TY - JOUR A1 - Bronstert, Axel A1 - de Araujo, Jose-Carlos A1 - Batalla Villanueva, Ramon J. A1 - Costa, Alexandre Cunha A1 - Delgado, José Miguel Martins A1 - Francke, Till A1 - Förster, Saskia A1 - Guentner, Andreas A1 - Lopez-Tarazon, José Andrés A1 - Mamede, George Leite A1 - Medeiros, Pedro Henrique Augusto A1 - Mueller, Eva A1 - Vericat, Damia T1 - Process-based modelling of erosion, sediment transport and reservoir siltation in mesoscale semi-arid catchments JF - Journal of soils and sediments : protection, risk assessment and remediation N2 - To support scientifically sound water management in dryland environments a modelling system has been developed for the quantitative assessment of water and sediment fluxes in catchments, transport in the river system, and retention in reservoirs. The spatial scale of interest is the mesoscale because this is the scale most relevant for management of water and land resources. This modelling system comprises process-oriented hydrological components tailored for dryland characteristics coupled with components comprising hillslope erosion, sediment transport and reservoir deposition processes. The spatial discretization is hierarchically designed according to a multi-scale concept to account for particular relevant process scales. The non-linear and partly intermittent run-off generation and sediment dynamics are dealt with by accounting for connectivity phenomena at the intersections of landscape compartments. The modelling system has been developed by means of data from nested research catchments in NE-Spain and in NE-Brazil. In the semi-arid NE of Brazil sediment retention along the topography is the main process for sediment retention at all scales, i.e. the sediment delivery is transport limited. This kind of deposition retains roughly 50 to 60 % of eroded sediment, maintaining a similar deposition proportion in all spatial scales investigated. On the other hand, the sediment retained in reservoirs is clearly related to the scale, increasing with catchment area. With increasing area, there are more reservoirs, increasing the possibility of deposition. Furthermore, the area increase also promotes an increase in flow volume, favouring the construction of larger reservoirs, which generally overflow less frequently and retain higher sediment fractions. The second example comprises a highly dynamic Mediterranean catchment in NE-Spain with nested sub-catchments and reveals the full dynamics of hydrological, erosion and deposition features. The run-off modelling performed well with only some overestimation during low-flow periods due to the neglect of water losses along the river. The simulated peaks in sediment flux are reproduced well, while low-flow sediment transport is less well captured, due to the disregard of sediment remobilization in the riverbed during low flow. This combined observation and modelling study deepened the understanding of hydro-sedimentological systems characterized by flashy run-off generation and by erosion and sediment transport pulses through the different landscape compartments. The connectivity between the different landscape compartments plays a very relevant role, regarding both the total mass of water and sediment transport and the transport time through the catchment. KW - Connectivity KW - Deposition KW - Erosion KW - Modelling KW - Sediment transfer KW - Semi-arid Y1 - 2014 U6 - https://doi.org/10.1007/s11368-014-0994-1 SN - 1439-0108 SN - 1614-7480 VL - 14 IS - 12 SP - 2001 EP - 2018 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Mamede, George Leite A1 - Guentner, Andreas A1 - Medeiros, Pedro Henrique Augusto A1 - de Araujo, Jose Carlos A1 - Bronstert, Axel T1 - Modeling the Effect of Multiple Reservoirs on Water and Sediment Dynamics in a Semiarid Catchment in Brazil JF - Journal of Hydrologic Engineering N2 - Taking into account the climatic conditions of the semiarid region of Brazil, with its intermittent rivers and long periods of water scarcity, a dense network of surface reservoirs (on average one dam every 5 km(2)) of very different sizes has been built. The impact of such a network on water and sediment dynamics constitutes a remarkable challenge for hydrologists. The main objective of this work is to present a novel way of simulating water and sediment fluxes through such high-density reservoir networks, which enables the assessment of water and sediment retention in those structures. The new reservoir modeling approach has been coupled with the fully process-oriented and semidistributed hydrological WASA-SED model, which was tailored for semiarid hydroclimatological characteristics. This integrated modeling system was applied to the 933-km(2) Bengue catchment, located in semiarid northeastern Brazil, which has a network of 114 reservoirs with a wide range of surface areas (from 0.003 to 350 ha). The small reservoirs were grouped into size classes according to their storage capacity and a cascade routing scheme was applied to describe the upstream-downstream position of the classes; the large reservoirs were handled explicitly in the reservoir modeling approach. According to the model results, the proposed approach is capable of representing the water and sediment fluxes though the entire reservoir network with reasonable accuracy. In addition, the model shows that the dynamics of water and sediment within the Bengue catchment are strongly impacted by the presence of multiple reservoirs, which are able to retain approximately 21% of the generated runoff and almost 42% of the sediment yield of the catchment for the simulation period, from 2000 to 2012. (C) 2018 American Society of Civil Engineers. KW - Reservoir network KW - Semiarid catchment KW - Sediment retention KW - Water storage dynamic Y1 - 2018 U6 - https://doi.org/10.1061/(ASCE)HE.1943-5584.0001701 SN - 1084-0699 SN - 1943-5584 VL - 23 IS - 12 PB - American Society of Civil Engineers CY - Reston ER - TY - JOUR A1 - Medeiros, Pedro Henrique Augusto A1 - de Araujo, Jose Carlos A1 - Mamede, George Leite A1 - Creutzfeldt, Benjamin A1 - Guentner, Andreas A1 - Bronstert, Axel T1 - Connectivity of sediment transport in a semiarid environment: a synthesis for the Upper Jaguaribe Basin, Brazil JF - Journal of soils and sediments : protection, risk assessment and remediation N2 - Hydrosedimentological studies conducted in the semiarid Upper Jaguaribe Basin, Brazil, enabled the identification of the key processes controlling sediment connectivity at different spatial scales (10(0)-10(4) km(2)). Water and sediment fluxes were assessed from discharge, sediment concentrations and reservoir siltation measurements. Additionally, mathematical modelling (WASA-SED model) was used to quantify water and sediment transfer within the watershed. Rainfall erosivity in the study area was moderate (4600 MJ mm ha(-1) h(-1) year(-1)), whereas runoff depths (16-60 mm year(-1)), and therefore the sediment transport capacity, were low. Consequently, similar to 60 % of the eroded sediment was deposited along the landscape, regardless of the spatial scale. The existing high-density reservoir network (contributing area of 6 km(2) per reservoir) also limits sediment propagation, retaining up to 47 % of the sediment at the large basin scale. The sediment delivery ratio (SDR) decreased with the spatial scale; on average, 41 % of the eroded sediment was yielded from the hillslopes, while for the whole 24,600-km(2) basin, the SDR was reduced to 1 % downstream of a large reservoir (1940-hm(3) capacity). Hydrological behaviour in the Upper Jaguaribe Basin represents a constraint on sediment propagation; low runoff depth is the main feature breaking sediment connectivity, which limits sediment transference from the hillslopes to the drainage system. Surface reservoirs are also important barriers, but their relative importance to sediment retention increases with scale, since larger contributing areas are more suitable for the construction of dams due to higher hydrological potential. KW - Brazil KW - Connectivity KW - Sediment redistribution KW - Semiarid KW - Spatial scale Y1 - 2014 U6 - https://doi.org/10.1007/s11368-014-0988-z SN - 1439-0108 SN - 1614-7480 VL - 14 IS - 12 SP - 1938 EP - 1948 PB - Springer CY - Heidelberg ER -