Tugas 4Analisa Resiko dan Daya Rusak Air

Dosen Prof. Ir. Iwan Kridasantausa, Ph.D.Nama Taty YuniartiNIM 95014318No. absen14

Diketahui :

- Luas Das (A) = 500 ha = 5E+06 m2

- (tc) = 5 jam ; asumsi

>> Intensitas Hujan (I)Rumus Mononobe

Stasiun Djangkar, Jawa Timur

No Tahun R24 (mm) I (mm/jam) - Koefisien Limpasan1 1916 118 13.992 1917 100 11.863 1918 134 15.894 1919 197 23.365 1920 190 22.536 1921 93 11.037 1922 160 18.978 1923 296 35.099 1924 173 20.51

10 1925 120 14.2311 1926 63 7.4712 1927 80 9.4913 1928 44 5.2214 1929 77 9.1315 1930 68 8.0616 1931 70 8.3017 1932 159 18.8518 1933 165 19.5619 1934 123 14.5820 1935 55 6.5221 1936 83 9.8422 1937 86 10.2023 1938 107 12.6924 1939 76 9.01

Rata-rata I 14.02 mm/jam 0.0000039 m/sStdev I 6.8847417 mm/jam 0.0000019 m/s

Koefisien Variansi I 0.4912358

>> Koefisien Run off ( C )Kawasan

ProsentaseRange Koefisien Run-Off ( C ) Rata-rata

design valu min maxA1 Hutan 25% 1,250,000 0.2 0.1 0.3 0.20 0.0416667A2 Industri 35% 1,750,000 0.75 0.6 0.9 0.75 0.0066667A3 Pemukiman 40% 2,000,000 0.5 0.4 0.6 0.50 0.0066667

Rumus nilai rata-rata: Rumus Koefisien Variansi:

- Nilai koefisien run-off gabungan:

= 0.5125

Waktu Konsentrasi

Luas (m2)Koef.Varian

si (Ω2)

SaluranA1 = Hutan

A2 = SawahA3 = Pemukiman

𝐼_𝑡=𝑅_24/24 (24/𝑡)^(2/3)

𝐶_𝑔𝑎𝑏= (𝐶_1 𝑥𝐴_1+𝐶_2 𝑥 𝐴_2+𝐶_3 𝑥𝐴_3 )/𝐴

)(3

1ucx )(

6

1

2

12

2 uuccx

x

- Koefisien variansi gabungan

= 0.1354006

>> Debit aliran (Loading)- Q = C.I.A

= 9.97606 m3/s

- Koefisien variansi loading:

= 0.5095546

>> Saluran (Resistance)Resiko

5% 10% 15% 20%Prob. Resiko desain 0.05 0.1 0.15 20%Kehandalan 1-resiko 0.95 0.9 0.85 80.00%

Loading

Debit 9.9761 9.9761 9.9761 9.9761Koef.Variansi 0.50955 0.50955 0.50955 0.50955

Stdev 5.08335 5.08335 5.08335 5.08335

Resistance

Debit 18.4335 16.5738 15.2901 14.3027 ; goalseekKoef.Variansi 0.05 0.05 0.05 0.05 ; asumsi

Stdev 0.92167 0.82869 0.764504 0.715135

Py 1.63706 1.28100 1.03375 0.84284 Prob. Resiko hitung 0.05081 0.10010 0.15063 0.19966

0.00 0.00 0.00 0.00

rumus Py:

- Dimensi Saluran Trapesium TerbaikQ design = Q resistance 18.4335 16.5738 15.2901 14.3027h 3.16627 3.04247 2.9519 2.8789 ; goalseek

3.6561 3.5131 3.4085 3.3243

1.7321 1.7321 1.7321 1.732128.9404 26.7216 25.1537 23.925516.3212 15.6830 15.2160 14.8398

1.773 1.704 1.653 1.612

n 0.023 0.023 0.023 0.023

S 0.0001 0.0001 0.0001 0.0001

Q hitung 18.4337 16.5738 15.2901 14.3028Qhitung - Q design 0.00 0.00 0.00 0.00

>> Gabungan

RESIKO

5% 10% 15% 20%

-10 0.0001306 0.00043052 0.00091778 0.00158183-9 0.000256 0.00078984 0.0016077 0.0026732-8 0.0004832 0.00139545 0.00271169 0.00434933-7 0.0008786 0.0023742 0.00440392 0.00681291-6 0.0015388 0.00388999 0.00688657 0.01027455-5 0.002596 0.00613774 0.01036889 0.01491804-4 0.0042183 0.00932604 0.01503232 0.02085355-3 0.0066025 0.01364628 0.02098383 0.02806518-2 0.0099542 0.01922913 0.02820386 0.03636429-1 0.0144555 0.02609355 0.03650037 0.045362990 0.0202203 0.03409847 0.04548318 0.054481331 0.0272439 0.04291065 0.05457195 0.062996012 0.0353574 0.05200241 0.06304534 0.070129023 0.0441997 0.06068903 0.07012961 0.075162624 0.0532213 0.06820642 0.07511296 0.077557795 0.0617278 0.07381907 0.0774628 0.077049236 0.068961 0.07693788 0.07691951 0.073693747 0.0742087 0.07722184 0.07354358 0.067859768 0.0769191 0.07463944 0.06770457 0.060160779 0.0767965 0.06947441 0.06001449 0.05134921

