CN1908615A - Continuous system based spray irrigation uniformity measurement method - Google Patents

Abstract

The disclosed sprinkling even level detection method based on continuous system comprises: interpolating the detected data to obtain the unknown rainfall depth; when arranging the rainfall cylinders radially, taking two times cubic-spline interpolation to the radial and axial data for the unknown rainfall depth; or when arranging the cylinder as mesh structure, taking two times cubic-spline interpolation to the horizontal and vertical data for the unknown rainfall depth. This invention improves detection precision in theory.

Description

A kind of uniformity coefficient of sprinkler irrigation measuring method based on continuous system

Technical field

The invention belongs to systematic analysis and evaluation method field, relate to a kind of measuring method that is used for the rainfall distribution uniformity of ejecting devices such as farmland, greenery patches, gardens and floral nursery, particularly a kind of uniformity coefficient of sprinkler irrigation measuring method based on continuous system.

Background technology

Sprinkling irrigation with its wide adaptability, be easy to advantage such as mechanized and become one of water-saving irrigation technique that extensively adopts in the world at present.Uniformity coefficient of sprinkler irrigation is an important indicator of weighing irrigation quality and shower nozzle hydraulic performance, is the important parameter in the spray irrigation system planning and design.Method by the measuring point that gathers can directly calculate uniformity coefficient of sprinkler irrigation, but it is general because the restriction of conditions such as experiment work amount, often measuring point can not be arranged overstockedly, limited measuring point bathymetric data is converted to the grid type data, calculate uniformity coefficient then but replace certain calculation method.At this moment just need the consideration measuring point to arrange the error problem that density and measuring method bring.

Present measuring point method for arranging mainly contains equidistant radial arrangement and grid is arranged two kinds.It is generally acknowledged, adopt grid to arrange the test of existing permanent sprinkler system uniformity coefficient; Adopt radial arrangement or grid to arrange for the test of single shower nozzle water distribution.Utilize single shower nozzle water distribution to inquire into combination during uniformity ratio, the general using computing machine is to the calculating that superposes of combination water distribution.

When measuring point is radial arrangement in single shower nozzle spray test, need to adopt certain method that radial data is converted to the grid type data.At present the most frequently used method is a method of interpolation, promptly utilizes 3 of known vicinities or measuring point data interpolation calculation to go out bathymetric data on the net point at 4.The method of interpolation mainly contains distance weighted interpolation (Zhang Xinhua, 1981; Xue Kezong, 1982), linear interpolation (Luo Jinyao, 1987), triangle interpolation (Evans, 1995), planar interpolation (Huang Xiuqiao, 1995) etc.In addition, when old eagle owl (1984) is selected optimum shower nozzle array configuration in research with the characteristic surface method, adopted along directions of rays (radially) and twice approach based on linear interpolation computing grid point of circular arc direction (circumferentially) depth of water.

It is pointed out that said method all do not consider the influence of far point data to interpolation point.The sprinkling irrigation water distribution is a continuous system in theory, and the far point data trend also has very significant effects to the calculation level water depth value.The aforementioned calculation method all is based on the Statistics of discrete system, has ignored the positional information between measuring point and the continuity Characteristics information of water distribution, and what calculate in fact is the sample standard deviation evenness of the limited measuring point that isolates.

Summary of the invention

Defective or deficiency at above-mentioned uniformity coefficient of sprinkler irrigation computing method existence, the objective of the invention is to, a kind of uniformity coefficient of sprinkler irrigation measuring method based on continuous system is provided, improves the uniformity coefficient of sprinkler irrigation computational accuracy, also for setting up shower nozzle or spray irrigation system water yield spatially distributed functions provides foundation.

To achieve these goals, the present invention takes following technical scheme:

A kind of uniformity coefficient of sprinkler irrigation measuring method based on continuous system is characterized in that, this method is under the theoretical condition of a continuous system to the sprinkling irrigation water distribution, and it is dark to utilize the dark data interpolating of actual measurement precipitation to calculate unknown point precipitation; When the rain gage bucket radial arrangement, by radially carrying out cubic spline interpolation with circumferential twice pair of measured data, it is dark to calculate unknown point precipitation, when the rain gage bucket grid is arranged, adopt horizontal and vertical twice pair of measured data to carry out cubic spline interpolation, it is dark to calculate unknown point precipitation.

