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Substituting values and sampling, we will receive:
Kh\ ctgfy - Ke\h2 + h3 (( + ej ) + l3h3 = 0 (10)
If a = Kctge = kb\; c = h3 (( + ej ) + l3h3 ,
we will receive: Where
ahh -eh + c = 0
(11)
"al
(12)
k ■ b11 ±J(kb! )2 - 4xctg$ h3 (( + b1 ) + h3i
h2 =-^-
iKCtgfy
The sizes irrigating furrow it is defined from equality of trapezes ABCO and OAEF (fig. 3). Designating the area of trapeze ABCO through S1 and the area of trapeze OAEE through S2, we find depth of an irrigating furrow h
Sj = S2 (13)
f + B
(14)
2a 1 + e, , 2d1 + el,
, = 2 (2d' -1) = .h,
2a1 + e, 2a1 + e.
(15
The general depth of a furrow after leveling by a layer of earth: h=hj+h3 (16) Where h — the general cross-section depth of a furrow, sm.
Figure 3. The scheme to definition of depth of an irrigating furrow
Considering that depth of a furrow should be uniform and accepting an inclination corners a (fig. 3), we will define its sizes:
e = 8j • cosa and 2a = 2a1 • cosa (17)
Being based on the sizes e1=12 sm, 2 a=4 sm, 2d=6 sm and a= =60 ° and accepting width of a furrow equal B=90 sm, A=20 sm we define the sizes for h3=1 sm, 2 sm, 3 sm, 4 sm, 5 sm and 6 sm.
Results are shown on figure 4, whence it is possible to establish depth of an irrigating furrow depending on height of a layer of earth on a surface of seeds of wheat.
Definition distance between the ends of wings. The distance between the ends of wings is defined as follows:
B1 = e ■ 2b1 + 2ell and B1 = e + 2L (18)
h1 - depth of a furrow, h2 - height a layer of earth, h3 - height of a layer of earth on a surface of seeds.
Figure 4. Dependence of height of a layer of earth and depth of a furrow on height spreading a layer of earth on wheat seeds
Definition of a corner of an inclination of wings a. The corner of an inclination ofwings is defined considering resistance of a layer of earth and also this layer should not be excessive (i. e. ahead of wings the excessive layer should not gather).
References:
1. Efimenko T. A., Milovanov E. D. «Keng ihtisosli yosh mehanizatorlar uchun qo'llanma». - Toshkent. O'qituvchi. - 1978.
2. Muhamedov J. M., Bayboboev N. G. «G'o'za qator oradariga bug'doy ekish tehnologiyasi va tehnik vositalarini yaratishning ilmiy-amaliy asoslari». Toshkent. Fan va tehnologiya. - 2015.
3. Quziev U. T. Kombinatsiyalashgan agregat pushta hosil qilgichining parametrlarini asoslash: dis. kan. teh. nauk. - Toshkent, - 2010.
DOI: http://dx.doi.org/10.20534/ESR-16-9.10-228-230
Choriev Jamshid Muzaffarovich, Bakiev Masharif Ruzmetovich, Tashkent Institute of Irrigation and Melioration, Tashkent, Uzbekistan E-mail: jamshidc77@gmail.com
Mobile water measuring weir with rectangular opening for farmlands
Abstract: The article shows the importance of equipping seasonal irrigation canals with water measuring devices and describes a mobile water measuring weir with a rectangular opening. It also provides some simple formulas for main sizes for weir elements and instructions for its installation.
Keywords: accurate water measurement, seasonal irrigation canals, mobile water measuring weir, rectangular opening, rubberized material.
Mobile water measuring weir with rectangular opening for farmlands
Public concept about limited water distribution and control changes continuously and the reason for it is the fact that the competition has been increasing between various water using spheres of economy, such as, for example, agriculture, industry, municipal water use, esthetic water use, recreation and many others. Since the water resources are limited, main researches in the sphere of water use must be based on the amount ofwater used, consciously wasted water amounts, water use impact on environment and etc. Water users will have to increase their share of water use by the means of the latest technologies and the most efficient key to such technology is accurate water measurement practices.
Organization of farm enterprises in the Republic of Uzbekistan resulted in the increase of the number of water consumers significantly. Therefore, the problem of delivering water to each consumer, i. e. farmer by their schedule complicated even further, but still each farmer must receive water according to determined irrigation norms, their plant type and other factors [1].
