A method for monitoring and predicting soil and water loss in small watersheds

Abstract

The invention relates to the technical field of soil and water monitoring, and discloses a method for monitoring and predicting soil and water loss in a small watershed. The method can predict the amount of soil erosion through an established general mathematical model, and provide data support for the implementation of soil and water loss prevention and control work. A collecting device and a data acquisition device are arranged in a selected monitoring field, the collecting device can collect slope runoff to the same outlet, the data acquisition device can respectively collect rainfall and suspended mass, and manual weighing can obtain displacement mass data. Multiple groups of erosion data can be obtained by collecting rainfall, suspended mass and displacement mass within a period of time, and a data correlation analysis method is used to perform curve fitting on multiple groups of erosion data to obtain a general mathematical model. The general mathematical model can predict the amount of soil loss within the rainfall period through the rainfall and suspended mass collected by the data acquisition device, and is conducive to formulating corresponding soil and water loss prevention and control measures according to different situations.

Description

Technical Field

[0001] The invention relates to the technical field of soil and water monitoring, and in particular to a method for monitoring and predicting soil and water loss in a small watershed. Background Art

[0002] Soil erosion refers to the phenomenon that due to natural or human factors, rainwater cannot be absorbed locally, flows down and washes the soil, causing the loss of both water and soil. The main causes of soil erosion are large ground slopes, improper land use, destruction of ground vegetation, unreasonable farming techniques, loose soil, deforestation, overgrazing, etc. Sloping farmland in a small watershed refers to farmland with a certain slope located within a small watershed. This type of farmland usually faces a higher risk of soil erosion because surface runoff and soil erosion are often more serious than on flat land. The management and protection of sloping farmland in a small watershed is of great significance to maintaining the local ecological environment, ensuring agricultural production, and promoting sustainable development.

[0003] At present, soil and water loss monitoring in small watersheds is still mainly based on manual monitoring, which is time-consuming and labor-intensive, has poor reliability, low automation level, and cannot continuously monitor soil and water loss. Therefore, the present invention proposes a method for monitoring and predicting soil and water loss in small watersheds, which can estimate the amount of soil erosion in small watersheds in real time through the automatically monitored suspended mass and rainfall, reduce the inconvenience caused by manual regular monitoring, and provide support for the precise implementation of soil and water loss prevention and control work. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for monitoring and predicting soil erosion in a small watershed, so as to solve the problem that manual monitoring of soil erosion in a small watershed is time-consuming and labor-intensive.

[0005] The technical solution proposed by the present invention is:

[0006] A method for monitoring and predicting soil erosion in a small watershed is applied to a system for monitoring and predicting soil erosion in a small watershed; the system comprises a collection device and a data acquisition device; the method comprises:

[0007] Select small watersheds to establish monitoring sites;

[0008] The collecting device and the data acquisition device are arranged in the monitoring field;

[0009] The push mass and the suspended mass under different rainfall amounts in the past first preset time period are obtained by the collection device and the data acquisition device, and the soil erosion amount under different rainfall amounts is calculated based on the push mass and the suspended mass, and multiple sets of erosion data are obtained;

[0010] Using data correlation analysis method, curve fitting is performed on multiple sets of erosion data to obtain a general mathematical model of soil erosion, suspended mass and rainfall.

[0011] Verifying whether the mathematical general model is qualified;

[0012] If qualified, the qualified universal mathematical model is used to predict the soil erosion situation of the monitoring field when rainfall occurs.

[0013] Preferably, the collecting device comprises a drainage ditch, a weir channel, a measuring trough and a sedimentation tank; the drainage ditch is used to guide the surface runoff of the monitoring field to the weir channel; the weir channel and the measuring trough are used to measure the runoff; the sedimentation tank is used to collect bed load; the measuring trough is arranged in the weir channel, and the measuring trough is arranged at the end of the weir channel away from the drainage ditch; the weir channel and the measuring trough share a midline; the end of the measuring trough away from the drainage ditch is connected to the sedimentation tank.

[0014] Preferably, the data acquisition device includes a photoelectric sand meter, a liquid level flow sensor and a rain gauge; the liquid level flow sensor is mounted above the measuring trough and is used to cooperate with the measuring trough to obtain the runoff; the photoelectric sand meter is arranged in the measuring trough and is used to measure the average suspended matter content in the runoff; the rain gauge is used to measure the rainfall.