When rain gage bucket is radial arrangement in the shower nozzle spray test, at first utilize the measured data on every measuring point (rain gage bucket) layout ray to carry out radial interpolation, calculate the water depth value of any unknown point (or uniformity coefficient calculation level) on every ray.The dark data of precipitation (for the data that distribute on the certain radius circumference) on several groups of actual measurement rays to the shower nozzle certain radius that utilize then that radial interpolation obtains, interpolation is carried out at any direction angle, the water depth value on the arbitrfary point in the sprinkler pattern range scope can be obtained like this, and then the uniformity coefficient of sprinkler irrigation value can be calculated.When rain gage bucket in the shower nozzle spray test is the grid layout, at first utilize every measured data on the horizontal rain gage bucket deployment line to carry out lateral interpolation, can calculate the water depth value of any unknown point (or uniformity coefficient calculation level) on every x wire.Utilize the water depth value on the vertical line of a determining deviation then, all water depth values on the vertical line of any spacing that interpolation is obtained, can obtain in the sprinkler pattern range scope like this or spray irrigation system uniformity coefficient reference area on the water depth value of arbitrfary point, and then measure the uniformity coefficient of sprinkler irrigation value.

Adopt cubic spline interpolation when measuring method of the present invention, each interpolation, considered that all measuring point bathymetric datas are to the influence of interpolation point water depth value on each direction.Radially and circumferentially twice interpolation of (or horizontal and vertical) considered in the sprinkler pattern range scope or spray irrigation system uniformity coefficient measuring and calculating area on all measuring point datas to the dark influence of interpolation point precipitation, thereby improved the measuring accuracy of uniformity coefficient of sprinkler irrigation in theory, also for setting up shower nozzle or spray irrigation system water yield spatially distributed functions provides foundation.

Description of drawings

Fig. 1 is a rain gage bucket arrangement in the shower nozzle spray test, among the figure, (A) is radial arrangement, (B) arranges that for grid the small circle among the figure is a rain gage bucket.

Fig. 2 is twice interpolation calculation sketch of cubic spline;

Fig. 3 is the three-dimensional water distribution figure of 30PSH shower nozzle square combination;

Fig. 4 is the three-dimensional water distribution isogram of the single shower nozzle of 30PSH;

Fig. 5 is the three-dimensional water distribution figure of 30PSH shower nozzle square combination;

Fig. 6 is the three-dimensional water distribution isogram of 30PSH shower nozzle square combination;

Fig. 7 is that 30PSH shower nozzle equilateral triangle makes up three-dimensional water distribution figure;

Fig. 8 is that 30PSH shower nozzle equilateral triangle makes up three-dimensional water distribution isogram;

Fig. 9 is a 30PSH shower nozzle square combination uniformity coefficient relative spacing index variation curve;

Figure 10 is a 30PSH shower nozzle equilateral triangle combination uniformity coefficient relative spacing index variation curve.

The present invention is described in further detail below in conjunction with instantiation that accompanying drawing and inventor finish.

Embodiment

Referring to Fig. 1, the present invention is a kind of uniformity coefficient of sprinkler irrigation measuring method based on continuous system, is example with the radial arrangement rain gage bucket, and the step of this method comprises:

Step 1: radial arrangement rain gage bucket

As round dot, sprinkler pattern range is a radius, the radial arrangement rain gage bucket with Fig. 1 shower nozzle position.For explaining conveniently, establishing the radial radiation number of lines here is 6.

Step 2: survey and fall water depth value

The beginning spray test is read the water depth value that falls in the rain gage bucket.

Step 3: set up coordinate system

Set up polar coordinate system OX with shower nozzle position among Fig. 1 as initial point, use l _i(i=1,2 ... 6) represent the rain gage bucket radiant rays in the shower nozzle test, as shown in Figure 2.With the utmost point to the shower nozzle solstics on the radiant rays directly is that radius is made circle Φ _l, the dark data of all actual measurement precipitation all are distributed in circumference Φ like this _lOn 6 interior radiant rays.Make Φ _lExternal square ABCD.In ABCD, given mesh spacing is determined mesh lines number and net point.Now need circumference Φ _lThe dark data of radially precipitation on the interior radiant rays are converted to the grid type data on the net point in the ABCD.

