Extraction of gully based on digital elevation model

Directory

1, dem pretreatment 1
2. Morphological characteristics Analysis of Gully 1
2.1 Calculate terrain with a slope greater than 7% 1
2.2 Terrain 5 for calculating the standard deviation of the aspect greater than 40
3. Analysis of hydrological characteristics of Gully 10
3.1 Compute the river network within the [200,7400] threshold range and generate a 200-meter buffer 10
3.2 Catchment area of gully development by extracting intersection of river reaches 13
4, the extraction of the range of the Gully 15
5, noise removal and other processing 16
6, the formation of the Groove object and geometric characteristics acreage 17

1. Pre-processing of DEM
Fill the depressions in the DEM before determining the flow direction. Open the Spacial Analyst Tools->hydrology->fill tool in Arctoolbox and fill in the DEM data.
2. Analysis of morphological characteristics of gully
2.1 Calculating terrain with a slope greater than 7%
(1) Open the Spacial Analyst tools->surface->slope tool in Arctoolbox, enter the DEM data after the fill, and find out the ramp. Set 2-1, as shown in result 2-2.

Figure 2-1 Slope dialog box

Figure 2-2 Slope Result graph
(2) in Arctoolbox, open the spacial Analyst tools->reclass->reclassify tool to reclassify the slope data. Click the Classify button in the Reclassify dialog box to set the classification level to 11 classes, 2-3, 2-4. This range of value greater than 2 is the range with a slope greater than 7%.

Figure 2-3 Reclassify dialog box

Figure 2-4 Classifation dialog box
(3) Reclassified result 2-5.

Figure 2-5 Reclassification Results
(4) Open the Spacial Analyst Tools->conditional->con tool in Arctoolbox, as shown in setting 2-6.

Figure 2-6 Con dialog box
(5) Get the data with a slope greater than 7%, as shown in 2-7.

Figure 2-7 Data with a slope greater than 7%
2.2 Calculating terrain with a standard deviation greater than 40 for the aspect

(1) Open the Spacial Analyst tools->surface>aspect tool in Arctoolbox and enter the DEM after the fill. Set up 2-8 as shown.

Figure 2-8 Aspect dialog box
(2) The results of the slope data are obtained, as shown in 2-9.

Figure 2-9 Slope Data result graph
(3) Open the Spacial Analyst tools->neighborhood->focal Statistics tool in Arctoolbox and enter the aspect data. Set up 2-10 as shown.

Figure 2-10 Focal Statistics dialog box
(4) The results of the slope standard deviation are obtained, as shown in 2-11.

Fig. 2-11 standard deviation result of slope direction
(5) In Arctoolbox, open the spacial Analyst tools->reclass->reclassify tool to reclassify the standard deviation of the aspect. Open the Spacial Analyst Tools->conditional->con tool in Arctoolbox, select reclassify data, and enter the SQL statement "Value>3", resulting in a standard deviation of more than 40 of the terrain. As shown in result 2-12.

Figure 2-12 Terrain results with a standard deviation greater than 40
2.3. Calculate terrain with absolute value of topographic curvature greater than 0.25
(1) Open the Spacial Analyst tools->surface->curvature tool in Arctoolbox and enter the DEM data after the fill. Get the topographic curvature graph, as shown in result 2-13.

Fig. 2-13 Topographic curvature result diagram
(2) in Arctoolbox, open the spacial Analyst tools->reclass->reclassify tool to reclassify the topographic curvature data.
(3) Open the Spacial Analyst Tools->conditional->con tool in Arctoolbox, select reclassify data and enter the SQL statement "Value>5", resulting in a standard deviation greater than 0.25 of the terrain. As shown in result 2-14.

Figure 2-14 Terrain with a standard deviation greater than 0.25
3. Analysis of hydrological characteristics of gully
3.1 Calculate the river network within the [200,7400] threshold range and generate a 200-meter buffer
(1) Open the Spacial Analyst tools->hydrology->flow Direction tool in Arctoolbox and enter the DEM data after the fill. Get the flow data, as shown in result 3-1.

Figure 3-1 Flow to the result graph
(2) Open the Spacial Analyst tools->hydrology->flow accumulation tool in Arctoolbox and enter the flow data. The confluence accumulation was obtained, as shown in result 3-2.

Fig. 3-2 The result diagram of the catchment cumulative amount

(3) in Arctoolbox, open the spacial Analyst tools->reclass->reclassify tool to reclassify the catchment accumulation.
(4) Open the Spacial Analyst Tools->conditional->con tool in Arctoolbox, select reclassify data, enter the SQL statement "value>3 and Value<13", The result is a network of thresholds that range between [200,7400]. As shown in result 3-3.

Figure 3-3 River networks within the threshold range
(5) Open the spacial Analyst tools->distance->euclidean Distance tool in Arctoolbox and do a buffer of 120 meters on both sides of the river network. Set up 3-4 as shown. As shown in result 3-5.

Figure 3-4 Euclidean Distance dialog box

Figure 3-5 Euclidean distance results
3.2 Catchment area of gully development by extracting the intersection of river reaches
(1) New point features, 3-6 to set the outlet.
(2) Open the spacial Analyst tools->hydrology->snap pour point tool in Arctoolbox, set 3-7 to get the corrected outlet data.

Figure 3-6 Adding water outlet data

Figure 3-7 Snap pour point dialog box
(3) Open the Spacial Analyst tools->hydrology->watershed tool in Arctoolbox, set 3-8, to get the development range of the gully, 3-9 is shown.

Figure 3-8 Watershed dialog box

Fig. 3-9 The development range of the punching ditch the result diagram
4. Extract the range of the gully
Open the spacial Analyst tools->map algebra->raster caculator tool in Arctoolbox and enter the formula in Figure 4-1, as required. As shown in result 4-2.

Figure 4-1 Raster caculator dialog box

Figure 4-2 The resulting plot of the Groove range extracted
5, noise removal and other processing
(1) Open the spacial Analyst tools->generalization->boundary Clean tool in Arctoolbox to clear the boundary.
(2) Open the spacial Analyst tools->generalization->majority flitter tool in Arctoolbox for further noise processing.
6. Acreage of the formation and geometrical characteristics of the gully object
(1) in Arctoolbox, open the spacial Analyst tools->convention->from raster-.raster to Polygon tool to convert the raster data to shapefile format.
(2) When importing SHP data into a geodatabase, geometric parameters, such as perimeter area, are automatically established, as shown in 6-1.

Figure 6-1 SHP Data property sheet

Extraction of gully based on digital elevation model