Riparian ecosystems are valued for ecosystem services which have impacts on the well-being of humans and the environment. Anthropogenic disturbances along rivers in arid and semiarid regions have altered historical flow regimes and compromised their integrity. Many rivers are hydroecologically deteriorated, have diminished native riparian forests, and are pressured for their water supplies. My first study is founded on the premise that river restoration has increased exponentially with little documentation on effectiveness. We designed a conference to discuss lessons learned from past restoration activities to benefit future efforts. Participants, including scientists, managers, and practitioners, agreed that creating measureable objectives with subsequent monitoring is essential for quantifying success and employing adaptive management. Attendees stated that current projects are local and have limited funding and time, whereas future efforts must have longer funding cycles, larger timeframes, should contribute to regional goals, and address factors responsible for ecological decline. Bridging gaps among science, management, and policy in the 21st century is a key component to success. My second study focused on the benefits of long-term monitoring of local riparian restoration. Many efforts include revegetation components to re-establish native cottonwood-willow communities, but do not address how high-density establishment impacts vegetation dynamics and sustainability. Over five years, we documented significantly higher growth rates, lower mortality, and higher cover in cottonwood compared to non-native tamarisk. Cottonwood height, diameter at breast height, growth rates, and foliar volumes were reduced at higher densities. Herbaceous species decreased every year but native shrubs volunteered after two years resulting in a reduction of overall plant diversity from 2007-2009 with a slight increase from 2009-2011.My third study focused on improving basin-scale evapotranspiration (ET), a large component of the water budget, to better inform water resource allocation. My research suggests that multiple models are required for basin-scale ET estimates due to vegetation variability across water-limitation gradients. We created two empirical models using remote sensing, a multiplicative riparian ET model (r²=0.92) using MODIS nighttime land surface temperature (LST(n)) and enhanced vegetation index, and an upland ET model (r²=0.77) using multiple linear regression replacing LST(n) with a precipitation input.

Revised; Originally Published: 2005 / 3 pp.

Revised; Originally Published: 2005 / 3 pp.

Evapotranspiration (ET) is a key parameter for irrigation planning and management, and it is a crucial factor for water conservation practices considering the challenges associated with agricultural water availability. Field ET determination is the most accurate, but remains to be expensive and limited in scope. On the other hand, remote sensing is becoming an alternative tool for the estimation of ET. Operational ET algorithms, like the Moderate Resolution Imaging Spectroradiometer (MODIS)-based ET, are now successful at generating ET estimates globally at 1km resolution, however their intent is not management of agriculture irrigation. This research was done to develop an integrated method for downscaling MODIS ET appropriate for farm-level applications using geostatistical and remote sensing techniques. The proposed methodology was applied in the Wellton-Mohawk Irrigation and Drainage District of Yuma, Arizona. In a first effort, ET data was downscaled from standard 1-km-MODIS to a medium 250-m-spatial resolution via cokriging using Land Surface Temperature and Enhanced Vegetation Index as covariates. Results showed consistent downscaled ET with a variance greater than the variance of the coarse scale input and nearly similar mean values. This 250m product can serve larger irrigation districts in developed countries, where plot size is fairly large and regular. However, the size and shapes of most farms in developing countries makes the 250m ET challenging. For this reason, the second part of this work was done to downscale global scale 1km ET to 30m farm level application for irrigation use. This approach involved the generation of daily vegetation indices (VI) at 30m in order to support the downscaling of MODIS 1km ET. Landsat and MODIS reflectances were combined with the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) algorithm and the resulting VI data was used as a covariate to downscale ET with the cokriging approach. The results showed that the MODIS ET data seriously underestimates ET over irrigated areas. To correct this problem the MODIS data was then adjusted using field measured values to make it useful for operational purposes. The proposed geospatial method was applied to different growth stages of cotton and results were validated with actual ET from The Arizona Meteorological Network (AZMET) and published consumptive use of water for the area. The adjusted downscaled ET was comparable to these two published data (maximum error of 33%). This methodology is a practical alternative in areas where there is no ancillary data to estimate ET and it is expected to help in the planning of irrigation agriculture that will lead to improved agricultural productivity and irrigation efficiency.