[0015] Preferably, the collection device and the data acquisition device are used to obtain the displacement mass and the suspended mass under different rainfall amounts in the past first preset time period, and the soil erosion amount under different rainfall amounts is calculated based on the displacement mass and the suspended mass, and multiple sets of erosion data are obtained, including:

[0016] The rainfall period is obtained by the liquid level flow sensor and the measuring tank Runoff volume during the period , the rainfall period is obtained by the photoelectric sand measuring instrument Average suspended matter content of internal flow , and based on the rainfall period Runoff volume during the period , and rainfall periods Average suspended matter content of internal flow Calculate the rainfall period Suspended mass due to internal loss:

[0017] ,

[0018] Where y is the rainfall period The suspended mass of internal loss, Rainy season The runoff volume during the period, Rainy season Average suspended matter content of internal flow;

[0019] Collect the sediment in the sedimentation tank and the measuring tank, weigh the collected sediment, and use the weighed weight as the rainfall period. The quality of internal loss;

[0020] The rainfall period can be calculated by the formula: soil erosion amount = suspended mass + pushed mass The amount of soil erosion within

[0021] The different rainfall periods in the first preset time period in the past The rainfall in different periods of time Suspended mass of internal loss and different rainfall periods The amount of soil erosion within the area is used as the erosion data.

[0022] Preferably, the verifying whether the mathematical general model is qualified comprises:

[0023] The actual soil loss amount of the monitoring field under different rainfall amounts in the past second preset time period is obtained by using the rod measurement method, and the predicted soil erosion amount under different rainfall amounts in the past second preset time period is obtained based on the general mathematical model;

[0024] Obtaining the difference between the actual soil loss amount and the predicted soil erosion amount under the same rainfall amount, and obtaining the ratio of the difference to the actual soil loss amount, and determining whether the ratio is less than a preset value;

[0025] If it is less than the preset value, it is determined that the mathematical general model is qualified.

[0026] Preferably, the method of obtaining the actual soil loss amount of the monitoring field under different rainfall amounts in the past second preset time period by using the rod measuring method, and obtaining the predicted soil erosion amount under different rainfall amounts in the past second preset time period based on the general mathematical model, comprises:

[0027] Dividing the monitoring site into a number of different sub-areas according to soil properties;

[0028] Get the area of ​​each sub-region and the soil density of each sub-area ;

[0029] In each sub-area, a plurality of measuring rods perpendicular to the ground are evenly inserted and arranged in a herringbone shape, and the initial reading of each measuring rod is recorded, wherein the insertion depth of the measuring rods in different sub-areas is different, and the top of the measuring rod is higher than the ground;

[0030] After the rain, the final reading of each measuring rod is read, and the difference between the initial reading and the final reading is used as the soil erosion thickness of the corresponding sub-area. ;

[0031] The soil erosion amount of each sub-area is calculated according to the soil erosion amount calculation formula of the rod measurement method: ,

[0032] In the formula, For the The amount of soil erosion in each sub-region, For the Soil erosion thickness in each sub-area, For the The area of ​​the sub-regions, For the Soil density in each sub-area;

[0033] The actual soil loss of the monitoring site is obtained by adding up the soil erosion amounts of all sub-areas:

[0034] ,

[0035] Where A is the actual soil loss in the monitoring field, For the The soil erosion amount in each sub-region is m, and m is the total number of sub-regions.

[0036] Preferably, the method further comprises obtaining the difference between the actual soil loss amount and the predicted soil erosion amount under the same rainfall amount, obtaining the ratio of the difference to the actual soil loss amount, and judging whether the ratio is less than a preset value, and then further comprising:

[0037] If it is greater than or equal to the preset value, increase the amount of the erosion data, and reselect the curve for fitting to obtain a new mathematical general model, and replace the current mathematical general model with the new mathematical general model;

[0038] Execute the method of using the rod measurement to obtain the actual soil loss amount of the monitoring field under different rainfall amounts in the past second preset time period, and obtain the predicted soil erosion amount under different rainfall amounts in the past second preset time period based on the general mathematical model, and subsequent steps.

[0039] Preferably, the system further comprises a control terminal in communication with the data acquisition device; if qualified, using the qualified universal mathematical model to predict the soil erosion of the monitoring field when rainfall occurs, comprising:

[0040] Obtaining the rainfall and suspended mass corresponding to the current rainfall period through the control terminal;

[0041] The predicted soil erosion amount of this rainfall is calculated based on the rainfall amount and suspended mass corresponding to this rainfall period and the general mathematical model;

[0042] Based on the predicted soil erosion amounts at different rainfall periods in the past third preset time period, the total predicted soil erosion amount in the past third preset time period is calculated.

