An optical image-based ancient landslide dam extraction method

Abstract

The application discloses an ancient landslide dam extraction method based on optical images, and specifically comprises the following steps: step one, image acquisition; step two, basic element indication; step three, ancient landslide interpretation; step four, river blocking analysis; step five, dam interpretation; step six, parameter calculation and verification; and step seven, database construction. The application relates to the technical fields of remote sensing interpretation and ancient disaster identification. The ancient landslide dam extraction method based on optical images combines the ancient landslide range outlined on the images with direct interpretation signs of ancient dams and indirect inference methods, can preferably extract the ancient dams, and is supplemented by field sampling verification. Compared with an automatic algorithm identification mode, the ancient landslide dam extraction correctness is greatly improved, and the time and labor of pure field investigation are effectively avoided, and the efficiency is greatly improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of remote sensing interpretation and ancient disaster identification, and particularly relates to an ancient landslide dam extraction method based on optical images. BACKGROUND

[0002] The landslide dam is a natural dam formed by the landslide blocking the river caused by external forces such as earthquake, heavy rainfall, snowmelt water and artificial excavation, and the service life of the dam is usually short, only 20% of the dams can last for more than one month, and the dam-break flood will be generated, the blocking-dam-break disaster chain formed by the dam has a wide influence range and a long-range effect, and poses a great threat to the life and property of the people along the river, mainly in the form of backwater inundation in the upstream and scouring and inundation in the downstream. However, by comparing the past with the present, the ancient landslide dam event is identified and extracted, and the disaster in the past is analyzed, which is an important means to understand the present disaster and predict the future large landslide dam event.

[0003] The ancient landslide dam is mostly formed in the high mountain and canyon area where the geological surface process is active, and the dam body is basically scoured by the later river incision, so that the error rate of the result obtained by the automatic identification method is large, and a large amount of manpower is still needed for correction and verification. Meanwhile, the field investigation workload is large, time-consuming and labor-intensive, and it is difficult to extract the ancient landslide dam in a large range in a short time. With the development of optical images from plane to three-dimensional, to high spatial resolution and high spectral resolution, the ancient landslide dam extraction method based on optical images enables us to observe the ground objects from a high position, and transfers part of the field work to the indoor work, thereby improving the work efficiency and reducing the field work intensity to a certain extent. Especially in dangerous and harsh weather areas, the method has obvious advantages. Meanwhile, the ancient landslide is easy to be identified on the image due to its unique optical characteristics.

[0004] In recent years, the identification of landslide dams by using optical images has developed rapidly, but at present, scholars mainly extract the landslide dam according to their own interpretation experience and serve specific research objects, and rarely mention the interpretation process of the ancient landslide dam, and lack of overall consideration. Meanwhile, due to the characteristics of large scale, low frequency and great harm of the landslide dam disaster, it is urgent to find samples from history. SUMMARY

[0005] (I) Technical problem solved

[0006] In view of the deficiencies in the prior art, the ancient landslide dam extraction method based on optical images is provided, and the problems of high error rate of automatic algorithm identification and time-consuming and labor-intensive pure field investigation are solved.

[0007] (II) Technical scheme

[0008] In order to achieve the above object, the present application provides the following technical scheme: a kind of extraction method of ancient landslide dam based on optical image, specifically including the following steps:

[0009] Step one, image acquisition: after obtaining remote sensing image using Google Earth interpretation platform, the topographic information is carried out three-dimensional topography display;

[0010] Step two, basic element schematic: according to the three-dimensional topography display in step one, the information of landslide wall, landslide perimeter and landslide body of ancient landslide is obtained by combining existing literature and book data, the dam length, dam width and dam height information of dam are obtained, and the blocking river process is clarified;

[0011] Step three, ancient landslide interpretation: the ancient landslide is interpreted by constructing direct interpretation mark and optical image capture as indirect interpretation mark, and is distinguished from river terrace and ancient glacial platform;

[0012] Step four, blocking river analysis: after clarifying the blocking river process and interpreting the ancient landslide in step two and step three, it is judged whether the ancient landslide appears blocking river condition;

[0013] Step five, dam interpretation: when it is determined that blocking river condition appears in step four, the dam is interpreted by constructing direct interpretation and indirect inference;

[0014] Step six, parameter calculation and verification: the related parameters of ancient landslide, dam and dammed lake are calculated by using Google Earth interpretation platform, empirical formula and GIS platform, and the interpretation results in step five are verified by supplementing existing literature data and field sampling investigation;

[0015] Step seven, database construction: the data of interpreted ancient landslide dam are arranged to form data list, attribute tags are added to each ancient landslide dam data and described, and ancient landslide dam database is constructed.