Residential irrigation efficiency is a long-term concern for any community that faces water supply stress. When ability to raise water prices is constrained, public education and conservation programs can produce reduced water usage. Understanding the factors behind residential irrigation efficiency allows the design of more effective conservation campaigns. Combining site-specific water budgets with usage data for four hundred homes in North Texas enables quantifying efficient irrigation behavior. A survey of homeowners tests for the presence of conservation-positive attitudes and the knowledge required to implement those attitudes. The influence of neighbors’ watering habits is investigated using spatial clustering tools. Findings are analyzed in the context of an attitude, knowledge, and habit model of conservation behavior. The presence of automatic irrigation systems, small irrigated areas, and having knowledge of the amount that one waters one’s lawn are found to contribute to more intensive irrigation. Mixed evidence for small-scale clustering in irrigation intensity is presented.

Utilizamos um modelo físico-matemático de relações biosfera-atmosfera para estimar a climatologia da evapotranspiração regional (ETR) entre 1980 e 2009 no estado de São Paulo, o modelo SiB2 (Simple Biosphere model). Os cálculos utilizaram dados horários da reanálise CFSR, por meio de etapas de comparação das forçantes com dados observados de superfície, e com dados de fluxos de superfície observados no campo. Os padrões da reanálise mostraram-se satisfatórios no domínio do estado de São Paulo para caracterizar a climatologia de chuva e temperatura da região, com pequenos vieses no ciclo diurno e no total anual de precipitação. Foram utilizados 6 cenários com cobertura de superfície homogênea em todo o estado (floresta de mata atlântica, cerrado, eucalipto, cana-de-açúcar, pastagem, urbanização), além de dois outros cenários (vegetação nativa e vegetação atual), que produziram médias de ETR substancialmente distintas. No cenário de eucalipto obteve-se a maior média anual, de 3,7 mm dia-1, seguido pelos valores calculados para floresta atlântica e vegetação nativa, próximos entre si, e com máximos valores do saldo de radiação e fração evaporativa. O impacto da mudança do uso da terra nos totais de ETR no estado de São Paulo pode ser discutido a partir do cenário de vegetação nativa, com ETR média de 3,3 mm dia-1, ~20% superior à ETR da vegetação atual. Obteve-se uma caracterização da climatologia da ETR real no estado de SP, com média de 930 mm ano-1, comparável com a climatologia do DAEE de 980 mm ano-1 no estado como um todo, e bem comparada com a ETR em várias sub-bacias hidrográficas. / We have used a biosphere-atmosphere relationships physical-mathematical model in order to estimate the regional evapotranspiration (ETR) climatology between 1980 and 2009, the SiB2 model (Simple Biosphere Model). The calculations used hourly data from CFSR reanalysis, through the steps of comparing forcing data with observed surface data, and with surface fluxes data observed in site. The reanalysis patterns proved satisfactory to characterize the climatology of rainfall and temperature in São Paulo state area, with small biases in the diurnal cycle and in total annual precipitation. Six homogeneous coverage surface scenarios throughout the state were used (Atlantic forest, brasilian savannah, eucalyptus, sugar cane, pasture, urbanization), and two other scenarios (native vegetation and nowadays vegetation), which produced substantially different mean ETR. The eucalyptus scenario obtained the highest annual average of 3.7 mm day-1, the greatest values were from eucalyptus, Atlantic forest and nowadays vegetation, close together, and with maximum values of net radiation and evaporative fraction. The land use change impact in the total ETR in São Paulo state can be discussed from the native vegetation scenario, with 3.3 mm day-1 average value, ~20% higher than nowadays vegetation. We obtained a characterization of real ETR climatology in São Paulo state, with an average of 930 mm year-1, comparable to DAEE climatology of 980 mm year-1 statewide, and well compared to ETR in various sub-basins.