Because the dark positional information of net point precipitation depends on utmost point footpath and two key elements of deflection of this point in the ABCD.Therefore, utilize existing radial data to carry out radial interpolation (utmost point is directly carried out interpolation) and circumferential interpolation (deflection is carried out interpolation) respectively, former radial mode data can be converted to the grid type data.

Step 4: radial interpolation

Radial interpolation is to utilize the dark data of existing precipitation on the radial spoke ray that the utmost point is directly carried out interpolation, calculates on each bar radial spoke ray deeply to the unknown precipitation of shower nozzle any distance, and radial interpolation computation process is as follows:

For arbitrary mess point P _{M * n}Utmost point footpath r _{M * n}With polar angle α _{M * n}Can determine to the distance R of shower nozzle is unique by solstics on the sequence number m that establishes mesh lines and n and the radiant rays.With r _{M * n}For radius is made circle Φ _a, with radiant rays l _i(i=1,2 ... 6) meet at an a respectively _i(i=1,2 ... 6).

If the measuring point precipitation on every radiant rays is d deeply _Ij(i=1,2 ... 6; J=1,2 ... x _i), x wherein _iBe respectively every radiant rays rain gage bucket number.Adopt the method for cubic spline interpolation to utilize d _IjTo r _{M * n}Carry out interpolation and can calculate a _iThe dark D of point dewatering _i, represent with following formula:

D _i＝F _i(d _ij，r _m×n)(i＝1，2，...6；j＝1，2，...x _i) (1)

F in the formula _iThe expression cubic spline functions.

Step 5: circumferential interpolation

Circumferentially interpolation be utilize on every radiant rays by radial interpolation calculate any utmost point footpath r _{M * n}On the dark data D of precipitation _iTo polar angle α _{M * n}Carry out interpolation, calculate the dark D of precipitation on the arbitrary mess point _{M * n}, computing formula is as follows:

D _m×n＝F(D _i，α _m×n)(i＝1，2，...6) (2)

F represents cubic spline functions in the formula.

Step 6: uniformity coefficient is calculated

According to shower nozzle array mode and Combination Distance, with D _{M * n}The dark D of net point precipitation in many shower nozzle combination control areas is obtained in stack _{M * n}', substitution uniformity ratio computing formula can be obtained uniformity coefficient of sprinkler irrigation.Here be example with Christiansen uniformity ratio and distribution uniformity coefficient, be respectively calculated as follows:

$\mathrm{CU}=100\×\{1.0-\frac{\mathrm{\Σ}|D_{m\×n}^{\′}-\stackrel{\‾}{D}}{\stackrel{\‾}{D}}\}---\left(3\right)$

In the formula: CU is the Christiansen uniformity ratio; D is D _{M * n}' mean value.

$\mathrm{DU}=\frac{{\stackrel{\‾}{D}}^{\′}}{\stackrel{\‾}{D}}\×100---\left(4\right)$

In the formula, D is 1/4 D _{M * n}The mean value of ' low value.

When rain gage bucket in the shower nozzle spray test is a grid when arranging, change the step 1 of said method into grid and arrange rain gage bucket, step 4 and step 5 change lateral interpolation and vertical interpolation into, still adopt cubic spline interpolation during each interpolation, and other step is identical.

The inventor provides a practical measuring examples to prove the feasibility and the accuracy of the inventive method.Measuring object is the combination uniformity coefficient of sprinkler irrigation of U.S. rain bird 30PSH shower nozzle.Table 1 is the dark data of actual measurement precipitation of reading after radially laying according to the rain gage bucket of measuring method of the present invention, and rain gage bucket is by equidistantly laying every 60 degree.

The dark data of actual measurement precipitation are carried out the combination of various combination mode and Combination Distance, in the hope of the uniformity coefficient of sprinkler irrigation after the combination.Array mode is divided into the square combination and equilateral triangle makes up two kinds.Combination Distance l determines with Combination Distance coefficient k (Combination Distance equals the product of Combination Distance coefficient and sprinkler pattern range), is divided into 1.00,1.05,1.10,1.15,1.20,1.25,1.30,1.35,1.40 nine kinds of situations.

