Generation, transport and retention of water and suspended sediments in large dryland catchments: Monitoring and integrated modelling of fluxes and connectivity phenomena
Final Report Abstract
Drylands often depend heavily on the storage of runoff water in reservoirs for the domestic, agricultural, energy and industrial sectors. At the same time they are particularly sensitive to erosion and soil loss because of their typically scarce vegetation cover, erodible soils and intense rainfall events following dry spells. Generation on the soil surface, transport in river systems and deposition in lakes or reservoirs are important aspects of catchment management on such environments. In this context, it is important to understand the transfer, storage and re-entrainment of water and sediments at the intersections of the main landscape compartments: hillslopes, valley bottoms, floodplains and reservoirs. Sedimentation of reservoirs due to accelerated hillslope erosion results in a decreased life expectancy of the reservoirs which in turn might place a critical economic burden on an entire region. Therefore, understanding "connectivity" of water and sediment pathways at the scale of river basins is crucial for effective management and intervention. To this end, a series of innovative field survey, remote sensing and modeling techniques were employed in a research in two sets of experimental nested dryland catchments in northeastern Spain and northeastern Brazil. Concerning measurement techniques, this project showed unique insights from a set of innovative techniques in the fields of eco-hydrology and geomorphology. Spectral fingerprinting of sediments and terrestrial laser scanning were employed to describe sediment dynamics in and between hillslopes, flood plains and river beds. Radio Frequency Identification (RFID) tagging was used for tracing particle pathways and velocity at the hillslope and channel segment scale. Terrestrial and aerial laser scanning together with satellite based topography were integrated for transferring connectivity indexes across scales. Automatic intermittent sampling with off-site analysis provided accurate quantitative and analytical insight on suspended sediments. However, the need for continuous hydro-sedimentological data series required data-driven models (quantile regression forests, bayesian inference) to reconstruct sedigraphs and hydrographs. The project could also demonstrate the potential of high spectral resolution imagery for mapping cover fractions of dry and green vegetation, bare soil and rock on a sub-pixel basis. These results were later combined with continuous hydro-sedimentological data series to drive a model for water and sediment fluxes and connectivity. Multi-temporal SAR satellite data for the monitoring of seasonal changes in a dense connected network of small surface reservoirs was successfully tested in a dryland Brazilian catchment using a threshold approach based on high-resolution TerraSAR-X data. Large asynchronous seasonal variations in the reservoirs’ water extents were found, pointing to diverse sources, sinks and connectivity patterns. All results of the project were combined in an integrated multiscale model of water, sediment fluxes and connectivity. The model integrated different connectivity indexes, seasonality in vegetation and land cover and high resolution hydrometeorological data. The concept of combined and inter-linked observation and modeling was found to be the appropriate approach to advance the understanding of such systems characterized by highly flashy generation of runoff, and subsequently of erosion and sediment transport pulses through the different landscape compartments. Perhaps not surprisingly, the single most important contribution to improve our understanding of hydrological processes in drylands was found to be the temporal and spatial resolution of rainfall observations. Finally, the project yielded a number of valuable follow up activities and opportunities for exchange with other research groups. Project members took the lead in a COST working group on connectivity, earned a Marie Curie Intra-European Fellowship and successfully applied for two follow-up projects.
Publications
- Modelling sediment export, retention and reservoir sedimentation in drylands with the WASA-SED model. Geosci. Model Dev. 3.1, pp. 275-291.
E. N. Mueller, A. Güntner, T. Francke, G. Mamede
(See online at https://dx.doi.org/10.5194/gmd-3-275-2010) - Modelling spatio-temporal patterns of sediment yield and connectivity in a semi-arid catchment with the WASA-SED model. Hydrological Sciences Journal 55.4, pp. 636-648.
P. H. A. Medeiros, A. Güntner, T. Francke, G. L. Mamede, J. C. d. Araújo
(See online at https://dx.doi.org/10.1080/02626661003780409) - Sediment redistribution due to a dense reservoir network in a large semi-arid Brazilian basin. Hydrological Sciences Journal, Vol. 56. 2011, Issue 2, pp. 319–333.
Lima Neto, E., Wiegand, M.C., de Araújo, J.C.
(See online at https://doi.org/10.1080/02626667.2011.553616) - A channel transmission losses model for different dryland rivers. Hydrology and Earth System Sciences, Vol. 16. 2012, issue 4, pp. 1111-1135.