O conhecimento da demanda hídrica de uma cultura é fundamental para o planejamento da implantação de novas áreas, bem como para a análise da viabilidade econômica de uma cultura em determinada região. A utilização de culturas para fontes de matéria prima alternativa vem sendo altamente estudada nos últimos anos. Dentre muitas, vem se destacando no cenário nacional e mundial a cultura do pinhão-manso (Jatropha curcas L.) para a produção de biodiesel. O consumo de água por parte do pinhão-manso é pouco conhecida, necessitando ser estudada a fim de aprofundar os conhecimentos sobre a cultura e fornecer parâmetros confiáveis para a prática da irrigação. Os objetivos desse trabalho foram determinar a evapotranspiração (ET), a evaporação (E), a transpiração (T), o coeficiente de cultivo (Kc), coeficiente de evaporação (Ke) e coeficiente de cultivo basal (Kcb) do pinhão-manso na fase de formação irrigados por pivô central, gotejamento e sem irrigação na cidade de Piracicaba, SP. O experimento foi realizado na Fazenda Areão da Escola Superior de Agricultura \"Luiz de Queiroz\" da USP durante o período de março de 2012 a abril de 2013. O experimento foi dividido em três tratamentos, sendo: irrigado por pivô central, gotejamento e sem irrigação. A determinação de ET foi realizada por meio lisímetros de pesagem em cada tratamento, contabilizando a variação de massa em função das entradas saídas de água no sistema. A determinação do Kc foi realizada pela razão entre ET e ETo (estimado a partir de dados coletados na estação meteorológicos automática da Fazenda Areão). Por meio de microlisímetros de pesagem, foi determinado E. De posso dos dados de E, foram determinados os valores de T pela diferença de E (determinado no microlisímetro) e ET (determinado no lisímetro). Os valores de Ke e Kcb foram determinados pela razão de E e T por ETo, respectivamente. Os valores de ET variaram, principalmente, em função do método de irrigação. Foi observado uma superioridade dos valores de ET para o tratamento irrigado por pivô central, seguido do tratamento irrigado por gotejamento e sem irrigação. As médias dos tratamentos durante o primeiro ano foram 3,17, 2,82 e 2,82 mm dia-1 para os tratamentos irrigado por pivô central, irrigado por gotejamento e sem irrigação, respectivamente. Essa mesma proporção de ET entre os tratamentos irrigados foi observado nos valores de Kc. A média do período de Kc foi 0,69 e 0,63 para os tratamentos irrigados por pivô central e gotejamento. Essas maiores taxas de ET e Kc do tratamento irrigado por pivô central em relação ao tratamento irrigado por gotejamento foi devido ao método de irrigação por gotejamento ser mais eficiente na utilização de água pelas plantas em relação ao método por pivô central. Nesse método, a água é aplicada de maneira localizada as plantas, diferentemente do método por pivô central, em que a água é aplicada em toda a superfície do solo. Isso faz com que as taxas de E no método por gotejamento seja menor em relação ao pivô central, diminuindo as taxas de ET. De maneira geral, as taxas de E e Ke foram maiores em relação aos valores de T e Kcb durante o período analisado. Isso foi devido as plantas estarem com porte baixo e o solo estar quase por completo exposto as variações atmosféricas, fazendo com que as taxas de E e Ke sejam superiores as de T e Kcb. A média de E e Ke foram 1,85 mm dia-1 e 1,03, respectivamente, e as médias de T e Kcb foram 0,4 mm dia-1 e 0,2, respectivamente. / The knowledge of the water demand of a culture is essential for planning of new areas, as well as for the economic viability analysis of a culture in a specific region. The use of crops for alternative feedstock sources has been extensively studied in the last years. Among many, jatropha (Jatropha curcas L.) has been highlighted for biodiesel production in the national and global scenarios. Water consumption by the jatropha is little known, which requires to be studied in order to increase the knowledge and provide reliable parameters for the irrigation practice. The objectives of this study were to determine the evapotranspiration (ET), evaporation (E), transpiration (T), crop coefficient (Kc), evaporation coefficient (Ke) and basal crop coefficient (Kcb) of jatropha in the formation phase irrigated by center pivot, drip and without irrigation in Piracicaba, SP. The experiment was conducted at Areão Farm of Escola Superior de Agricultura \"Luiz de Queiroz\" of USP during March 2012 to April 2013. The experiment included three treatments: center pivot irrigated, drip irrigated and dryland. The determination of ET was made by weighing lysimeters for each treatment, accounting the inputs and outputs of water in the lysimeter system. The determination of Kc was made by the ratio between ET and ETo (estimated from data collected at the automatic meteorological station of Areão Farm). The determination of E was made by microlysimeters and T was determined between the difference of ET and E. Ke and Kcb values were determined by the ratio of E and T by ETo, respectively. ET values varied, mainly, according to the irrigation method. It was observed superiority of ET values for the treatment irrigated by center pivot, followed by the treatment irrigated by drip and without irrigation. The average during the first year was 3.17, 2.82 and 2.82 mm day-1 for the treatment irrigated by center pivot, irrigated by drip irrigated and without irrigation, respectively. The same proportion of ET from irrigated treatments was observed in the values of Kc. In the period, the average of Kc was 0.69 and 0.63 for the treatments irrigated by center pivot and irrigated by drip. These higher rates of ET and Kc of the treatment irrigated by center pivot compared to the treatment irrigated by drip was due to the method of drip irrigation is more efficient in water use by plants in relation to the method irrigated by central pivot. In this method, the water application is made in a localized way, differently in relation to the center pivot method in which water is applied all over the soil surface. This makes E rates given by drip irrigation method lower than the center pivot irrigation method, decreasing its ET averages. In general, rates of E and Ke were higher compared T and Kcb values during the period analyzed. This was explained due the short plants stature and the soil was almost completely exposed to atmospheric variations, causing rates of E and Ke exceed from T and Kcb rates. The average of Ke and E were 1.85 mm day-1 and 1.03, respectively, and the average of T and Kcb were 0.4 mm day-1 and 0.2, respectively.