In order further to compare and twice method of interpolation measurement result of checking cubic spline, the applicant has also calculated Keller and Bliesner (1990) returns distribution uniformity coefficient DU _KBAnd Li Jiusheng (1999) returns distribution uniformity coefficient DU _L:

CU _KB＝0.63DU+37 (5)

DU _L＝1.21CU-24 (6)

It almost is impossible that twice method of interpolation of cubic spline adopts artificial calculating, and the applicant has worked out the sprinkling irrigation combination uniformity coefficient software for calculation " SIUEW1.0 (Sprinkler Irrigation Uniformity Evaluation for Windows) " that can realize twice method of interpolation of cubic spline with the MATLAB language for this reason.Rain gage bucket measured value in the test of input shower nozzle on each bar radiant rays, SIUEW1.0 will calculate the combination uniformity coefficient value under various combination mode and the Combination Distance as requested automatically, provide the combination uniformity coefficient with the Combination Distance change curve, and can draw single shower nozzle and three-dimensional water distribution figure of many shower nozzles and isogram.

At first prove the feasibility of uniformity coefficient measuring method of the present invention.The dark data of shower nozzle actual measurement precipitation in the input table 1, SIUEW1.0 combination uniformity coefficient measurement result sees Table 2 and 3.

The dark data of rain gage bucket actual measurement precipitation of table 1 30PSH shower nozzle

Rain gage bucket radiant rays angle	Water depth value (mm) falls in the rain gage bucket actual measurement to the shower nozzle different distance
																				0m	1m	2m	3m	4m	5m	6m	7m	8m	9m	10m	11m	12m	13m	14m	15m	16m	17m	18m
	0° 60° 120° 180° 240° 300°	8.7 8.7 8.7 8.7 8.7 8.7	8.6 8.7 8.7 8.8 8.7 8.7	6.2 6.5 6.6 6.7 6.5 6.4	3.3 3.2 3.5 3.9 3.7 3.9	3.5 3.4 3.8 4.3 3.6 3.5	3.8 3.9 4.2 4.8 4.4 4.6	5.1 4.1 4.7 5.2 4.5 4.7	6.9 6.4 5.8 5.6 5.4 6.3	5.2 4.9 4.9 4.6 4.8 4.5	3.6 4.0 4.6 4.2 4.3 4.9	2.9 3.7 3.9 3.0 3.6 3.8	2.6 3.2 3.3 2.0 3.3 3.9	3.5 3.1 3.4 3.1 3.2 3.7	2.5 2.0 2.9 2.2 2.5 2.8	1.0 2.5 2.9 2.6 2.7 2.2	0.3 1.2 1.9 2.0 1.4 1.2	0.0 0.7 1.5 1.7 1.4 0.9	0.0 0.3 0.9 1.3 0.8 0.3																				0.0 0.0 0.3 0.6 0.3 0.0

Table 2 30PSH shower nozzle square combination uniformity coefficient result of calculation

Uniformity ratio	Various combination spacing shower nozzle combination uniformity coefficient
										k＝1.00 (l＝18m)	k＝1.05 (l＝19m)	k＝1.10 (l＝20m)	k＝1.15 (l＝21m)	k＝1.20 (l＝22m)	k＝1.25 (l＝23m)	k＝1.30 (l＝23m)	k＝1.35 (l＝24m)	k＝1.40 (l＝25m)
	CU DU DU KB DU L	85.2 75.2 76.2 78.9	83.8 73.2 73.2 76.6	81.9 70.1 70.4 74.5	82.2 69.9 69.9 74.1	81.8 71.4 70.8 74.7	81.8 71.1 70.1 74.3	81.8 71.1 70.1 74.3	80.7 67.3 66.7 71.7										77.1 62.6 62.1 68.1

Annotate: k---Combination Distance coefficient; L---Combination Distance.L=kr, r are sprinkler pattern range, r=18m.

Table 3 30PSH shower nozzle equilateral triangle combination uniformity coefficient result of calculation

Uniformity ratio	Various combination spacing shower nozzle combination uniformity coefficient
										k＝1.00 (l＝18m)	k＝1.05 (l＝19m)	k＝1.10 (l＝20m)	k＝1.15 (l＝21m)	k＝1.20 (l＝22m)	k＝1.25 (l＝23m)	k＝1.30 (l＝23m)	k＝1.35 (l＝24m)	k＝1.40 (l＝25m)
	CU DU DU KB DU L	80.3 67.0 68.6 73.1	78.6 65.2 66.0 71.1	79.1 65.9 66.7 71.7	80.9 69.2 69.6 73.9	82.0 71.4 71.4 75.3	80.6 70.9 69.1 73.5	80.6 70.9 69.1 73.5	78.5 67.5 65.8 71.0										76.0 64.5 61.8 68.0

Annotate: k---Combination Distance coefficient; L---Combination Distance.L=kf, r are sprinkler pattern range, r=18m.