[0043] When the total predicted soil erosion amount in the past third preset time period is greater than the first preset amount, generating a first warning information through the control terminal;

[0044] When the total predicted soil erosion amount in the past third preset time period is greater than the second preset amount, generating second warning information through the control terminal;

[0045] When the total predicted soil erosion amount in the past third preset time period is greater than the third preset amount, the third warning information is generated by the control terminal.

[0046] Preferably, the measuring trough comprises a contraction section, a throat and a diffusion section; the bottom of the contraction section is inclined downstream, and the bottom of the diffusion section is inclined upstream; the contact between the measuring trough and the weir channel is filled and sealed with concrete; the liquid level flow sensor is installed above the contraction section; and the photoelectric sand meter is arranged at the bottom of the diffusion section.

[0047] Preferably, the rain gauge is arranged at the monitoring field via a bracket, a solar panel is arranged on the bracket, and the rain gauge is electrically connected to the solar panel.

[0048] Through the above technical solution, the following beneficial effects can be achieved:

[0049] The method for monitoring and predicting soil erosion in a small watershed proposed by the present invention can predict the amount of soil erosion through the established general mathematical model, and provide data support for the implementation of soil erosion prevention and control work. In specific application, a collection device and a data acquisition device are set in the selected monitoring field, the collection device can collect the slope runoff to the same outlet, the data acquisition device can collect rainfall and suspended mass respectively, and the displacement mass can be obtained by manual weighing. Multiple groups of erosion data can be obtained by collecting rainfall, suspended mass and displacement mass over a period of time, and multiple groups of erosion data can be curve fitted using the data correlation analysis method to obtain a general mathematical model. The general mathematical model can predict the amount of soil loss in the rainfall period through the rainfall and suspended mass collected by the data acquisition device, so as to formulate corresponding soil erosion prevention and control measures according to different situations; the soil erosion obtained by the rod measurement method is used to verify the general mathematical model, which can improve the accuracy of the general mathematical model. In summary, the method for monitoring and predicting soil erosion in a small watershed proposed by the present invention can solve the problem of time-consuming and labor-intensive manual monitoring of soil erosion in a small watershed, and improve the automation and accuracy of soil erosion monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0051] Figure 1 It is a flowchart of the steps of the method for monitoring and predicting soil erosion in a small watershed of the present invention;

[0052] Figure 2 It is a schematic diagram of the arrangement of the monitoring field of the method for monitoring and predicting soil erosion in a small watershed of the present invention;

[0053] Figure 3 The present invention is a schematic diagram of the arrangement of the probes of the method for monitoring and predicting soil erosion in a small watershed.

[0054] Description of Figure Numbers:

[0055] 1- monitoring field; 2- drainage ditch; 3- weir channel; 4- photoelectric sand meter; 5- level flow sensor; 6- measuring trough; 7- concrete; 8- sedimentation tank; 9- rain gauge; 10- solar panel; 11- bracket; 12- measuring rod.

[0056] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0059] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0060] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0062] The invention provides a method for monitoring and predicting soil erosion in a small watershed.

[0063] Please refer to Figures 1 to 3 In the first embodiment of a method for monitoring and predicting soil and water loss in a small watershed proposed by the present invention, the method is applied to a system for monitoring and predicting soil and water loss in a small watershed; the system includes a collection device and a data acquisition device; the embodiment includes the following steps:

[0064] Step S110: Select a small watershed to establish a monitoring site;

[0065] The selection of the monitoring site should be able to represent the typical characteristics of the entire small watershed (including topography, soil type, vegetation coverage, land use pattern, etc.), and the monitoring site should be able to reflect the soil and water erosion conditions of the entire small watershed.

[0066] In this embodiment, the monitoring field includes at least one small watershed sloping farmland with a natural boundary, and the monitoring field is bounded by the natural boundary of the small watershed sloping farmland.

[0067] Step S120: setting the collection device and the data acquisition device in the monitoring field;

[0068] Specifically, the collecting device can collect the slope runoff in the monitoring field to the same outlet.

[0069] Step S130: obtaining the displacement mass and the suspended mass under different rainfall amounts in the past first preset time period (e.g., one year) through the collection device and the data acquisition device, calculating the soil erosion amount under different rainfall amounts based on the displacement mass and the suspended mass, and obtaining multiple sets of erosion data;

[0070] Specifically, the rainfall and suspended mass can be automatically monitored by the data acquisition device, and the displacement mass can be obtained by manual weighing. The mass of suspended sediment lost in the internal monitoring field and the mass of displacement during a single rainfall period The mass of bed load lost in the internal monitoring field. The erosion data is ,in is the rainfall, is the suspended mass, is the amount of soil erosion, and n is the total number of erosion data.

