Daily change forecasting method and system for moisture content of dead forest combustible in dry season

Abstract

The invention discloses a dry season forest dead combustible matter moisture content daily change measuring and reporting method and system. The method comprises the steps that a dead combustible matter moisture content observed value at any time of a measuring and reporting day and any other to-be-measured and reported time of the day are obtained; converting the any time and the time to be measured and reported into a measuring time sequence number and a measuring and reporting time sequence number; on the basis of the measurement time sequence number, calculation is conducted through a moisture content change rate fitting curve model of the dead combustible, and the moisture content change rate of the dead combustible at the measurement time is obtained; calculating the moisture content of the dead combustible at the initial moment of the forecasting day based on the moisture content change rate of the dead combustible at the measuring moment; calculating through a moisture content change rate fitting curve model of the dead combustible material on the basis of the forecasting time sequence number to obtain the moisture content change rate of the dead combustible material at the forecasting time, and calculating the moisture content of the dead combustible material at the initial time of the forecasting day on the basis of the moisture content change rate of the dead combustible material at the forecasting time; and obtaining the moisture content of the dead combustible at the forecasting time in the forecasting day change.

Description

Technical Field

[0001] The invention belongs to the technical field of natural disaster prevention and control, and in particular relates to a method and system for measuring and reporting daily changes in moisture content of dead combustible matter in forests during the dry season. Background Art

[0002] The moisture content of dead forest fuel is the main factor affecting the occurrence, development and spread of forest fires, and is a key factor in the forecast of forest fire risk levels. The spatiotemporal monitoring and reporting of the moisture content of dead forest fuel is of great significance for carrying out near-real-time fire weather level monitoring and reporting, forest fire occurrence and spread forecasts, and map publishing in areas with severe fire prevention situations.

[0003] In recent years, with the delay of the start of rainy season in southwest my country, the extension of dry season cycle, frequent forest fires, and the increase in the number of days with high forest fire risk level, the fire risk has intensified. It is urgent to accurately carry out forest fire risk monitoring and early warning on a time scale. However, according to previous studies and surveys, the newly emerged drought conditions in recent years have led to no significant difference in the time changes of dead combustible moisture content among different tree species. This shows that under the new drought meteorological conditions, it is of little practical significance to carry out fire risk level monitoring and reporting of major tree species with a single tree species as the object. Therefore, it is urgent to take all major tree species as the object, only distinguish the dead combustible type, and carry out the method and system of daily change monitoring and reporting of dead combustible moisture content in the dry season, so as to shorten the time interval of forest fire risk level monitoring and reporting, effectively reduce the cost of forest fire risk level monitoring and reporting, and improve the efficiency of forest fire prevention.

[0004] The sample data of the traditional dead combustible moisture content fitting model are mostly obtained in relatively ideal scenarios such as indoor experimental boxes simulating climatic conditions or real-time measurement on nearby flat ground after weighing in the laboratory, which cannot effectively express the effects of natural geographical conditions, meteorological conditions, etc. on moisture content in real geographical scenarios. Therefore, it is very necessary to carry out real-time measurement of dead combustible moisture content in real geographical scenarios to establish a more scientific and practical dead combustible moisture content measurement and reporting model. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a method and system for measuring and reporting daily changes in moisture content of dead combustible matter in dry forests in order to solve the problems existing in the above prior art.

[0006] To achieve the above object, the present invention provides a method for measuring and reporting daily changes in moisture content of dead fuel in forests during the dry season, comprising:

[0007] Obtain the observed value of dead combustible moisture content at any time during the observation day and any other time to be measured on the same day;

[0008] Convert the arbitrary time to the time to be measured and reported into a measurement time sequence number and a measurement time sequence number;

[0009] Based on the measurement time sequence number, the moisture content change rate of the dead combustibles is calculated through the fitting curve model of the moisture content change rate of the dead combustibles to obtain the moisture content change rate of the dead combustibles at the measurement time;

[0010] Based on the change rate of moisture content of dead combustibles at the time of measurement, the moisture content of dead combustibles at the initial time of the measurement day is calculated;

[0011] Based on the measurement and reporting time sequence number, the moisture content change rate of dead combustibles is calculated through the fitting curve model, and the moisture content change rate of dead combustibles at the time to be measured and reported is obtained.

[0012] Based on the change rate of moisture content of dead combustibles at the time of measurement and reporting and the moisture content of dead combustibles at the initial time of the measurement and reporting day, the moisture content of dead combustibles at the time to be measured and reported during the measurement and reporting day change is obtained.

[0013] Optionally, the types of dead fuel include twigs, twigs, shrubs, and humus.

[0014] Optionally, the process of obtaining the measurement time sequence number and the measurement and reporting time sequence number includes:

[0015] Get the initial time, the latest time and the time interval; subtract the initial time from the arbitrary time and the time to be measured and reported, and take the approximation to get the corresponding approximate hour value; divide the corresponding approximate hour value by the ratio of the time interval to one hour, and then add 1 to get the measurement time number and the measurement time number.