A. C. Costa, A. Bronstert, J. C. Araújo
(See online at https://doi.org/10.5194/hess-16-1111-2012) - Hydrological Impact of a High-Density Reservoir Network in Semiarid Northeastern Brazil. Journal of Hydrologic Engineering, Vol. 17. 2012, Issue 1, pp. 109- 117.
V. Malveira, J. Araújo, A. Güntner
(See online at https://doi.org/10.1061/(ASCE)HE.1943-5584.0000404) - The sediment budget of a highly dynamic mesoscale catchment: The River Isábena. Geomorphology 138.1, pp. 15-28.
J. A. López-Tarazón, R. J. Batalla, D. Vericat, T. Francke
(See online at https://doi.org/10.1016/j.geomorph.2011.08.020) - Analysis of channel transmission losses in a dryland river reach in north-eastern Brazil using streamflow series, groundwater level series and multi-temporal satellite data. Hydrological Processes, Vol. 27. 2013, Issue 7, pp. 1046-1060.
A. C. Costa, S. Foerster, J. C. Araújo, A. Bronstert
(See online at https://doi.org/10.1002/hyp.9243) - Analysis of runoff, sediment dynamics and sediment yield of subcatchments in the highly erodible Isábena catchment, Central Pyrenees. Journal of Soils and Sediments, Vol. 14. 2014, Issue 12, pp 1909–1920.
T. Francke, S. Werb, E. Sommerer, J. A. López-Tarazón
(See online at https://doi.org/10.1007/s11368-014-0990-5) - Assessment of sediment connectivity from vegetation cover and topography using remotely sensed data in a dryland catchment in the Spanish Pyrenees. Journal of Soils and Sediments, Vol. 14. 2014, Issue 12, pp 1982–2000.
S. Foerster, C. Wilczok, A. Brosinsky, K. Segl
(See online at https://doi.org/10.1007/s11368-014-0992-3) - Connectivity of sediment transport in a semiarid environment: a synthesis for the Upper Jaguaribe Basin, Brazil. Journal of Soils and Sediments, Vol. 14. 2014, Issue 12, pp 1938–1948.
P. H. A. Medeiros, J. C. d. Araújo, G. L. Mamede, B. Creutzfeldt, A. Güntner, A. Bronstert
(See online at https://doi.org/10.1007/s11368-014-0988-z) - Dominant discharges for suspended sediment transport in a highly active Pyrenean river. Journal of Soils and Sediments, Vol. 14. 2014, Issue 12, pp 2019–2030.
J. A. López-Tarazón, R. J. Batalla
(See online at https://doi.org/10.1007/s11368-014-0961-x) - Monitoring Seasonal Changes in the Water Surtace Areas of Reservoirs Using TerraSAR-X Time Series Data in Semiarid Northeastern Brazil. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Vol. 7. 2014, Issue 8, pp. 3190-3199.
I. Heine, T. Francke, C. Rogass, P. Medeiros, A. Bronstert, S. Foerster
(See online at https://doi.org/10.1109/JSTARS.2014.2323819) - Process-based modelling of erosion, sediment transport and reservoir siltation In mesoscale semi-arid catchments. Journal of Soils and Sediments, Vol. 14. 2014, Issue 12, pp 2001–2018.
A. Bronstert, J.-C. d. Araújo, R. J. Batalla, A. C. Costa, J. M. Delgado, T. Francke, S. Foerster, A. Guentner, J. A. López-Tarazón, C. L. Mamede, P. H. Medeiros, E. Mueller, D. Vericat
(See online at https://doi.org/10.1007/s11368-014-0994-1) - Spectral fingerprinting: characterizing suspended sediment sources by the use of VNTR-SWIR spectral information. Journal of Soils and Sediments, Vol. 14. 2014, Issue 12, pp 1965–1981.
A. Brosinsky, S. Foerster, K. Segl, J. A. López-Tarazón, G. Piqué, A. Bronstert
(See online at https://doi.org/10.1007/s11368-014-0927-z) - Spectral fingerprinting: sediment source discrimination and contribution modelling of artificial mixtures based on VNIR-SWIR spectral properties. Journal of Soils and Sediments, Vol. 14. 2014, Issue 12, pp 1949–1964.
A. Brosinsky, S. Foerster, K. Segl, H . Kaufmann
(See online at https://doi.org/10.1007/s11368-014-0925-1) - Isábena 2011 - An EnMAP Preparatory Flight Campaign. GFZ Data Services, 2015,
S. Förster, A. Brosinsky, C. Wilczok, M. Bauer
(See online at https://doi.org/10.5880/enmap.2015.007)
