Hidrologi HutanKiki P. Utomo

1 But Alarming

Gambar 1. Siklus hidrologi (www.projectwet.org)

Gambar 2. Siklus hidrologi dengan area boundary (local hydrology cycle)(Waniliesta, 1990: 28)

Gambar 3. Potongan melintang sebuah daerah tangkapan air (de Laat, --- : 7)

Kelembaban tanah (SM)

Evapotranspirasi (E)

Presipitasi(P)

Limpasan(RO)

Input = output ± DSP = E + RO ± SM

Gambar 4. Sistem hidrologi yang disederhanakan untuk menghitung neracaair (Thompson, 1999 : 189)

Lautan DaratanLuas (km2) 361 300 000 148 800 000

Presipitasi (km3/th) 458 000 119 000

(mm/th) 1 270 800

Evaporasi (km3/th) 505 000 72 000

(mm/th) 1 400 484

Limpasan ke laut

Sungai (km3/th) 44 700

Air tanah (km3/th) 2 200

Total limpasan ke laut (km3/th) 47 000

(mm/th) 316

(Kiely, 1996:149, diadaptasi dari UNESCO, 1978)

Tabel 1. Neraca air dunia

Benua Luas (106

km2)P (mm/th) E (mm/th) R (mm/th)

Eropa 10,0 657 375 282

Asia 44,1 696 420 276

Afrika 29,8 695 582 114

Australia 7,6 447 420 27

Amerika Utara 24,1 645 403 242

Amerika Selatan 17,9 1564 946 618

Antartika 14,1 169 28 141

Total neraca air didaratan

148,9 746 480 266

Tabel 2. Neraca air berdasarkan benua

(Kiely, 1996:152, berdasarkan data dari Baumgartner dan Reichel, 1975)

Penggunaan lahan P (mm) E (mm) D (mm)

ΔS/Δt (mm)

Neraca air tahunan Tanah terbuka 841 201 640 0

Semak belukar 841 480 361 0

Pepohonan 841 1213 469 0

Neraca air Tanah terbuka 46 33,4 25,9 -13,3bulan Juni Semak belukar 46 66,8 6,8 -27,6

Pepohonan 46 143,6 10,6 -58,6

Neraca air Tanah terbuka 91,4 10,9 67,5 13bulan Oktober Semak belukar 91,4 27,4 23,7 40,3

Pepohonan 91,4 83,7 17 82,1

Tabel 3. Neraca air yang diukur dengan alat lysimeter di Castricum, Belanda

Keterangan:D : discharge out, ΔS/Δt : perubahan tampungan menurut waktu

(Modifikasi dari de Laat, ---:7)

Tomo’omi Kumagai, Hironari Kanamori, and Tetsuzo Yasunari (2013), Deforestation-induced reduction in rainfall, Hydrol. Process. 27, 3811–3814 (2013)

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Gambar 6. Curah hujan tahunan 2008 - 2017 di Camp Induk Stasiun Riset Cabang Panti

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Gambar 7. Curah hujan tahunan 2013 - 2016 di Sukadana dan Camp Induk Stasiun Riset Cabang

Panti

Gambar 8. Curah hujan bulanan tahun 2015 di Sukadana dan Camp Induk Stasiun Riset Cabang

Panti

Sep 2015SKDN CP

P (mm) 0 31,6

Hari hujan 0 5

Figure 1. (c) The decreasing trend (– 12.7 mm year-1) in annual precipitation integrated over Borneo, in the period 1951–2007. A significant regression line is also shown (p <0.0001). Note that even though precipitation data in 1997 and 1998, when a strong

El Niño event occurred and caused an extreme drought, were excluded, this decreasing trend was unchanged

Mean annual precipitation measured from 2009 to 2012 was 2900 ± 610 mmyr-1,~20–35% lower than two 1990 era measurements reported for the same region [Curran and Leighton, 2000; Lawrence and Schlesinger, 2001]

Figure 2. Maps of (a) annual mean moisture convergence and (b) annual mean precipitation in the western Pacific Ocean (constructed using Japanese 25-year Reanalysis and Tropical Rainfall Measuring Mission satellite measurements 3B42 Ver.7

datasets, respectively, with values averaged over the period 1998–2010).

Tomo’omi Kumagai, and Masayuki Hara (2017), Impact of Tropical Deforestation and Forest Degradation on Precipitation over Borneo Island, Journal of Hydrometeorology, September

2017 DOI: 10.1175/JHM-D-17-0008.1

FIG. 3. Monthlymean LHF

FIG. 9. As in Fig. 3, but for Pmon.

Figure 14.57 Hyetographs and stream flow hydrographs after Elsenbeer, H. and Lack, A., 1996a. Hydrometric and hydrochemical evidence for fast flowpaths at La Cuenca, Western Amazonia. J. Hydrol., 180: 237–250

Source: M. Bonell, (2005) Runoff generation in tropical forests in Forests, Water and People in the Humid Tropics, ed. M. Bonell and L. A. Bruijnzeel. Published by Cambridge University Press

0.00E+00

2.00E+07

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E + RO P (2014) P (2015) P (2016)

Gambar 7. Neraca air Lubuk Baji berdasarkan data curah hujan Stasiun Sukadana 2014 - 2016

Source: Carlson, K. M., L. M. Curran, A. G. Ponette-González, D. Ratnasari, Ruspita, N.Lisnawati, Y. Purwanto, K. A. Brauman, and P. A. Raymond (2014), Influence of watershed-

climate interactions on stream temperature, sediment yield, and metabolism along a land use intensity gradient in Indonesian Borneo, J. Geophys. Res. Biogeosci., 119,

DOI:10.1002/2013JG002516.

Streams draining watersheds characterized by five land uses: intact forest, logged forest, mixed agroforest, and young(<3 years) and mature (>10 years) oil palm plantation

Praktik 1 Juli 2019

• Pengukuran kecepatan aliran air di sungai• Menghitung debit aliran• Kualitas air sungai: DO, pH, temperatur, NO2, NO3, mineral

Topik Latihan Lapangan:1. Neraca air: pengukuran debit aliran,

hubungan curah hujan dan debit aliran

2. Potensi air: neraca air DAS Panti3. Sifat hujan di Gunung Palung dan

pengaruhnya pada ekosistem (curah hujan vs ketinggian)

4. Kualitas air sungai5. Merencanakan riset hidrologi hutan

Gambar 4. Curah hujan harian di Camp Induk Stasiun Riset Cabang Panti 2007 - 2017

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Gambar 5. Temperatur harian di Camp Induk Stasiun Riset Cabang Panti 2007 - 2017