The Curve Number (CN) method is extensively used for predict surface runoff from storm events. However, remain some uncertainties in the method, such as in the use of an initial abstraction (λ) standard value of 0.2 and on the choice of the most suitable CN values. Here, we compute λ and CN values using rainfall and runoff data to a rural basin located in Midwestern Brazil. We used 30 observed rainfall-runoff events with rainfall depth greater than 25 mm to derive associated CN values using five statistical methods. We noted λ values ranging from 0.005 to 0.455, with a median of 0.045, suggesting the use of λ = 0.05 instead of 0.2. We found a S0.2 to S0.05 conversion factor of 2.865. We also found negative values of Nash-Sutcliffe Efficiency (to the estimated and observed runoff). Therefore, our findings indicated that the CN method was not suitable to estimate runoff in the studied basin. This poor performance suggests that the runoff mechanisms in the studied area are dominated by subsurface stormflow.

The Brazilian savanna (Cerrado) has been heavily impacted by agricultural activities over the last four to five decades, and reliable estimates of reference evapotranspiration (ET_o) are needed for water resource management and irrigation agriculture. The Penman–Monteith (PM) is one of the most accepted models for ET_o estimation, but it requires many inputs that are not commonly available. Therefore, assessing the FAO guidelines to compute ET_o when meteorological data are missing could lead to a better understanding of which variables are critically important for reliable estimates of ET_o and how climatic variables are related to water requirements and atmospheric demands. In this study, ET_o was computed for a grass-dominated part of the Cerrado from April 2010 to August 2019. We tested 12 different scenarios considering radiation, relative humidity, and/or wind speed as missing climatic data using guidelines given by the FAO. Our results presented that wind speed and actual vapor pressure do not affect ET_o estimates as much as the other climatic variables; therefore, in the Cerrado’s conditions, wind speed and relative humidity measurements are less required than temperature and radiation data. When radiation data were missing, the computed ET_o was overestimated compared to the benchmark. FAO procedures to estimate the net radiation presented good results during the wet season; however, during the dry season, their results were overestimated because the method could not estimate negative R_n. Our results indicate that radiation data have the highest impact on ET_o for our study area and presumably for regions with similar climatic conditions. In addition, those FAO procedures for estimating radiation are not suitable when radiation data are missing.

This study analyzed the performance of the Brunt (1932), Swinbank, (1963), Idso and Jackson (1969), Brutsaert (1975), Idso (1981), and Bignami et al. (1995) methods to estimate atmospheric emissivity under grass-dominated savannas (known as campo sujo Cerrado), in the region of Baixada Cuiabana. The estimates were compared with data obtained by energy balance equation in two seasons, dry season (May to August), and wet season (September to December) of 2009. The Swinbank and Idso and Jackson methods, that consider only air temperature, show better performances for the wet season. However, methods that consider water vapor pressure and air temperature (Brunt, Brutsaert, Bignami and Idso) show good performances for the dry season. The Idso and Brutsaert methods show the highest index of agreement and are recommended to estimate atmospheric emissivity for the region.

Este estudo visa realizar pesquisas na base de dados Scopus e Web of Science sob o intuito de procurar trabalhos relativos ao mapeamento hídrico com o enfoque em áreas de risco utilizando VANTs. O software VOSViewer, gera infográficos fundamentados no sistema de nós exibindo os principais termos da pesquisa, autores, elementos recorrentes e palavras-chave. Categorizando os trabalhos, de forma quantitativa, em autores colaboradores, abordagem referente ao tema, tipos de publicações, principais revistas, índices, principais países, redes de colaboração e palavras-chaves, indicou os principais trabalhos pertinentes ao tema, em que, esses foram discutidos para a verificação de como o tema é abordado. 91,15% dos trabalhos estão escritos em inglês, sendo os EUA o segundo país que mais publica sobre, na retaguarda da China. Os principais termos concatenados a pesquisa são UAV – Unmanned Aerial Vehicles, Photogrammetry e DEM - Digital elevation Model, que fazem alusão ao uso de VANTs para obtenção do MDE e MDS pelo método fotogramétrico. Dentre os trabalhos, 10 apresentaram material metodológico e resultados promissores na utilização de VANT ́para mapeamento de risco hidrológico, com destaque aos trabalhos de Mazzoleni, Muthusamy Annis, Luppichini, que apresentam softwares de processamento de imagem (Agisoft PhotoScan) e de simulações hidrodinâmicas de águas pluviais e fluviais (FLO-2D e HEC-RAS). Logo, esse estudo viabilizou reconhecer condutas metodológicas, tendências, dificuldades e as vantagens da ferramenta VANT, na aplicação técnica, como alta precisão, custo relativamente baixo e alcance em áreas de difícil acesso.