Um dos maiores desafios da humanidade neste século é garantir segurança alimentar para todas as pessoas. O Brasil é um dos poucos países do mundo capaz de expandir sua produção de alimentos de forma sustentável, com destaque para a região do Cerrado, que tem função estratégica no alcance do aumento da produção de alimentos esperada. O desenvolvimento sustentável da agricultura irrigada, por sua vez, dependendo da disponibilidade hídrica oriunda de pequenos reservatórios. Diversas pequenas barragens foram construídas nas últimas décadas na região com o intuito de armazenar água excedente das chuvas e disponibilizá-la no período de estiagem. Neste contexto, a evaporação é uma perda efetiva de água que deve ser melhor quantificada para que se possa desenvolver estratégias e políticas de gestão hídrica mais eficientes. O objetivo desta dissertação foi avaliar e propor métodos de estimativa de evaporação de água em pequenas barragens, bem como simular os impactos provenientes de mudanças climáticas nas perdas por evaporação. Avaliaram-se 14 métodos de estimativa de evaporação difundidos na literatura, além de ajustes de modelos empíricos baseados em Tanque Classe A (TCA), regressões lineares múltiplas e técnicas de aprendizado de máquina. A partir de um TCA instalado próximo ao reservatório, foram obtidos coeficientes de correção da evaporação do tanque considerando base mensal, sazonal e anual. Os modelos de regressão Cubist, Random Forest, Redes Neurais com Regularização Bayesiana e regressões lineares múltiplas foram ajustados utilizando dados climáticos coletados por uma estação meteorológica próxima ao reservatório. Dentre os métodos avaliados, o de Kohler, Nordenson e Fox (1955) e Linacre (1993) tiveram desempenho adequado, bem como os coeficientes de correção, duas equações lineares e os modelos de aprendizado de máquina. A evaporação apresentou tendências significativas de aumento, tanto para uma forçante de saldo de radiação de 4,5 W m-2, como para 8,5 W m-2. Estimou-se um aumento médio da evaporação na bacia do Rio Preto até o ano de 2100 de 18,4% e, quanto menor o reservatório, maior o risco de falta de água ao fim da estação seca. | Food safety is one of the century’s major challenges for humanity. Brazil is one of the few countries capable of increasing sustainable food production, highlighting the savanna region (Cerrado), which plays a key role in achieving this expected raise in production. However, the sustainable development of irrigated agriculture depends on small reservoirs water availability. A large number of small dams have been built during the last decades in the region. The objectives of these structures are to store runoff water and to supply water demands during drought periods, however small reservoirs evaporation is an effective water loss and should be better quantified in order to develop efficient management strategies and policies. The objective of this dissertation was to assess and propose methods for estimating small reservoir water evaporation, as well as to simulate the impacts advent from climatic changes on evaporation. Fourteen widespread in literature methods were assessed for estimating evaporation. Empirical models based on Class A pan, multiple linear regressions and machine learning techniques were also adjusted to estimate small reservoir evaporation. Monthly, seasonal and annual pan coefficients were calibrated for Class A pan installed near the reservoir. The Cubist regression, Random Forest, Bayesian regularized neural networks and multiple linear regressions were adjusted using climatic data observed near the reservoir. Among the assessed methods, Kohler, Nordenson and Fox (1955) and Linacre (1993) presented adequate performance, as did the pan coefficients, two linear regressions and the machine learning models. Evaporation showed significant increase trends for both representative concentration pathways of 4.5 W m-2 and 8.5 W m-2. Considering an increase of up to 18.4% estimated until 2100 for the Rio Preto basin, higher will be the risk of failure in water supply on the end of the drought period for smaller reservoirs.