O trigo é uma importante cultura agrícola no mundo, sendo uma das poucas na qual o Brasil não é autossuficiente, produzindo apenas cerca de 50% da sua demanda interna. Estudos relacionados ao crescimento da cultura e suas trocas de massa e energia com a atmosfera podem auxiliar no planejamento e manejo da cultura. O objetivo desse trabalho foi estudar o balanço de energia, o consumo hídrico e a recomendação de valores de Kc, com enfoque no acoplamento copa-atmosfera. Para isso foi instalado um experimento na Escola Superior Luiz de Queiroz- ESALQ, semeado no dia 30 de maio de 2017 sob sistema de irrigação. Os resultados indicam que o fluxo de calor latente (LE), calor sensível (H) e calor no solo (G) representaram 81,17 %,14,13% e 4,7% do saldo de radiação (Rn). A evapotranspiração acumulada para a cultura do trigo foi de 301 mm, tendo uma evapotranspiração média diária de 2,8 mm.d-1. A cultura teve um fator de desacoplamento (&Omega;) médio para o ciclo de 0,53, porém variou em relação as fases fenológicas: 0,68 (emborrachamento), 0,55 (floração), 0,26 (formação de grãos) e 0,3 (maturação). O coeficiente de cultura ao longo do ciclo foi 0,58, 1,12, 1,46, 1,23, 1,32 e 0,73 para as fases de estabelecimento, perfilhamento, emborrachamento, floração, formação de grão e maturação, e o valor médio para todo o ciclo foi de 1,08. Os valores de Kc indicaram uma queda quando houve elevação da evapotranspiração de referência (ETo). Assim os valores de Kc para diferentes intervalos de ETo foram: 1,09 (ETo &le; 2); 1,34 (2< ETo &le; 3); 1,25 (3 < ETo &le; 4); 0,77 (ETo > 4). / The wheat is one of the most important crop of the world, and the few one that Brazil is not self-sufficient, producing only 50% of domestic demand. Studies related crop growth and its mass and energy exchange with atmosphere may help to improve the crop planning and management. The objective here was to study on the energy balance and water use of wheat crop, take into account the canopy-atmosphere coupling approach in such study. To do so, an irrigated experiment was conducted in Piracicaba-SP, at the Escola Superior Luiz de Queiroz-ESALQ, sown on May of 2017. The results showed that the latent heat flux (LE), sensible heat (H) and soil heat (G) represented 81.17%, 14.13% and 4.7% of the net radiation (Rn). Cumulative evapotranspiration for the whole wheat crop was 301 mm, with na average daily evapotranspiration of 2.8 mm.d-1. The crop had a mean decoupling fator (&Omega;) for the cycle of 0.53, but varied with the phenological phases as: 0.68 (head development), 0.55 (flowering), 0.26 (grain formation) and 0.3 (maturation). The crop coefficient along the cycle was 0.58, 1.12, 1.46, 1.23, 1.32 and 0.73 for the respective phases establishment, tillering, head development, flowering, grain formation and maturation, with the average Kc for the cycle was 1.08. The values of Kc indicated a decrease when there was elevation of reference evapotranspiration (ETo). Thus, Kc values for different ETo intervals were: 1.09 (ETo &le; 2); 1.34 (2 < ETo &le; 3); 1.25 (3 < ETo &le; 4); 0.77 (ETo > 4).