[0016] Among them, Google Earth, the satellite image of the platform is derived from Landsat TM / ETM, QuickBird, WorldView-II, Google Earth Eye-1, SPOT5, IKONOS and other data, the image resolution is divided into several levels, the highest resolution is 0.15m, and Google Earth combines global digital elevation data to carry out three-dimensional display on remote sensing image, which can truly reflect topographic information, and provides a tool for identification and extraction of ancient landslide dam.

[0017] The present application is further provided: the direct interpretation mark in step three includes the texture of landslide wall and landslide body, the color of landslide wall and landslide body, the shape of ancient landslide and the topography compared with surrounding environment.

[0018] Wherein the landslide wall is granular texture characteristics, the landslide body is smooth texture characteristics;

[0019] Due to the time is long, the landslide wall has grown new vegetation, and the color tone presented by the surrounding vegetation is not much different, green; the landslide body is often affected by the influence of human activities, and the green tone presented by the surrounding natural vegetation has a big difference, and is mostly light gray, and the local front edge appears light red;

[0020] The ancient landslide has various shapes, including circle chair shape, semi-elliptical shape, dustpan shape, dumbbell shape, long tongue shape, rectangular shape, long arc shape (saddle shape), triangular shape (regular triangle, inverted triangle), pear shape, spoon shape, and the like, and the common shapes are circle chair shape, dustpan shape and long tongue shape;

[0021] Since Google Earth combines global digital elevation data to perform three-dimensional display on the remote sensing image, the ancient landslide presents a negative terrain appearance compared with the surrounding environment, and the landslide profile is mostly concave arc.

[0022] The application is further provided that: the distinguishing method of the ancient landslide and the river terrace in step three is: according to the three-dimensional landform display in step one, the intersection part of the back wall and the ground is observed after adjusting the display angle, it can be found that the ancient landslide has a very obvious ridge structure, and the river terrace is relatively flat and integrated with the two sides; at the same time, whether there is a similar platform nearby and whether it is distributed in a strip along the river bank, combined with related literature, the river terrace can also be excluded.

[0023] The application is further provided that: the distinguishing method of the ancient landslide and the ancient glacial erosion platform in step three is: distinguishing according to the characteristics of the ancient glacial erosion platform, wherein the ancient glacial erosion platform is mostly distributed near the ridge line with high altitude, the back edge of the ancient glacial erosion platform is similar to the back edge of the ancient landslide, and is easy to be confused, but it can be excluded according to the platform characteristics of the ancient glacial erosion platform, first, the platform is relatively high and far away from the river, and the front edge slope is steep and mostly bedrock; second, the platform surface is smooth and flat, and is less affected by human activities, and sometimes a landslide occurs below the platform.

[0024] The ancient landslide has a relatively steep landslide back wall, and the landslide body is mostly a platform, which is similar to the river terrace and the ancient glacial erosion platform, and is easy to be misjudged, and the above technical solution is adopted, so that the misjudgment condition is effectively avoided.

[0025] The application is further provided that: the judgment of the river blocking condition in step four specifically includes:

[0026] Ancient landslide scale: from the image, the size of the ancient landslide is observed, and whether it has enough material basis to reach the other side is judged;

[0027] Valley shape: Generally speaking, the river valley is "V" type, which means the slope on both sides is steep and the river is narrow, and it is easy to cause the river to be blocked, while the river valley is "U" type, which means the slope on both sides is gentle and the river is wide, and the landslide body needs to reach the other side of the river, and it is not easy to cause the river to be blocked;

[0028] Whether there is a residual accumulation body or a dam body on both sides: from the image, according to whether the color and texture on both sides of the river are consistent, it can be judged whether there is a residual accumulation body or a dam body, and thus whether it has been blocked can be determined;

[0029] Whether the river is wide in the upstream and narrow in the downstream: generally, in the upstream area of the blocked river position, the terrain is flat and open, and the downstream is mostly a valley, which is similar to the balloon closing position, so that after the river is blocked, a dammed lake is formed in the upstream, the river becomes wide, and the downstream becomes narrow due to the small flow, and due to this unique geographical feature, this place has become the preferred site for many artificial dams, reservoirs and hydropower stations today;

[0030] Whether there is lacustrine deposit on both sides of the upstream river: on the image, the color of the lacustrine deposit is mostly light yellow, and it is distributed parallel to the upstream river.