[0016] Optionally, a cubic polynomial model is used as a fitting curve model for the moisture content change rate of dead combustibles, which is obtained by fitting historical data.

[0017] Optionally, the fitting curve model of the moisture content change rate of dead combustibles is:

[0018] f_cz(x)=-1.373-0.667x-0.046x 2 +0.002x 3

[0019] f_xz(x)=-4.611+1.394x-0.345x 2 +0.011x 3

[0020] f_gc(x)=-7.256+0.074x-0.3x 2 +0.011x 3

[0021] f_fzz(x)=1.15-2.244x-0.232x 2 +0.01x 3

[0022] Among them, f_cz(x), f_xz(x), f_gc(x), and f_fzz(x) are the fitting models of the change rate of moisture content of coarse branches, thin branches, shrubs and humus, respectively. The corresponding values ​​are the change rates of moisture content, and x is the time sequence number.

[0023] Optionally, the process of calculating the moisture content of dead combustibles at the initial time of the observation day includes:

[0024] The moisture content of the dead combustibles at the initial moment of the measurement day is obtained by dividing the change rate of the moisture content of the dead combustibles at the measurement time by 1 and adding the sum of the change rate of the moisture content of the dead combustibles at the measurement time.

[0025] Optionally, the process of obtaining the moisture content of dead combustibles at the time of testing and reporting includes:

[0026] Calculate the product of the change rate of the moisture content of the dead combustibles at the time to be measured and reported and the moisture content of the dead combustibles at the initial moment of the measurement and reporting day, and sum the product result with the moisture content of the dead combustibles at the initial moment of the measurement and reporting day to obtain the moisture content of the dead combustibles at the time to be measured and reported.

[0027] In order to better achieve the above technical objectives, the present invention also provides a dry season forest dead combustible moisture content daily change monitoring system for executing the above method.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] The present invention can predict the daily change of moisture content of dead combustibles in forests on a time scale, support the time-scale spatiotemporal monitoring and reporting of forest fire risk levels, and provide forest fire prevention departments and industries with time-scale forest fire prevention auxiliary decision-making at a low investment cost during the fire prevention period. The present invention can directly support the increase of the time scale of forest fire risk monitoring and reporting in the fire prevention period in the central Yunnan region of Yunnan Province to once every 30 minutes.

[0030] Considering the time scale, cost and scientificity, the technology proposed in the present invention is more suitable for the monitoring and reporting of the moisture content of dead combustible materials in forests under the latest drought meteorological conditions. It can effectively support the improvement of real-time forest fire monitoring and early warning technology, increase the time interval for fire risk monitoring and reporting, and thus produce significant ecological, social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1 A schematic diagram of a method flow chart of an embodiment of the present invention;

[0033] Figure 2 The fitting curve of the average change rate of moisture content of dead combustibles in coarse branches according to the embodiment of the present invention;

[0034] Figure 3 The fitting curve of the average change rate of moisture content of dead combustibles in twigs of the embodiment of the present invention;

[0035] Figure 4 The fitting curve of the average change rate of moisture content of dead combustibles of shrubs and grasses according to the embodiment of the present invention;

[0036] Figure 5 It is a fitting curve of the average change rate of moisture content of humus dead combustibles in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0039] In view of the above background and the urgent needs of forest fire prevention, the present invention proposes a method and system for measuring and reporting the daily variation of moisture content of dead combustibles in dry season forests using the sample data of moisture content of dead combustibles measured in real time in the main forest fire prevention key areas in central Yunnan (time range: 8:30-17:30; time interval: 30 minutes). According to the present invention, the time scale of moisture content of dead combustibles can be quickly measured and reported for fire prevention management departments and industries during the fire prevention period at a relatively low cost, supporting the real-time measurement and reporting of forest fire risks in dry seasons.

[0040] In the technical solution of the present invention, for the current day when the moisture content needs to be measured, i.e. the monitoring day, the moisture content of the dead combustibles at any time (observation time) in the monitoring day is used as the basis, combined with the fitting curve model of the moisture content change rate of the dead combustibles, the moisture content of the dead combustibles at the initial moment of the current day is calculated, and the moisture content of the dead combustibles at the initial moment is used as the basis for the moisture content that may change at different monitoring moments in the monitoring day, and is again combined with the fitting curve model of the moisture content change rate of the dead combustibles to invert the moisture content at different monitoring moments.

