A device for observing rainfall erosion process

Abstract

The invention discloses an observation device for rainfall erosion process, which relates to the technical field of soil and water conservation research, including an experimental shed, a rainfall simulator, an experimental trough, a splash collector and a runoff sediment collector. The experimental trough is used to hold experimental soil, the rainfall simulator is installed on the experimental shed, and the rainfall simulator is located directly above the experimental trough, and is used to simulate rainfall erosion of the soil in the experimental trough. The splash collector is located at the periphery of the upper end of the experimental trough, and is used to collect splash soil particles. The runoff sediment collector is located on one side of the experimental trough, and the upper end of the runoff sediment collector is connected to the upper end of the experimental trough, and is used to collect runoff sediment samples. The observation device for rainfall erosion process can observe the raindrop splash amount and runoff migration amount of soil particles in the rainfall erosion process, thereby improving the authenticity of the research results.

Description

Technical Field

[0001] The invention relates to the technical field of soil and water conservation research, and in particular to an observation device for a rainfall erosion process. Background Art

[0002] Hydraulic erosion refers to the process of soil particles being stripped, transported, and deposited under the action of water, which not only causes the soil layer to become thinner and the soil quality to deteriorate, but also reduces land productivity. Rainfall is the main driving force of hydraulic erosion. Raindrops can destroy the surface soil structure and block soil pores, thereby reducing soil permeability and providing favorable conditions for the formation of surface runoff.

[0003] At present, the research on soil particle fragmentation and migration is mostly focused on raindrop splash erosion. However, in the splash erosion test, the water storage phenomenon on the surface of the soil in the experimental device will have a great influence on the splash erosion results. There are two reasons: First, the rainfall intensity range selected in the study is 30-100 mm·h -1(Ma RM, Li ZX, Cai CF, et al. The dynamic response of splash erosion to aggregate mechanical breakdown through rainfall simulation events in Ultisols (subtropical China) Catena, 2014, 121 (7): 279-287.), and the rainfall duration is long (45-120 min), and the soil should be in a full flow state in the later stage of rainfall (Liu T, Luo J, Zhang ZC, et al. Effects of rainfall intensity on splash erosion and its spatial distribution undermaize canopy. Natural Hazards, 2016, 84: 233-247.), the accumulated water layer will reduce the impact of raindrops, thus causing errors in the results; secondly, the experimental devices for splash erosion are mostly placed horizontally. In addition to infiltration, it is impossible to discharge excess water. Therefore, as the duration of rainfall increases, water will accumulate on the soil surface and appear muddy. In this case, the excess water carries some soil particles from the outer edge of the splash erosion area and enters the collection device, which in turn causes errors in the splash results. At this time, the collected splash erosion amount cannot accurately represent the migration amount of eroded soil particles. In the natural rainfall process, rainfall and runoff are complementary and mutually influential. It is insufficient to discuss the changes in a single process. However, the traditional rainfall erosion collection method cannot distinguish and quantify the splashed soil particles and the washed soil particles under the same erosion conditions. Therefore, the soil particle fragmentation mechanism can only be revealed from the perspective of splash erosion or wash volume. This leads to a lack of research on the dispersion and transportation of eroded soil particles driven by rainfall, and it is also difficult to identify how many broken soil particles rainfall can contribute to slope runoff in a rainfall event. During rainfall, the amount of erosion caused by raindrop splashing is much greater than that caused by runoff scouring, and the former contributes about 5 times more to slope erosion than the latter. Therefore, exploring the distribution characteristics of eroded soil particles driven by rainfall and explaining the differences in the distribution of splashed soil particles and scouring soil particles in each test from the perspective of soil particle sorting is a prerequisite for clarifying the fragmentation characteristics of eroded soil particles. Summary of the invention

[0004] The purpose of the present invention is to provide an observation device for the rainfall erosion process to solve the problems existing in the above-mentioned prior art. It is capable of observing the raindrop splashing amount and runoff migration amount of soil particles during the rainfall erosion process to improve the authenticity of the research results.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides an observation device for a rainfall erosion process, comprising a test shed, a rainfall simulator, a test trough, a splash collector and a runoff sediment collector, wherein the test trough is used to hold experimental soil, the rainfall simulator is installed on the test shed, and the rainfall simulator is located directly above the test trough, and is used to simulate rainfall erosion of the soil in the test trough, the splash collector is located on the periphery of the upper end of the test trough, and is used to collect splash soil particles, the runoff sediment collector is located on one side of the test trough, and the upper end of the runoff sediment collector is connected to the upper end of the test trough, and is used to collect runoff sediment samples.

