The work was developed in the Laboratory of Hydraulic of Department of Biossystems Engineering (LEB), at Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP). The system of control shows a device of acid injection (actuators) controlled though a solenoid valve, commended by electrics pulse that it sent by the processor, that is associated with a reading circuit of sensor, that it detects the pH of water in the real time. The logical control is based on the difference between the input and output of controller, so that the future controller decisions are based on answers caused by early actions. The cycle of each action on the actuator has the medium duration of 3 s, that it meaning the time between 2 consecutive reading of pH and acid injection in the water. The system was tested in waters of different values of pH (ranging 6.2 to 9.2) under constant (264 L h-1) and variable flow. Moreover, it was installed a lateral line of irrigation with length of the 44 m, it was composed of microtubes (emitters) spaced 1 m, where it was verified the pH of water in outlet of emitters along of lateral line (begin, 1/3, 2/3 and end) and in different intervals of time after starting of tests. The results obtained proved the efficiency of the device to maintain the water pH in the desired range, for the both conditions, constant as variable flow. In relation to the water pH in the outlet of emitters, it wasnt verified meaningful variations, both temporal and spatial, it always maintained into the desired range.

Partial rootzone drying (PRD) is an irrigation management technique designed to reduce water use in grapevines without a decline in yield, thereby increasing water–use efficiency (measured as t/ML) (WUE). The principle of PRD is to keep part of the root system at a constant drying rate to produce soil-derived signals to above–ground plant organs to induce a physiological response. Major PRD effects include a reduced canopy size and greatly increased WUE with possible improvements in fruit quality. Although we have a good understanding of the hormonal physiology of PRD, little is known on the effect of PRD on partitioning of C, N and inorganic ions such as K. This thesis broadens our knowledge on the effects of PRD on grapevine field performance, growth and dry matter accumulation as well as its effects on physiology and biochemistry. In field experiments over 3 seasons, PRD reduced water use in grapevines without a significant decline in yield. PRD effects included reduced shoot growth and greatly increased WUE. Field–grown Cabernet Sauvignon, where the PRD grapevines were irrigated at half the control rate, and Shiraz where the PRD grapevines were irrigated at same rate as controls, confirmed that PRD is not simply an irrigation strategy that applies less water, rather it alters the way in which the plant responds to its environment, e.g. PRD alters the sensitivity of the stomatal response to atmospheric conditions and significantly influence enzymes that regulate nutrient accumulation and partitioning. PRD did not change the total amount of carbon and nitrogen on a whole plant basis. However, it caused a significant partitioning of carbon and nitrogen towards trunk, roots and fruit at the expense of shoot growth. This change in partitioning occurred as a result of altered activity of the enzymes controlling the assimilation of carbon and nitrogen. PRD significantly reduced nitrate reductase (NR) activity in grapevine leaves, which catalyses the first step in the assimilation of nitrate irrespective of the amount of water applied. The reduction in NR activity is correlated with the development of the PRD cycle and the associated reduction in stomatal conductance. PRD also significantly altered grapevine sucrolytic enzyme activity that regulate source:sink relationships. PRD showed transient increases in leaf sucrose phosphate synthase (SPS) activity (formation of sucrose) compared to control, but significantly reduced leaf neutral invertase (sucrose cleavage) and leaf starch content in both field and potted experiments. This may indicate an increased photosynthetic capacity and a reduction in its sink strength for sucrose in favor of organs such as fruit and roots. This hypothesis was reinforced by the fact that berries showed significantly higher levels in glucose and fructose early in the season. Berry sugar content and Brix at harvest however was unaffected. Although PRD had no significant effect on berry characteristics at harvest such as Brix and pH, it occasionally reduced per berry K+ content and increased total amino acid concentration that may lead to positive outcomes for wine quality. PRD–treated grapevine roots on the 'wet'– and 'drying'–sides differed greatly in enzyme activity and osmolality. PRD significantly increased osmolality in both wet and drying roots by increasing total osmolyte concentration that may facilitate the movement of water from wet to dry roots. The increases in osmolality were also associated with increased free polyamine production (spermidine and spermine) in PRD roots that may be related to increased root growth and density. / Thesis (Ph.D.)--School of Agriculture and Wine, 2005.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 198-204). Also available on the World Wide Web.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 6 uppsatser.