[0041] In the technical solution of the present invention, the sample value of the moisture content fitting curve represents the rate of change of the moisture content of dead combustibles at all times of the day under the average level relative to the first moment of the day, which is obtained by averaging multiple continuous observations in real geographical scenes. The observation data required for the measurement and reporting day is the data observed at a certain moment of the day in the real geographical scene. The perturbation of the day's average level (the moisture content of dead combustibles at the initial moment) can be obtained through the observable data at that moment of the measurement and reporting day. Assuming that the perturbation is fixed on the day and changes with time, the moisture content of combustibles at other moments that need to be measured and reported on the measurement and reporting day is measured and reported by the moisture content value of the combustibles at the daily average level and its rate of change with time, and the perturbation at other moments is measured and reported, and then the moisture content at other moments is calculated. The complex changes of the moisture content of dead combustibles on different days and months are expressed as perturbations through the values ​​of the observation moment of the measurement and reporting day. Therefore, the present invention can provide an effective solution for the measurement and reporting of moisture content of dead combustibles with a small error and low cost.

[0042] And it can better fit the real geographical scene and the current day's space and time requirements, and the moisture content change rate fitting curve model of dead combustibles is mainly a fitting curve of the moisture content change rate at different times of the day under the current real geographical scene. For the same real geographical scene, due to the limitations of environmental factors and geographical factors of the same real geographical scene, the fitting curve of the moisture content change rate in a day will not change significantly due to the changes in the time of different days and months, and can reflect the changes in its change rate in a day. Therefore, the present invention can provide an effective solution for the measurement and reporting of moisture content of dead combustibles with smaller errors and low costs.

[0043] Embodiment 1

[0044] The present invention proposes a method for measuring and reporting daily changes in moisture content of dead forest combustibles in dry seasons, which can predict the moisture content at other times of the same day at intervals of 30 minutes based on the observed moisture content of dead forest combustibles at a certain time in a forest area during the dry season.

[0045] like Figure 1 As shown, taking the central Yunnan region of Yunnan Province as an example, this embodiment provides a method for measuring and reporting daily changes in moisture content of dead forest combustibles in a dry season, including:

[0046] S01. Obtain the observed value of moisture content of dead combustibles at sparse sampling points at any time during the day (measurement day).

[0047] For the four types of forest dead fuel, namely, thick branches, thin branches, shrubs and grasses, and humus, the observed values ​​of moisture content of thick branches, thin branches, shrubs and grasses, and humus at any time t1 in the forest area during the day were obtained.

[0048] S02. Convert the above arbitrary time, i.e. the observation time, into a measurement time sequence number, and convert any other time to be measured and reported on the same day into a measurement time sequence number.

[0049] The approximate hour value of any time t1 and the time to be measured and reported t2 minus 8:00 is divided by 0.5, and then added by 1 to obtain the converted measurement time number and measurement time number, which are recorded as i and j respectively.

[0050] The observed values ​​of moisture content of coarse branches, fine branches, shrubs and humus at any time t1 during the day are recorded as W_cz_i, W_xz_i, W_gc_i, and W_fzz_i; the observed values ​​of moisture content of coarse branches, fine branches, shrubs and humus at the daytime measurement time t2 are recorded as W_cz_j, W_xz_j, W_gc_j, and W_fzz_j, where 1 <i<22,1<j<22。

[0051] The minimum value of the measurement time sequence number i is 1, that is, the initial time, which is 8:00 in the morning; the measurement time sequence number j reaches its maximum before the sun sets; the present invention limits the latest time to be measured and reported during the day to 19:00, so the maximum value of the measurement time sequence number j is 22.

[0052] S03. Calculate the rate of change of moisture content of thick branches, thin branches, shrubs and humus during the measurement period.

[0053] Substitute the converted measurement time sequence number i into the fitting curve model of the change rate of moisture content of thick branches, thin branches, shrubs and humus during the daytime in the dry season f_cz(x) = -1.373-0.667x-0.046x 2 +0.002x 3 , f_xz(x)=-4.611+1.394x-0.345x 2 +0.011x 3 , f_gc(x)=-7.256+0.074x-0.3x 2 +0.011x 3 , f_fzz(x)=1.15-2.244x-0.232x 2 +0.01x 3 , where x is the time sequence number, calculate the change rate of moisture content of thick branches, thin branches, shrubs and humus at the measurement time f_cz(i), f_xz(i), f_gc(i), f_fzz(i).

[0054] S04. Calculate the moisture content of coarse branches, fine branches, shrubs and humus at the initial moment of the monitoring day.

[0055] The moisture contents of coarse branches, fine branches, shrubs and humus W_cz_i, W_xz_i, W_gc_i, and W_fzz_i observed at the measurement time sequence i are divided by 1+f_cz(i), 1+f_xz(i), 1+f_gc(i), and 1+f_fzz(i), respectively, to obtain the moisture contents of coarse branches, fine branches, shrubs and humus W_cz_0, W_xz_0, W_gc_0, and W_fzz_0 at the initial moment of the measurement day.

[0056] S05, calculating the change in the moisture content of coarse branches, thin branches, shrubs and humus at the time of measurement and reporting compared with the initial time of the measurement and reporting day.

