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  • 1
    In: Hydrological Processes, Wiley, Vol. 34, No. 26 ( 2020-12-30), p. 5489-5504
    Abstract: Drainage networks delineated from Digital Elevation Models (DEMs), are the basis for the modelling of geomorphological and hydrological processes, biogeochemical cycling, and water resources management. Besides providing effective models of water flows, automatically extracted drainage networks based on topography can diverge from reality to varying degrees. The variability of such disagreement within catchments has rarely been examined as a function of the heterogeneity of land cover, soil type, and slope in the catchment of interest. This research gap might not only substantially limit our knowledge of the uncertainty of hydrological prediction, but can also cause problems for users attempting to use the data at a local scale. Using 1:100000 scale land cover maps, Quaternary deposits maps, and 2 m resolution DEMs, it is found that the accuracy of delineated drainage networks tends to be lower in areas with denser vegetation, lower hydraulic conductivity, and higher erodibility. The findings of this study could serve as a guide for the more thoughtful usage of delineated drainage networks in environmental planning, and in the uncertainty analysis of hydrological and biochemical predictions. Therefore, this study makes a first attempt at filling the knowledge gap described above.
    Type of Medium: Online Resource
    ISSN: 0885-6087 , 1099-1085
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 1479953-4
    SSG: 14
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  • 2
    In: Journal of Contemporary Water Research & Education, Wiley, Vol. 155, No. 1 ( 2015-07), p. 73-82
    Abstract: The soon‐to‐be completed Grand Ethiopian Renaissance Dam (GERD), which will be the largest hydroelectric power plant and among the largest reservoirs in Africa, has highlighted the need for expanding traditional integrated water resources management to better include the cultural, social, and political complexities of large water infrastructure in development projects. The GERD will store a maximum of 74 billion cubic meters of water corresponding to approximately the average annual outflow of the Nile from the Aswan high dam. Undoubtedly, the GERD will be vital for energy production and a key factor for food production, economic development, and poverty reduction in Ethiopia and the Nile Basin. However, the GERD is also a political statement that in one stroke has re‐written the hydropolitical map of the Nile Basin. The GERD has become a symbol of Ethiopian nationalism or “renaissance” (hidase in Amharic). A contrasting concept to nationalism is hydrosolidarity. This concept has been put forward to better stress equitable use of water in international water management challenges that would lead to sustainable socioeconomic development. We use the opposing notions of nationalism and hydrosolidarity at three different scales, everyday politics, state policies, and interstate and global politics to analyse some aspects of the new hydropolitical map of the Nile Basin. We argue that nationalism and national interests are not necessarily negative standpoints but that there may instead be a meeting point where regional and national interests join with hydrosolidarity principles. We believe that this meeting point can maximize not only the common good, but also the good from a national interest point of view. For this, it is important not increase collaboration instead of being locked in to the historical narrative of nationalistic culture and historical discourse. This would benefit and improve future sustainability.
    Type of Medium: Online Resource
    ISSN: 1936-7031 , 1936-704X
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 2424495-8
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  • 3
    Online Resource
    Online Resource
    Wiley ; 2014
    In:  Transactions in GIS Vol. 18, No. 1 ( 2014-02), p. 108-124
    In: Transactions in GIS, Wiley, Vol. 18, No. 1 ( 2014-02), p. 108-124
    Abstract: In this study, we present a newly developed method for the estimation of surface flow paths on a digital elevation model ( DEM ). The objective is to use a form‐based algorithm, analyzing flow over single cells by dividing them into eight triangular facets and to estimate the surface flow paths on a raster DEM . For each cell on a gridded DEM , the triangular form‐based multiple flow algorithm ( TFM ) was used to distribute flow to one or more of the eight neighbor cells, which determined the flow paths over the DEM . Because each of the eight facets covering a cell has a constant slope and aspect, the estimations of – for example – flow direction and divergence/convergence are more intuitive and less complicated than many traditional raster‐based solutions. Experiments were undertaken by estimating the specific catchment area ( SCA ) over a number of mathematical surfaces, as well as on a real‐world DEM . Comparisons were made between the derived SCA by the TFM algorithm with eight other algorithms reported in the literature. The results show that the TFM algorithm produced the closest outcomes to the theoretical values of the SCA compared with other algorithms, derived more consistent outcomes, and was less influenced by surface shapes. The real‐world DEM test shows that the TFM was capable of modeling flow distribution without noticeable ‘artefacts’, and its ability to track flow paths makes it an appropriate platform for dynamic surface flow simulation.
