A method for calculating river section water volume based on upstream and downstream remote sensing data

Abstract

The application relates to a kind of river reach water quantity calculation methods based on upstream and downstream remote sensing data, belong to river reach water quantity measurement and remote sensing application technical field.The steps are to obtain the survey basic data of upstream and downstream river channel section of the measured river reach, obtain the remote sensing image covering the required observation river channel section through satellite, pre-process and set the extraction image grid size as DD;The river water body is extracted by the normalized water body index calculation after the pre-processed image;According to the water body extraction result, the grid number of the upstream and downstream river channel river surface is measured, and the upstream and downstream river surface width is calculated;According to the survey basic data of upstream and downstream river channel section and river surface width, the river reach water quantity is calculated.The application does not need personnel to carry out field measurement on site, can directly utilize computer to carry out calculation and supervision analysis at a distance, and provides convenience for the measurement of water quantity data.

Description

TECHNICAL FIELD

[0001] The application relates to a water quantity calculation method, in particular to a river section water quantity calculation method based on upstream and downstream remote sensing data, and belongs to the technical fields of river section water quantity measurement and remote sensing application. BACKGROUND

[0002] River section water quantity calculation is one of important calculations in the field of hydrology, and has important significance in aspects of basin development, flood control scheduling, river regulation, rational utilization and optimization of water resources. Traditional calculation of river section water quantity generally adopts manual measurement of river surface width data and water level data monitored by a hydrological monitoring station to calculate the river section water quantity. The method is time-consuming and laborious, has high labor cost, cannot realize measurement of the river surface width in time under influence of extremely severe weather, and cannot obtain water level data and water quantity data in the case that the river is not provided with a monitoring station. SUMMARY

[0003] The application aims at overcoming the above-mentioned defects, and provides a river section water quantity calculation method based on upstream and downstream remote sensing data, which can quickly and conveniently obtain water quantity data.

[0004] The technical scheme adopted by the application is as follows.

[0005] A river section water quantity calculation method based on upstream and downstream remote sensing data comprises the following steps.

[0006] (1) obtaining upstream and downstream river channel section survey basic data of a to-be-measured river section, including upstream section river bottom width B1, right bank slope coefficient m 1右 , left bank slope coefficient m 1左 ; downstream section river bottom width B2, right bank slope coefficient m 2右 , left bank slope coefficient m 2左 ; river section length H between the upstream and downstream sections;

[0007] (2) obtaining remote sensing images covering the required observation river channel sections through a satellite, pre-processing and setting the extracted image grid size as D D;

[0008] (3) extracting the river channel water body through normalized water body index calculation of the pre-processed images;

[0009] (4) measuring the grid numbers of the upstream and downstream river channel surfaces according to the water body extraction results and calculating the upstream and downstream river surface widths:

[0010] S1 = n1 D,

[0011] S2 = n2 D,

[0012] S1 is the width of the river surface of the upstream river section,

[0013] S2 is the width of the river surface of the downstream river section,

[0014] n1 is the number of grids covering the river surface of the upstream river section,

[0015] n2 is the number of grids covering the river surface of the downstream river section,

[0016] D is the size of the grid length;

[0017] (5) According to the survey data of the upstream and downstream river sections and the river surface width, the water volume of the river section is calculated:

[0018] ,

[0019] In the formula, V represents the water volume of the river section.

[0020] In the above method, the preprocessing of step (2) includes atmospheric correction, radiation calibration and image cropping.

[0021] The calculation method of the normalized water body index in step (3) is:

[0022] ,

[0023] NDWI: normalized water body index, p(Green): green band remote sensing reflectivity, p(NIR): near-infrared band remote sensing reflectivity.

[0024] In step (4), the grid layout is set by using ArcGIS, and the number of grids contained in the river width is calculated.

[0025] The specific process of the river section water volume calculation in step (5) is:

[0026] According to the definition of the slope coefficient,

[0027] (1),

[0028] (2),

[0029] b 1左 is the projection length in the horizontal direction of the left slope surface of the upstream,

[0030] b 1右 is the projection length in the horizontal direction of the right slope surface of the upstream,

[0031] b 2左 is the projection length in the horizontal direction of the left slope surface of the downstream,

[0032] b 2右 is the projection length in the horizontal direction of the right slope surface of the downstream,

[0033] h1 is the water depth of the upstream river section;

[0034] h2 is the water depth of the downstream river section;

[0035] According to the river section, it is known that:

[0036] (3),

[0037] (4),

[0038] Substitute formula (1) and (2) into formula (3) and (4) to obtain h1 and h2, and then obtain the cross-sectional areas of the upstream and downstream through the trapezoidal area formula:

[0039] (5),

[0040] (6),

[0041] W1 is the cross-sectional area of the upstream river section,

[0042] W2 is the cross-sectional area of the downstream river section,

[0043] According to the trapezoidal cubic volume formula, the water quantity of the upstream and downstream river sections is:

[0044] (7),

[0045] Substitute formula (5) and formula (6) into formula (7) to obtain the river section water quantity:

[0046] .