[0007] Preferably, the test shed comprises a support frame, a shed cloth and a plurality of columns, the shed cloth cover is arranged on the support frame, and a rain outlet is opened in the middle of the shed cloth, the rain outlet is used to install the rainfall simulator, and each column is respectively installed at each corner of the support frame.

[0008] Preferably, the rainfall simulator includes a water tank, a submersible pump, a water supply pipe, a rainfall box and a plurality of needle rainmakers, the water tank is used to store water, the two ends of the water supply pipe are respectively connected to the water tank and the rainfall box, and the submersible pump is used to introduce the water in the water tank into the rainfall box through the water supply pipe, the needle rainmaker is located on the lower bottom surface of the water tank, and the needle rainmaker is located above the test trough and is used to simulate rainfall.

[0009] Preferably, a valve is installed on the water supply pipe, and the valve is used to control the on / off and flow rate of water flow in the water supply pipe.

[0010] Preferably, an overflow pipe is also installed on the side wall of the rain box, and the overflow pipe can connect the inner cavity of the rain box with the outside.

[0011] Preferably, the test trough comprises a bracket and a trough body, the bracket is used to support the trough body, and the trough body is used to contain soil.

[0012] Preferably, the splash collector includes a splash plate and a plurality of baffle groups, each of the baffle groups is evenly installed on the upper end surface of the splash plate, each of the baffle groups includes four baffles, and each of the baffles is perpendicular to the splash plate, and the four baffles form a rectangle, each of the baffle groups is sequentially sleeved on the outer periphery of the test trough, and each corner of each baffle group is provided with a drainage hole, and the drainage hole is used to drain the water on the splash plate without discharging soil particles.

[0013] Preferably, the runoff sediment collector comprises a triangular collecting trough and a collecting bucket, the upper end of the triangular collecting trough is flush with the upper end surface of the test trough, and the collecting bucket is located below the triangular collecting trough and is used to collect runoff sediment samples in the test trough.

[0014] Compared with the prior art, the present invention has achieved the following technical effects:

[0015] The present invention provides an observation device for the rainfall erosion process, wherein a rainfall simulator is located directly above a test trough, and rainfall is then simulated by the rainfall simulator to simulate rainfall erosion of soil in the test trough, a splash collector is located at the periphery of the upper end of the test trough, and is used to collect splash soil particles, a runoff sediment collector is located at one side of the test trough, and the upper end of the runoff sediment collector is connected to the upper end of the test trough, and is used to collect runoff sediment samples, and then through the settings of the splash collector and the runoff sediment collector, the raindrop splash amount and runoff migration amount of soil particles in the rainfall erosion process are simultaneously observed, providing a powerful means for quantitatively studying the impact of rainfall on the soil erosion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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 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 these drawings without paying creative work.

[0017] Figure 1 It is a structural schematic diagram of the observation device for the rainfall erosion process provided by the present invention;

[0018] Figure 2 It is a structural schematic diagram of the water storage tank in the present invention;

[0019] Figure 3 It is a schematic diagram of the structure of the rain box in the present invention;

[0020] Figure 4 It is a structural schematic diagram of the test shed in the present invention;

[0021] Figure 5 It is a structural schematic diagram of the test tank in the present invention;

[0022] Figure 6 It is a schematic diagram of the structure of the sputtering collector in the present invention;

[0023] Figure 7 It is a structural schematic diagram of the runoff sediment collector of the present invention;

[0024] In the figure: 100-an observation device for the rainfall erosion process, 1-a rainfall simulator, 2-a test shed, 3-a test trough, 4-a splash collector, 5-a runoff sediment collector, 6-a water storage tank, 7-a submersible pump, 8-a water supply pipe, 9-a valve, 10-a rainfall box, 11-a needle rainmaker, 12-an overflow pipe, 13-a support frame, 14-a column, 15-a shed cloth, 16-a trough body, 17-a bracket, 18-a splash plate, 19-a baffle, 20-a drainage hole, 21-a triangular collecting trough, 22-a collection barrel. DETAILED DESCRIPTION

[0025] 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.