    Type of Medium: Online Resource
    ISSN: 1361-1682 , 1467-9671
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 2035222-0
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  • 4
    In: Ecohydrology, Wiley, Vol. 7, No. 4 ( 2014-08), p. 1147-1162
    Abstract: Northern high‐latitude regions could feed back strongly on global warming because of large carbon pools and the fact that those regions are predicted to experience temperature increases greater than the global average. Furthermore, ecological functioning and carbon cycling are both strongly related to the prevailing hydrological conditions. In this study, we address these issues and present a newly developed model LPJ distributed hydrology (LPJ‐DH) with distributed hydrology based on the dynamic global ecosystem and biogeochemistry model LPJ‐GUESS. The new model is an enhanced version of LPJ‐GUESS, introducing parametrizations of surface water routing and lateral water fluxes between grid cells. The newly introduced topographic variables in LPJ‐DH are extracted from digital elevation models. LPJ‐DH is tested at a 50‐m resolution in the Stordalen catchment, northern Sweden. Modelled runoff is evaluated against the measured runoff from 2007 to 2009 at six outlet points. We demonstrate that the estimated monthly runoff from LPJ‐DH agrees more closely with the measured data (adjusted R 2  = 0·8713) than did the standard LPJ‐GUESS model (adjusted R 2  = 0·4277). However, there are still difficulties in predicting low‐flow periods. The new model shows a possible advantage in representing the drainage network as well as topographic effects on water redistribution. The modelled birch tree line is in the range of the imagery observation, and the model captures the observed values of vegetation biomass in the region. Significant changes in biomass and carbon fluxes are also observed in the new model. Generally, the study justifies the feasibility and advantages of incorporating distributed topographic indices into the dynamic ecosystem model LPJ‐GUESS. Copyright © 2013 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 1936-0584 , 1936-0592
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 2418105-5
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Wiley ; 1990
    In:  International Journal of Climatology Vol. 10, No. 5 ( 1990-07), p. 473-494
    In: International Journal of Climatology, Wiley, Vol. 10, No. 5 ( 1990-07), p. 473-494
    Type of Medium: Online Resource
    ISSN: 0899-8418 , 1097-0088
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 1990
    detail.hit.zdb_id: 1491204-1
    SSG: 14
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  • 6
    Online Resource
    Online Resource
    Wiley ; 2022
    In:  Transactions in GIS Vol. 26, No. 3 ( 2022-05), p. 1572-1588
    In: Transactions in GIS, Wiley, Vol. 26, No. 3 ( 2022-05), p. 1572-1588
    Abstract: A user‐friendly high‐resolution intermediate complexity dynamic and spatially distributed flow model is crucial in urban flood modeling. Planners and consultants need to improve the accuracy of floods and estimation of risks. A new flow model will serve as a rapid tool to improve identification of these. This article provides a detailed explanation of a model based on a multiple flow algorithm. Model testing was performed on selected urban and rural areas. Additionally, a sensitivity analysis is conducted to analyze functionality. The model includes basic hydrological processes and is therefore less complex than fully physical models. The data needed to set up and run the new model include spatially and temporally distributed basic geometric and hydrologic variables (i.e., digital elevation model, precipitation, infiltration, and surface roughness). The model is implemented using open‐source coding and can easily be applied to any selected area. Outputs are water volumes, depths, and velocities at different modeling times. Using GIS, results can be visualized and utilized for further analyses. The test, applied in urban as well as rural areas, demonstrates its user‐friendliness, and that the estimated distributed water depths and water velocity at any time step can be saved and visualized.
