CN112433029B - Method for calculating tree roughness of beach land - Google Patents
Method for calculating tree roughness of beach land Download PDFInfo
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- CN112433029B CN112433029B CN202011250796.8A CN202011250796A CN112433029B CN 112433029 B CN112433029 B CN 112433029B CN 202011250796 A CN202011250796 A CN 202011250796A CN 112433029 B CN112433029 B CN 112433029B
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Abstract
The invention relates to a method for calculating tree roughness of a beach, which is closer to reality by roughening trees with different diameters and intervals in a subarea mode, and can calculate the roughness of the trees by parameters of the diameters of the trees, the intervals of the trees and the water depth, thereby having less consideration factors and greatly simplifying the roughness calculation process. Meanwhile, the roughness calculated by the method is high in accuracy, and the accuracy of the beach tree resistance in the river channel flood traveling process researched by a mathematical model or a physical model can be improved.
Description
Technical Field
The invention belongs to the technical field of river dynamics, relates to the water blocking influence of trees on a beach under the condition of river channel flood drainage, and particularly relates to a calculation method of the tree roughness of the beach.
Background
River course ecological environment receives people to attach attention increasingly, and the beach tree planting plays important role in river course ecological remediation, when beautifying environment, scour protection and soil stabilization, has also increased river course water resistance, has raised the river course water level of carrying floods, and the influence of research trees to carrying floods is crucial to river course flood control. At present, a mathematical model or a physical model is usually adopted to study the flood discharge capacity of a river channel, wherein one of methods for considering the resistance of trees on a beach is to study the resistance coefficient of trees to further obtain a resistance calculation formula, and then add a resistance term in a digital model to carry out simulation calculation, or realize the simulation of the resistance of the beach by roughening in a physical model test. In the research of a digital model or an object model, the method for generalizing the tree resistance into the roughness is a simpler and more intuitive method, in the existing plant roughness research, the comprehensive roughness is often adopted, more influence factors such as the average flow rate of the cross section of a river channel, the river width and the like are considered, and in fact, the trees in the river channel are only located in partial areas of the beach, the resistance to water flow belongs to the influence of local resistance, and therefore the accuracy of the roughness is poor.
Disclosure of Invention
The invention provides a method for calculating the tree roughness of the beach land with higher accuracy.
The technical scheme adopted by the invention is as follows:
a method for calculating the roughness of trees on a beach land comprises the following steps:
step a, measuring the diameters of a plurality of trees on the beach in the area to be researched, and simultaneously measuring the distance between any two trees on the beach in the area to be researched for many times; dividing a region to be researched into a plurality of sub-research regions according to the diameter and the distance of trees on the beach, wherein the deviation between the diameter of the trees on the beach in each sub-research region and the average value of the diameters of the trees on the beach in the sub-research region is within a first set range, and the deviation between the distance of the trees on the beach in each sub-research region and the average value of the distances between the trees on the beach in the sub-research region is within a second set range;
b, optionally selecting a sub-research area, and taking the average value of the diameters of the trees in the beach in the sub-research area as the diameter D of the trees in the beach in the sub-research area; taking the average value of the distances between trees in the beach in the sub-research area as the distance L between trees in the beach in the research area;
c, determining the water depth H of the position of the tree in the beach of the selected sub-research area;
step d, repeating the steps b and c, and obtaining the product by a formula:
and calculating the roughness n of trees in the beach of all the sub-research areas.
Further, in step a, the first and second setting ranges are both 10%.
Further, in the step a, when the trees on the beach are measured, a caliper is adopted for measurement; and when the distance between trees on the beach land is measured, a laser range finder is adopted for measurement.
Further, in step b, the diameter of trees on the beach in any sub-study area
Beach tree spacing
M is more than 2, and the number of the trees on the beach land with the measured diameter in the sub research area is counted; n is more than 2, and is the number of times of measuring the distance between trees on the beach in the sub-research area; i and j are both serial numbers.
Further, in the step c, collecting water level information of the river corresponding to the sub-research area, wherein the water level information comprises a design flood level, a multi-year average water level and a beach elevation, and the water depth H of the beach under different water levels can be determined by subtracting the beach elevation from the water level.
