Regional avalanche history reconstruction method based on tree ring

Abstract

The invention discloses a regional avalanche history reconstruction method based on tree rings. The method comprises the following steps: aiming at an avalanche disaster, collecting a field tree ring sample core emphasizing angles and directions; the field tree ring sample is processed to obtain a sample core, the width of the sample core is obtained in cooperation with a high-power microscope, the growth abnormality year is determined according to the width change of the sample core, growth abnormality comprises growth inhibition and growth release, other interference signals existing in the sample core are recognized, and the growth abnormality is determined according to the other interference signals. The other interference signals comprise scars, calluses and traumatic resin traces; and judging the avalanche year according to the interference signal. As a common dating means, the tree ring has the advantages of being accurate in dating, high in precision, wide in distribution, easy to obtain and the like, obvious signals including scars, calluses, traumatic resin traces and the like can be left in the tree ring after an avalanche occurs, the year where the avalanche occurs can be accurately tracked by utilizing the signals, and the avalanche can be accurately tracked. And the regional avalanche recording time sequence can be prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of avalanche disaster analysis, and more specifically, to a method for reconstructing regional avalanche history based on tree rings. Background Art

[0002] Under the background of climate change, precipitation patterns in Asia's high mountains have changed, the instability of the snow cover has increased, and the susceptibility of avalanches has increased. Because people have paid less attention to avalanches before, there are few records of avalanche processes. Avalanches are generally small-scale processes, and there is a lack of meteorological and hydrological recorders in avalanche-prone environments. Therefore, research on the formation mechanism of avalanches and their response to climate change is not mature.

[0003] In the prior art, for example, patent number CN101221246B discloses a method for remote sensing quantitative exploration of avalanches, the steps of which are A. Acquisition of multi-phase high-resolution satellite stereo images / airborne LIDAR scanning data; B. Stereo restoration of high-resolution satellite images / airborne LIDAR data; C. Stereo remote sensing identification of avalanche disasters and extraction of avalanche factors based on images; D. Establishment of high-density, high-precision DEM and generation of high-resolution DOM; E. Automatic extraction of avalanche hazard factors based on high-density, high-precision DEM; F. Establishment of avalanche disaster prediction model and stability and hazard assessment; G. Site selection of engineering schemes and comparison and optimization of schemes. This patent enables automatic quantitative analysis of avalanche exploration, identifies avalanche disasters with higher accuracy, and can identify the occurrence and development trends of avalanche disasters, realize the stability and hazard assessment of avalanche disasters, avoid the impact of avalanche disasters on engineering, play a role in disaster reduction and prevention, and produce significant economic, social and environmental benefits. Obviously, the prior art realizes the prediction of avalanches based on remote sensing technology, but cannot realize the reconstruction of the avalanche process when an avalanche has occurred but there is a lack of corresponding recorded data.

[0004] Therefore, how to reconstruct an avalanche that has already occurred in order to facilitate the study of the formation mechanism of avalanches is a technical problem that urgently needs to be solved. Summary of the invention

[0005] The present invention is provided to solve the above problems existing in the prior art. Therefore, a method for reconstructing regional avalanche history based on tree rings is needed.

[0006] The present invention provides a method for reconstructing regional avalanche history based on tree rings, the method comprising: Collect field tree ring disaster samples and reference cores in avalanche disaster disturbance areas and non-disturbance areas respectively; pay attention to the angle and direction of tree ring core collection; Processing the field tree ring sample to obtain a sample core, obtaining the width of the sample core, determining growth abnormality according to the change in the width of the sample core, wherein the growth abnormality includes growth inhibition and growth release; and identifying interference signals present in the sample core, wherein the interference signals include scars, callus tissue, and traumatic resin ducts; The avalanche year is determined based on growth anomalies and interference signals.

[0007] Furthermore, collecting tree ring samples in the field specifically includes: Mapping of landforms based on avalanche paths; Along the avalanche path, select trees with typical characteristics, including trees that are obviously bent or have scars. When sampling, record the sampling height, tree characteristics, latitude and longitude, and altitude; For trees with scars, samples were collected 15-25 cm above the scars. For bent trees, samples were collected at the point of maximum bending. For trees without scars, samples were collected at 1.1-1.5 m in height. Multiple samples were collected from each tree, including at least one sample collected along the slope direction and at least one sample collected in the opposite direction of the slope. Reference cores are collected in areas undisturbed by avalanches within a set distance from the avalanche zone.