[0026] The purpose of the present invention is to provide an observation device for rainfall erosion process, so as to solve the technical problem of inaccurate observation of the existing rainfall erosion process observation device.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1-Figure 7 As shown, the present invention provides an observation device 100 for a rainfall erosion process, comprising a test shed 2, a rainfall simulator 1, a test trough 3, a splash collector 4 and a runoff sediment collector 5. The test trough 3 is used to hold experimental soil. The rainfall simulator 1 is installed on the test shed 2, and the rainfall simulator 1 is located directly above the test trough 3. Then, rainfall is simulated by the rainfall simulator 1 to simulate rainfall erosion of the soil in the test trough 3. The splash collector 4 is located at the periphery of the upper end of the test trough 3 and is used to collect splash soil particles. The runoff sediment collector 5 is located on one side of the test trough 3, and the upper end of the runoff sediment collector 5 is connected to the upper end of the test trough 3 and is used to collect runoff sediment samples. Then, by setting the splash collector 4 and the runoff sediment collector 5, the raindrop splash amount and runoff migration amount of soil particles in the rainfall erosion process are observed at the same time, which provides a powerful means for quantitatively studying the impact of rainfall on the soil erosion process.

[0029] Specifically, Figure 4As shown, the test shed 2 includes a support frame 13, a shed cloth 15 and a plurality of columns 14. The shed cloth 15 is covered on the support frame 13, and the shed cloth 15 is supported by the support frame 13. At the same time, the top of the test trough 3 is shielded by the shed cloth 15 to prevent other debris from entering the test trough 3 and affecting the accuracy of the test results. A rainfall port is opened in the middle of the shed cloth 15, and the rainfall port is used to install the rainfall simulator 1, thereby ensuring that the water in the rainfall simulator 1 can reach the test trough 3 and splash the soil in the test trough 3. Each column 14 is respectively installed at each corner of the support frame 13 to improve the support stability.

[0030] like Figure 2-Figure 3 As shown, the rainfall simulator 1 includes a water tank 6, a submersible pump 7, a water supply pipe 8, a rainfall box 10 and a plurality of needle rainmakers 11. The water tank 6 is used to store water to achieve continuous rainfall. Both ends of the water supply pipe 8 are connected to the water tank 6 and the rainfall box 10 respectively, and the submersible pump 7 is used to introduce the water in the water tank 6 into the rainfall box 10 through the water supply pipe 8. During the simulated rainfall process, the submersible pump 7 remains turned on to ensure the stability of the rainfall intensity. The needle rainmaker 11 is located on the lower bottom surface of the water tank 6, and the needle rainmaker 11 is located above the test tank 3 and is used to simulate rainfall. The plurality of needle rainmakers 11 are evenly arranged. During the test, the simulated rainfall intensity is adjusted by adjusting the diameter of the needle rainmaker 11.

[0031] A valve 9 is installed on the water supply pipe 8, and the valve 9 is used to control the on-off and flow rate of the water flow in the water supply pipe 8, so as to facilitate real-time regulation.

[0032] An overflow pipe 12 is also installed on the side wall of the rain box 10. The overflow pipe 12 can connect the inner cavity of the rain box 10 with the outside world. When the water level in the rain box 10 reaches the height of the overflow pipe 12, the water can flow out through the overflow pipe 12 to ensure the stability of the rainfall intensity.

[0033] like Figure 5 As shown, the test tank 3 includes a bracket 17 and a tank body 16. The bracket 17 is used to support the tank body 16, and the tank body 16 is used to contain soil.