Fig. 3 and 4 is respectively three-dimensional water distribution figure of the single shower nozzle of 30PSH and isogram thereof.Fig. 5 and Fig. 6 are respectively 30PSH shower nozzle square combination (the Combination Distance coefficient is 1.2) three-dimensional water distribution figure and isogram thereof.Fig. 7 and 8 is respectively 30PSH shower nozzle equilateral triangle combination (the Combination Distance coefficient is 1.2) three-dimensional water distribution figure and isogram thereof.Fig. 9 and 10 is respectively the change curve of the relative Combination Distance coefficient of uniformity coefficient when the 30PSH shower nozzle is square to be made up with equilateral triangle.

By Fig. 9 and 10 as can be known, the recurrence distribution uniformity coefficient DU of Keller and Bliesner (1990) _KBCoincide better with the distribution uniformity coefficient DU of 1/4 low value.The recurrence distribution uniformity coefficient DU of Li Jiusheng (1999) _LIdentical relatively poor with DU, reason may be that the regression relation of Li Jiusheng (1999) is in bigger combination uniformity coefficient variation range (CU=44～98) internal regression.But DU _LAnd DU _KBVariation tendency all basic identical with DU.

For square combination (Fig. 9), when Combination Distance coefficient k=1.0, combination uniformity coefficient maximum.Along with k increases, the combination uniformity coefficient begins to descend.In k=1.1～1.3 scopes, the combination uniformity coefficient tends towards stability.When k＞1.3, the combination uniformity coefficient begins quick decline.For equilateral triangle combination (Figure 10), in k=1.1～1.3 scopes, the combination uniformity coefficient changes less, combination uniformity coefficient maximum during k=1.2.When k＞1.3, the combination uniformity coefficient also begins quick decline.

By making up uniformity coefficient measurement result and each uniformity ratio comparative result as can be known, twice method of interpolation of cubic spline of utilizing computer program to realize can calculate the sprinkling irrigation combination uniformity coefficient that shower nozzle is represented at various combination mode, various combination spacing and different uniformity ratio reliably, and draws out shower nozzle and make up three-dimensional water distribution figure and isogram thereof.

The inventor adopts example that the accuracy of method of the present invention has also been carried out the contrast proof.Except adopting measuring method of the present invention that 30PSH shower nozzle in the last example is measured, adopt the measuring method of the densely covered measuring point of grid and tradition to measure simultaneously based on the measuring method of discrete system.The uniformity coefficient of sprinkler irrigation that the measuring method of the densely covered measuring point of grid is directly measured here as the true value of uniformity coefficient, is used to verify method of the present invention and traditional accuracy based on discrete system uniformity coefficient of sprinkler irrigation measuring method for the actual measurement uniformity coefficient of sprinkler irrigation.Shown in table 4 and table 5, the coefficient of the description uniformity coefficient of sprinkler irrigation of this example calculating is the Christiansen uniformity ratio to the uniformity coefficient results of measuring that square combination and equilateral triangle make up following three kinds of methods respectively, and CU represents uniformity coefficient true value, CU _dTraditional uniformity coefficient value that calculates based on the uniformity coefficient of sprinkler irrigation measuring method of discrete system is adopted in expression, and CU represents to adopt the uniformity coefficient value that calculates based on the uniformity coefficient of sprinkler irrigation measuring method of continuous system of the present invention.

The mean deviation that the measured value of reckoner 4 and table 5 and the deviation of true value can get traditional uniformity coefficient of sprinkler irrigation measuring method based on discrete system is 2.0, the mean deviation of the uniformity coefficient of sprinkler irrigation measuring method based on continuous system of the present invention is 0.79, hence one can see that, and the measuring accuracy of uniformity coefficient of sprinkler irrigation measuring method of the present invention is apparently higher than the precision of traditional measurement method.