[0031] The application is further provided: the direct interpretation mode in step five is: according to the three-dimensional landform display in step one, the color and texture consistent area on both sides of the river is circled, and the circled part is the range of the dam, and the dam is mostly irregular in shape.

[0032] The application is further provided: the indirect inference mode in step five is used in the case that the dam has been completely washed away on the three-dimensional landform display, and the color and texture on both sides of the river are inconsistent, and specifically includes:

[0033] When the intersection mode of the landslide body into the river direction and the river is orthogonal, the landslide body is orthogonal to the river, then the dam is mostly elliptical, circular or rectangular, the shape is not obviously stretched, and the interpretation result of the dam is regular;

[0034] When the intersection mode of the landslide body into the river direction and the river is oblique: when the main sliding direction of the landslide body is deviated to the upstream, the dam is accumulated to the upstream; when the main sliding direction of the landslide body is deviated to the downstream, the dam is accumulated to the downstream;

[0035] When the main sliding direction of the landslide body is opposite to the gentle slope, the landslide body is less blocked in the movement process, the climbing area is relatively large, the movement distance is far, and the shape of the dam is elliptical;

[0036] When the main sliding direction of the landslide body is opposite to the steep slope, the landslide body is blocked to the other side, spreads to both sides, the climbing area is relatively small, the movement distance is short, and the shape of the dam is trapezoidal.

[0037] The application is further provided with: the related parameters of the ancient landslide in the sixth step include the front edge elevation, the back edge elevation, the main sliding direction, the average slope, the length, the width, the area and the volume of the landslide body, the related parameters of the dam include the dam length, the dam width, the dam height, the area and the volume, and the related parameters of the dammed lake include the area and the volume.

[0038] (Three) beneficial effects

[0039] The application provides an ancient landslide dam extraction method based on optical images.

[0040] (1) The ancient landslide dam extraction method based on optical images can better extract the dam by combining the ancient landslide range outlined on the image with direct interpretation signs and indirect inference methods, and then supplemented by field sampling verification, which greatly improves the correctness of the ancient landslide dam extraction compared with the automatic algorithm recognition method, and effectively avoids the time-consuming and laborious situation in pure field investigation, greatly improving the efficiency.

[0041] (2) The ancient landslide dam extraction method based on optical images can quickly extract large-scale ancient landslide dams on optical images by summarizing a set of methods that can be used even without background knowledge, thereby providing a fast, scientific and reliable method for the identification and reconstruction of single ancient landslide dam events, the study of regional ancient landslide dam event distribution rules and the construction of an ancient landslide dam event database. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a flowchart of the application;

[0043] Figure 2 It is a basic element diagram of the application;

[0044] In the figure, a is a basic element diagram of an ancient landslide, b is a basic element diagram of a dam, and c is a damming diagram;

[0045] Figure 3 It is an interpretation diagram of the ancient landslide of the application;

[0046] Figure 4 It is an interpretation diagram of the ancient landslide of the application;

[0047] Figure 5 It is a diagram for distinguishing river terraces and ancient glacial erosion platforms;

[0048] Figure 6 It is an interpretation diagram of the dam of the application. DETAILED DESCRIPTION

[0049] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0050] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application. Figures 1-6 The embodiments of the present application provide a technical solution: an ancient landslide dam extraction method based on optical images, specifically comprising the following steps:

[0051] Step one, image acquisition: constructing a Google Earth interpretation platform, obtaining satellite images from land satellite TM / ETM, QuickBird, WorldView-II, Google Earth Eye-1, SPOT5, IKONOS, the image resolution is divided into several levels, the highest resolution is 0.15m, and in order to truly reflect the topographic information, Google Earth combines global digital elevation data to perform three-dimensional display on the remote sensing image;

[0052] Step two, basic element indication: according to the three-dimensional topographic display in step one, combining the existing literature and book information to obtain the landslide wall, landslide perimeter and landslide body information of the ancient landslide, obtain the dam length, dam width and dam height information of the dam, and clarify the blocking river process,

