Aerial and terrestrial-based monitoring of channel erosion, headcutting, and sinuosity

Multitemporal Analysis of Gully Erosion in Olive Groves by Means of Digital Elevation Models Obtained with Aerial Photogrammetric and LiDAR Data

“…These values are significantly higher than the values calculated for the study area and in the middle range of those found in the province and the references [10,11,49]. If only the gully areas are considered, the rates become near to 700 t/ha*year, comparable with some extreme values of the references [28,40,47,78].…”

“…From these, the uncertainties of DoDs are calculated, resulting in values around 1 m, in the same order of magnitude to those estimated in reference studies with similar methodologies and resolutions [20,28,47,48,58]. Higher accuracies are only obtained when images of higher resolution are processed: 10 −3 m order and even lower in close-range photogrammetry [20,34,36]; 10 −2 to 10 −1 m order in terrestrial photogrammetry [23,25,35,[38][39][40] or UAV photogrammetry [21,23,24,[39][40][41][42]. These last accuracies are comparable with those obtained by means of GNSS or TS surveys [13,19,20].…”

“…2020, 9, 260 of 30 10 t/ha*year [10,11,78]. However, most study areas with similar approaches and extension as those considered in this study present rates much higher, even when the whole catchment is considered: 39.7 t/ha*year [49], 331 t/ha*year [47], between 160 and 430 t/ha*year [48], around 700 t/ha*year [28], 871 t/ha*year [40] and extreme values of 1500-2500 t/ha*year [78]. If only the gully area (16.75 ha) is considered, the rates estimated in our analysis reach values of 255 t/ha*year for depletion, 42 t/ha*year for deposition and 213 t/ha*year for the (negative) balance, more similar to those found in the references.…”

“…They have enabled to determine that gully soil losses at least doubled the rates measured in experimental plots or RUSLE models [49]. However, the most appropriate approach is to generate digital elevation models, both DSMs and DTMs (filtered and/or edited) of high resolution and precision [15,[20][21][22][23][24][25]28,29,32,34,[38][39][40][41][42][45][46][47][48]51]. Based on these DEMs, morphometric measurements and volumetric estimations can also be performed [15,20,21,28,32,33,[38][39][40][41][42][45][46][47][48].…”

“…Accuracy analysis can be made from qualitative visual observations but also from different quantitative methods [16,32,41]. In some cases the accuracy can be estimated from errors (usually the root mean square or RMS) of the image orientation or the laser point cloud registration processes, at ground control and/or check points [14,21,23,32,[39][40][41][42][43]47,48,57,58]. Other accuracy analyses are those based on the comparison of the height of profile points or DEMs, with respect to points measured with a more accurate method such as the TS/GNSS [15,20,23,37,39,42,45] or TLS [16,25,38].…”