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This article reports the conception and design of a mission critical microgrid to serve a critical infrastructure application, namely, the Alcântara Space Launch Center, a government military facility in Brazil. The assumptions, general characteristics, requirements and particularities arising from the application are established and discussed in detail. High resilience and energy security are required in critical periods of operation, demanding a power supply infrastructure composed of redundant and dispachable sources capable of supporting n − 1 generation contingencies. Whereas, in the remaining time, economic and environmental aspects take place as main requests. Operation scenarios, on both grid-connected (on-grid) and isolated (off-grid) modes, are formulated as optimization problems and simulations have been performed to analyze these scenarios, which are reported and analyzed here. The off-grid operation, which is clearly more complex, is preferentially addressed, especially in scenarios with contingencies. In this context, the proposed microgrid is conceived to satisfactorily balance requirements such as the economy, pollutant emission reduction, high reliability, resilience and operational security, which are requested by this critical infrastructure application. [ABSTRACT FROM AUTHOR]

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Non-perennial rivers have attracted significant attention due to the progressive increase in water demand and pollution, river engineering side effects and climate change. The present study investigates the interannual, seasonal and spatial variability of nine water quality variables (pH, colour, turbidity, biochemical oxygen demand, total phosphorus, total inorganic nitrogen, chlorophyll-a, total solids and thermotolerant coliforms) from 93 monitoring river sites distributed over 11 watersheds in the highly populated Brazilian semiarid region. Shapiro–Wilk and Kruskal–Wallis tests were applied for assessing data normality and statistical differences, respectively. Additionally, principal component analysis (PCA) was performed for comparison between temporal and spatial data sets, while the Standardized Precipitation Index (SPI) was used to characterize meteorological drought. The results revealed that spatial variability is more evident than temporal variability. In the temporal scale, the interannual variability is more relevant than the seasonal one. The discharge of wastewater seems to attenuate a seasonal hydrological effect on water quality. There is a deterioration of water quality in most watersheds in the drier years, even in the rainy season. This is especially for colour, total phosphorus, total inorganic nitrogen and thermotolerant coliforms. The abrupt transition from dry to wet years also played an important role in changes in river water quality. This study provides new insights for the understanding of the water quality patterns in non-perennial rivers. In addition, we go on to identify important aspects for the management of these water sources, such as the need for wastewater discharge guidelines within scope of each watershed, and restrictions on the use of soil and water in the driest periods. [ABSTRACT FROM AUTHOR]

The semiarid northeast of Brazil is one of the most densely populated dryland regions in the world and recurrently affected by severe droughts. Thus, reliable seasonal forecasts of streamflow and reservoir storage are of high value for water managers. Such forecasts can be generated by applying either hydrological models representing underlying processes or statistical relationships exploiting correlations among meteorological and hydrological variables. This work evaluates and compares the performances of seasonal reservoir storage forecasts derived by a process-based hydrological model and a statistical approach. Driven by observations, both models achieve similar simulation accuracies. In a hindcast experiment, however, the accuracy of estimating regional reservoir storages was considerably lower using the process-based hydrological model, whereas the resolution and reliability of drought event predictions were similar by both approaches. Further investigations regarding the deficiencies of the process-based model revealed a significant influence of antecedent wetness conditions and a higher sensitivity of model prediction performance to rainfall forecast quality. Within the scope of this study, the statistical model proved to be the more straightforward approach for predictions of reservoir level and drought events at regionally and monthly aggregated scales. However, for forecasts at finer scales of space and time or for the investigation of underlying processes, the costly initialisation and application of a process-based model can be worthwhile. Furthermore, the application of innovative data products, such as remote sensing data, and operational model correction methods, like data assimilation, may allow for an enhanced exploitation of the advanced capabilities of process-based hydrological models. [ABSTRACT FROM AUTHOR]

Scarcity of hydrological data, especially streamflow discharge and groundwater level series, restricts the understanding of channel transmission losses (TL) in drylands. Furthermore, the lack of information on spatial river dynamics encompasses high uncertainty on TL analysis in large rivers. The objective of this study was to combine the information from streamflow and groundwater level series with multi-temporal satellite data to derive a hydrological concept of TL for a reach of the Middle Jaguaribe River (MJR) in semi-arid north-eastern Brazil. Based on this analysis, we proposed strategies for its modelling and simulation. TL take place in an alluvium, where river and groundwater can be considered to be hydraulically connected. Most losses certainly infiltrated only through streambed and levees and not through the flood plains, as could be shown by satellite image analysis. TL events whose input river flows were smaller than a threshold did not reach the outlet of the MJR. TL events whose input flows were higher than this threshold reached the outlet losing on average 30% of their input. During the dry seasons (DS) and at the beginning of rainy seasons (DS/BRS), no river flow is expected for pre-events, and events have vertical infiltration into the alluvium. At the middle and the end of the rainy seasons (MRS/ERS), river flow sustained by base flow occurs before/after events, and lateral infiltration into the alluvium plays a major role. Thus, the MJR shifts from being a losing river at DS/BRS to become a losing/gaining (mostly losing) river at MRS/ERS. A model of this system has to include the coupling of river and groundwater flow processes linked by a leakage approach. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]