[0053] Step three, ancient landslide interpretation: constructing direct interpretation marks and optical image capture as indirect interpretation marks to interpret the ancient landslide, and distinguishing from the river terrace and ancient glacial platform;

[0054] The direct interpretation marks include the texture of the landslide wall and the landslide body, the color tone of the landslide wall and the landslide body, the morphology of the ancient landslide, and the topography compared to the surrounding environment. Specifically, the texture: the landslide wall has granular texture characteristics, and the landslide body has smooth texture characteristics (as shown in Fig. 1a); Figure 3

[0055] The color tone: due to the long time, the landslide wall has grown new vegetation, and the color tone is not much different from the surrounding vegetation, which is green; the landslide body is often affected by the later human activities, and the green tone of the surrounding natural vegetation has a great difference, which is mostly light yellowish gray, and the local front edge appears light red (as shown in Fig. 1a); Figure 3

[0056] ​​Morphology: The ancient landslide morphology is diverse, including circle chair shape, semi-elliptical shape, dustpan shape, dumbbell shape, long tongue shape, rectangular shape, long arc shape (saddle shape), triangular shape (regular triangle, inverted triangle), pear shape, spoon shape, etc. Commonly seen are circle chair shape, dustpan shape and long tongue shape;

[0057] Groove-shaped negative terrain: Since Google Earth combines global digital elevation data with remote sensing images for three-dimensional display, we can observe from the side view that the ancient landslide presents a negative terrain compared to the surrounding environment, and the landslide profile is mostly concave arc;

[0058] Among them, for indirect interpretation signs, there are various micro-landforms on the ancient landslide that can be captured from optical images. For example, the ancient landslide has a unique double-gully homologous image feature (as shown in Fig. 1c); the landslide body is mostly flat, with a relatively gentle terrain (as shown in Fig. 1d); there are sometimes kurgans and depressions on the landslide platform (as shown in Fig. 1d, e); some landslide backwalls develop multiple gullies under the action of later surface water and other geological forces (as shown in Fig. 1d); and generally, it is easier to interpret the existence of ancient landslides at river junctions, near faults, near current artificial dams, reservoirs and power stations (as shown in Fig. 1f, g, h); Figure 3 Figure 3 Figure 3 Figure 3 Figure 4 Step four, river blocking analysis: After determining the river blocking process and interpreting the ancient landslide in steps two and three, it is determined whether the ancient landslide has blocked the river;

[0059] Among them, the judgment of the river blocking situation specifically includes:

[0060]

[0061] Ancient landslide scale: From the image, the size of the ancient landslide is visually estimated to determine whether it has enough material basis to reach the other side;

[0062] Valley morphology: Generally speaking, a "V"-shaped valley indicates steep slopes on both sides and a narrow river channel, making it easy to block the river, while a "U"-shaped valley indicates gentle slopes on both sides and a wide river channel, making it difficult for the landslide to reach the other side;

[0063] Whether there are residual accumulations or dam bodies on both sides: From the image, whether there are residual accumulations or dam bodies can be determined by whether the color and texture on both sides of the river are consistent, and thus whether it has ever been blocked;

[0064] ​​​​​Is the river channel wide upstream and narrow downstream: usually in the upstream area of the blocked river location, the terrain is mostly flat and open, and the downstream is mostly a canyon. This location is similar to the balloon's closing place, making the upstream form a dammed lake after the blocked river occurs, and the river channel becomes wider, while the downstream becomes narrower due to the reduced flow. Due to this unique geographical feature, this location is often the preferred site for many artificial dams, reservoirs, and hydropower stations today;

[0065] Is there lake sediment on both sides of the upstream river channel: on the image, the color tone of the lake sediment is mostly light yellow, and it is distributed parallel to the upstream river channel (as shown in Fig. 1a); Figure 6

[0066] Step five, interpretation of the dam: when it is determined that the river is blocked in step four, direct interpretation and indirect inference methods are used to interpret the dam;

[0067] The direct interpretation method is used for cases where the color tone and texture on both sides of the river channel on the image are consistent. The range of the dam can be directly circled, which is mostly irregular in shape (as shown in Fig. 1a); Figure 6

[0068] The indirect inference method is used for cases where the dam has been completely washed away, and the color tone and texture on both sides of the river channel are inconsistent. This method summarizes the following two inference methods:

[0069] 1) Intersection direction of landslide into river and river channel:

[0070] Orthogonal: the landslide is orthogonal to the river channel, and the dam is mostly elliptical, circular, or rectangular, with no obvious shape stretching, and the interpretation result is relatively regular (as shown in Fig. 1b); Figure 6

[0071] Oblique: when the main sliding direction of the landslide is biased upstream, the dam is mostly accumulated upstream (as shown in Fig. 1c); when the main sliding direction of the landslide is biased downstream, the dam is mostly accumulated downstream (as shown in Fig. 1d). Figure 6 Figure 6

[0072] 2) Controlled by the steepness of the opposite bank:

[0073] When the opposite bank is gentle: the landslide has less resistance during movement, the climbing area is relatively large, the movement distance is far, and the shape of the dam is mostly elliptical (as shown in Fig. 1e); Figure 6

[0074] When the opposite bank is steep: the landslide is blocked when it reaches the opposite bank, spreads to both sides, the climbing area is relatively small, the movement distance is short, and the shape of the dam is mostly trapezoidal (as shown in Fig. 1f) Figure 6 ​​​​​​​

[0075] Step six, parameter verification: the related parameters of ancient landslide, dam and lake are calculated by Google Earth interpretation platform, empirical formula and GIS platform, and the results of step five are verified by existing literature and field sampling investigation;

[0076] Step seven, database construction: the data of interpreted ancient landslide and dam are sorted to form a data list, and attribute labels are added to each ancient landslide and dam data for description, and an ancient landslide and dam database is constructed.

[0077] As a preferred solution, since the ancient landslide has a relatively steep back wall of the landslide, and the landslide body is mostly a platform, it is similar to the river terrace and ancient glacial erosion platform, and is easy to be misjudged. In order to realize the differentiation from the river terrace and ancient glacial erosion platform, the intersection line part of the back wall and the ground is observed by rotating the image angle. It can be found that the ancient landslide has a very obvious "ridge", and the river terrace is relatively flat and integrated with the two sides. At the same time, whether there is a similar platform nearby and whether it is distributed along the river bank in a strip shape can be found, and in combination with the related literature, it can also be excluded (as shown in Fig. 2a). The ancient glacial erosion platform is mostly distributed near the ridge line with high altitude, and its back edge is similar to the back edge of the ancient landslide, which is easy to be confused, but it can be excluded according to the characteristics of the platform. First, the platform is relatively high and far from the river, and the front edge slope is steep and mostly bedrock. Second, the platform surface is smooth and flat, and is less modified by human activities. Sometimes, landslides occur below the platform (as shown in Fig. 2b). Figure 5 Figure 5

[0078] As a detailed description, the related parameters of the ancient landslide in step six include the front edge elevation, back edge elevation, main sliding direction, average slope, length, width, area and volume of the landslide body, the related parameters of the dam include the dam length, dam width, dam height, area and volume of the dam, and the related parameters of the dammed lake include the area and volume of the dammed lake.

[0079] Further, the front edge elevation, back edge elevation, main sliding direction, average slope, length, width and area of the landslide body, and the dam length, dam width, dam height and area of the dam can be measured on the Google Earth platform.

[0080] The volume of the landslide body and the dam is calculated according to the empirical formula proposed by Larsen IJ, Montgomery DR, Korup O. Landslide erosion controlled by hillslope material [J]. Nature Geoscience, 2010, 3(4): 247-251.

[0081] ​​The area and volume of the barrier lake are calculated by using the GIS platform to calculate the digital elevation model data.

[0082] By using the method, 228 ancient landslide dams in the Daduhe River and Minjiang River basins are deciphered, and the accuracy is more than 88% through verification by existing literature and field sampling investigation.

[0083] Application prospect,

[0084] A series of national major strategic projects such as the Sichuan-Tibet Railway and the hydropower projects in the lower reaches of the Yarlung Zangbo River will be deployed in the Qinghai-Tibet Plateau and surrounding mountainous areas. The active internal and external coupling forces in this area cause the frequent and sudden occurrence of large landslide disasters and river-blocking events, which pose a great threat to engineering construction. The landslide-blocking disaster is large in scale and low in frequency, and samples need to be found from history. Therefore, the ancient landslide dam extraction method based on optical images proposed in the method can play an important role in this regard. At the same time, it can provide early technical support for macroscopically grasping the historical distribution law of large landslide dam events, predicting future landslide dam events, and the safe implementation and operation of major strategic projects.