Universidad Nacional Agraria La Molina. Facultad de Ingeniería Agrícola. Departamento Académico de Ordenamiento Territorial y Construcción | El tanque baffled es un reactor anaerobio diseñado para ser empleado en zonas peri urbanas o rurales, aunque existe evidencia de que se ha utilizado para tratar aguas residuales domésticas pertenecientes a un municipio en África. En la presente investigación se evaluó la operación y eficiencia de un tanque baffled ubicado en la Planta Piloto de Tratamiento de Aguas Residuales de la Universidad Nacional Agraria la Molina; el tanque baffled consta de 3 cámaras o compartimentos y ha sido diseñado para tratar 6 m3 /d de agua residual doméstica. Se monitoreó la eficiencia del tratamiento durante un período de 8 semanas, con muestreos semanales; considerando 2 puntos de muestreo: ingreso y salida del agua residual. Se midieron parámetros físico-químico y microbiológicos, alcanzándose eficiencias de remoción de 70% para DBO5, 78% para DQO, 73% para turbiedad, 92% para SST, 99% para sólidos sedimentables y 2 unidades logarítmicas para coliformes totales. Hidráulicamente el tanque operó con un caudal promedio de 2.82 m3 /d, con un tiempo de retención real de 13 horas, aproximadamente. Las eficiencias alcanzadas muestran un desempeño muy prometedor para que el sistema sea instalado en poblaciones rurales y pequeños municipios a nivel nacional, donde mayoritariamente se emplean tanques sépticos con eficiencia de remoción de DBO5 entre 30 y 40% y tanquesimhoff, con eficiencia de remoción en DQO entre 25 y 50%. (Tilley et.al., 2014) | The baffled tank is an anaerobic reactor designed to be used in peri-urban or rural areas, although there is evidence that it has been used to treat domestic wastewater belonging to a municipality in Africa. In this research, the operation and efficiency of a baffled tank located in the Pilot Plant for Wastewater Treatment of the “Universidad Nacional Agraria la Molina” was evaluated; the baffled tank consists of 3 chambers or compartments and has been designed to treat 6 m3/d of domestic wastewater. Treatment efficiency was monitored over a period of 8 weeks, with weekly samplings; considering 2 sampling points: entry and exit of wastewater. Physical-chemical and microbiological parameters were measured, reaching removal efficiencies of 70% for BOD5, 78% for COD, 73% for turbidity, 92% for TSS, 99% for settleable solids and 2 logarithmic units for total coliforms. Hydraulically, the tank operated with an average flow of 2.82 m3/d, with a real retention time of approximately 13 hours. The efficiencies achieved show a very promising performance for the system to be installed in rural populations and small municipalities nationwide, where mostly septic tanks are used with BOD5 removal efficiency between 30 and 40% and imhoff tanks, with removal efficiency in COD between 25 and 50%. (Tilley et.al., 2014)

Proyecto de Graduación (Licenciatura en Ingeniería Ambiental) Instituto Tecnológico de Costa Rica, Escuela de Química, 2014. | The Aqueduct of San Isidro de El Guarco is in need of a immediate intervention due to water shortages during the dry season was presented in the catchments El Cubano, Casa Blanca #1 and Casa Blanca #2, the flow is insufficient to meet the demand during summer. New water sources near the population was proposed to achieve the maximum daily flow of 13 L / s is required over a period of 20 years. During rainy season, the increase of solid color and was in the water storage tank. The causes of the presence of high water turbidity and condition of slow upward flow filter were evaluated. The methodology used to afford data análisis was visits and interviews with the plumber and the manager of the ASADA were scheduled, in order to assess the current situation of the aqueduct; through the database SENARA, which two streams flow more was chosen to ensure the demand for current and future population needs. Each of the structures were measured internally, because there were no plans or the functioning of the chlorination was known and for 12 hours the volume change was measured in the storage tank for the use by users of San Isidro. The main results are that using the headwaters, the topographic profile of the pipe driving was obtained, this to ensure easy installation and lower costs. Also, with the high value of 12.95 NTU turbidity in the water filter in November indicates the status of the filter should be checked and constructing two filters to treat the flow entering the treatment plant. Expanding volume of 197 m3 is required in the storage tank. As finding in the months of December to April a decrease in precipitation is presented, as illustrated in the water balance, indicating a deficit of water in summer. Is recommended that the technical study, to determine whether the construction of a dam is the only technically feasible solution.