[0057] Substitute the measurement time sequence number j into the fitting curve model f_cz(x), f_xz(x), f_gc(x), f_fzz(x) of the change rate of moisture content of coarse branches, fine branches, shrubs and humus during the daytime in the dry season described in step S03, and calculate the change rate of moisture content of coarse branches, fine branches, shrubs and humus at the jth time relative to the initial time f_cz(j), f_xz(j), f_gc(j), f_fzz(j);

[0058] Multiply the change rates f_cz(j), f_xz(j), f_gc(j), and f_fzz(j) by the moisture contents of coarse branches, fine branches, shrubs, and humus W_cz_0, W_xz_0, W_gc_0, and W_fzz_0 at the initial moment of the reporting day obtained in step S04, respectively, to obtain the change in the moisture contents of coarse branches, fine branches, shrubs, and humus at the reporting moment compared with the initial moment of the day, recorded as ΔW_cz, ΔW_xz, ΔW_gc, and ΔW_fzz.

[0059] S06. Calculate the moisture content of coarse branches, fine branches, shrubs and humus at the time of testing.

[0060] Add the changes in the moisture content of coarse branches, fine branches, shrubs and humus at the time of reporting in step S05 compared with the initial time of the day ΔW_cz, ΔW_xz, ΔW_gc, ΔW_fzz to the moisture content of coarse branches, fine branches, shrubs and humus W_cz_0, W_xz_0, W_gc_0, W_fzz_0 at the initial time of the reporting day in step S04 to obtain the moisture content of coarse branches, fine branches, shrubs and humus at the time of reporting, which are recorded as W_cz_j, W_xz_j, W_gc_j, W_fzz_j.

[0061] The above technical solution is described in detail as follows:

[0062] S01. Obtain the observed values ​​of moisture content of dead fuel at sparse sample points at any time during the day. For the four types of forest dead fuel, namely, coarse branches, fine branches, shrubs and grasses, and humus, obtain the observed values ​​of moisture content of coarse branches, fine branches, shrubs and grasses, and humus at any time t1 in the forest area during the day, recorded as W_cz_t1, W_xz_t2, W_gc_t3, and W_fzz_t4.

[0063] Optionally, the steps for obtaining the observed values ​​of moisture content of dead combustibles at sparse sampling points at any time during the day are:

[0064] Four types of forest dead combustible samples, including thick branches, thin branches, shrubs and grass, and humus, were collected in the field. Among them, dry branches on the ground with a radius greater than 0.3mm were coarse branch dead combustibles, dry branches on the ground with a radius less than 0.3mm were twig dead combustibles, dry shrubs and herbs on the surface were shrub and grass dead combustibles, and rotten dead combustibles on the surface were humus dead combustibles.

[0065] Weigh and measure in the field and then bag the samples to obtain the wet weight;

[0066] The samples were dried in an indoor drying oven and then measured to obtain the dry weight of the samples;

[0067] The observed value of moisture content of the dead combustible material is obtained according to the moisture content calculation formula commonly used in the forest fire prevention industry.

[0068] S02, convert the above observation time into a measurement time sequence number, and convert the time to be measured and reported into a measurement time sequence number. Divide the approximate hour value of the arbitrary time t1 point and the measurement and reporting time t2 point minus 8:00 by 0.5, then add 1, and obtain the converted measurement time and measurement and reporting time sequence numbers, which are recorded as i and j respectively.

[0069] The observed values ​​of moisture content of coarse branches, fine branches, shrubs and humus at any time t1 during the day are recorded as W_cz_i, W_xz_i, W_gc_i, and W_fzz_i; the observed values ​​of moisture content of coarse branches, fine branches, shrubs and humus at the daytime measurement time t2 are recorded as W_cz_j, W_xz_j, W_gc_j, and W_fzz_j, where 1 <i<22,1<j<22。

[0070] The minimum value of the measurement time sequence number i is 1, that is, the initial time, which is 8:00 in the morning; the measurement time sequence number j reaches its maximum before the sun sets; the present invention limits the latest time to be measured and reported during the day to 19:00, so the maximum value of the measurement time sequence number j is 22.

[0071] S03. Calculate the rate of change of moisture content of thick branches, thin branches, shrubs and humus at the time of measurement.

[0072] The measurement time sequence number is substituted into the fitting curve model of the change rate of the moisture content of coarse branches, fine branches, shrubs and humus during the daytime in the dry season. The change rates of the moisture content of coarse branches, fine branches, shrubs and humus at the measurement time are calculated, f_cz(i), f_xz(i), f_gc(i), f_fzz(i), where x is the time sequence number.