[0071] Step S140: Use data correlation analysis to perform curve fitting on multiple sets of erosion data to obtain a general mathematical model for soil erosion, suspended mass and rainfall. ;

[0072] Specifically, the data analysis function in Origin software is used to perform curve fitting on the erosion data, or the MATLAB software is used to perform programming fitting on the erosion data. The more erosion data there are, the more general mathematical model In this embodiment, the number of the erosion data is at least 50 groups.

[0073] Step S150: verifying whether the general mathematical model is qualified;

[0074] Specifically, model verification can use internal verification (using remaining data verification) or external verification (using data obtained by another independent method to verify). In this embodiment, in order to improve the credibility of the model and considering that manual weighing and pushing of mass is relatively cumbersome, external verification (such as the rod measurement method) is selected.

[0075] Step S160: If qualified, use the qualified mathematical general model The soil erosion situation of the monitoring site is predicted when rainfall occurs.

[0076] The method for monitoring and predicting soil erosion in a small watershed proposed by the present invention can predict the amount of soil erosion through the established general mathematical model, and provide data support for the implementation of soil erosion prevention and control work. In specific application, a collection device and a data acquisition device are set in the selected monitoring field, the collection device can collect the slope runoff to the same outlet, the data acquisition device can collect rainfall and suspended mass respectively, and the displacement mass can be obtained by manual weighing. Multiple groups of erosion data can be obtained by collecting rainfall, suspended mass and displacement mass over a period of time, and multiple groups of erosion data can be curve fitted using the data correlation analysis method to obtain a general mathematical model. The general mathematical model can predict the amount of soil loss in the rainfall period through the rainfall and suspended mass collected by the data acquisition device, so as to formulate corresponding soil erosion prevention and control measures according to different situations; the soil erosion obtained by the rod measurement method is used to verify the general mathematical model, which can improve the accuracy of the general mathematical model. In summary, the method for monitoring and predicting soil erosion in a small watershed proposed by the present invention can solve the problem of time-consuming and labor-intensive manual monitoring of soil erosion in a small watershed, and improve the automation and accuracy of soil erosion monitoring.

[0077] The present invention also proposes a small watershed soil erosion monitoring and prediction system, which applies a small watershed soil erosion monitoring and prediction method; the system includes a collecting device; the collecting device includes a drainage ditch 2, a weir channel 3, a measuring trough 6 and a sedimentation tank 8; the drainage ditch 2 is used to guide the surface runoff of the monitoring field to the weir channel 3; the weir channel 3 and the measuring trough 6 are used to measure the runoff; the sedimentation tank 8 is used to collect bed load; the measuring trough 6 is arranged in the weir channel 3, and the measuring trough 6 is arranged at the end of the weir channel 3 away from the drainage ditch 2; the weir channel 3 and the measuring trough 6 share a midline; the end of the measuring trough 6 away from the drainage ditch 2 is connected to the sedimentation tank 8.

[0078] Specifically, the drainage ditch 2 is set at the boundary of the sloping farmland in each small watershed; the slope of the drainage ditch 2 is consistent with the slope of the sloping farmland in the small watershed where the drainage ditch 2 is located; the drainage ditch 2 and the weir channel 3 are both cast in concrete; the slope of the weir channel 3 is set according to the average slope of the sloping farmland in each small watershed of the monitoring field; the weir channel 3 and the measuring trough 6 share the same center line so that the water flow does not deviate when entering the measuring trough 6. In one embodiment, the drainage ditch 2 is 0.3 m wide and 0.2 m deep; the weir channel 3 is 0.9 m wide and 0.7 m deep, and the slope is 5%.

[0079] The present invention also proposes a small watershed soil erosion monitoring and prediction system, which applies a small watershed soil erosion monitoring and prediction method; the system also includes a data acquisition device; the data acquisition device includes a photoelectric sand meter 4, a liquid level flow sensor 5 and a rain gauge 9; the liquid level flow sensor 5 is mounted above the measuring trough 6, and is used to cooperate with the measuring trough 6 to obtain the runoff; the photoelectric sand meter 4 is arranged in the measuring trough 6, and is used to measure the average suspended matter content in the runoff; the rain gauge 9 is used to measure the rainfall.

