Spatially Distributed Hydrological Modelling : Wetness Derived from Digital Elevation Models to Estimate Peatland Carbon
To study the hydrology of peatlands and explore wetness distribution is difficultmainly due to the complexity of the surface of peatlands, and also due to the presence of permafrost underlain peatlands in the arctic regions. I have chosen the area called Stordalen mire in the arctic region in northe...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Lund University
2012
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| Online Access: | https://lup.lub.lu.se/record/04c6692e-575d-4825-97d0-2cc8a637fdd2 https://portal.research.lu.se/files/77108439/Abdulghani_Hasan_Thesis_2012_X.pdf |
| Summary: | To study the hydrology of peatlands and explore wetness distribution is difficultmainly due to the complexity of the surface of peatlands, and also due to the presence of permafrost underlain peatlands in the arctic regions. I have chosen the area called Stordalen mire in the arctic region in northern Sweden for my study.In this thesis, I aimed to study spatially distributed hydrological modelling in general, focusing mainly on evaluation and developing tools that can be used to improve wetness estimation using Digital Elevation Models (DEMs). The estimated wetness can be used as an input for peatland carbon models.DEMs with different resolutions are created using high resolution LiDAR data.Different search radiuses are used in the interpolations. The accuracy of the generated DEMs is studied to select the most accurate DEM for each selected resolution. The search radius, but not the cell size, significantly influences the accuracy of a DEM, and the accuracy is generally higher the shorter the interpolation search radius. DEM resolution versus topographic wetness index variables (i.e. slope and drainage area) is studied. Slope values become lower and drainage area values become higher when the resolution decreases. Further, a study of DEM accuracy related to different slopes is also carried out and shows that the errors in elevation are greater when the terrain is steep than when it is flat.A new triangular form-based multiple flow distribution and flow accumulationalgorithm (TFM) was created in this study. We have estimated flow distribution by using our new TFM algorithm. With this TFM algorithm, it becomes possible to deal with artefacts that normally interrupt flow distribution, like flat areas, sinks and manmade structures. This will help to overcome the complexity of peatland hydrology.The results of comparing our new algorithm with other well-known algorithms used in most GIS programs show that the TFM algorithm produces more realistic results than other algorithms. Testing shows the capability of the new ... |
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