[0008] Further, the field tree ring samples are processed to obtain sample cores, specifically including: The field tree ring samples are naturally dried, the sample cores are fixed in wooden grooves, and the sample cores are polished with sandpaper until the cells are clearly visible under a microscope, and the width is measured and cross-dated.

[0009] Furthermore, the determination of the avalanche year based on abnormal tree growth and interference signals specifically includes: Dividing the interference signal into three different intensity levels, namely strong, medium and weak; according to t The number of disturbed trees monitored in each year and t Calculation of the total number of surviving trees per year I t index; Different interference signals are assigned different weights according to the intensity level of the interference signal, and the W It index; according to W It The avalanche year was determined based on the index, the number of interference signals and the number of surviving trees.

[0010] Furthermore, the interference signal is divided into three different intensity levels, namely strong, medium and weak, specifically including: If the traumatic resin duct signal is visible and not completely continuous, the intensity level of the traumatic resin duct signal is determined to be medium; if the traumatic resin duct signal is visible and completely continuous, the intensity level of the traumatic resin duct signal is determined to be strong; If the growth inhibition signal is 45-55%, the intensity level of the growth inhibition signal is determined to be weak; if the growth inhibition signal is 30-45%, the intensity level of the growth inhibition signal is determined to be medium; if the growth inhibition signal is less than 30%, the intensity level of the growth inhibition signal is determined to be strong; If the growth release signal is 180-200%, the intensity level of the growth release signal is determined to be weak; if the growth release signal is 200-220%, the intensity level of the growth release signal is determined to be medium; if the growth release signal is greater than 220%, the intensity level of the growth release signal is determined to be strong; For scar and callus signals, no signal strength classification is performed.

[0011] Further, assigning different weights to different interference signals according to the intensity levels of the interference signals specifically includes: If the intensity level of the scar, callus signal and / or traumatic resin duct signal is strong, assigning a first weight to the scar, callus signal and / or traumatic resin duct signal; If the intensity level of the traumatic resin duct signal is medium, the intensity level of the growth inhibition signal is strong, and / or the intensity level of the growth release signal is strong, assigning a second weight to the traumatic resin duct signal, the growth inhibition signal, and / or the growth release signal; If the intensity level of the growth inhibition signal is medium and / or the intensity level of the growth release signal is medium, assigning a third weight to the growth inhibition signal and / or the growth release signal; If the intensity level of the growth inhibition signal is weak and / or the intensity level of the growth release signal is weak, a fourth weight is assigned to the growth inhibition signal and / or the growth release signal.

[0012] Furthermore, the following formula is used to calculate I t index: ; In the formula, R t for t The number of disturbed trees monitored in the year, A t for t The total number of trees alive in the year.

[0013] Furthermore, the following formula is used to calculate W It index: ; In the formula, i , n are both cumulative summation symbols, is the signal of scar, callus and strong traumatic resin duct in year t, is the signal of traumatic resin duct and strong growth release signal in year t and the strong growth release signal in year t + 1, is the growth release signal in year t and the growth release signal in year t + 1, is the weak growth release signal in year t and the weak growth release signal in year t + 1.

[0014] Furthermore, the determination of the avalanche year according to W It the index, the number of interference signals and the number of surviving trees specifically includes: When a certain year meets the following three conditions: Taking n as the sampling quantity, When 10 < n ≤ 20, 1) W It The index is greater than 2.0; 2) The number of interference signals is greater than 2 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive; When 20 < n ≤ 50, 1) W It The index is greater than 1.0; 2) The number of interference signals is greater than 3 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive; When n > 50, 1) W It The index is greater than 0.75; 2) The number of interference signals is greater than 3 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive Then this year is regarded as a large avalanche year.

[0015] Furthermore, the method further includes: If there are only growth inhibition signals and / or growth release signals in the core sample and there are also growth inhibition signals and / or growth release signals in the reference core sample, it is determined that no avalanche has occurred.