[0080] Specifically, the liquid level flow sensor 5 is used to measure the water level, and the measuring tank 6 provides the basis for flow measurement. The relationship between the water level and the flow is established through its geometric parameters and flow coefficient, and then the runoff is obtained. The measuring tank 6 can be a Parshall tank or a Venturi tank. Taking the Parshall tank as an example: through the formula: ,in is the runoff, is the flow coefficient (determined by the design of the Parshall flume), is the water level height, α is a related index (a fixed value determined by the design of the Parshall flume, usually 1.5-2), and the runoff can be obtained. The liquid level flow sensor 5 is usually connected to a data recorder, which can record and display the measured runoff data. The displacement mass is obtained by collecting and weighing the sediment at the bottom of the measuring trough 6 and the sedimentation tank 8.

[0081] In a second embodiment of a method for monitoring and predicting soil erosion in a small watershed proposed by the present invention, based on the first embodiment, step S130 includes the following steps:

[0082] Step S210: Obtain the rainfall period through the liquid level flow sensor 5 and the measuring tank 6 Runoff volume during the period , the rainfall period is obtained by the photoelectric sand measuring instrument 4 Average suspended matter content of internal flow , and based on the rainfall period Runoff volume during the period , and rainfall periods Average suspended matter content of internal flow Calculate the rainfall period Suspended mass due to internal loss:

[0083] ,

[0084] Where y is the rainfall period The suspended mass of internal loss, Rainy season The runoff volume during the period, Rainy season Average suspended matter content of internal flow;

[0085] Step S220: Collect the sediment in the sedimentation tank 8 and the measuring tank 6, weigh the collected sediment, and use the weighed weight as the rainfall period. The quality of internal loss;

[0086] Step S230: Calculate the rainfall period by the formula: soil erosion amount = suspended mass + pushed mass The amount of soil erosion within

[0087] Step S240: The different rainfall periods in the first preset time period are obtained. The rainfall in different periods of time Suspended mass of internal loss and different rainfall periods The amount of soil erosion within the area is used as the erosion data.

[0088] Specifically, this embodiment provides a specific solution for obtaining multiple sets of erosion data.

[0089] In a third embodiment of a method for monitoring and predicting soil erosion in a small watershed proposed by the present invention, based on the first embodiment, step S150 includes the following steps:

[0090] Step S310: using the rod measurement method to obtain the actual soil loss of the monitoring field under different rainfalls in the past second preset time period (for example, one month), and obtain the soil loss based on the general mathematical model Obtaining predicted soil erosion amounts under different rainfall amounts in the past second preset time period;

[0091] Specifically, the general mathematical model The use of the probe method for verification can improve the objectivity of verification and enhance the credibility of the general mathematical model. At the same time, the probe method is convenient and quick to operate, which can reduce the difficulty of verification.

[0092] Step S320: obtaining a difference between the actual soil loss amount and the predicted soil erosion amount under the same rainfall amount, and obtaining a ratio of the difference to the actual soil loss amount, and determining whether the ratio is less than a preset value;

[0093] Specifically, the preset value is 5%.

[0094] Step S330: If it is less than the preset value, determine the mathematical general model qualified.

[0095] In a fourth embodiment of a method for monitoring and predicting soil erosion in a small watershed proposed by the present invention, based on the third embodiment, step S310 includes the following steps:

[0096] Step S410: Divide the monitoring field into a number of different sub-areas according to soil properties;

[0097] Specifically, when dividing the sub-areas, they can be divided according to factors such as soil slope, soil type, and vegetation coverage.

[0098] Step S420: Obtain the area of ​​each sub-region and the soil density of each sub-area ;

[0099] Specifically, the area of ​​the sub-region can be calculated by importing map data using geographic information system (GIS) technology and creating a sub-region vector layer. The area of ​​each sub-region can then be calculated using GIS software or by using remote sensing technology to obtain high-resolution images and extracting sub-region boundaries from the images. The area of ​​each sub-region can then be calculated using computing software or by manual field measurements.

[0100] Specifically, the soil density of the sub-area was obtained using the ring knife method, that is, soil samples were obtained in each sub-area, and the density was calculated by measuring the volume and mass of each soil sample.

[0101] Step S430: multiple measuring rods 12 perpendicular to the ground are evenly inserted and arranged in a herringbone shape in each sub-area, and the initial readings of each measuring rod 12 are recorded, wherein the insertion depths of the measuring rods 12 in different sub-areas are different, and the tops of the measuring rods 12 are higher than the ground;

[0102] Specifically, the insertion depth of the measuring rod 12 should be greater than the possible erosion depth of the soil in the sub-region where it is located, and the top of the measuring rod 12 is higher than the ground to facilitate reading.