Table 4 30PSH shower nozzle square combination uniformity coefficient results of measuring

Uniformity ratio	Various combination spacing shower nozzle combination uniformity coefficient
										k＝1.00 (l＝18m)	k＝1.05 (l＝19m)	k＝1.10 (l＝20m)	k＝1.15 (l＝21m)	k＝1.20 (l＝22m)	k＝1.25 (l＝23m)	k＝1.30 (l＝23m)	k＝1.35 (l＝24m)	k＝1.40 (l＝25m)
	CU CU d CU c	85.1 87.2 85.2	83.2 85.2 83.8	81.4 82.1 81.9	81.1 82.9 82.2	81.6 80.4 81.8	81.2 82.1 81.8	81.2 80.1 81.8	79.1 81.3 80.7										76.2 78.6 77.1

Annotate: k---Combination Distance coefficient; L---Combination Distance.L=kr, r are sprinkler pattern range, r=18m.

Table 5 30PSH shower nozzle equilateral triangle combination uniformity coefficient result of calculation

Uniformity ratio	Various combination spacing shower nozzle combination uniformity coefficient
										k＝1.00 (l＝18m)	k＝1.05 (l＝19m)	k＝1.10 (l＝20m)	k＝1.15 (l＝21m)	k＝1.20 (l＝22m)	k＝1.25 (l＝23m)	k＝1.30 (l＝23m)	k＝1.35 (l＝24m)	k＝1.40 (l＝25m)
	CU CU d CU c	80.3 83.0 80.1	78.6 80.2 79.1	79.1 80.9 79.7	80.9 83.2 81.9	82.0 85.4 83.3	80.6 83.9 81.5	80.6 83.9 81.5	78.5 80.5 80.0										76.0 78.5 77.0

Annotate: k---Combination Distance coefficient; L---Combination Distance.L=kr, r are sprinkler pattern range, r=18m.

Claims (3)

1. the uniformity coefficient of sprinkler irrigation computing method based on continuous system is characterized in that, this method is under the theoretical condition of a continuous system to the sprinkling irrigation water distribution, and it is dark to utilize the dark data interpolating of actual measurement precipitation to calculate unknown point precipitation; When in the shower nozzle spray test during rain gage bucket radial arrangement, by radially carrying out cubic spline interpolation with circumferential twice pair of measured data, it is dark to calculate unknown point precipitation, when rain gage bucket grid in the shower nozzle spray test is arranged, adopt horizontal and vertical twice pair of measured data to carry out cubic spline interpolation, it is dark to calculate unknown point precipitation.

2. the method for claim 1 is characterized in that, follows these steps to carry out when rain gage bucket is for radial arrangement in the shower nozzle spray test:

(1) with the shower nozzle is central point, the radial arrangement rain gage bucket;

(2) beginning spray test, it is dark to read in the rain gage bucket precipitation;

(3) on the uniformity coefficient reference area, be initial point, set up rectangular coordinate system, the dark data of precipitation are begun to handle with the shower nozzle.

(4) utilize every measured data on the horizontal rain gage bucket deployment line to carry out horizontal cubic spline interpolation, calculate any unknown point on every x wire or the water depth value of uniformity coefficient calculation level;

(5) utilize water depth value on the vertical line of a determining deviation, adopt all water depth values on the vertical line of any spacing that cubic spline interpolation obtains; Utilize every measuring point, promptly rain gage bucket arranges that measured data on the ray carries out cubic spline interpolation radially, calculates any unknown point on every ray or the water depth value of uniformity coefficient calculation level;

(6) utilize the interpolation point water depth value, calculate uniformity coefficient of sprinkler irrigation.

3. the method for claim 1 is characterized in that, follows these steps to carry out when rain gage bucket in the shower nozzle spray test is the grid layout:

(1) with the shower nozzle be central point, grid is arranged rain gage bucket;

(2) beginning spray test, it is dark to read in the rain gage bucket precipitation;

(3) on the uniformity coefficient reference area, set up rectangular coordinate system;

(4) utilize every measured data on the horizontal rain gage bucket deployment line to carry out horizontal cubic spline interpolation, calculate any unknown point on every x wire or the water depth value of uniformity coefficient calculation level;

(5) utilize water depth value on the vertical line of a determining deviation, adopt all water depth values on the vertical line of any spacing that cubic spline interpolation obtains;

(6) utilize the interpolation point water depth value, calculate uniformity coefficient of sprinkler irrigation.

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