The invention has the beneficial effects that:
the method disclosed by the invention is closer to reality by carrying out regional roughening on trees on the beach with different diameters and intervals, and meanwhile, the roughness of the trees is calculated through the parameters of the diameters of the trees, the intervals of the trees and the water depth, the considered factors are few, and the roughness calculation process can be greatly simplified. Meanwhile, the calculated roughness rate is high in accuracy, and the accuracy of the mathematical model or the physical model for researching the tree resistance in the flood discharge of the river can be improved (after the roughness value of the subarea is calculated, the setting of the roughness value in the area of the beach area in a digital model or an object model is easy to realize).
Drawings
FIG. 1 is a schematic view of the elevation of a beach tree and the position of a trunk plane in a research area;
FIG. 2 is a schematic view of a test water tank;
FIG. 3 is a plot of roughness as a function of water depth;
FIG. 4 is a plot of calculated roughness versus experimental values;
Detailed Description
The technical solution of the present invention will be further described in detail with reference to the accompanying drawings.
A method for calculating the tree roughness of a beach, as shown in figure 1, is suitable for the situation that the plane projection of trees on the beach is square and the trees are not submerged (the crowns are not submerged), and comprises the following steps:
step a, measuring the diameters of a plurality of beach land trees in the area to be researched, and simultaneously measuring the distance between any two beach land trees in the area to be researched for many times. According to the diameter and the distance of the trees in the beach areas, the area to be researched is divided into a plurality of sub research areas, the deviation between the diameter of the trees in the beach areas in each sub research area and the average value of the diameters of the trees in the beach areas in the sub research areas is within a first set range, and the deviation between the distance of the trees in the beach areas in each sub research area and the average value of the distances of the trees in the beach areas in the sub research areas is within a second set range. The first and second setting ranges are both 10%. When the trees on the beach land are measured, calipers are adopted for measurement. And when the distance between trees on the beach land is measured, a laser range finder is adopted for measurement.
And b, optionally selecting a sub-research area, and taking the average value of the diameters of the trees in the beach of the sub-research area as the diameter D of the trees in the beach of the sub-research area. And taking the average value of the distances between trees in the beach in the sub-research area as the distance L between trees in the beach in the research area.
Trees diameter on beach in any sub-area of study
Beach tree spacing
M is more than 2, and the number of the trees on the beach land with the measured diameter in the sub-research area is determined. N is more than 2, and the number of times of measuring the distance between trees on the beach in the sub-research area is obtained. i and j are both serial numbers.
And c, determining the water depth H of the position of the tree in the selected sub-research area beach.
Collecting water level information of the riverway corresponding to the sub-research area, wherein the water level information comprises design flood level, multi-year average water level and beach elevation, and subtracting the beach elevation from the water level to determine the water depth H of the beach under different water levels.
Step d, repeating the stepb and c, and by the formula:
and calculating the roughness n of trees in the beach of all the sub-research areas.
In order to verify the beach land tree roughness calculation method, the inventor carried out a water tank test. As shown in figure 2, the length of the water tank for the test is 20m, the width is 0.8m, the height is 0.5m, the bottom slope is 3 per mill, the upstream flow is controlled by a rectangular measuring weir, a turning weir is arranged at the inlet of the water tank, the energy dissipation device applies gentle water flow, and the downstream water level is controlled by a manual turning plate tail gate. The test section is 1.5m long and 0.8m wide, is located in the middle section of the water tank, the upper stream and the lower stream of the test section are respectively provided with a water level station, and the water level is measured by a water level measuring needle.
The trees are simulated by stainless steel wires, the diameter is 3mm, the length is 33cm, and the arrangement intervals are 3cm, 6cm, 12cm and 24cm respectively. The tested water depth conditions are 0.1m, 0.15m, 0.2m, 0.25m and 0.3m, the tested water depth is controlled through a tail gate, the upstream flow is adjusted, and the roughness conditions under different water flow conditions are researched.
Fig. 3 shows the open channel roughness as a function of depth at different "tree" spacings, and it can be seen that as depth increases, the roughness tends to increase, which is the difference between the non-submerged plant roughness change and the submerged plant and non-plant open channel currents. Under the same water depth condition, obviously, the smaller the spacing of the plants, the larger the roughness.
Fig. 4 is a comparison result of a roughness value calculated by the roughness of the present invention and a roughness test value obtained by the present test, and it can be seen that the roughness test value and the calculated value are substantially around the diagonal line, so that the roughness formula of the present invention has a good fitting degree.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any alternative or alternative method that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered by the scope of the present invention.