[0073] Optionally, the acquisition process of the curve fitting models f_cz(x), f_xz(x), f_gc(x), and f_fzz(x) of the moisture content change rate of coarse branches, thin branches, shrubs, and humus during the dry season is as follows:

[0074] At multiple sampling points set up in key forest areas, samples of moisture content of coarse branches, fine branches, shrubs, grass, humus and dead fuel were collected every 30 minutes between 8:00 and 19:00.

[0075] Assume 8:00 as the first moment, 8:30 as the second moment, ..., 19:00 as the 22nd moment, with 30 minutes as the interval, the moment number as the independent variable, and the change rate of the moisture content of coarse branches, fine branches, shrubs and grasses, and humus fuel relative to 8:00 as the dependent variable. Use the conventional mathematical statistics fitting method to fit the fitting curve of the change rate of moisture content of coarse branches, fine branches, shrubs and grasses, and humus during the daytime in the dry season, as shown in Figure 2-5 shown.

[0076] According to the sample data, the cubic polynomial model was used to fit the fitting curve of the change rate of moisture content of coarse branches, fine branches, shrubs and humus during the daytime in central Yunnan during the dry season, and the fitting models of the change rate of moisture content of coarse branches, fine branches, shrubs and humus f_cz(x), f_xz(x), f_gc(x), and f_fzz(x) were obtained respectively:

[0077] f_cz(x)=-1.373-0.667x-0.046x 2 +0.002x 3

[0078] f_xz(x)=-4.611+1.394x-0.345x 2 +0.011x 3

[0079] f_gc(x)=-7.256+0.074x-0.3x 2 +0.011x 3

[0080] f_fzz(x)=1.15-2.244x-0.232x 2 +0.01x 3

[0081] After statistical testing, the independent variables and dependent variables of the above models are highly correlated and the equations all pass the F significance test (at the P = 0.05 level). The R value of the coarse branch moisture content change rate curve fitting model f_cz(x) is 2 =0.72, F=37.11>F(1,517)=3.86; R of the twig moisture content change rate curve fitting model f_xz(x) 2 =0.77, F=45.02>F(1,751)=3.85; R of the curve fitting model f_gc(x) for the change rate of shrub and grass moisture content 2 =0.80, F=55.40>F(1,705)=3.85; R of the humus moisture content change rate curve fitting model f_fzz(x) 2 =0.81, F=59.18>F(1,636)=3.86.

[0082] S04, calculate the moisture content of coarse branches, fine branches, shrubs and humus at the initial moment of the measurement day. Divide the moisture content of coarse branches, fine branches, shrubs and humus W_cz_i, W_xz_i, W_gc_i, W_fzz_i observed at the measurement time i by 1+f_cz(i), 1+f_xz(i), 1+f_gc(i), 1+f_fzz(i), respectively, to obtain the moisture content of coarse branches, fine branches, shrubs and humus W_cz_0, W_xz_0, W_gc_0, W_fzz_0 at the initial moment.

[0083] In the above process, the moisture content and change rate are converted to floating-point data types with an accuracy of 2 decimal places.

[0084] S05. Calculate the change in the moisture content of coarse branches, fine branches, shrubs and humus at the time of the measurement and reporting compared with the initial time of the measurement and reporting day. Substitute the measurement and reporting time serial number j into the fitting curve model of the change rate of the moisture content of coarse branches, fine branches, shrubs and humus during the daytime in the dry season f_cz(x), f_xz(x), f_gc(x), f_fzz(x), calculate the change rate of the moisture content of coarse branches, fine branches, shrubs and humus at the jth time relative to the initial time f_cz(j), f_xz(j), f_gc(j), f_fzz(j); substitute the above-mentioned change rate f_cz( j), f_xz(j), f_gc(j), f_fzz(j) are respectively multiplied by the moisture contents of coarse branches, fine branches, shrubs and humus W_cz_0, W_xz_0, W_gc_0, W_fzz_0 at the initial moment obtained by S02 to obtain the changes ΔW_cz, ΔW_xz, ΔW_gc, ΔW_fzz in the moisture contents of coarse branches, fine branches, shrubs and humus at the measuring time of the measuring day compared with the initial moment of the day.

[0085] S06, calculate the moisture content of coarse branches, fine branches, shrubs and humus at the time to be measured. Add the change ΔW_cz, ΔW_xz, ΔW_gc, ΔW_fzz of the moisture content of coarse branches, fine branches, shrubs and humus at the time to be measured on the measurement day compared with the initial time of the day to the moisture content of coarse branches, fine branches, shrubs and humus W_cz_0, W_xz_0, W_gc_0, W_fzz_0 of coarse branches, fine branches, shrubs and humus at the initial time of the measurement day to obtain the moisture content W_cz_j, W_xz_j, W_gc_j of coarse branches, fine branches, shrubs and humus at the time to be measured corresponding to the measurement time sequence number j.