[0047] The beneficial effects of the present application are:

[0048] 1. The present application can improve the disadvantages of the existing river section water quantity monitoring means, and can quickly and conveniently obtain the required river section remote sensing image, obtain the river width data through technical means, and calculate the river section water level data and the amount of river section water quantity, so that the process does not need personnel to carry out on-site measurement, and the computer can be directly used for remote calculation and supervision analysis, thereby providing convenience for water quantity data measurement.

[0049] 2. The calculation of river section water quantity can provide timely and accurate hydrological information, which is of great help for timely understanding of hydrological changes in river monitoring. In addition, river section water quantity information can help water conservancy departments and general users to reasonably manage and protect underground and surface water resources, ensure their sustainable use, and is a necessary technical means for effective management and maintenance of river ecological environment and water resources. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 Flow chart of the method of the present application;

[0051] Figure 2 Schematic diagram of upstream and downstream river section, a schematic diagram of upstream river section, b schematic diagram of downstream river section;

[0052] Figure 3 River section survey drawing of the embodiment;

[0053] Figure 4 Satellite remote sensing image covering the river section to be measured in the embodiment;

[0054] Figure 5 Water body extraction result graph in the embodiment. DETAILED DESCRIPTION

[0055] The present application will be further described in conjunction with specific embodiments and examples.

[0056] A river section water volume calculation method based on upstream and downstream remote sensing data, comprising the following steps:

[0057] (1) Obtain upstream and downstream river section survey basic data of the river section to be measured:

[0058] Through engineering design drawings, river section survey drawings and other basic measurement information, several key parameters of the upstream section and the downstream section of the river to be measured can be known, including the upstream section river bottom width B1, the right bank slope coefficient m 1右 , the left bank slope coefficient m 1左 ; the downstream section river bottom width B2, the right bank slope coefficient m 2右 , the left bank slope coefficient m 2左 ; the river section length H between the upstream section and the downstream section.

[0059] (2) Obtain remote sensing images covering the required observation river section through satellite, and pre-process the remote sensing images, including atmospheric correction, radiation calibration, image cropping, and setting the extraction image grid size D D (vector grid, for example, one grid size is 20 meters 20 meters), and the unit of D is meter.

[0060] (3) Extract the river water body through normalized water body index calculation of the pre-processed images:

[0061] The extraction principle is as follows:

[0062] ,

[0063] NDWI: normalized water body index, p(Green): green band remote sensing reflectivity, p(NIR): near-infrared band remote sensing reflectivity;

[0064] The specific operation includes: based on ENVI5.3 software, selecting Basic Tools->Band Math in menu bar, then inputting expression: (float(b2)-float(b4)) / (b2+b4) in enter an expression, wherein b2 is green wave band, b4 is near infrared wave band, selecting export position to obtain water body index image; next, water body and non-water body are distinguished, selecting Classification->Decision Tree->Build New Decision Tree in menu bar, clicking Node 1, inputting calculation formula b1 GT 0.2 in expression, selecting water body index image generated just now, clicking execute to obtain binary result, wherein water body is white. In available vector lists window, selecting file->export layers to shpfile to convert water body into.shp data.

[0065] (4) According to the water body extraction result, the grid numbers of the upstream and downstream river surfaces are measured and the upstream and downstream river surface widths are calculated:

[0066] According to the water body NDWI extraction result, grid layout is set by using ArcGIS, the grid number n contained by river width is calculated, and the grid size is D D, then the river width S is obtained:

[0067] S1=n1 D,

[0068] S2=n2 D,

[0069] S1: upstream river section river surface width (m),

[0070] S2: downstream river section river surface width (m),

[0071] n1: the number of upstream river section river surface grids,

[0072] n2: the number of upstream river section river surface grids,

[0073] D: grid side length size (m).

[0074] (5) According to the survey basic data of the upstream and downstream river sections and the river surface width, the river section water quantity is calculated:

[0075] According to the definition of slope coefficient,

[0076] (1),

[0077] (2),

[0078] b 1左 is the projection length of the left slope surface in the horizontal direction of the upstream,

[0079] b 1右 is the projection length of the right slope surface in the horizontal direction of the upstream,

[0080] b 2左 is the projection length of the left slope surface in the horizontal direction of the downstream,

[0081] b 2右 is the projection length of the right slope surface in the horizontal direction of the downstream,

[0082] h1 is the water depth of the upstream river section,

[0083] h2 is the water depth of the downstream river section;

[0084] According to Figure 2 the river section, it is known that:

