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  • Wiley  (2)
  • 2015-2019  (2)
  • 2017  (2)
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  • Wiley  (2)
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  • 2015-2019  (2)
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  • 2017  (2)
  • 1
    In: Vadose Zone Journal, Wiley, Vol. 16, No. 10 ( 2017-10), p. 1-12
    Abstract: PCA identified patterns within collocated time‐lapse measurements of θ and ECa. The factors controlling the observed spatial patterns of θ and ECa were quantified. Results demonstrate the nonstationary control of the spatial pattern of θ and ECa. Characterizing the spatial and temporal patterns of soil properties and states such as soil moisture (θ) remains an important challenge in environmental monitoring. At the Schäfertal hillslope site, the spatial patterns of θ measured by a distributed monitoring network and those of apparent electrical conductivity (ECa) measured by electromagnetic induction were characterized based on an integrated monitoring approach, and their possible controlling factors were investigated. With this study, we aimed to quantify the factors controlling the observed spatial patterns of θ and ECa and their interrelation. A principal component analysis was used to identify patterns within a data set comprising θ measured on seven dates within one hydrological year at 40 locations (three depths each) and ECa extracted from spatial maps for the same positions and dates. The first three independent principal components were all important for characterizing the spatial organization of topsoil moisture and its temporal changes. The dominant pattern responded to time‐invariant soil attributes such as spatial soil properties and terrain attributes and could explain the spatial organization of ECa only on four of the seven measurement dates. The second and third principal components described the spatial reorganization of the patterns in response to θ dynamics within the soil profile and water removal processes, respectively, and showed distinct time‐varying effects on the spatial pattern of θ and ECa. Our results can help with designing field monitoring campaigns and improving modeling approaches by providing insights into the nonstationary control of static and dynamic attributes on the spatial pattern of θ and ECa.
    Type of Medium: Online Resource
    ISSN: 1539-1663 , 1539-1663
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 2088189-7
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    In: Vadose Zone Journal, Wiley, Vol. 16, No. 10 ( 2017-10), p. 1-21
    Abstract: The FCM SEA was used for sampling and spatial estimation of soil moisture patterns. Multispectral remote sensing and terrain data were combined to guide the sampling and estimation. Selected vegetation patterns and terrain data provided reasonable estimates of soil moisture. The FCM SEA was stable to explain about 50% of the total observed variance. The FCM SEA was superior to an approach driven solely by terrain data. Detailed information on the temporal and spatial evolution of soil moisture patterns is of fundamental importance to improve runoff prediction, optimize irrigation management and to enhance crop forecasting. However, obtaining representative soil moisture measurements at the catchment scale is challenging because of the dynamic spatial and temporal behavior of soil moisture. High‐resolution remote sensing data provide detailed spatial information about catchment characteristics (e.g., terrain and land use) that can be used as proxies to estimate soil moisture. We assessed the potential use of combined multitemporal multispectral remote sensing (RS) and terrain data for estimating spatial soil moisture patterns at the small catchment scale. The fuzzy c ‐means sampling and estimation approach (FCM SEA) was applied to conduct a sensor (proxy) directed (guided) sampling and to reconstruct multitemporal soil moisture patterns based on time domain reflectometry measurements. A comprehensive soil moisture database for the Schäfertal catchment, located in central Germany, was used to test, validate, and compare the FCM SEA performances of the combined remote sensing data with those of a benchmark approach driven solely by terrain data. Results from the study show that a FCM SEA model that integrates bi‐temporal RS imagery and terrain data was more effective in estimating spatial soil moisture patterns relative to the benchmark model. It outperformed the benchmark model in 58% of the cases and was stable to explain about 50% of the total observed variance for a range of different catchment moisture conditions. This was achieved with only a small sample size ( n = 30). The results of this study are promising because they highlight the importance of considering multitemporal RS and terrain data and demonstrate how in situ sensors can be optimally placed to enable cost‐efficient monitoring and prediction of spatial soil moisture patterns at the small catchment scale.
    Type of Medium: Online Resource
    ISSN: 1539-1663 , 1539-1663
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 2088189-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
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