[0086] Embodiment 2

[0087] The present invention also provides a dry season forest dead combustible daily change monitoring and reporting system, the system includes: a forest dead combustible moisture content observation data acquisition module, a forest dead combustible moisture content observation time and measurement time conversion module, a forest dead combustible moisture content change rate calculation module at the measurement time, a forest dead combustible moisture content calculation module at the initial time of the measurement day, a forest dead combustible moisture content change calculation module compared with the initial time at the measurement time, and a forest dead combustible moisture content calculation module at the measurement time.

[0088] The forest dead fuel moisture content observation data acquisition module is used to obtain the moisture content data of four types of forest dead fuels, namely, coarse branches, fine branches, shrubs and grasses, and humus, observed at the time of observation.

[0089] The module for converting the observation time and reporting time of the moisture content of dead forest fuel is used to convert any observation time and reporting time from 8:00 to 19:00 during the day into observation time sequence numbers and reporting time sequence numbers at intervals of 30 minutes.

[0090] The module for calculating the change rate of moisture content of dead forest combustibles at the time of measurement is used to fit a curve model according to the change rate of moisture content of coarse branches, fine branches, shrubs and humus of dead forest combustibles, and obtain the change rate of moisture content of coarse branches, fine branches, shrubs and humus at the time of observation.

[0091] The calculation module of the moisture content of dead forest combustibles at the initial moment of the observation day is used to calculate the moisture content of coarse branches, fine branches, shrubs and grasses, and humus at the initial moment of the observation day. The moisture content of the four types of dead forest combustibles, namely, coarse branches, fine branches, shrubs and grasses, and humus, observed at the observation moment is divided by the sum of the change rate of the moisture content of the coarse branches, fine branches, shrubs and grasses, and humus at the observation moment and 1, to obtain the moisture content of coarse branches, fine branches, shrubs and grasses, and humus at the initial moment of the observation day.

[0092] The calculation module of the change in moisture content of dead forest combustibles at the time of measurement and reporting compared with the initial time is used to calculate the change in moisture content of coarse branches, fine branches, shrubs and grasses, and humus at the time of measurement and reporting compared with the initial time. Substitute the measurement and reporting time into the fitting curve model of the moisture content change rate of coarse branches, fine branches, shrubs and grasses, and humus during the daytime in the dry season f_cz(x), f_xz(x), f_gc(x), f_fzz(x), calculate the change rate of moisture content of coarse branches, fine branches, shrubs and grasses, and humus at the time to be measured and reported relative to the initial time; multiply the aforementioned change rate by the moisture content of coarse branches, fine branches, shrubs and grasses, and humus at the aforementioned initial time, and obtain the change in moisture content of coarse branches, fine branches, shrubs and grasses, and humus at the measurement and reporting time of the measurement and reporting day compared with the initial time of the day.

[0093] The forest dead combustible moisture content calculation module at the measurement time is used to add the moisture content of coarse branches, fine branches, shrubs and humus at the initial time of the measurement day to the change in the moisture content of coarse branches, fine branches, shrubs and humus at the measurement time compared with the initial time of the day, and calculate the moisture content of coarse branches, fine branches, shrubs and humus in the forest dead combustibles to be measured at the time to be measured.

[0094] The specific process of the system corresponds to the method content in the above-mentioned embodiment 1, and will not be repeated here.

[0095] Experimental example

[0096] 20 sample points were randomly selected in the key forest areas of Qujing, Yuxi, Chuxiong and Kunming in central Yunnan, and the moisture content of combustibles measured on the spot from 11:01 to 11:30 was used as an example to measure the moisture content of combustibles from 11:31 to 12:00. The central Yunnan region is located in the central and eastern part of Yunnan Province, in the plateau basin of eastern Yunnan, at 100°43′E-104°50′E, 23°19′E-27°03′N, and mainly includes Kunming, Qujing, Yuxi and Chuxiong. In recent years, rainfall in central Yunnan has decreased, the dry season has been extended, and the forest fire prevention situation is severe. Carrying out near-real-time measurement and reporting of the moisture content of combustibles is an important part of achieving near-real-time forest fire risk measurement and reporting during the fire prevention period in the area.

[0097] Taking 11:01-11:30 as the measurement time, the moisture content values ​​of four dead combustibles, namely, thick branches, thin branches, shrubs and grasses, and humus, observed at this time as the source data, and 11:31-12:00 as the prediction time, the process of measuring and reporting the moisture content of thick branches, thin branches, shrubs and grasses, and humus at this time and the error test are as follows:

[0098] (1) Obtaining the observed moisture content of dead combustibles at sparse sampling points

[0099] Four types of forest dead fuel, namely coarse branches, fine branches, shrubs and grasses, and humus, were collected at 11:01-11:30 respectively. After wet weight measurement and sample drying to measure dry weight, the observed values ​​of moisture content of coarse branches, fine branches, shrubs and grasses, and humus at 11:31-12:00 during the day in the forest area (unit: %) were calculated, as shown in Table 1.