[0103] Step S440: After the rainfall, read the final reading of each of the probes 12, and use the difference between the initial reading and the final reading as the soil erosion thickness of the corresponding sub-area. ;

[0104] Specifically, when a plurality of the measuring rods are inserted in a sub-area, the soil erosion thicknesses obtained by the plurality of the measuring rods should be averaged, and the average soil erosion thickness should be used to represent the soil erosion thickness of the sub-area.

[0105] Step S450: Calculate the soil erosion amount of each sub-area according to the soil erosion amount calculation formula of the rod measurement method: ,

[0106] In the formula, For the The amount of soil erosion in each sub-region, For the Soil erosion thickness in each sub-area, For the The area of ​​the sub-regions, For the Soil density in each sub-area;

[0107] Step S460: Add the soil erosion amounts of all sub-areas to obtain the actual soil loss amount of the monitoring field:

[0108] ,

[0109] Where A is the actual soil loss in the monitoring field, For the The soil erosion amount in each sub-region is m, and m is the total number of sub-regions.

[0110] In a fifth embodiment of a method for monitoring and predicting soil erosion in a small watershed proposed by the present invention, based on the fourth embodiment, step S320 further includes the following steps:

[0111] Step S510: If it is greater than or equal to the preset value, increase the erosion data The number of and reselect the curve for fitting to obtain a new mathematical general model , and the new mathematical general model Replace the current mathematical general model ;

[0112] Specifically, when the ratio is greater than or equal to the preset value, a curve that is more consistent with the erosion data can be selected from the Origin software for fitting, or the erosion data can be programmed using the matlab software for fitting. Increasing the number of samples and selecting a suitable fitting curve can further improve the accuracy of the general mathematical model.

[0113] Step S520: Execute the method of using the rod to obtain the actual soil loss of the monitoring field under different rainfalls in the past second preset time period, and obtain the soil loss data based on the general mathematical model. Obtain the predicted soil erosion amount under different rainfall amounts in the past second preset time period, and the following steps

[0114] Specifically, after refitting the new mathematical general model The difference between the predicted soil erosion and the actual soil loss obtained by the rod measurement method under the same rainfall is less than 5% of the actual soil loss, indicating that the new mathematical general model qualified.

[0115] In a sixth embodiment of a method for monitoring and predicting soil erosion in a small watershed proposed by the present invention, the system further includes a control terminal in communication connection with the data acquisition device; based on the first embodiment, step S160, and then further includes the following steps:

[0116] Step S610: Obtain the rainfall and suspended mass corresponding to the current rainfall period through the control terminal (the control terminal here may be a computer terminal in the monitoring room);

[0117] Step S620: Based on the rainfall and suspended mass corresponding to the current rainfall period, and the general mathematical model The predicted soil erosion amount of this rainfall is calculated;

[0118] Step S630: based on the predicted soil erosion amounts in different rainfall periods in the past third preset time period (for example, one year), the total predicted soil erosion amount in the past third preset time period is calculated;

[0119] Specifically, each rainfall period in the past third preset time period corresponds to a predicted soil erosion amount, and the sum of multiple predicted soil erosion amounts in the past third preset time period is the total predicted soil erosion amount in the past third preset time period.

[0120] Step S640: when the total predicted soil erosion amount in the past third preset time period is greater than the first preset amount, generating a first warning message through the control terminal;

[0121] Specifically, the first preset amount is less than 10 tons of soil erosion per hectare per year, and the first preset amount reflects that the small watershed is experiencing mild soil and water loss; the first early warning information prompts protective cultivation of the sloping farmland in the small watershed of the monitoring site, and increases the vegetation coverage of the monitoring site, and if necessary, farmland water conservancy measures (such as small drainage ditches, small reservoirs, etc.) can be built;

[0122] Step S650: when the total predicted soil erosion amount in the past third preset time period is greater than the second preset amount, generating second warning information through the control terminal;

[0123] Specifically, the second preset amount is that the soil erosion per hectare per year is between 10 tons and 25 tons, and the second preset amount reflects that the small watershed is experiencing moderate soil erosion; the second early warning information prompts the construction of terraces on the sloping farmland in the small watershed of the monitoring site, and the planting of protective forest belts on the edges of the terraces, as well as the soil improvement of the sloping farmland in the small watershed, and the construction of soil and water conservation projects (such as sand dams, retaining walls, etc.).

[0124] Step S660: When the total predicted soil erosion amount in the past third preset time period is greater than the third preset amount, a third warning information is generated through the control terminal.