[0016] The present invention has at least the following beneficial effects: Tree rings are a commonly used dating method with the advantages of accurate dating, high precision, wide distribution, and easy acquisition. After an avalanche occurs, it will leave obvious signals in the tree rings, including scars, callus tissue, traumatic resin canals, etc. These signals can be used to accurately track the year when the avalanche occurred, and the regional avalanche record time series can be extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a regional avalanche reconstruction method based on tree rings according to an embodiment of the present invention is shown.

[0018] Figure 2 A flow chart of field tree ring sample collection according to an embodiment of the present invention is shown.

[0019] Figure 3 A flow chart of indoor experiments and feature extraction according to an embodiment of the present invention is shown.

[0020] Figure 4 A flowchart of avalanche year screening according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments, but are not intended to limit the present invention. For the various steps described herein, if there is no necessity for a causal relationship between each other, the order in which they are described as examples herein should not be regarded as a limitation, and those skilled in the art should know that they can be adjusted in order, as long as the logic between them is not destroyed, resulting in the inability to implement the entire process.

[0022] The embodiment of the present invention provides a regional avalanche reconstruction method based on tree rings, such as Figure 1 As shown, the method comprises the following steps: Step S1, collecting tree ring samples in the field.

[0023] In a specific embodiment, if Figure 2 As shown in the figure, the tree ring samples were collected in the field through the following steps: Step S101, selecting a typical avalanche path and drawing a topographic map.

[0024] Step S102, along the avalanche path, select affected trees with typical characteristics, including bent trees, trees with scars, etc., and record the sampling height, tree characteristics, longitude and latitude, altitude and other information during sampling.

[0025] Step S103, for trees with scars, samples are collected about 20 cm above the scars, for bent trees, samples are collected at the maximum bend, and for trees without obvious features, samples are collected at a height of about 1.3 m. At least two sample cores are collected from each tree, one along the slope direction and the other in the opposite direction.

[0026] Step S104, in areas near the avalanche zone that are not disturbed by avalanches, reference core samples are collected according to the international tree-ring database standards to assist in dating and eliminate interference from climate signals.

[0027] Step S2: indoor experiment and feature extraction.

[0028] In a specific embodiment, if Figure 3 As shown, indoor experiments and feature extraction are carried out through the following steps: Step S201, performing experimental pretreatment on the collected sample cores, including natural drying, fixing the tree cores in wooden grooves, and polishing the sample cores with sandpaper until the cells are clearly visible under a microscope; Step S202, measuring the width of the tree ring using a width gauge (Velmex, etc.); Step S203, using COFECHA to check the dating results, and for samples with poor dating results, cross dating is performed by comparing the width curves of different samples; Step S204, determining growth anomalies based on the width changes of the sample cores, wherein the growth anomalies include growth inhibition and growth release, identifying interference signals in the sample cores, wherein the interference signals include scars, callus tissues, and traumatic resin ducts, and recording the year of tree growth mutation by calculating the width changes of each sample core.

[0029] Step S3, avalanche year screening.

[0030] In a specific embodiment, if Figure 4 As shown, the avalanche year screening is performed through the following steps: Step S301, classify the interference signal identified in the previous step into different levels: strong, medium, and weak.

[0031] For example, the specific classification criteria are shown in Table 1.

[0032] Table 1 Classification criteria for different types of interference strength

[0033] Combined with Table 1, the specific division method is as follows: If the traumatic resin duct signal is visible and not completely continuous, the intensity level of the traumatic resin duct signal is determined to be medium; if the traumatic resin duct signal is visible and completely continuous, the intensity level of the traumatic resin duct signal is determined to be strong; If the growth inhibition signal is 45-55%, the intensity level of the growth inhibition signal is determined to be weak; if the growth inhibition signal is 30-45%, the intensity level of the growth inhibition signal is determined to be medium; if the growth inhibition signal is less than 30%, the intensity level of the growth inhibition signal is determined to be strong; If the growth release signal is 180-200%, the intensity level of the growth release signal is determined to be weak; if the growth release signal is 200-220%, the intensity level of the growth release signal is determined to be medium; if the growth release signal is greater than 220%, the intensity level of the growth release signal is determined to be strong.

[0034] For scar and callus signals, no signal strength classification is performed. Step S302: Calculate I t index; ; In the formula, R t for t The number of disturbed trees monitored in the year, A t for t The total number of trees alive in the year.

