CN105547957B - Soil bacterial diversity wetted front suction and rainfall spurt volume computational methods - Google Patents

Abstract

A calculation method for soil infiltration peak suction and rainfall initial loss, comprising the following steps: through a double-loop infiltration experiment, measuring and recording the change of water supply volume with infiltration time, and calculating the real-time cumulative infiltration amount; based on the infiltration time and Real-time cumulative infiltration, fitting necessary parameters; based on fitting parameters and fixed infiltration head height, calculating wet peak suction; based on fitting parameters, initial soil water content and soil porosity, calculating soil saturated hydraulic conductivity; based on wet Peak suction, soil saturated hydraulic conductivity, rainfall intensity, initial soil water content and soil porosity, to calculate initial rainfall loss.

Description

Calculation method of soil infiltration peak suction and initial rainfall loss

technical field

The disclosure relates to the determination of soil parameters of a hydrological rainfall runoff model, in particular to a calculation method for soil infiltration peak suction and initial rainfall loss based on double-ring infiltration.

Background technique

my country is one of the countries where rainstorms and floods occur most frequently. Timely and accurate forecasting and early warning of flood disasters is very important for reducing disaster losses. One of the key issues in flood disaster forecasting and early warning is to accurately simulate the process of rainfall and runoff generation. The Green-Ampt model is a runoff model with a clear physical mechanism, but it is difficult to determine the fixed suction parameters of the wet peak, which severely limits the application of the model. The traditional double-ring infiltration experiment can only test the soil saturated hydraulic conductivity, and cannot determine the fixed suction parameters of the wet peak in the Green-Ampt model, which is difficult to meet the soil parameter requirements of the Green-Ampt model applied to watershed hydrology. Therefore, there is an urgent need for a reliable and practical method that can quickly calculate the fixed suction parameters of the wet peak and the initial rainfall loss in the Green-Ampt model.

Contents of the invention

In order to make up for the deficiencies in the prior art, the present disclosure provides a calculation method for soil infiltration peak suction and initial rainfall loss.

The present disclosure employs the following solutions:

A calculation method for soil infiltration peak suction and rainfall initial loss, comprising the following steps:

Step 1: Through the double-loop infiltration experiment, measure and record the change of the water supply Q with the infiltration time t, and calculate the real-time cumulative infiltration h according to the formula (1):

Among them, S represents the area of the inner ring of the double-ring infiltration instrument used;

Step 2: Based on the infiltration time t and the real-time cumulative infiltration amount h, fitting parameter A and parameter B according to formula (2):

Step 3: Calculate the wet peak suction h _f according to formula (3):

h _f =Bh ₀ (3)

Among them, h ₀ represents the fixed infiltration head height;

Step 4: Calculate soil saturated hydraulic conductivity K according to formula (4):

Among them, θ ₀ represents the initial water content of the soil, and θ _s represents the soil porosity;

Step 5: Calculate the initial rainfall loss I _a according to the formula (5):

Among them, P represents the rainfall intensity.

Preferably, said soil porosity θ _s is measured by ring knife sampling.

Preferably, the initial soil water content θ ₀ is determined by a soil water content test.

Preferably, said parameter A and parameter B are fitted by a least square method.

Preferably, the water supply quantity Q is the water quantity of the water supply Martens flask.

The beneficial effect of the present disclosure is that the calculation of soil infiltration peak suction and initial rainfall loss based on the double-ring infiltration can quickly and accurately determine the soil parameters involved in the Green-Ampt model, and then perform flood disaster forecasting and early warning.

Description of drawings

The above and other objects, features and advantages of the present disclosure will become more apparent by describing the exemplary embodiments of the present disclosure in more detail with reference to the accompanying drawings, wherein, in the exemplary embodiments of the present disclosure, the same reference numerals are generally represent the same part.

Fig. 1 shows the flow chart of the method for calculating the peak suction of soil infiltration and initial rainfall loss according to an exemplary embodiment;

FIG. 2 shows a graph of infiltration amount versus infiltration time, according to an exemplary embodiment.

Detailed ways

Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

Fig. 1 shows the flow chart of the calculation method of soil infiltration peak suction and rainfall initial loss according to an exemplary embodiment, the method includes the following steps:

Step 1. Through the double-loop infiltration experiment, measure and record the change of the water supply Q with the infiltration time t, and calculate the real-time cumulative infiltration h according to the following formula (1):

Among them, S represents the area of the inner ring of the double-ring infiltration instrument used.

In actual operation, it is preferable to use a double-ring infiltration instrument to carry out double-ring infiltration experiments. A double-loop infiltration meter is a device commonly used in the art to measure the rate of infiltration of water into soil. A standard dual-ring infiltrator includes outer and inner rings of different diameters. The outer ring acts as an insulator when the vertically percolating water flows towards the edge. Since the water in the inner ring flows vertically, measurements are limited to the inner ring.

As a preferred solution, the Martens bottle is used as the water supply equipment, so the water supply quantity Q refers to the water quantity of the water supply Martens flask, and when other water supply equipment is used, the water supply quantity Q refers to the water quantity of the water supply equipment adopted.

