PERHITUNGAN SALURAN SEKUNDER 6 ( SS 6)

Luas area sawah ( A) = 45 Ha

Panjang Saluran = 1652 m

DR max= 3,12 L/det/Ha

Qsawah = A x DR max

= 45 Ha x 3,12 L/det/Ha

= 140,4 L/det

Q saluran = (Qsawah /1000) / 0,85

= (140,4/1000)/0,85

= 0,165 m3/det

Elevasi awal = 4,7 m

Elevasi akhir = 4,5 m

∆H=0,2 m kemiringan ( I) = ∆ HL

= 0,21652

= 0,00012 ( I )1/2 =

√0,0001 2=0 ,011 1

m = 1 m2 = 1 √m2+1=√12+1=1,414

koefisien manning ( n) = 0,013 b= 2h

Luas penampang basah ( A ) = ( b+mh)h = (2h+h)h = 3h2

Keliling basah = b+2h √m2+1 = 2h+2h( 1,414) = 4,828 h

Jari –jari hidrolis = R= AP

= 3h2

4,828h=0,621h R2/3 = ( 0,621 h)2/3 = 0,728 h2/3

Kecepatan aliaran (v) = 1n

(R2/3 x I1/2 ) = 1

0,013(0,728 h2/3 x 0,0111 ) = 0,621 h2/3

Q = A x v = 3h2 x 0,621 h2/3 = 1,86 h8/3

0,165 = 1,86 h8/3

h = ( 0,1651,86

)38 = 0,403 m ≈ 0,4 m b = 2h = 0,806 m ≈ 0,81 m

tinggi jagaan ( w ) = 0,2 x h

= 0,2 ( 0,4)

= 0,08 m