Sökning: "Per-Erik Jansson"

Visar resultat 6 - 10 av 24 avhandlingar innehållade orden Per-Erik Jansson.

  1. 6. Environmental Modelling : Learning from Uncertainty

    Författare :John M. Juston; Per-Erik Jansson; Jens Christian Refsgaard; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Models; data; error; uncertainty; hydrology; soil carbon; wetlands; phosphorus;

    Sammanfattning : Environmental models are important tools; however uncertainty is pervasive in the modeling process.   Current research has shown that under­standing and representing these uncertainties is critical when decisions are expected to be made from the modeling results. LÄS MER

  2. 7. Water and Carbon Balance Modeling: Methods of Uncertainty Analysis

    Författare :John Juston; Per-Erik Jansson; Georg Lindgren; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Modeling; uncertainty analysis; water balance; carbon balance; GLUE; Environmental engineering; Miljöteknik;

    Sammanfattning : How do additional data of the same and/or different type contribute to reducing model parameter and predictive uncertainties? This was the question addressed with two models – the HBV hydrological water balance model and the ICBM soil carbon balance model – that were used to investigate the usefulness of the Generalized Likelihood Uncertainty Estimation (GLUE) method for calibrations and uncertainty analyses.  The GLUE method is based on threshold screening of Monte Carlo simulations using so-called informal likelihood measures and subjective acceptance criterion. LÄS MER

  3. 8. Irrigation with saline water using low-cost drip-irrigation systems in sub-Saharan Africa

    Författare :Louise Karlberg; Per-Erik Jansson; Reinder Feddes; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Water use efficiency; Radiation use efficiency; Management techniques; Modelling; Tomato; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Sammanfattning : In the scope of future population support, agricultural productivity, in particular in sub-Saharan Africa, has to increase drastically to meet the UN’s millennium development goals of eradicating extreme poverty and hunger by 2015. Water availability in the root-zone limits crop production in large parts of the developing world. LÄS MER

  4. 9. Monitoring transport and fate of de-icing salt in the roadside environment : Modelling and field measurements

    Författare :Annika Lundmark; Per-Erik Jansson; Bo Olofsson; Ann-Catrine Norrström; Helen K. French; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chloride; De-icing salt; Groundwater; Modelling; Monitoring; Road; Roadside; Soil water; Water in nature and society; Vatten i natur och samhälle;

    Sammanfattning : Roads and traffic are a major non-point source of pollutants and may have severe impacts on surface water, groundwater, soil and vegetation. In cold climates, de-icing salt is one such pollutant that may cause increased chloride concentrations and induce other effects on the environment. LÄS MER

  5. 10. Road disasters? Modeling and assessment of Swedish roads within crucial climate conditions

    Författare :Alireza Nickman; Bo Olofsson; Per-Erik Jansson; Nils-Otto Kitterød; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Road; Flood; Moisture; Temperature; Groundwater; GIS; Uncertainity; Sweden; Mark- och vattenteknik; Land and Water Resources Engineering;

    Sammanfattning : An efficient maintenance of roads to ensure high accessibility and durability of the transport capacity requires an understanding of how the hydrological response depends on both the road and the landscape characteristics. New methods and data were used to identify and explain interaction between roads and surrounding environment and their influence on hydrologic responses both in watershed scale and road-section scale. LÄS MER