[0034] like Figure 6As shown, the splash collector 4 includes a splash plate 18 and a plurality of baffle groups, each baffle group is evenly installed on the upper end surface of the splash plate 18, each baffle group includes four baffles 19, and each baffle 19 is perpendicular to the splash plate 18, thereby being able to block the splashed soil particles, the four baffles 19 form a rectangle, and each baffle group is sequentially sleeved on the outer periphery of the test tank 3, that is, the innermost circle is the test tank 3, and the outer periphery of the test tank 3 is surrounded by multiple circles of baffle groups, and the spacing between adjacent baffle groups is 10 cm, and each corner of each baffle group is provided with a drainage hole 20, the drainage hole 20 is used to discharge the water on the splash plate 18 without discharging the soil particles, thereby realizing the collection of the splashed soil particles, preferably, the diameter of the drainage hole 20 is 2 cm.

[0035] like Figure 7 As shown, the runoff sediment collector 5 includes a triangular collecting trough 21 and a collecting bucket 22. The upper end of the triangular collecting trough 21 is flush with the upper end surface of the test trough 3, and the collecting bucket 22 is located below the triangular collecting trough 21 and is used to collect the runoff sediment samples in the test trough 3, so that the soil particles flushed out of the test trough 3 can be collected into the collecting bucket 22 along the triangular collecting trough 21 to realize the collection of runoff sediment samples.

[0036] As a specific embodiment, a simulated rainfall test is taken as an example to illustrate the specific steps of using the observation device 100 for the rainfall erosion process. The test is conducted in the rainfall test room of the experimental forest farm of Northeast Forestry University at Maoershan, Harbin, Heilongjiang Province.

[0037] Step 1: Trial Tank 3 Sampling Overview

[0038] The soil in the test trough 3 was collected from the 0-20 cm surface soil of the cultivated land. Before sampling, the surface litter and other debris were removed and the soil surface was trimmed and leveled. Then, the self-made test trough 3 (40 cm long × 10 cm wide × 10 cm high) was placed on the leveled soil surface. The soil around the bottom of the test trough 3 was trimmed with a soil knife and the test trough 3 was slowly pressed until it was completely immersed in the soil. After taking the test trough 3 out of the soil, the test trough 3 filled with the original soil was wrapped with gauze and sponge, and then the upper and lower bottom covers were covered to ensure that the soil in the test trough 3 was not deformed and reduce the interference steps during the sample transportation process. Before the rainfall test, the test trough 3 was placed in the water tank for 12 hours to saturate the soil in the test trough 3. The water level in the water tank should be slightly lower than the upper edge of the test trough 3 to ensure that the water absorption in the test trough 3 depends on the water absorption capacity of the soil at the bottom of the test trough 3.

[0039] Step 2: Equipment deployment

[0040] Rainfall simulator 1 layout: After placing the submersible pump 7 into the water storage tank 6, connect one end of the water supply pipe 8, and the diameter of the end of the water supply pipe 8 close to the water storage tank 6 is 32mm. Install a valve 9 on the water supply pipe 8 to adjust the flow rate; secondly, install the other end of the water supply pipe 8 on the rain box 10, and the diameter of the water supply pipe 8 close to the rain box 10 is 20mm. Observe the relative position of the water level in the rain box 10 and the overflow pipe 12 and adjust the valve 9 to control the change of rainfall intensity. The rainfall intensity can also be achieved by replacing the needle rainmaker 11. Rainfall simulator 1 is built 2m above the test tank 3. Before the formal test, the test tank 3 is covered with a stainless steel baffle, and the rainfall intensity required for the test is calibrated: use a 100ml measuring cylinder to collect the rainfall per unit area, and use a stopwatch to time it, convert it into rainfall per unit time, calibrate 3 to 5 times, and start the test after it stabilizes.

[0041] Layout of the runoff sediment collector 5: a triangular collecting trough 21 is placed on one side of the test trough 3, the upper end of the triangular collecting trough 21 is flush with the upper end of the test trough 3, and a collecting bucket 22 is arranged just below the lower end of the triangular collecting trough 21, and the collecting bucket 22 is used to collect runoff sediment.