[0085] Although embodiments of the present application have been shown and described, it will be understood by those having ordinary skill in the art that various changes, modifications, substitutions and alterations can be made hereto without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for extracting ancient landslide dams based on optical images, characterized in that: Specifically comprising the following steps: Step one, image acquisition: using Google Earth interpretation platform, after obtaining remote sensing image, the geomorphic information is displayed in three-dimensional landform; Step two, basic element diagram: according to the three-dimensional landform display in step one, combined with the existing literature and book information, the information of landslide wall, landslide perimeter and landslide body of ancient landslide is obtained, the information of dam length, dam width and dam height of dam is obtained, and the blocking river process is clear; Step three, ancient landslide interpretation: the ancient landslide is interpreted by constructing direct interpretation signs and optical image capture as indirect interpretation signs, and is distinguished from river terrace and ancient glacial platform; Step four, blocking river analysis: after the blocking river process and the interpretation of ancient landslide are clear in step two and step three, it is judged whether the ancient landslide appears blocking river situation; Step five, dam interpretation: when it is determined that the blocking river situation appears in step four, the dam is interpreted by constructing direct interpretation and indirect inference method; Step six, parameter calculation and verification: the related parameters of ancient landslide, dam and dammed lake are calculated by using Google Earth interpretation platform, empirical formula and GIS platform, and the interpretation results in step five are verified by supplementing the existing literature data and field sampling investigation; Step seven, database construction: the data of interpreted ancient landslide and dam are sorted, a data list is formed, attribute tags are added to each ancient landslide and dam data and are described, and an ancient landslide and dam database is constructed; The indirect inference method in step five is used when the dam has been completely washed away on the three-dimensional landform display, and the color and texture of the river channel on both sides are inconsistent, specifically including: When the intersection of the landslide body into the river direction and the river channel is orthogonal, the landslide body is orthogonal to the river channel, and the dam interpretation result is regular; When the intersection of the landslide body into the river direction and the river channel is oblique: when the main sliding direction of the landslide body is deviated to the upstream, the dam is accumulated to the upstream; when the main sliding direction of the landslide body is deviated to the downstream, the dam is accumulated to the downstream; When the main sliding direction of the landslide body is a gentle slope on the opposite bank, the shape of the dam is oval; When the main sliding direction of the landslide body is a steep slope on the opposite bank, the shape of the dam is trapezoidal. 2.The method of extracting ancient landslide dam based on optical image according to claim 1, characterized in that: The direct interpretation signs in step three include the texture of landslide wall and landslide body, the color of landslide wall and landslide body, the shape of ancient landslide and the topography formed by comparing the surrounding environment. 3.The method of extracting ancient landslide dam based on optical image according to claim 1, characterized in that: The distinguishing method of ancient landslide and river terrace in step three is: according to the three-dimensional landform display in step one, the intersection line part of the back wall and the ground is observed after adjusting the display angle, when the ridge structure appears, it is determined as ancient landslide, when it appears flat and integrates with both sides, it is determined as river terrace. 4.The method of extracting ancient landslide dam based on optical image according to claim 1, characterized in that: The distinguishing method of ancient landslide and ancient glacial platform in step three is: according to the characteristics of ancient glacial platform.

5. The method of claim 1, wherein the method is characterized by: The judgment of blocking river situation in step four specifically includes: ancient landslide scale, river valley shape, whether there is residual accumulation body and dam body on both sides of the river, whether the river is wide in the upstream and narrow in the downstream, whether there is lacustrine sediment on both sides of the upstream river. 6.The method of extracting ancient landslide dam based on optical image according to claim 1, characterized in that: The direct interpretation method in step five is: according to the three-dimensional landform display in step one, the color and texture consistent area on both sides of the river is circled, and the circled part is the range of dam. 7.The method of extracting ancient landslide dam based on optical image according to claim 1, characterized in that: The related parameters of the ancient landslide in step six include the front edge elevation, the back edge elevation, the main sliding direction, the average slope, the length, the width, the area and the volume of the landslide body, the related parameters of the dam include the dam length, the dam width, the dam height, the area and the volume of the dam, and the related parameters of the dammed lake include the area and the volume of the dammed lake.

Images