[0125] Specifically, the third preset amount is that the amount of soil erosion per hectare per year is greater than 25 tons, and the third preset amount reflects that the small watershed is suffering from severe soil erosion; the third early warning information prompts the small watershed sloping farmland in the monitoring field to be left fallow and returned to forest / grass, and to build large-scale water conservancy projects (such as large reservoirs, large sand-trapping dams, etc.).

[0126] Preferably, the measuring trough 6 comprises a contraction section, a throat and a diffusion section; the bottom of the contraction section is inclined downstream, and the bottom of the diffusion section is inclined upstream; the contact point between the measuring trough 6 and the weir channel 3 is filled and sealed with concrete 7; the liquid level flow sensor 5 is mounted above the contraction section; and the photoelectric sand measuring instrument 4 is arranged at the bottom of the diffusion section.

[0127] Specifically, the measuring groove 6 is made of stainless steel; the width of the two ends of the measuring groove 6 away from the throat is consistent with the width of the weir channel 3.

[0128] Preferably, the rain gauge 9 is arranged at the monitoring field via a bracket 11 , a solar panel 10 is arranged on the bracket 11 , and the rain gauge 9 is electrically connected to the solar panel 10 .

[0129] Specifically, the bracket 11 is arranged in an open area of ​​the monitoring field so that the upper part of the rain gauge 9 is not blocked; the bracket 11 is a steel frame, and the bottom of the bracket 11 is fixed by pouring concrete. Furthermore, an installation box is also arranged on the bracket 11, and a battery is arranged in the installation box. The battery is electrically connected to the solar panel 10, and the battery is electrically connected to the rain gauge 9 to ensure the power supply of the rain gauge 9.

[0130] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0131] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for monitoring and predicting soil erosion in a small watershed, characterized in that: The invention is applied to a small watershed soil erosion monitoring and prediction system; the system comprises a collection device and a data acquisition device; the collection device comprises a drainage ditch (2), a weir channel (3), a measuring trough (6) and a sedimentation tank (8); the drainage ditch (2) is used to guide the surface runoff of the monitoring field to the weir channel (3); the weir channel (3) and the measuring trough (6) are used to measure the runoff; the sedimentation tank (8) is used to collect bed load; the measuring trough (6) is arranged in the weir channel (3), and the measuring trough (6) is arranged at a position away from the weir channel (3). one end of the drainage ditch (2); the weir channel (3) and the measuring trough (6) share a centerline; the end of the measuring trough (6) away from the drainage ditch (2) is connected to the sedimentation tank (8); the data acquisition device comprises a photoelectric sand meter (4), a liquid level flow sensor (5) and a rain gauge (9); the liquid level flow sensor (5) is mounted above the measuring trough (6) and is used to cooperate with the measuring trough (6) to obtain the runoff; the photoelectric sand meter (4) is arranged in the measuring trough (6) and is used to measure the average suspended matter content in the runoff; The rain gauge (9) is used to measure rainfall; the method comprises: Select small watersheds to establish monitoring sites; The collecting device and the data acquisition device are arranged in the monitoring field; The push mass and the suspended mass under different rainfall amounts in the past first preset time period are obtained by the collection device and the data acquisition device, and the soil erosion amount under different rainfall amounts is calculated based on the push mass and the suspended mass, and multiple groups of erosion data are obtained, including: The rainfall period is obtained by the liquid level flow sensor (5) and the measuring tank (6). Runoff volume during the period , the rainfall period is obtained by the photoelectric sand measuring instrument (4) Average suspended matter content of internal flow , and based on the rainfall period Runoff volume during the period , and rainfall periods Average suspended matter content of internal flow Calculate the rainfall period Suspended mass due to internal loss: ， Where y is the rainfall period The suspended mass of internal loss, Rainy season The runoff volume during the period, Rainy season Average suspended matter content of internal flow; The sediment in the sedimentation tank (8) and the measuring tank (6) is collected, and the collected sediment is weighed, and the weighed weight is used as the rainfall period. The quality of internal loss; The rainfall period can be calculated by the formula: soil erosion amount = suspended mass + pushed mass The amount of soil erosion within The different rainfall periods in the first preset time period in the past The rainfall in different periods of time Suspended mass of internal loss and different rainfall periods The amount of soil erosion within the area is used as the erosion data; Using data correlation analysis method, curve fitting is performed on multiple sets of erosion data to obtain a general mathematical model of soil erosion, suspended mass and rainfall. Verifying whether the mathematical general model is qualified; If qualified, the qualified universal mathematical model is used to predict the soil erosion situation of the monitoring field when rainfall occurs.

