Browsing by Subject "hydrology"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Calibrating single-ended fiber-optic Raman spectra distributed temperature sensing data.
    (Sensors (Basel), 2011) Hausner, Mark B; Suárez, Francisco; Glander, Kenneth E; van de Giesen, Nick; Selker, John S; Tyler, Scott W
    Hydrologic research is a very demanding application of fiber-optic distributed temperature sensing (DTS) in terms of precision, accuracy and calibration. The physics behind the most frequently used DTS instruments are considered as they apply to four calibration methods for single-ended DTS installations. The new methods presented are more accurate than the instrument-calibrated data, achieving accuracies on the order of tenths of a degree root mean square error (RMSE) and mean bias. Effects of localized non-uniformities that violate the assumptions of single-ended calibration data are explored and quantified. Experimental design considerations such as selection of integration times or selection of the length of the reference sections are discussed, and the impacts of these considerations on calibrated temperatures are explored in two case studies.
  • Thumbnail Image
    ItemOpen Access
    Ecological restoration of rich fens in Europe and North America: from trial and error to an evidence-based approach.
    (Biol Rev Camb Philos Soc, 2015-02) Lamers, Leon PM; Vile, Melanie A; Grootjans, Ab P; Acreman, Mike C; van Diggelen, Rudy; Evans, Martin G; Richardson, Curtis J; Rochefort, Line; Kooijman, Annemieke M; Roelofs, Jan GM; Smolders, Alfons JP
    Fens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Land-use change and drainage has severely damaged or annihilated these services in many parts of North America and Europe; restoration plans are urgently needed at the landscape level. We review the major constraints on the restoration of rich fens and fen water bodies in agricultural areas in Europe and disturbed landscapes in North America: (i) habitat quality problems: drought, eutrophication, acidification, and toxicity, and (ii) recolonization problems: species pools, ecosystem fragmentation and connectivity, genetic variability, and invasive species; and here provide possible solutions. We discuss both positive and negative consequences of restoration measures, and their causes. The restoration of wetland ecosystem functioning and services has, for a long time, been based on a trial-and-error approach. By presenting research and practice on the restoration of rich fen ecosystems within agricultural areas, we demonstrate the importance of biogeochemical and ecological knowledge at different spatial scales for the management and restoration of biodiversity, water quality, carbon sequestration and other ecosystem services, especially in a changing climate. We define target processes that enable scientists, nature managers, water managers and policy makers to choose between different measures and to predict restoration prospects for different types of deteriorated fens and their starting conditions.
  • Thumbnail Image
    ItemOpen Access
    The biogeochemistry of carbon across a gradient of streams and rivers within the Congo Basin
    (Journal of Geophysical Research: Biogeosciences, 2014-04) Mann, PJ; Spencer, RGM; Dinga, BJ; Poulsen, JR; Hernes, PJ; Fiske, G; Salter, ME; Wang, ZA; Hoering, KA; Six, J; Holmes, RM
    Dissolved organic carbon (DOC) and inorganic carbon (DIC, pCO2), lignin biomarkers, and theoptical properties of dissolved organic matter (DOM) were measured in a gradient of streams and rivers within the Congo Basin, with the aim of examining how vegetation cover and hydrology influences the composition and concentration of fluvial carbon (C). Three sampling campaigns (February 2010, November 2010, and August 2011) spanning 56 sites are compared by subbasin watershed land cover type (savannah, tropical forest, and swamp) and hydrologic regime (high, intermediate, and low). Land cover properties predominately controlled the amount and quality of DOC, chromophoric DOM (CDOM) and lignin phenol concentrations (8) exported in streams and rivers throughout the Congo Basin. Higher DIC concentrations and changing DOM composition (lower molecular weight, less aromatic C) during periods of low hydrologic flow indicated shifting rapid overland supply pathways in wet conditions to deeper groundwater inputs during drier periods. Lower DOC concentrations in forest and swamp subbasins were apparent with increasing catchment area, indicating enhanced DOC loss with extended water residence time. Surface water pCO2in savannah and tropical forest catchments ranged between 2,600 and 11,922 μatm, with swamp regions exhibiting extremely high pCO2(10,598-15,802 μatm), highlighting their potential as significant pathways for water-air efflux. Our data suggest that the quantity and quality of DOM exported to streams and rivers are largely driven by terrestrial ecosystem structure and that anthropogenic land use or climate change may impact fluvial C composition and reactivity, with ramifications for regional C budgets and future climate scenarios. Key Points Vegetation cover predominately controls fluvial C concentration and composition Small streams (20 m wide) and wetlands are significant sources of aquatic CO2Changing vegetation cover, or hydrologic conditions impact regional carbon budgets ©2014. American Geophysical Union. All Rights Reserved.