Step 2, based on the infiltration time t and the real-time cumulative infiltration h in step 1, according to the following formula (2), fitting parameter A and parameter B:

In the actual implementation process, the computer program can be compiled by the least square method or the general data processing software (such as TableCurve 2D) can be used to fit the parameters A and B.

Step 3, calculate the wet peak suction _hf according to the following formula (3):

h _f =Bh ₀ (3)

Among them, h ₀ represents the fixed infiltration head height.

Step 4, calculate the soil saturated hydraulic conductivity K according to the following formula (4):

Among them, θ ₀ represents the initial water content of soil, which can be determined by soil moisture test, and θ _s represents the soil porosity, which can be measured by ring knife sampling.

Step 5, calculate the initial rainfall loss I _a according to the following formula (5):

Among them, P represents the rainfall intensity. Depending on the practical application, P can be measured by a rain gauge, or it can be the designed rainfall intensity.

Application example

This example provides a calculation method for soil infiltration peak suction and initial rainfall loss based on field double-ring infiltration experiments, including the following steps:

Step 1: Carry out a double-loop infiltration experiment, with a sampling period of 1 second, use a hanging electronic scale to connect to the serial port of the computer to measure and record the change of the water volume of the water supply Martens flask with the infiltration time t, and calculate the real-time cumulative infiltration according to formula (1). Infiltration amount h, the obtained real-time cumulative infiltration amount h and infiltration time t curves are shown in Figure 2.

Step 2: Based on the data of real-time cumulative infiltration h and infiltration time t in step 1, according to formula (2), fit parameter A and parameter B in formula (2) by least square method, and obtain A=32.45 s/cm, B=25.91 cm, R ² =0.9997, where R ² represents the fitting determination coefficient.

Step 3: Measure the fixed infiltration head height h ₀ =10 cm, and calculate the wetting peak suction h _f =15.91 cm according to the formula (3).

Step 4: Obtain the initial soil water content θ ₀ =0 through the soil moisture test measurement, the soil porosity θ _s =36% measured by the ring knife sampling, and calculate the soil saturated hydraulic conductivity K=399.22mm according to the formula (4) /hr.

Step 5: Calculate the initial rainfall loss according to formula (5):

The above-mentioned technical solution is only an embodiment of the present invention. For those skilled in the art, on the basis of the application methods and principles disclosed in the present invention, it is easy to make various types of improvements or deformations, and is not limited to The methods described in the above specific embodiments of the present invention, therefore, the above-described methods are only preferred and not limiting.

Claims (5)

1. a kind of calculation method of wetted peak suction under soil and rainfall initial loss is characterized in that, comprises the following steps: Step 1: Through the double-loop infiltration experiment, measure and record the change of the water supply Q with the infiltration time t, and calculate the real-time cumulative infiltration h according to the formula (1): <mrow><mi>h</mi><mo>=</mo><mfrac><mi>Q</mi><mi>S</mi></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mrow> Among them, S represents the area of the inner ring of the double-ring infiltration instrument used; Step 2: Based on the infiltration time t and the real-time cumulative infiltration amount h, fitting parameter A and parameter B according to formula (2): <mrow><mfrac><mi>t</mi><mi>A</mi></mfrac><mo>=</mo><mi>h</mi><mo>-</mo><mi>B</mi><mo>*</mo><mi>ln</mi><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mfrac><mi>h</mi><mi>B</mi></mfrac><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow> Step 3: Calculate the wet peak suction h _f according to formula (3): h _f =Bh ₀ (3) Among them, h ₀ represents the fixed infiltration head height; Step 4: Calculate soil saturated hydraulic conductivity K according to formula (4): <mrow><mi>K</mi><mo>=</mo><mfrac><mrow><msub><mi>&amp;theta;</mi><mi>s</mi></msub><mo>-</mo><msub><mi>&amp;theta;</mi><mn>0</mn></msub></mrow><mi>A</mi></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mrow> Among them, θ ₀ represents the initial water content of the soil, and θ _s represents the soil porosity; Step 5: Calculate the initial rainfall loss I _a according to the formula (5): <mrow><msub><mi>I</mi><mi>a</mi></msub><mo>=</mo><msub><mi>h</mi><mi>f</mi></msub><mrow><mo>(</mo><msub><mi>&amp;theta;</mi><mi>s</mi></msub><mo>-</mo><msub><mi>&amp;theta;</mi><mn>0</mn></msub><mo>)</mo></mrow><mfrac><mi>K</mi><mrow><mi>P</mi><mo>-</mo><mi>K</mi></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>5</mn><mo>)</mo></mrow></mrow> Among them, P represents the rainfall intensity. 2. The method for calculating soil infiltration peak suction and initial rainfall loss according to claim 1, wherein the soil porosity θ _s is measured by ring knife sampling. 3 . The method for calculating soil infiltration peak suction and initial rainfall loss according to claim 1 , wherein the initial soil water content θ ₀ is determined by a soil water content test. 4 . 4. The soil infiltration and wetting peak suction according to claim 1 and the calculation method for initial rainfall loss, wherein the parameter A and parameter B are fitted by the least square method. 5. The calculation method for soil infiltration peak suction according to claim 1 and initial rainfall loss, wherein the water supply quantity Q is the water quantity of a water supply Martens bottle.