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An assessment of the effects of cell size on AGNPS modeling of watershed runoff / S.S. Wu in Cartography and Geographic Information Science, vol 35 n° 4 (October 2008)  

Public [article]  inCartography and Geographic Information Science > vol 35 n° 4 (October 2008) . - pp 265 - 278 Titre : An assessment of the effects of cell size on AGNPS modeling of watershed runoff Type de document : Article/Communication Auteurs : S.S. Wu, Auteur ; E. Lynn Usery, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 265 - 278 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] agriculture [Termes IGN] analyse comparative [Termes IGN] analyse de données [Termes IGN] analyse de groupement [Termes IGN] bassin hydrographique [Termes IGN] modélisation spatiale [Termes IGN] ruissellement Résumé : (Auteur) This study investigates the changes in simulated watershed runoff from the Agricultural NonPoint Source (AGNPS) pollution model as a function of model input cell size resolution for eight different cell sizes (30 m, 60 m, 120 m, 210 m, 240 m, 480 m, 960 m, and 1920 m) for the Little River Watershed (Georgia, USA). Overland cell runoff (area-weighted cell runoff), total runoff volume, clustering statistics, and hot spot patterns were examined for the different cell sizes and trends identified. Total runoff volumes decreased with increasing cell size. Using data sets of 210-m cell size or smaller in conjunction with a representative watershed boundary allows one to model the runoff volumes within 0.2 percent accuracy. The runoff clustering statistics decrease with increasing cell size; a cell size of 960 m or smaller is necessary to indicate significant high-runoff clustering. Runoff hot spot areas have a decreasing trend with increasing cell size; a cell size of 240 m or smaller is required to detect important hot spots. Conclusions regarding cell size effects on runoff estimation cannot be applied to local watershed areas due to the inconsistent changes of runoff volume with cell size; but, optimal cells sizes for clustering and hot spot analyses are applicable to local watershed areas due to the consistent trends. Copyright CaGISociety Numéro de notice : A2008-439 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1559/152304008786140542 En ligne : https://doi.org/10.1559/152304008786140542 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29508 [article]

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Urban land-use classification using variogram-based analysis with an aerial photograph / S.S. Wu in Photogrammetric Engineering & Remote Sensing, PERS, vol 72 n° 7 (July 2006)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 72 n° 7 (July 2006) . - pp 813 - 822 Titre : Urban land-use classification using variogram-based analysis with an aerial photograph Type de document : Article/Communication Auteurs : S.S. Wu, Auteur ; B. Xu, Auteur ; L. Wang, Auteur Année de publication : 2006 Article en page(s) : pp 813 - 822 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse texturale [Termes IGN] bati [Termes IGN] classification dirigée [Termes IGN] classification spectrale [Termes IGN] Kappa de Cohen [Termes IGN] milieu urbain [Termes IGN] photographie aérienne [Termes IGN] photographie infrarouge couleur [Termes IGN] utilisation du sol [Termes IGN] variogramme [Termes IGN] zone urbaine Résumé : (Auteur) In this study, a variogram-based texture analysis was tested for classifying detailed urban land-use classes, such as mobile home, single-family house, multi-family house, industrial, and commercial from a digital color infrared aerial photograph. Spectral classification was first carried out to separate the building class from non-building classes. Then, a building-presence binary image was generated so that building pixels were assigned a value of "1 " and non-building pixels were assigned a value of "0. " Multiple texture bands were further generated employing a variogram-based texture analysis and used for land-use classification. The generation of the building presence binary image allowed us not only to fully explore the capability of variogram-based analysis on spatial pattern detection, but also to prevent the variogram-based analysis from being disturbed by the natural fluctuation of spectral signals. The result from using a mosaic test image was considered satisfactory with a kappa coefficient of 0.72. Copyright ASPRS Numéro de notice : A2006-264 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.72.7.813 En ligne : https://doi.org/10.14358/PERS.72.7.813 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27991 [article]