[0100] Table 1

[0101]

[0102] (2) Convert the observation time and the measurement time into the measurement time and measurement time.

[0103] According to the approximate hour value of the first moment 11:01-11:30 minus 8:00, divided by 0.5, and then added 1, the converted measurement time and measurement time sequence number are obtained, which is 8 time. Similarly, 11:31-12:00 is 9 time. In this embodiment, the observations of the moisture content of coarse branches, fine branches, shrubs and grasses, and humus at the measurement time are recorded as W_cz_8, W_xz_8, W_gc_8, and W_fzz_8; the observations of the moisture content of coarse branches, fine branches, shrubs and grasses, and humus at the measurement time are recorded as W_cz_9, W_xz_9, W_gc_9, and W_fzz_9.

[0104] (3) Calculate the change rate of moisture content of thick branches, thin branches, shrubs, and humus at the time of measurement

[0105] Substitute the observation time, i.e. the serial number of the 8 time points, into the fitting model f_cz(x) of the moisture content change rate of coarse branches. When i=8, f_cz(8)=-1.373-0.667×8-0.046×8 2 +0.002×8 3 =-8.63, and the moisture content change rate of the coarse branches at the 8th observation time is -8.63%; similarly, substituting into f_xz(x), when i=8, f_xz(8)=-4.611+1.394×8-0.345×8 2 +0.011×8 3 = -9.91, and the change rate of twig moisture content at the 8th observation time is -9.91%; Substituting into f_gc(x), when i=8, f_gc(8)=-7.256+0.074×8-0.3×8 2 +0.011×8 3 = -20.23, and the moisture content change rate of the shrub at the 8th observation time is -20.23%; Substituting into f_fzz(x), when i=8, f_fzz(8)=1.15-2.244×8-0.232×8 2 +0.01×8 3=-26.53, and the change rate of humus moisture content at the 8th observation time is -26.53%.

[0106] (4) Calculate the moisture content of coarse branches, fine branches, shrubs, and humus at the initial time of the forecast day

[0107] Calculate the sum of the change rate of the moisture content of coarse branches, fine branches, shrubs and humus at the measuring moment and 1, then 1+f_xz(8)=0.9137, 1+f_cz(8)=0.9090, 1+f_gc(8)=0.7977, 1+f_fzz(8)=0.7347; divide the moisture contents of coarse branches, fine branches, shrubs and humus W_cz_8, W_xz_8, W_gc_8, W_fzz_8 (specific values ​​are shown in Table 1) observed at the 8 moments by the above 0.9137, 0.9090, 0.7977, 0.7347, respectively, to obtain the moisture contents of coarse branches, fine branches, shrubs and humus W_cz_0, W_xz_0, W_gc_0, W_fzz_0 at the initial moment of the measurement day. The moisture content (unit: %) of coarse branches, fine branches, shrubs and humus at the initial time of the measurement day at the 20 sample points of Example 1 is shown in Table 2 below.

[0108] Table 2

[0109]

[0110]

[0111] (5) Calculate the change in moisture content of coarse branches, fine branches, shrubs, and humus at the time of the measurement compared to the initial time of the measurement day

[0112] Substitute the measurement time 9 into the fitting curve model of the change rate of moisture content of coarse branches, fine branches, shrubs and humus during the daytime in the dry season in central Yunnan f_cz(x) = -1.373-0.667x-0.046x 2 +0.002x 3 , f_xz(x)=-4.611+1.394x-0.345x 2 +0.011x 3 , f_gc(x)=-7.256+0.074x-0.3x 2 +0.011x 3 , f_fzz(x)=1.15-2.244x-0.232x 2 +0.01x 3, calculate the change rate of the moisture content of coarse branches, fine branches, shrubs and humus at the 9th moment f_cz(9), f_xz(9), f_gc(9), f_fzz(9), and get f_cz(9) = -0.0964, f_xz(9) = -0.1199, f_gc(9) = -0.2287, f_fzz(9) = -0.3055; the above coarse branches, fine branches, shrubs and humus moisture content at the 9th moment The change rate at each moment is multiplied by the moisture content of coarse branches, fine branches, shrubs and humus W_cz_0, W_xz_0, W_gc_0, W_fzz_0 at the initial moment obtained in step (4) to obtain the change in moisture content of coarse branches, fine branches, shrubs and humus at the measuring moment of the measuring day compared with the initial moment of the day ΔW_cz, ΔW_xz, ΔW_gc, ΔW_fzz (unit: %). The calculation results are shown in Table 3 below.

