TY - JOUR A1 - Soares Pereira, Francisco Jairo A1 - Gomes Costa, Carlos Alexandre A1 - Förster, Saskia A1 - Brosinsky, Arlena A1 - de Araujo, Jose Carlos T1 - Estimation of suspended sediment concentration in an intermittent river using multi-temporal high-resolution satellite imagery JF - International journal of applied earth observation and geoinformation N2 - There is a shortage of sediment-routing monitoring worldwide, despite its relevance to environmental processes. In drylands, where water resources are more vulnerable to the sediment dynamics, this flaw is even more harmful. In the semi-arid Caatinga biome in the North-east of Brazil, rivers are almost all intermittent and hydro-sedimentological monitoring is scarce. In the biome, water supply derives from thousands of surface reservoirs, whose water availability is liable to be reduced by siltation and sediment-related pollution. The goal of this research was to evaluate the potential of multi-temporal high-resolution satellite imagery (RapidEye) to assess the suspended sediment concentration (SSC) in the medium-sized intermittent Jaguaribe River, Brazil, during a 5-year period. We validated 15 one-, two- and three-band indices for SSC estimation based on RapidEye spectral bands deduced in the context of the present investigation and nine indices proposed in the literature for other optical sensors, by comparing them with in-situ concentration data. The in-situ SSC data ranged from 67 mg.L-1 to 230 mg.L-1. We concluded that RapidEye images can assess moderate SSC of intermittent rivers, even when their discharge is low. The RapidEye indices performed better than those from literature. The spectral band that best represented SSC was the near infrared, whose performance improved when associated with the green band. This conclusion agrees with literature findings for diverse sedimentological contexts. The three-band spectral indices performed worse than those with only one or two spectral bands, showing that the use of a third band did not enhance the model ability. Besides, we show that the hydrological characteristics of semi-arid intermittent rivers generate difficulties to monitor SSC using optical satellite remote sensing, such as time-concentrated sediment yield; and its association with recent rainfall events and, therefore, with cloudy sky. KW - Remote sensing KW - Sediment load KW - Dryland KW - Brazil Y1 - 2019 U6 - https://doi.org/10.1016/j.jag.2019.02.009 SN - 0303-2434 VL - 79 SP - 153 EP - 161 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Braga, Brennda A1 - Anchieta de Carvalho, Thayslan Renato A1 - Brosinsky, Arlena A1 - Förster, Saskia A1 - Medeiros, Pedro Henrique Augusto T1 - From waste to resource BT - Cost-benefit analysis of reservoir sediment reuse for soil fertilization in a semiarid catchment JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Reservoir networks have been established worldwide to ensure water supply, but water availability is endangered quantitatively and qualitatively by sedimentation. Reuse of sediment silted in reservoirs as fertilizer has been proposed, thus transforming nutrient-enriched sediments from waste into resource. The aim of this study is to assess the potential of reusing sediment as a nutrient source for agriculture a semiarid basin in Brazil. where 1029 reservoirs were identified. Sedimentation was modelled for the entire reservoir network, accounting for 7 x 10(5) tons of y(-1)sediment deposition. Nutrients contents in reservoir sediments was analysed and com- pared to nutrients contents of agricultural soils in the catchment. The potential of reusing sediment as fertilizer was assessed for maize crops (Zea mays L) and the sediment mass required to fertilize the soil was computed considering that the crop nitrogen requirement would be fully provided by the sediment. Economic feasibility was analysed by comparing the costs of the proposed practice to those obtained if the area was fertilized by traditional means. Results showed that, where reservoirs fall dry frequently and sediments can be removed by excavation, soil fertilization with sediment presents lower costs than those observed for application of commercial chemical fertilizers. Compared to conventional fertilization, when using sediments with high nutrient content, 25% of costs could be saved, while when using sediments with low nutrient content costs are 9% higher. According to the local conditions, sediments with nitrogen content above 1.5 g kg(-1) are cost efficient as nitrogen source. However, physical and chemical analyses are recommended to define the sediment mass to be used and to identify any constraint to the application of the practice, like the high sodium adsorption ratio observed in one of the studied reservoirs, which can contribute to soil salinization. (C) 2019 Elsevier B.V. All rights reserved. KW - Reservoir sedimentation KW - Sediment reuse KW - Fertilizer KW - Agriculture KW - Semiarid KW - Cost-benefit analysis Y1 - 2019 U6 - https://doi.org/10.1016/j.scitotenv.2019.03.083 SN - 0048-9697 SN - 1879-1026 VL - 670 SP - 158 EP - 169 PB - Elsevier CY - Amsterdam ER -