2. The method for monitoring and predicting soil erosion in a small watershed according to claim 1, characterized in that: The verifying whether the mathematical general model is qualified includes: The actual soil loss amount of the monitoring field under different rainfall amounts in the past second preset time period is obtained by using the rod measurement method, and the predicted soil erosion amount under different rainfall amounts in the past second preset time period is obtained based on the general mathematical model; Obtaining the difference between the actual soil loss amount and the predicted soil erosion amount under the same rainfall amount, and obtaining the ratio of the difference to the actual soil loss amount, and determining whether the ratio is less than a preset value; If it is less than the preset value, it is determined that the mathematical general model is qualified.

3. The method for monitoring and predicting soil erosion in a small watershed according to claim 2, characterized in that: The method of using the measuring rod method to obtain the actual soil loss amount of the monitoring field under different rainfall amounts in the past second preset time period, and obtaining the predicted soil erosion amount under different rainfall amounts in the past second preset time period based on the general mathematical model, includes: Dividing the monitoring site into a number of different sub-areas according to soil properties; Get the area of ​​each sub-region , and soil density in each sub-area , ; A plurality of measuring rods (12) perpendicular to the ground are evenly inserted and arranged in a herringbone shape in each sub-area, and an initial reading of each measuring rod (12) is recorded, wherein the insertion depths of the measuring rods (12) in different sub-areas are different, and the tops of the measuring rods (12) are higher than the ground; After the rainfall, the final reading of each measuring rod (12) is read, and the difference between the initial reading and the final reading is used as the soil erosion thickness of the corresponding sub-area. , ; The soil erosion amount of each sub-area is calculated according to the soil erosion amount calculation formula of the rod measurement method: , In the formula, For the The amount of soil erosion in each sub-region, For the Soil erosion thickness in each sub-area, For the The area of ​​the sub-regions, For the Soil density in each sub-area; The actual soil loss of the monitoring site is obtained by adding up the soil erosion amounts of all sub-areas: ， Where A is the actual soil loss in the monitoring field, For the The soil erosion amount in each sub-region is m, and m is the total number of sub-regions.

4. The method for monitoring and predicting soil erosion in a small watershed according to claim 3, characterized in that: The step of obtaining the difference between the actual soil loss amount and the predicted soil erosion amount under the same rainfall amount, and obtaining the ratio of the difference to the actual soil loss amount, and determining whether the ratio is less than a preset value, further comprises: If it is greater than or equal to the preset value, increase the amount of the erosion data, and reselect the curve for fitting to obtain a new mathematical general model, and replace the current mathematical general model with the new mathematical general model; Execute the method of using the rod measurement to obtain the actual soil loss amount of the monitoring field under different rainfall amounts in the past second preset time period, and obtain the predicted soil erosion amount under different rainfall amounts in the past second preset time period based on the general mathematical model, and subsequent steps.

5. The method for monitoring and predicting soil erosion in a small watershed according to claim 1, characterized in that: The system also includes a control terminal in communication with the data acquisition device; If qualified, the qualified universal mathematical model is used to predict the soil erosion of the monitoring field when rainfall occurs, including: Obtaining the rainfall and suspended mass corresponding to the current rainfall period through the control terminal; The predicted soil erosion amount of this rainfall is calculated based on the rainfall amount and suspended mass corresponding to this rainfall period and the general mathematical model; Based on the predicted soil erosion amounts at different rainfall periods in the past third preset time period, a total predicted soil erosion amount in the past third preset time period is calculated; When the total predicted soil erosion amount in the past third preset time period is greater than the first preset amount, generating a first warning information through the control terminal; When the total predicted soil erosion amount in the past third preset time period is greater than the second preset amount, generating second warning information through the control terminal; When the total predicted soil erosion amount in the past third preset time period is greater than the third preset amount, the third warning information is generated by the control terminal.

6. The method for monitoring and predicting soil erosion in a small watershed according to claim 1, characterized in that: The measuring trough (6) comprises a contraction section, a throat and a diffusion section; the bottom of the contraction section is inclined downstream, and the bottom of the diffusion section is inclined upstream; the contact point between the measuring trough (6) and the weir channel (3) is filled and sealed with concrete (7); the liquid level flow sensor (5) is mounted above the contraction section; and the photoelectric sand measuring instrument (4) is arranged at the bottom of the diffusion section.

7. The method for monitoring and predicting soil erosion in a small watershed according to claim 1, characterized in that: The rain gauge (9) is arranged in the monitoring field via a bracket (11); a solar panel (10) is arranged on the bracket (11); and the rain gauge (9) is electrically connected to the solar panel (10).

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