O estresse causado pelo deficit hídrico em plantas de feijão é descrito como responsável por alterações na assimilação de carbono e produção de etileno. O objetivo deste estudo foi avaliar e caracterizar o desempenho fotossíntético e hormonal de plantas de feijão, variedade IAC Imperador, condicionadas a diferentes teores de água no solo durante seu ciclo. Plantas cultivadas em vasos foram submetidas a dois, quatro e seis dias sem irrigação na fase vegetativa ou reprodutiva da cultura, avaliando-se evapotranspiração da cultura, potencial hídrico das folhas, temperatura foliar, condutância estomática, transpiração, fotossíntese, produção de etileno, número de vagens por planta, número de grãos por vagem, massa média de grãos e produtividade por planta, comparando-se os tratamentos sob estresse com um controle de irrigação diária. As plantas apresentaram reduções significativas na condutância estomática, transpiração e fotossíntese com apenas dois dias sem irrigação em ambas as fases de desenvolvimento. Não foi verificado aumento de produção de etileno nas plantas de nenhum dos tratamentos sob estresse quando comparadas com plantas do controle com irrigação diária. Não houve diferença estatística entre os tratamentos para nenhum dos componentes de produtividade. O cultivar apresenta características que podem favorecer a tolerância a períodos de seca. / The stress caused by water deficit in bean plants is described as responsible for changes in carbon assimilation rates and ethylene production. The goal of this study was assess and characterize the photosynthetic and hormonal behaviour of bean plants, variety IAC Imperador, under different soil moisture contents during its cycle. Plants grown in pots were imposed to two, four and six days without irrigation at vegetative or reproductive phases, assessing crop evapotranspiration rate, leaf water potential, leaf temperature, stomatal conductance, transpiration, photosynthesis, ethylene production, number of pods per plant, number of grains per pod, grain average weight and yield per plant, comparing treatments under water stress against control with daily irrigation. Plants showed significant decreases in stomatal conductance, transpiration and photosynthesis with only two days without irrigation in both plant development stages. Plants from none of the seven treatments showed increased ethylene production when compared against plants from control with daily irrigation. There was no significant statistical difference among treatments for yield components. The variety showed characteristics that may favour the tolerance to low soil moisture periods.

O aprimoramento das práticas agronômicas e a utilização de alta tecnologia nas lavouras contribuiu para os aumentos significativos na produtividade das culturas e, pode ter alterado a dinâmica de absorção e partição dos nutrientes pelas plantas. As recomendações oficiais de adubação para a cultura de milho no Brasil estão baseadas no teor crítico do nutriente no solo e são provenientes de literaturas mais antigas. Por serem dinâmicos, os fatores que interagem em um sistema de produção agrícola podem ser melhor estudados através de modelos matemáticos. A técnica de modelagem em agricultura pode expandir a compreensão das interações que ocorrem no sistema solo-planta-atmosfera. Sendo assim, o objetivo deste estudo é propor um modelo para o cálculo de recomendação de adubação da cultura de milho, a partir da modelagem da marcha de absorção de nutrientes, da evapotranspiração potencial da cultura e, da partição dos nutrientes nas plantas, levando em consideração a taxa de absorção de cada nutriente para cada genótipo em um determinado sistema de produção. O modelo proposto considera que a recomendação de adubação deve ser realizada com base na variação temporal da taxa de absorção de nutrientes, a qual define melhor a demanda da cultura, em comparação com o teor crítico dos nutrientes no solo. Para a validação do modelo, sugere-se um ensaio de campo comparando as metodologias. / The improvement of agronomic practices and the use of high technology in field crops contributed for their significant increases in productivity, and could also have altered the dynamics of nutrient uptake and partition by the plant. Official recommendations for fertilizer applications to the maize crop in Brazil are based on the critical soil nutrient content and are relatively outdated. Since the factors that interact in an agricultural production system are dynamic, mathematical modeling turns out to be an appropriate tool for these studies. Agricultural modeling can expand our knowledge about the interactions prevailing in the soilplant- atmosphere system. In this way, the objective of this study is to propose a model for fertilizer recommendation of the maize crop, based on modelling nutrient uptake, potential evapotranspiration of the crop, and the partition of nutrients in the plant, taking into account the nutrient uptake rate of each genotype in a given production system. The proposed model considers that the fertilizer recommendation should be made based on the temporal variation of the uptake rate, which should better define crop needs in relation to the classic recommendation based on the critical soil nutrient content. To validate the model an experiment is suggested to compare methodologies.