Claims (5)
1. A method for calculating the tree roughness of a beach is characterized by comprising the following steps:
step a, measuring the diameters of a plurality of trees on the beach in the area to be researched, and simultaneously measuring the distance between any two trees on the beach in the area to be researched for many times; dividing a region to be researched into a plurality of sub-research regions according to the diameter and the distance of trees on the beach, wherein the deviation between the diameter of the trees on the beach in each sub-research region and the average value of the diameters of the trees on the beach in the sub-research region is within a first set range, and the deviation between the distance of the trees on the beach in each sub-research region and the average value of the distances between the trees on the beach in the sub-research region is within a second set range;
b, selecting a sub-research area optionally, and taking the average value of the diameters of the trees in the beach of the sub-research area as the diameter D of the trees in the beach of the sub-research area; taking the average value of the inter-beach land tree distances in the sub-research area as the inter-beach land tree distance L of the research area;
c, determining the water depth H of the position of the tree in the selected sub-research area beach;
step d, repeating the steps b and c, and obtaining the product by a formula:
and calculating the roughness n of trees in the beach of all the sub-research areas.
2. The method for calculating tree roughness of beach of claim 1 wherein in step a, the first and second predetermined ranges are both 10%.
3. The method for calculating the tree roughness of the beach of claim 1, wherein in the step a, when the tree on the beach is measured, a caliper is used for measurement; and when the distance between trees on the beach land is measured, a laser range finder is adopted for measurement.
4. The method for calculating tree roughness of beaches of claim 1, wherein in step b, the diameter of trees in beaches in any sub-research area
Beach tree spacing
M is more than 2, and the number of the trees on the beach land with the measured diameter in the sub research area is counted; n is more than 2, and is the number of times of measuring the distance between trees on the beach in the sub-research area; i and j are both serial numbers.
5. The method for calculating tree roughness of beach of claim 1 wherein in step c, water level information of the river corresponding to the sub-research area is collected, including design flood level, mean water level for many years and beach elevation, and the water depth H of the beach at different water levels can be determined by subtracting the beach elevation from the water level.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103526716A (en) * | 2013-10-25 | 2014-01-22 | 水利部交通运输部国家能源局南京水利科学研究院 | River model plastic grass roughening method |
| CN104765977A (en) * | 2015-04-27 | 2015-07-08 | 河海大学 | Method for calculating integrated reach roughness considering local head losses |
| CN106529108A (en) * | 2015-09-07 | 2017-03-22 | 中国水利水电科学研究院 | Method for calculating manning roughness coefficient of aquatic plant-contained river channel |
| CN107816009A (en) * | 2017-10-23 | 2018-03-20 | 云南省水利水电勘测设计研究院 | A kind of universal method for inquiring into multistage compound cross-section stage discharge relation |
| CN108491634A (en) * | 2018-03-26 | 2018-09-04 | 河海大学 | A kind of beach forest against wave wash plantation is unfavorable for the quantitative analysis method of river course flood |
-
2020
- 2020-11-11 CN CN202011250796.8A patent/CN112433029B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103526716A (en) * | 2013-10-25 | 2014-01-22 | 水利部交通运输部国家能源局南京水利科学研究院 | River model plastic grass roughening method |
| CN104765977A (en) * | 2015-04-27 | 2015-07-08 | 河海大学 | Method for calculating integrated reach roughness considering local head losses |
| CN106529108A (en) * | 2015-09-07 | 2017-03-22 | 中国水利水电科学研究院 | Method for calculating manning roughness coefficient of aquatic plant-contained river channel |
| CN107816009A (en) * | 2017-10-23 | 2018-03-20 | 云南省水利水电勘测设计研究院 | A kind of universal method for inquiring into multistage compound cross-section stage discharge relation |
| CN108491634A (en) * | 2018-03-26 | 2018-09-04 | 河海大学 | A kind of beach forest against wave wash plantation is unfavorable for the quantitative analysis method of river course flood |
Non-Patent Citations (2)
| Title |
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| Yu Yao等.Boussinesq modeling of solitary wave run-up reduction by emergent vegetation on a sloping beach.《Journal of Hydro-environment Research》.2018, * |
| 姬昌辉等.水深及滩地糙率对复式断面河道过流能力的影响.《人民黄河》.2015,第37卷(第1期), * |
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