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Projekt Druckansicht

Generation, transport and retention of water and suspended sediments in large dryland catchments: Monitoring and integrated modelling of fluxes and connectivity phenomena

Fachliche Zuordnung Hydrogeologie, Hydrologie, Limnologie, Siedlungswasserwirtschaft, Wasserchemie, Integrierte Wasserressourcen-Bewirtschaftung
Förderung Förderung von 2010 bis 2019
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 160797836
 
Erstellungsjahr 2016

Zusammenfassung der Projektergebnisse

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.

Projektbezogene Publikationen (Auswahl)

 
 

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