[0085] (3),

[0086] (4),

[0087] S1 is the river surface width of the upstream river section (m),

[0088] S2 is the river surface width of the downstream river section (m),

[0089] B1 is the river bottom width of the upstream section (m),

[0090] B2 is the river bottom width of the downstream section (m),

[0091] Substitute formula (1) and (2) into formula (3) and (4) to obtain h1 and h2, and combine the trapezoidal area formula to obtain the cross-sectional areas of the upstream and downstream sections:

[0092] (5),

[0093] (6),

[0094] W1 is the cross-sectional area of the upstream river section,

[0095] W2 is the cross-sectional area of the downstream river section,

[0096] According to the trapezoidal cubic volume formula, the water quantity of the upstream and downstream sections is:

[0097] (7),

[0098] Substitute formula (5) and formula (6) into formula (7), and the water quantity of the river section is obtained as follows:

[0099] .

[0100] Embodiment: the water quantity of a river section of Yihe River is calculated and analyzed as follows, firstly, the survey data of the upstream and downstream sections of the river section are obtained, for example Figure 3 , according to the drawing of the survey of the section, the river bottom width B1 of the upstream is 85m, the right bank slope coefficient m 1右 is 2.5, the left bank slope coefficient is m 1左 2.5; the river bottom width B2 of the downstream is 130m, the right bank slope coefficient m 2右 is 3, and the left bank slope coefficient is m 2左 3; the length H of the river section between the upstream and downstream sections is 340m.

[0101] The image data covering the river section are obtained by downloading satellite remote sensing image data, the grid size of the image is 20m 20m, for example Figure 4 , the water body of the image is extracted, the extraction result is as shown in Figure 5 , the number of the upstream river section grid n1 is 9, and the number of the downstream river section grid n2 is 10, so that the upstream river surface width S1=9 20=180m, and the downstream river surface width S2=10 20=200m.

[0102] Substitute the above water quantity calculation formula, and the water quantity V=752976m 3 of the current river section is obtained by calculation.

[0103] The above only describes one embodiment of the present application, and is not used for limiting the present application, any modification, equivalent replacement, improvement, etc. made in the spirit and principle range of the present application should be included in the protection range of the present application.

Claims

1. A method for calculating the water volume of a river section based on upstream and downstream remote sensing data, characterized in that, The steps include the following: (1) Obtain the survey basic data of the upstream and downstream river section of the river section to be measured, including the upstream section river bottom width B1, the right bank slope coefficient m 1右 , and the left bank slope coefficient m 1左 ; The width of the river bottom at the downstream section is B2, the right bank slope coefficient is m 2右 , the left bank slope coefficient is m 2左 ; the length of the river section between the upstream section and the downstream section is H; (2) Obtain remote sensing images covering the required observation river section by satellite, preprocess and set the image grid size D for extraction D; (3) The pre-processed image is extracted by normalized water index calculation to extract the river water body; (4) According to the water extraction result, the grid number of the upstream and downstream river surface is measured and the upstream and downstream river surface width is calculated: S1 = n1 D, S2 = n2 D, S1 is the upstream river section river surface width, S2 is the downstream river section river surface width, n1 is the number of upstream river section river surface grid, n2 is the number of upstream river section river surface grid, D is the grid length size; (5) According to the survey basic data of the upstream and downstream river section and the river surface width, the river section water quantity is calculated: ， In the formula, V represents the river section water quantity.

2. The method according to claim 1, wherein, The preprocessing of step (2) includes atmospheric correction, radiation calibration and image cropping.

3. The method according to claim 1, wherein the method is characterized by, The calculation method of the normalized water index in step (3) is: ， NDWI: normalized water index, p(Green): green band remote sensing reflectivity, p(NIR): near-infrared band remote sensing reflectivity.

4. The method according to claim 1, wherein, In step (4), the grid layout is set by using ArcGIS, and the number of grids contained in the river width is calculated.

5. The method according to claim 1, wherein, The specific process of river section water quantity calculation in step (5) is: According to the definition of slope coefficient, （1）， （2）， b 1左 Lup is the projected length of the upstream left side slope surface in the horizontal direction, b 1右 Lup is the projected length of the upstream right slope face in the horizontal direction, b 2左 L is the length of the left side of the downstream slope face in the horizontal direction, b 2右 Lp is the projected length of the downstream right slope face in the horizontal direction, h1 is the upstream river section water depth; h2 is the downstream river section water depth; According to the river section, （3）， （4）， Substitute formula (1) and (2) into formula (3) and (4) to obtain h1 and h2, and then obtain the upstream and downstream section areas by the trapezoidal area formula: （5）， （6）， W1 is the upstream river section area, W2 is the downstream river section area, According to the trapezoidal cubic volume formula, the upstream and downstream river section water quantity is: （7）， Substitute formula (5) and formula (6) into formula (7) to obtain the river section water quantity: 。

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