[0042] Step 3: Simulate the slope erosion process under rainfall conditions

[0043] Each set of test conditions was repeated three times, and the rainfall time after each runoff generation was 30 minutes. Before the test, the rainfall intensity was calibrated, and the test tank 3 was covered with a stainless steel baffle. The rainfall per unit area was collected with a 100ml measuring cylinder, and the collection time was recorded at the same time. The rainfall was converted into rainfall intensity (mm / min). Multiple calibrations were performed to ensure that the relative error between the actual rainfall intensity and the designed rainfall intensity was within 5%. After the rainfall intensity calibration reached the design requirements, the stainless steel baffle was removed, and a stopwatch was used to time the time. When the rainfall caused the slope to generate runoff (runoff flowed out from the triangular collecting trough 21), the time when the runoff reached the upper end of the triangular collecting trough 21 was recorded as the runoff generation time, and the soil particles splashed out before the runoff generation occurred were collected at the same time. After the runoff generation began, the runoff sediment sample was collected once and the splashed soil particles were collected once every 5 minutes, and the volume, mass and collection time of the runoff sediment sample and the splashed soil particles were obtained. At the same time, the potassium permanganate solution color tracing method was used to measure the flow rate by spraying potassium permanganate solution at three locations on the slope, in the middle and below, and each flow rate measurement was repeated 3 times.

[0044] The present specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An observation device for rainfall erosion process, Features: It includes a test shed, a rainfall simulator, a test trough, a splash collector and a runoff sediment collector, wherein the test trough is used to hold experimental soil, the rainfall simulator is installed on the test shed, and the rainfall simulator is located directly above the test trough, and is used to simulate rainfall erosion of the soil in the test trough, the splash collector is located on the periphery of the upper end of the test trough, and is used to collect splash soil particles, the runoff sediment collector is located on one side of the test trough, and the upper end of the runoff sediment collector is connected to the upper end of the test trough, and is used to collect runoff sediment samples; The splash collector includes a splash plate and a plurality of baffle groups, each of which is evenly mounted on the upper end surface of the splash plate, each of which includes four baffles, and each of which is perpendicular to the splash plate, and the four baffles form a rectangle, each of which is sequentially sleeved on the outer periphery of the test tank, and each corner of each of which is provided with a drainage hole, and the drainage hole is used to drain the water on the splash plate without discharging soil particles; The rainfall simulator comprises a water storage tank, a submersible pump, a water supply pipe, a rainfall box and a plurality of needle rainmakers, wherein the water storage tank is used to store water, the two ends of the water supply pipe are respectively connected to the water storage tank and the rainfall box, and the submersible pump is used to introduce the water in the water storage tank into the rainfall box through the water supply pipe, the needle rainmaker is located on the lower bottom surface of the water storage tank, and the needle rainmaker is located above the test tank and is used to simulate rainfall; An overflow pipe is also installed on the side wall of the rain box, and the overflow pipe can connect the inner cavity of the rain box with the outside world.

2. The observation device for rainfall erosion process according to claim 1, Features: The test shed includes a support frame, a shed cloth and a plurality of columns. The shed cloth is covered on the support frame, and a rain outlet is opened in the middle of the shed cloth. The rain outlet is used to install the rainfall simulator. The columns are respectively installed at the corners of the support frame.

3. The observation device for rainfall erosion process according to claim 1, Features: A valve is installed on the water supply pipe, and the valve is used to control the on / off and flow rate of the water flow in the water supply pipe.

4. The observation device for rainfall erosion process according to claim 1, Features: The test trough comprises a bracket and a trough body, wherein the bracket is used to support the trough body, and the trough body is used to contain soil.

5. The observation device for rainfall erosion process according to claim 1, Features: The runoff sediment collector comprises a triangular collecting trough and a collecting bucket, the upper end of the triangular collecting trough is flush with the upper end surface of the test trough, and the collecting bucket is located below the triangular collecting trough and is used to collect runoff sediment samples in the test trough.

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