Stationary water discharge measuring weirs made of steel sheets are well known. Stationary weirs are bulky and their installation at seasonal irrigation canals is unreasonable since seasonal irrigation canals are built for one season. Besides, the number of sectional and seasonal canals is so large, that their equipping with measuring devices requires significant material costs and land alienations. They cannot be carried over from one place to another [2].
Farmer must know, what amount of water is necessary to grow a plant and order that amount exactly, therefore water measurement must be organized directly in the field. Installation of 31 thousand water measuring devices throughout the republic has been foreseen. Besides that, equipping field water distribution canals with water measurers would be reasonable [3].
Based on the above-mentioned facts, mobile water measuring weir with rectangular opening has been constructed by Prof. M. R. Bakiev, Ph. D. E. I. Kirillova, assistant J. M. Choriev in the department of Hydraulic construction and engineering structures of the Tashkent institute of Irrigation and melioration. These mobile water measuring weirs are 3-4 times cheaper than the stationary ones, and they can be carried over to the next field after watering the previous one or can be reassembled and kept for use next season.
Picture 1 illustrates the structure of the mobile water measuring weir with rectangular opening.
The body of the weir is made of rubberized fabric (1), it has a rectangular opening (2) for water passage, glued or sewed sleeves (3) for vertical bars (4, 5), horizontal bars (6, 7), openings (8) for stakes (9) to fasten the weir on the canal bottom, scale (10) to measure pressure head and discharge, apron (11) to protect canal bottom from scouring, glued or sewed patches (12, 13) for strengthening angles and holes. Measuring rod (17) and cross level (18) are also added to the weir. The measuring rod is installed at the distance of 3H (H-water depth) from the weir at the head race. The cross level is used to make sure the weir is installed horizontally level.
Horizontal and vertical bars have curved ends to make sure they overpass through sleeves.
In order to raise the stability of weir the horizontal bars are doubled in separate sleeves.
Pressure head measuring scale can be printed on the fabric directly or can be glued or sewed separately. The scale shows the pressure head and discharge value, so the discharge passing through the weir can be read directly.
Such mobile water measuring weir can be fabricated individually by a farmer.
1. For individual fabrication the canal sizes and maximal discharge must be known.
2. For mass production of it the typical sizes and maximal discharges of sectional canals and seasonal canals are taken as a basis.
3. The necessary width of rubberized material (1) BT depends on the width of the weir opening, and the distance from sides to slopes on each side must be no less than h .
l max
4. Weir material height
6)
It
bt
18
11
Picture 1. Mobile water measuring weir with rectangular opening
a) head race view; 6) tail race view; b) joints; r) patches. 1 - rubberized material body; 2 - discharge opening; 3 - vertical and horizontal bar sleeves; 4 - side bars; 5 - berm bars; 6 - bottom horizontal bars; 7 - upper horizontal bars; 8 - openings for bottom stakes; 9 - bottom stakes; 10 - measuring scale; 11 - apron; 12 -angle patch; 13 - circle patch; 14 - material bending line; 15 - material cutting line; 16 - seam; 17 - measuring rod; 18 - cross level;
V T - weir threshold mark; V nECC - water level at tail race;
V yT - canal bottom level at tail race.
¿r = Kax + P' + Ht +1 + K , mm (1)
where: P' = V T-AnECC = 30 to 50 mm (for free air access under threshold at tail race);
V T - tail race mark;
V nECC - water mark at tail race for maximal discharge;
t - bent part of the material for upper horizontal bar sle eves (3) t = 2t' + a + 2a' mm (2)
where: t'=1,75d — sleeve width;
' c '
a' = 2 mm seam width;
a = 2 mm if sewed; a = 10 mm if glued;
d — side vertical bar and threshold horizontal bar diameters
c
can be determined from the condition of thin wall weirs. d
— < 0,5 or d<0,5H H c
K — height of buried part of material below canal bottom, K=200 mm.
5. The diameter of upper horizontal bars may be taken equal to threshold ones or determined designed statically by the condition of their stability.
6. Side vertical bar length
t =
Ä=0° ß=90 Sinß=1
sin в
- + K ,
t c = tT + К mm
(3)
(4)
(5)
(6)
7. Length of vertical bars on berms (2')
l6 =(0,5 0,8)
8. Upper horizontal bar length (3)
i p = BT + 2e6
where e6 = 100 mm — berm width for seasonal canals;
e.=500 mm — berm width for sectional canals.