[0035] Step S303, calculate W It The index assigns different weights to different signals according to the strength of the interference signal, among which growth release is considered to be the lag effect of avalanche occurrence and is regarded as the avalanche signal of the previous year: ; In the formula, i , n They are all cumulative summation symbols. For scars, callus tissue and strong traumatic resin duct signals, is the traumatic resin duct and strong growth release signal in year t and the strong growth release signal in year t+1, is the growth release signal in year t and the growth release signal in year t+1, It is the weak growth release signal in year t and the weak growth release signal in year t+1.

[0036] The weight assignment standard is shown in Table 2.

[0037] Table 2 Weight assignment of different interference signals

[0038] As shown in Table 2, the specific method of assigning different weights to different interference signals according to the strength levels of the interference signals is as follows: If the intensity level of the scar, callus signal, and / or traumatic resin duct signal is strong, assign the first weight (i.e., intensity 1) to the scar, callus signal, and / or traumatic resin duct signal.

[0039] If the intensity level of the traumatic resin duct signal is medium, the intensity level of the growth inhibition signal is strong, and / or the intensity level of the growth release signal is strong, assign the second weight (i.e., intensity 2) to the traumatic resin duct signal, growth inhibition signal, and / or growth release signal.

[0040] If the intensity level of the growth inhibition signal is medium and / or the intensity level of the growth release signal is medium, assign the third weight (i.e., intensity 3) to the growth inhibition signal and / or growth release signal.

[0041] If the intensity level of the growth inhibition signal is weak and / or the intensity level of the growth release signal is weak, assign the fourth weight (i.e., intensity 4) to the growth inhibition signal and / or growth release signal.

[0042] Step S4, determine the large avalanche year according to the following indicators: Let n be the number of samples. When 10 < n ≤ 20, 1) W It The index is greater than 2.0; 2) The number of interference signals is greater than 2 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive; When 20 < n ≤ 50, 1) W It The index is greater than 1.0; 2) The number of interference signals is greater than 3 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive; When n > 50, 1) W It The index is greater than 0.75; 2) The number of interference signals is greater than 3 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive Then consider this year as a large avalanche year.

[0043] It should be noted that if there is only a growth mutation signal and the same / similar growth mutation signal appears in the reference sample, it is not regarded as an avalanche signal.

[0044] In addition, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present invention with equivalent elements, modifications, omissions, combinations (e.g., various embodiments intersecting schemes), adaptations or changes. The elements in the claims are to be interpreted broadly based on the language adopted in the claims, and are not limited to the examples described in this specification or during the prosecution of this application, which examples are to be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered as examples only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0045] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more of them) may be used in combination with each other. For example, a person of ordinary skill in the art may use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features may be grouped together to simplify the present invention. This should not be interpreted as an intention that a feature of an invention that is not claimed for protection is necessary for any claim. On the contrary, the subject matter of the present invention may be less than all the features of an embodiment of a particular invention. Thus, the following claims are incorporated herein as examples or embodiments in the specific embodiments, wherein each claim is independently a separate embodiment, and it is considered that these embodiments may be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the appended claims and the full scope of equivalent forms granted by these claims.

Claims

1. A method for reconstructing regional avalanche history based on tree rings, characterized in that: The method comprises: Field tree ring disaster samples and reference cores were collected in avalanche disaster-disturbed areas and non-disturbed areas; Processing the field tree ring sample to obtain a sample core, obtaining the width of the sample core, determining growth abnormality according to the change in the width of the sample core, wherein the growth abnormality includes growth inhibition and growth release; and identifying interference signals present in the sample core, wherein the interference signals include scars, callus tissue, and traumatic resin ducts; The avalanche year is determined based on growth anomalies and interference signals.

2. The method according to claim 1, characterized in that: The collecting of tree ring samples in the field specifically includes: Mapping of landforms based on avalanche paths; Along the avalanche path, select trees with typical characteristics, including trees that are obviously bent or have scars. When sampling, record the sampling height, tree characteristics, latitude and longitude, and altitude; For trees with scars, samples were collected 15-25 cm above the scars. For bent trees, samples were collected at the point of maximum bending. For trees without scars, samples were collected at 1.1-1.5 m in height. Multiple samples were collected from each tree, including at least one sample collected along the slope direction and at least one sample collected in the opposite direction of the slope. Reference cores are collected in areas undisturbed by avalanches within a set distance from the avalanche zone.