10 0.0738545 0.06227442 0.05122231 0.0421962311 0.0684134 0.05375549 0.04209468 0.0333835812 0.0610426 0.04468526 0.03330889 0.02542796

Prob.Resiko hitung - Prob resiko design

Koefisien manning

Kemiringan saluran

Q (Tahanan - Beban )

Ω_𝐶𝑔𝑎𝑏=√((〖 Ω1〗 _^2+〖 Ω2〗 _^2+〖 Ω3〗 _^2)/3)

Ω_𝑙𝑜𝑎𝑑𝑖𝑛𝑔=√(〖 Ω𝐶 〗 ^2+〖 Ω𝐼〗 _^2 )

𝑏=2/√3 ℎ𝑚=√3𝐴=(𝑏+𝑚ℎ)ℎ𝑃=𝑏+2ℎ√(1+𝑚^2 )𝑅=𝐴/𝑃

2222

LRLR LR

LRLRP

13 0.052463 0.03577124 0.02537804 0.0186470214 0.0434311 0.02757605 0.01861748 0.0131651815 0.034632 0.02047191 0.0131507 0.0089487816 0.0266 0.01463568 0.0089442 0.0058562517 0.0196795 0.01007618 0.00585732 0.0036897418 0.0140241 0.00668047 0.00369336 0.0022381619 0.0096264 0.00426527 0.00224238 0.0013070920 0.0063647 0.00262249 0.00131088 0.0007349221 0.0040535 0.00155278 0.00073787 0.0003978222 0.0024866 0.00088539 0.00039991 0.0002073323 0.0014693 0.00048617 0.00020869 0.00010403

- Grafik

>> Resiko dan Safety Factor

- C gab = 0.5125- Luas Das = 5,000,000 m2

TahunHujan I Q = CIA mm mm/jam m3/s

1916 118 13.99 9.961917 100 11.86 8.441918 134 15.89 11.311919 197 23.36 16.631920 190 22.53 16.031921 93 11.03 7.851922 160 18.97 13.501923 296 35.09 24.981924 173 20.51 14.601925 120 14.23 10.131926 63 7.47 5.321927 80 9.49 6.751928 44 5.22 3.711929 77 9.13 6.501930 68 8.06 5.741931 70 8.30 5.911932 159 18.85 13.421933 165 19.56 13.921934 123 14.58 10.381935 55 6.52 4.641936 83 9.84 7.001937 86 10.20 7.261938 107 12.69 9.031939 76 9.01 6.41

Rata-rata 9.98Stdev 4.9006Koef.Variansi 0.49124

- Asumsi berupa distribusi normal

P L=Qt (m3/s)

2 0.5 9.985 0.2 14.10

10 0.1 16.2620 0.05 18.0425 0.04 18.5650 0.02 20.04

100 0.01 21.38

Kala Ulang T (tahun)

-15 -10 -5 0 5 10 15 20 250

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

Distribusi Normal Resiko

5% 10% 15% 20%

m3/s

- Asumsi resistance saluran dipilih dengan resiko gabungan 5%Periode Beban TahananUlang Loading Stdev resiko Nominal Resistance Stdev resiko Nominal Resiko Resiko

(tahun) (L) σL αL (*asumsi) (Ln) (R ) σR αR (*asumsi) (Rn) (%)2 9.98

4.90 0.20

14.10051

18.43 0.92 0.05 16.92

1.1998 0.082 8.1965 14.10 18.22495 0.9283 0.286 28.606

10 16.26 20.38088 0.8301 0.447 44.72720 18.04 22.16127 0.7634 0.589 58.88125 18.56 22.67991 0.7459 0.629 62.87350 20.04 24.16510 0.7001 0.734 73.445

100 21.38 25.50100 0.6634 0.814 81.440

- Grafik

SF=Rn/Ln

9 11 13 15 17 19 21 230.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

0

10

20

30

40

50

60

70

80

90

Grafik SF dan Resiko

SFResiko

Debit Rata-rata (m3/s)

SF

%

0 10 20 30 40 50 60 70 80 90 1000.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

0

10

20

30

40

50

60

70

80

90

Grafik SF dan Resiko

SFResiko

Periode Ulang (tahun)SF

%