Dimensi saluran Primer

1. Saluran Primer ( Intake )

Luasan area (A) = 50

Kebutuhan air bersih (NFR) = 1.825

Koefisien (c) = 0.65

Maka :

Q =NFR X A

=c

Q =1.825 x 50

0.65

Q = 0.14

A. Hitungan Dimensi Saluran :

Kemiringan talud (m) = 1

Koefisien Strickler (K) = 35

Tinggi jagaan (w) = 0.30

Panjang saluran = 110.5

Maka :

V = 0.30 ( Tabel De vos)

Dengan :

b= n = 2

h

b = 2 h ...................................................................( Pers I )

Sehingga :

A =QV

A =0.14

= 0.470.30

A = ( b + m h ) h =

m3/dt

A = 3.0 ..................................................................... (Pers III )

Eliminasi Persamaan II dan III :

0.47 = 3.00 h =

Nilai h disibtitusikan ke persamaan I :

b = 2 x h

b = 2 x 0.40 = 0.79

B. Kontrol Dimensi Saluran :

a. Kontrol terhadap nilai A

A = ( b + m h ) h

A = 0.79 + 1.0 x

A = 0.47 ............................................................................ Ok

b. Kontrol terhadap nilai V

V =QV

V =0.14

= 0.300.47

C. Hitung Kemiringan penampang basah ( P ) :

P = b + 2 h 1 +

P = 0.79 + 2 x 0.40

P = 0.79 + 0.79008 x 2.00

P = 0.79 + 0.79008 x 1.41

P = 1.91 m

D. Hitung Kemiringan Saluran ( I ) :

R =A

= R =P

Maka :

V =

h2

h2

m2

K x R2/3 x I 1/2

0.30 = 35 x 0.25 x

0.30 = 13.721 x

I =0.30 2

13.721

I = 0.000478

E. Kesimpulan :L = 111 m

A = 50 ha

Q = 0.14 m3/dtV = 0.30 m/dt

b = 0.79 m « 0.80 mW = 0.30 mK = 35m = 1.0 mh = 0.40 m

i = 0.000478

Elevasi Tanah Asli :P0 P1 P2

35.00 33.92 33.05Elevasi Muka Air Rencana :

P0 P1 P234.24412 34.118 33.9934.14412

Elevasi Dasar Saluran :P0 P1 P2

33.75 33.72 33.60Elevasi Tanggul :

P0 P1 P234.54 34.42 34.29

i2/3

I1/2

ha

lt/dt/ha

( tabel )

1.8250.9 x 0.875 x 0.825

: 1.0

m ( Tabel )

m

...................................................................( Pers I )

............................................. ( Pers II)

A = 2 h + 1.0 h h

m2

..................................................................... (Pers III )

0.47h = 0.40 m

3.0

0.79 m ( dibulatkan menjadi b = 1.40 m )

0.40 0.40

............................................................................ Ok

m/dt .................................... Ok

1 + 1.0 2

0.47= 0.25 m

1.91

m2

m

I1/2

Q =

Dimensi saluran Tersier

1. Saluran Primer AG.0-AG.1

Luasan area (A) = 48 ha

Kebutuhan air bersih (NFR) = 2.5 lt/dt/ha

Koefisien (c) = 0.83

Maka :

Q =NFR X A

=2.5

c 1 1.0 x 0.8

Q =2.5 x 48

0.83

Q = 0.145

2. Hitungan Dimensi Saluran :

Kemiringan talud (m) = 1 : 1

Koefisien Strickler (K) = 35 (Saluran lining)

Tinggi jagaan (w) = 0.30 m

Panjang saluran = 170.7 m

Maka :

V = 0.3 ( Tabel De vos)

Dengan :

b= n = 1

h

b = 1 h ...................................................................( Pers I )

Sehingga :

A =QV

A =0.15

= 0.48 .................................... ( Pers II) 0.3

A = ( b + m x h ) h = A = 1 h + 1.0 h h

A = 2 ..................................................................... (Pers III )

m3/dt

m2

h2

Eliminasi Persamaan II dan III :

0.48 = 2 h =0.48

h = 0.49 m2.0

Nilai h disibtitusikan ke persamaan I :

b = 1 x h

b = 1 x 0.49 = 0.49 m

3. Kontrol Dimensi Saluran :

a. Kontrol terhadap nilai A

A = ( b + m x h ) h

A = 0.49 + 1.0 x 0.49 0.49

A = 0.48 .......................................................................... Ok

b. Kontrol terhadap nilai V

V =QA

V =0.15

= 0.30 m/dt .................................... Ok0.48

4. Hitung Kemiringan penampang basah ( P ) :

P = b + 2 h 1 +

P = 0.49 + 2 x 0.49 1 + 1.0 2

P = 0.49 + 0.9847 x 2.00

P = 0.49 + 0.9847 x 1.41

P = 1.88 m

5. Hitung Kemiringan Saluran ( I ) :

R =A

= R =0.48

= 0.26 mP 1.88

Maka :

V =

h2

m2

m2

K x R2/3 x I 1/2

0.30 = 35 x 0.26 x

0.30 = 14.156 x

I =0.30 2

14.16

I = 0.000449

6. Kesimpulan :

A = 48.0 ha

Q = 0.15 m3/dt

V = 0.30 m/dt

b = 0.49 m

W = 0.30 m

K = 35

m = 1.0 m

h = 0.49 m

i = 0.000449

Elevasi Tanah Asli :P3 P4 P5

33.58 34.22 34.27Elevasi Muka Air Rencana :P3 P4 P5

33.87 33.74 33.615Elevasi Dasar Saluran :

P3 P4 P533.37 33.25 33.12

Elevasi Tanggul :P3 P4 P5

34.17 34.04 33.42

i2/3 I1/2

I1/2

...................................................................( Pers I )

.................................... ( Pers II)

..................................................................... (Pers III )

.......................................................................... Ok

.................................... Ok

33.86533.99

34.1175934.24412

34.14412

33.9933.8665933.7396433.61463