    Type of Medium: Online Resource
    ISSN: 1361-1682 , 1467-9671
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2035222-0
    SSG: 14
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  • 7
    In: Transactions in GIS, Wiley, Vol. 16, No. 5 ( 2012-10), p. 701-713
    Type of Medium: Online Resource
    ISSN: 1361-1682
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2012
    detail.hit.zdb_id: 2035222-0
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  • 8
    Online Resource
    Online Resource
    Wiley ; 1994
    In:  Environmetrics Vol. 5, No. 4 ( 1994-12), p. 433-449
    In: Environmetrics, Wiley, Vol. 5, No. 4 ( 1994-12), p. 433-449
    Type of Medium: Online Resource
    ISSN: 1180-4009 , 1099-095X
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 1994
    detail.hit.zdb_id: 1466308-9
    SSG: 21
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  • 9
    Online Resource
    Online Resource
    Wiley ; 2018
    In:  Hydrological Processes Vol. 32, No. 10 ( 2018-05-15), p. 1322-1333
    In: Hydrological Processes, Wiley, Vol. 32, No. 10 ( 2018-05-15), p. 1322-1333
    Abstract: Drainage networks are the basis for segmentation of watersheds, an essential component in hydrological modelling, biogeochemical applications, and resource management plans. With the rapidly increasing availability of topographic information as digital elevation models (DEMs), there have been many studies on DEM‐based drainage network extraction algorithms. Most of traditional drainage network extraction methods require preprocessing of the DEM in order to remove “spurious” sink, which can cause unrealistic results due to removal of real sinks as well. The least cost path (LCP) algorithm can deal with flow routing over sinks without altering data. However, the existing LCP implementations can only simulate either single flow direction or multiple flow direction over terrain surfaces. Nevertheless, terrain surfaces in the real world are usually very complicated including both convergent and divergent flow patterns. The triangular form‐based multiple flow (TFM) algorithm, one of the traditional drainage network extraction methods, can estimate both single flow and multiple flow patterns. Thus, in this paper, it is proposed to combine the advantages of the LCP algorithm and the TFM algorithm in order to improve the accuracy of drainage network extraction from the DEM. The proposed algorithm is evaluated by implementing a data‐independent assessment method based on four mathematical surfaces and validated against “true” stream networks from aerial photograph, respectively. The results show that when compared with other commonly used algorithms, the new algorithm provides better flow estimation and is able to estimate both convergent and divergent flow patterns well regarding the mathematical surfaces and the real‐world DEM.
    Type of Medium: Online Resource
    ISSN: 0885-6087 , 1099-1085
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 1479953-4
    SSG: 14
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  • 10
    In: Ecohydrology, Wiley, Vol. 8, No. 4 ( 2015-06), p. 570-583
    Abstract: This paper compares two flow routing algorithms' influences on ecohydrological estimations in a northern peatland catchment, within the framework of an arctic‐enabled version of the dynamic ecosystem model LPJ‐GUESS. Accurate hydrological estimations are needed to fully capture vegetation dynamics and carbon fluxes in the subarctic peatland enviroment. A previously proposed distributed hydrological method based on the single flow (SF) algorithm extracted topographic indices has shown to improve runoff estimations in LPJ‐GUESS. This paper investigates model performance differences caused by two flow routing algorithms, and importantly both permafrost processes and peatland hydrology are included in the model. The newly developed triangular form‐based multiple flow (TFM) is selected due to its improved consideration of flow continuity and more realistic flow estimation over flat surfaces. A variety of measured data is included to assess both hydrological and ecological accuracy, and the results demonstrate that the choice of flow algorithm does matter for mesoscale ecohydrology applications. The allowance of flow convergence and consideration of flow partition differences from different terrain forms in the TFM algorithm yield better correspondence with the observed hydrological processes and also carbon fluxes. By directing flow to only one downslope cell together with its poorer depiction of flow over flat areas, the SF algorithm can result in too high runoff estimations for low‐flat regions and overestimate carbon uptake and release in the peatland. The results of this study also highlight the need for care when selecting flow routing algorithms for biogeochemical estimations, especially within hydrologically and climatically sensitive environments. Copyright © 2014 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 1936-0584 , 1936-0592
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 2418105-5
    SSG: 12
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