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 - Lobera, G. A1 - Batalla Villanueva, Ramon J. A1 - Vericat, D. A1 - López-Tarazón, José Andrés A1 - Tena, A. T1 - Sediment transport in two mediterranean regulated rivers JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Mediterranean climate is characterized by highly irregular rainfall patterns with marked differences between wet and dry seasons which lead to highly variable hydrological fluvial regimes. As a result, and in order to ensure water availability and reduce its temporal variability, a high number of large dams were built during the 20th century (more than 3500 located in Mediterranean rivers). Dams modify the flow regime but also interrupt the continuity of sediment transfer along the river network, thereby changing its functioning as an ecosystem. Within this context, the present paper aims to assess the suspended sediment loads and dynamics of two climatically contrasting Mediterranean regulated rivers (i.e. the Esera and Siurana) during a 2-yr period. Key findings indicate that floods were responsible for 92% of the total suspended sediment load in the River Siurana, while this percentage falls to 70% for the Esera, indicating the importance of baseflows on sediment transport in this river. This fact is related to the high sediment availability, with the Esera acting as a non-supply-limited catchment due to the high productivity of the sources (i.e. badlands). In contrast, the Siurana can be considered a supply-limited system due to its low geomorphic activity and reduced sediment availability, with suspended sediment concentration remaining low even for high magnitude flood events. Reservoirs in both rivers reduce sediment load up to 90%, although total runoff is only reduced in the case of the River Esera. A remarkable fact is the change of the hydrological character of the River Lem downstream for the dam, shifting from a humid mountainous river regime to a quasi-invariable pattern, whereas the Siurana experiences the opposite effect, changing from a flashy Mediterranean river to a more constant flow regime below the dam. (C) 2015 Elsevier B.V. All rights reserved. KW - Suspended sediment transport KW - Sediment load KW - Flow regime KW - Barasona Reservoir KW - Siurana Reservoir KW - Ebro basin KW - Mediterranean Y1 - 2016 U6 - https://doi.org/10.1016/j.scitotenv.2015.08.018 SN - 0048-9697 SN - 1879-1026 VL - 540 SP - 101 EP - 113 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bai, Yongliang A1 - Dong, Dongdong A1 - Brune, Sascha A1 - Wu, Shiguo A1 - Wang, Zhenjie T1 - Crustal stretching style variations in the northern margin of the South China Sea JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - Linking deep seismic profiles with regional-scale gravity inversion is a powerful tool to deduce the architecture of rifted margins and their structural evolution. Here we map upper and lower crustal thicknesses of the northern South China Sea (SCS) margin in order to investigate the occurrence of depth-dependent crustal extension from the proximal to the distal margin. By comparing upper and lower crustal stretching factors, we find that the northern margin of the SCS is segmented in three parts: (1) sedimentary basins where upper crust is stretched more than lower crust, (2) distal margin where lower crust is stretched more than upper crust, (3) mostly proximal margin regions where the two layers have similar stretching factors. Our results suggest that sedimentary basins and distal margin prominently feature depth-dependent extension, however accommodated by different processes. While differential thinning within sedimentary basins appears to be governed by lateral pressure variations inducing lower crustal flow, we suggest the distal margin to be affected by a combination of mantle flow-induced lower crustal shearing and sequential fault activity during crustal hyper-extension. KW - Crustal stretching style KW - Lower crustal flow KW - The northern margin of the South China Sea KW - Gravity inversion KW - Sediment load KW - Divergent mantle flow Y1 - 2018 U6 - https://doi.org/10.1016/j.tecto.2018.12.012 SN - 0040-1951 SN - 1879-3266 VL - 751 SP - 1 EP - 12 PB - Elsevier CY - Amsterdam ER -