Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - The normalized topographic method
T2 - an automated procedure for gully mapping using GIS
AU - Castillo, Carlos
AU - Taguas, Encarnación V.
AU - James, Michael
AU - Zarco-Tejada, P
AU - Gómez, José A.
PY - 2014/12
Y1 - 2014/12
N2 - Gully delineation is a critical aspect of accurately determining soil losses but associated methodologies are rarely detailed. Here, we describe a new gully mapping method, the normalized topographic method (NorToM), based on processing digital elevation model (DEM) data, and we assess associated errors when it is applied over a range of geomorphological scales. The NorToM is underpinned by two gully detection variables (normalized slope and elevation) calculated over local windows of prescribed size, and a group of filtering variables. For four study sites, DEMs of gullies were obtained using field and airborne photo-reconstruction and evaluated using total station and differential global positioning system (dGPS) survey. NorToM provided accurate areal and volume estimates at the individual gully scale but differences increased at the larger gully system and gully network scales. We were able to identify optimal parameters for using the NorToM approach and so confirm that is represents a useful scale-independent means of gully mapping that is likely to be valid in other environments. Its main limitations are that the normalization process might be time-consuming at regional scales and the need for a fixed window size when applied to landforms with extreme variations in dimensions.
AB - Gully delineation is a critical aspect of accurately determining soil losses but associated methodologies are rarely detailed. Here, we describe a new gully mapping method, the normalized topographic method (NorToM), based on processing digital elevation model (DEM) data, and we assess associated errors when it is applied over a range of geomorphological scales. The NorToM is underpinned by two gully detection variables (normalized slope and elevation) calculated over local windows of prescribed size, and a group of filtering variables. For four study sites, DEMs of gullies were obtained using field and airborne photo-reconstruction and evaluated using total station and differential global positioning system (dGPS) survey. NorToM provided accurate areal and volume estimates at the individual gully scale but differences increased at the larger gully system and gully network scales. We were able to identify optimal parameters for using the NorToM approach and so confirm that is represents a useful scale-independent means of gully mapping that is likely to be valid in other environments. Its main limitations are that the normalization process might be time-consuming at regional scales and the need for a fixed window size when applied to landforms with extreme variations in dimensions.
KW - gully erosion
KW - mapping
KW - resolution
KW - GIS
KW - photo-reconstruction
KW - DEM
U2 - 10.1002/esp.3595
DO - 10.1002/esp.3595
M3 - Journal article
VL - 39
SP - 2002
EP - 2015
JO - Earth Surface Processes and Landforms
JF - Earth Surface Processes and Landforms
SN - 0197-9337
IS - 15
ER -