[0113] Table 3

[0114]

[0115]

[0116] (6) Calculate the moisture content of coarse branches, fine branches, shrubs, and humus at the time of measurement

[0117] The changes in the moisture content of coarse branches, fine branches, shrubs and humus at the 9th moment, i.e., j=9, ΔW_cz, ΔW_xz, ΔW_gc, ΔW_fzz compared with the initial moment of the day are added to the moisture content of coarse branches, fine branches, shrubs and humus W_cz_0, W_xz_0, W_gc_0, W_fzz_0 at the initial moment of the measurement day, to obtain the moisture content of coarse branches, fine branches, shrubs and humus W_cz_9, W_xz_9, W_gc_9, W_fzz_9 (unit: %) at the measurement moment 9. The results are shown in Table 4 below

[0118] Table 4

[0119]

[0120] (7) Error check

[0121] The error analysis was performed by taking the reported moisture content of coarse branches, fine branches, shrubs and humus at the 9th moment as the reported value and the actual observed moisture content of coarse branches, fine branches, shrubs and humus at the 9th moment as the measured value. According to the conventional method of statistical analysis error test, the reported error (unit: %) of the moisture content of coarse branches, fine branches, shrubs and humus was calculated, as shown in Table 5. According to Table 5, the average absolute error of the reported moisture content of coarse branches, fine branches, shrubs and humus was 0.25%, 0.62%, 0.72%, and 1.36%, respectively; the average RMSE of the reported moisture content of coarse branches, fine branches, shrubs and humus was 0.36%, 1.50%, 1.00%, and 2.42%, respectively. The error test results show that the error of the reported results is small and the reported results are accurate and reliable.

[0122] Table 5

[0123]

[0124] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for measuring and reporting daily changes in moisture content of dead fuel in forests during the dry season, characterized in that: include: Obtain the observed value of moisture content of dead combustibles at any time during the observation and reporting day and any other time to be measured and reported on the same day; Convert the arbitrary time to the time to be measured and reported into a measurement time sequence number and a measurement time sequence number; Based on the measurement time sequence number, the moisture content change rate of the dead combustibles is calculated through the fitting curve model of the moisture content change rate of the dead combustibles to obtain the moisture content change rate of the dead combustibles at the measurement time; Based on the change rate of moisture content of dead combustibles at the time of measurement, the moisture content of dead combustibles at the initial time of the measurement day is calculated; Based on the measurement and reporting time sequence number, the moisture content change rate of dead combustibles is calculated through the fitting curve model, and the moisture content change rate of dead combustibles at the time to be measured and reported is obtained. Based on the change rate of moisture content of dead combustibles at the time of measurement and reporting and the moisture content of dead combustibles at the initial time of the measurement and reporting day, the moisture content of dead combustibles at the time to be measured and reported during the measurement and reporting day change is obtained.

2. The method according to claim 1, characterized in that The types of dead combustibles include thick branches, thin branches, shrubs, and humus.

3. The method according to claim 1, characterized in that The process of obtaining the measurement time sequence number and the measurement and reporting time sequence number includes: Get the initial time, the latest time and the time interval; subtract the initial time from the arbitrary time and the time to be measured and reported, and take the approximation to get the corresponding approximate hour value; divide the corresponding approximate hour value by the ratio of the time interval to one hour, and then add 1 to get the measurement time number and the measurement time number.

4. The method according to claim 1, characterized in that: The fitting curve model of the moisture content change rate of dead combustibles adopts a cubic polynomial model, which is obtained by fitting historical data.

5. The method according to claim 2, characterized in that: The fitting curve model of the moisture content change rate of dead combustibles is: f_cz(x)=-1.373-0.667x-0.046x 2 +0.002x 3 f_xz(x)=-4.611+1.394x-0.345x 2 +0.011x 3 f_gc(x)=-7.256+0.074x-0.3x 2 +0.011x 3 f_fzz(x)=1.15-2.244x-0.232x 2 +0.01x 3 Among them, f_cz(x), f_xz(x), f_gc(x), and f_fzz(x) are the fitting models of the change rate of moisture content of coarse branches, thin branches, shrubs and humus, respectively. The corresponding values ​​are the change rates of moisture content, and x is the time sequence number.

6. The method according to claim 1, characterized in that The process of calculating the moisture content of dead combustibles at the initial time of the forecast day includes: The moisture content of the dead combustibles at the initial moment of the measurement day is obtained by dividing the change rate of the moisture content of the dead combustibles at the measurement time by 1 and adding the sum of the change rate of the moisture content of the dead combustibles at the measurement time.

7. The method according to claim 1, characterized in that The process of obtaining the moisture content of dead combustibles at the time of testing includes: Calculate the product of the change rate of the moisture content of the dead combustibles at the time to be measured and reported and the moisture content of the dead combustibles at the initial moment of the measurement and reporting day, and sum the product result with the moisture content of the dead combustibles at the initial moment of the measurement and reporting day to obtain the moisture content of the dead combustibles at the time to be measured and reported.

8. A system for measuring and reporting daily changes in moisture content of dead fuel in forests during the dry season, characterized in that: Used to execute the method according to any one of claims 1 to 7.

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