6
9. Length of threshold horizontal bars (3')
ip = B + 0,5(BT -Bcy )mm (7)
10. Bending width for side vertical bars.
t= t +2 a (8)
where t = 2,5 d — sleeve width.
c
11. Width of weir linen for bar direction
t = t + a (9)
12. Apron sizes for tail race scouring prevention: width B=eK, length if = 2hmax, where e— canal bottom width.
Below there is a worked example for determining the sizes for individual fabrication of a mobile water measuring weir with a rectangular opening.
Given: Design discharge Q = 40 l/s, channel bottom width bc = =0.3m, maximum depth h = 0.23 m, overall height H = 0.3 m,
' L max ' c c '
berm width bb = 0.1 m, slope ratio m = 1.0, roughness coefficient n = =0.03, flow velocity V = 0.37 m/s, longitudinal channel slope i = =0.002.
We take the standard threshold width to be B = 250 mm. From the table we determine, that for the given discharge the pressure of H = 19.5 would be enough, so we take H = 20 sm.
According to above given formulas we determine the structure parameters: By = 400mm , BT = 1100mm , t' = 10,5mm, t = 30mm,
lT = 740mm , lc = 912mm, l6 = 597mm , lp ■
4300mm , I. = 150mm ,
l't = 650mm
t1 = 22mm , t2 = 24,5mm ф = 300mm, 1ф = 460mm.
l' = 230mm , l" = 299mm ,
Based on the obtained sizes we determine the material amounts for mobile weir individial fabrication: ribberized linen — 1.96 m2, steel rod d6mm — 6.88 m, measuring rod — 0.4 m, scale — 1 ea, paint — 0,5 l, fabric for encasement — 0.4 m2.
The installation recommendations for mobile water measuring weir are as follows:
a) it must be installed on straight part of canal;
b) weir is installed perpendicularly to canal axes. The water level measuring rod is installed at the distance of at least 3H, where H is the depth of water at head race;
c) at the head race the canal berms must be raised to the height It to prevent overflow and sufficiently compacted;
d) the distance from the edge of the weir to canal slope at head race must be no less than hmax;
e) free air access under weir threshold at tail race must be provide, therefore P= V T- Vn6CC=30;
f) water seepage through sides and bottom is not accepted, i. e. must be hermetic;
g) after completing watering the field, the weir can be carried over to the next seasonal canal;
h) at the end of vegetation period the weir can be reassembled and kept for the use next year.
Conclusions
1. Irrigation canals including sectional and seasonal ones must be equipped with water measuring devices.
2. Each farmer must measure water entering the irrigated land for each plant specifically.
3. Mobile water measurement weirs for farmers can be fabricated individually based on canal sizes and maximal discharge or mass produced based on the typical sizes and maximal discharges of sectional canals and seasonal canals.
References:
1. Постановление Президента Республики Узбекистан от 19 апреля, 2013 г. №ПП-1958 «О мерах по дальнейшему улучшению мелиоративного состояния орошаемых земель и рациональному использованию водных ресурсов на период 2013-2017 годы (Decree of the President of the Republic of Uzbekistan №ПП-1958 dated April 19, 2013 "About measures on further improvement of reclamation condition of irrigated lands and rational use of water resources for the period of2013-2017).
2. Хамадов И. Б., Бутырин М. В. Эксплуатационная гидрометрия в ирригации. Колос, - М., - 1975 г., - 208 с. (Hamadov I. B., Buti-rin M. B. Operational hydrometry in irrigation. - Kolos, - M., - 1975., - 208 p.)
3. Бочкарев Я. В. Эксплуатационная гидрометрия и автоматизация оросительных систем. Агропромиздат, - М. - 1987 г. - 175 с. (Operational hydrometry and irrigation system automatization. Agropromizdat publishing, - M. - 1987. - 175 p.)
4. URL: http: www.dissercat.com/content/propusknaya-sposobnost-vodoslivov-prakticheskogo-treugolnogo-poperechnogo-profilya-s-zakrugl#ixzz3zC7QiOFz
5. URL: http: www.dissercat.com/content/razrabotka-i-issledovanie-sredstv-ucheta-vody-i-avtomatizatsii-podachi-zadannykh-rask-hodov-n#ixzz3zC7QiOFz
