A methodology is presented to assess the impact of reservoir silting on water availability for semiarid environments, applied to seven representative watersheds in the state of Ceará, Brazil. Water... L'article présente une méthodologie pour évaluer l'impact de l'envasement des réservoirs sur la disponibilité en eau en contextes semi-arides, et son application à sept bassins versants représentat...

The conversion efficiency of a crystalline silicon photovoltaic (PV) module increases as its temperature decreases. Considering this characteristic of the PV technology, in this study the authors analyse the use of cooled floating PV modules in a fraction of the area occupied by three reservoirs – Castanhão, Orós and Banabuiú – in the Brazilian semi‐arid region. Comparing with conventional ground‐mounted PV modules, an average conversion efficiency increase of 12.5% was measured for floating PV modules under the local weather conditions. In a second phase, measurements are used as input data in the PVSYST software in conjunction with a spreadsheet for the construction of electricity production scenarios. According to these scenarios, the potential PV production in the mentioned reservoirs would supply 7.4 and 18.8% of the electricity demand of Brazil's Ceará state (8.84 million inhabitants) and its largest city Fortaleza (2.6 million inhabitants), respectively.

Dense reservoir networks, with thousand of small dams, can be increasingly found throughout the world, especially in water-scarce environments, such as the Brazilian northeastern region. Although the effect of individual small dams might be negligible, their joint effect has proved to be relevant on water and sediment connectivity. Literature, however, is scarce concerning the effect of such networks on water availability and/or sustainability of mesoscale or large-scale basins. This research intended both to assess the effect of the dense reservoir network of the semiarid Upper Jaguaribe Basin (UJB; 24,200 km2 , in Brazil) for a 45-year period (1961–2005) and to investigate a network arrangement that maximized its hydrologic sustainability. Imagery of the years 1970 and 2002 was analyzed to assess temporal evolution of the network. The Water Availability in Semiarid Environments (WASA) model, which proved valid for the Upper Jaguaribe Basin, was used to assess its sustainability for almost 100 different...

Sustainability of communities, agriculture, and industry is strongly dependent on an effective storage and supply of water resources. In some regions the economic growth has led to a level of water demand that can only be accomplished through efficient reservoir networks. Such infrastructures are not always planned at larger scale but rather made by farmers according to their local needs of irrigation during droughts. Based on extensive data from the upper Jaguaribe basin, one of the world’s largest system of reservoirs, located in the Brazilian semiarid northeast, we reveal that surprisingly it self-organizes into a scale-free network exhibiting also a power-law in the distribution of the lakes and avalanches of discharges. With a new self-organized-criticality-type model we manage to explain the novel critical exponents. Implementing a flow model we are able to reproduce the measured overspill evolution providing a tool for catastrophe mitigation and future planning.

Abstract Water resources in dryland areas are often provided by numerous surface reservoirs. As a basis for securing future water supply, the dynamics of reservoir systems need to be simulated for large river basins, accounting for environmental change and an increasing water demand. For the State of Ceará in semiarid Northeast Brazil, with several thousands of reservoirs, a simple deterministic water balance model is presented. Within a cascade-type approach, the reservoirs are grouped into six classes according to storage capacity, rules for flow routing between reservoirs of different size are defined, and water withdrawal and return flow due to human water use is accounted for. While large uncertainties in model applications exist, particularly in terms of reservoir operation rules, model validation against observed reservoir storage volumes shows that the approach is a reasonable simplification to assess surface water availability in large river basins. The results demonstrate the large impa...

This paper investigates for a 25-year period the sediment distribution in a semi-arid Brazilian basin (2 × 10⁴ km²) with a network containing more than 4000 surface reservoirs. The methodology is based on rating curves and fitted parameters derived from field data. The results showed that suspended load corresponded to 70% of the total sediment yield (148 t km^-2 year^-1). The relatively low contribution of the suspended load (compared with other semi-arid regions) was attributed to the impact of the numerous upstream reservoirs, which retained 235 t km^-2 year^-1. The micro (50 hm³) reservoirs responded to, respectively, 5, 17, 30 and 48% of the total sediment retention by the reservoir network. This indicates that retention in the non-strategic reservoirs has a positive impact on water availability, since siltation of the strategic reservoirs would be expected to more than double if only such reservoirs existed. Citation Lima Neto, I. E., Wiegand, M. C. & de Araújo, J. C. (2011) Sediment redistribution due to a dense reservoir network in a large semi-arid Brazilian basin. Hydrol. Sci. J. 56(2), 319–333.