3. The method according to claim 1, characterized in that Processing the field tree ring samples to obtain sample cores specifically includes: The field tree ring samples are naturally dried, the sample cores are fixed in wooden grooves, and the sample cores are polished with sandpaper until the cells are clearly visible under a microscope, and the width is measured and cross-dated.

4. The method according to claim 1, characterized in that: The determination of the avalanche year based on abnormal tree growth and interference signals specifically includes: Dividing the interference signal into three different intensity levels, namely strong, medium and weak; according to t The number of disturbed trees monitored in each year and t Calculation of the total number of surviving trees per year I t index; Different interference signals are assigned different weights according to the intensity level of the interference signal, and the W It index; according to W It The avalanche year was determined based on the index, the number of interference signals and the number of surviving trees.

5. The method according to claim 4, characterized in that The interference signal is divided into three different intensity levels, namely strong, medium and weak, specifically including: If the traumatic resin duct signal is visible and not completely continuous, the intensity level of the traumatic resin duct signal is determined to be medium; if the traumatic resin duct signal is visible and completely continuous, the intensity level of the traumatic resin duct signal is determined to be strong; If the growth inhibition signal is 45-55%, the intensity level of the growth inhibition signal is determined to be weak; if the growth inhibition signal is 30-45%, the intensity level of the growth inhibition signal is determined to be medium; if the growth inhibition signal is less than 30%, the intensity level of the growth inhibition signal is determined to be strong; If the growth release signal is 180-200%, the intensity level of the growth release signal is determined to be weak; if the growth release signal is 200-220%, the intensity level of the growth release signal is determined to be medium; if the growth release signal is greater than 220%, the intensity level of the growth release signal is determined to be strong; For scar and callus signals, no signal strength classification is performed.

6. The method according to claim 4, characterized in that The assigning different weights to different interference signals according to the intensity levels of the interference signals specifically includes: If the intensity level of the scar, callus signal and / or traumatic resin duct signal is strong, assigning a first weight to the scar, callus signal and / or traumatic resin duct signal; If the intensity level of the traumatic resin duct signal is medium, the intensity level of the growth inhibition signal is strong, and / or the intensity level of the growth release signal is strong, then assign a second weight to the traumatic resin duct signal, the growth inhibition signal, and / or the growth release signal; If the intensity level of the growth inhibition signal is medium and / or the intensity level of the growth release signal is medium, then assign a third weight to the growth inhibition signal and / or the growth release signal; If the intensity level of the growth inhibition signal is weak and / or the intensity level of the growth release signal is weak, then assign a fourth weight to the growth inhibition signal and / or the growth release signal.

7. The method according to claim 4, characterized in that Calculated by the following formula I t index: ； In the formula, R t for t The number of disturbed trees monitored in the year, A t for t The total number of trees alive in the year.

8. The method according to claim 4, characterized in that Calculated by the following formula W It index: ； In the formula, i , n They are all cumulative summation symbols. For scars, callus tissue and strong traumatic resin duct signals, is the traumatic resin duct and strong growth release signal in year t and the strong growth release signal in year t+1, is the growth release signal in year t and the growth release signal in year t+1, It is the weak growth release signal in year t and the weak growth release signal in year t+1.

9. The method according to claim 4, characterized in that The basis W It The avalanche year is determined by the index, the number of interference signals and the number of surviving trees, including: When a certain year meets the following three conditions: Taking n as the number of samples, When 10 < n ≤ 20, 1) W It The index is greater than 2.0; 2) The number of interference signals is greater than 2 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive; When 20 < n ≤ 50, 1) W It The index is greater than 1.0; 2) The number of interference signals is greater than 3 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive; When n > 50, 1) W It The index is greater than 0.75; 2) The number of interference signals is greater than 3 and the intensity level of at least one interference signal is strong; 3) At least 10 trees survive Then consider that year as a large avalanche year.

10. The method according to claim 9, characterized in that The method further includes: If there are only growth inhibition signals and / or growth release signals in the sample core and the same growth inhibition signals and / or growth release signals also exist in the reference sample core, then determine that no avalanche has occurred.

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