Siklus Air

2. II. Penyebaran dan struktur
perairan Tawar

3. Freshwater
• Water in lakes & streams - 0.02%
of water on earth
• Covers <2% of world’s land area
• Most water found in just 20 deep
(>400 m) lakes throughout world

4. Water never leaves the Earth. It is constantly being
cycled through the atmosphere, ocean, and land. This
process, known as the water cycle, is driven by
energy from the sun. The water cycle is crucial to the
existence of life on our planet.

6. The Water Cycle

7. During part of the water cycle, the sun heats up liquid
water and changes it to a gas by the process of
evaporation. Water that evaporates from Earth’s
oceans, lakes, rivers, and moist soil rises up into the
atmosphere.

9. The process of evaporation from plants is called
transpiration. (In other words, it’s like plants
sweating.)

11. As water (in the form of gas) rises higher in the atmosphere, it
starts to cool and become a liquid again. This process is called
condensation. When a large amount of water vapor
condenses, it results in the formation of clouds.

13. When the water in the clouds gets too heavy, the
water falls back to the earth. This is called
precipitation.

15. When rain falls on the land, some of the water is absorbed into
the ground forming pockets of water called groundwater. Most
groundwater eventually returns to the ocean. Other
precipitation runs directly into streams or rivers. Water that
collects in rivers, streams, and oceans is called runoff.

17. Distribusi Perairan Tawar
1 % Air Tawar
Sungai:
0,001/0,1%

18. The Hydrosphere
Hydrosphere: the part
of Earth that
contains water
• 97% of Earth’s
water is salt water
• Only 3% is fresh
water: (30%
groundwater, 68%
frozen, 2% on surface)

19. Saltwater
• Oceans cover 71% of Earth’s surface (about ¾)
• Land takes up 29% of Earth’s surface (about ¼)
• 2 categories of water in the Hydrosphere…based
on Salinity = % salt content
• Saltwater:
• 97% of Earth’s water
• Oceans
• 35 g salt/kg of water
• How many oceans are currently recognized
today??!!

20. Freshwater
• Freshwater:
• < 1 g salt/kg of water
• ONLY 3% of Earth’s water is fresh
• 2/3 of that is frozen in glaciers, ice
caps, & icebergs (pieces of glaciers
floating in ocean)
• 1/3 of that is liquid & accessible in
lakes, ponds, rivers, streams, or
underground

21. Freshwater Resources
• Most freshwater
is frozen at the
polar ice caps!!
• Glaciers are masses
of ice and snow
that move slowly
over the Earth’s
surface.

23. The Great Lakes are the largest freshwater
System on earth. They contain 84% of
North America’s surface freshwater and
21% of the world’s surface fresh water
supply. Only the polar ice caps contain
more fresh water.

24. Freshwater Resources
• 1/3 of Earth’s freshwater is
groundwater!!
• Groundwater forms when water
moves through soils and
sediment and collects in spaces
underground.
• An aquifer is a rock layer that
stores water in the spaces
between the rock and allows
water to flow through it.

25. Water Drainage Patterns
• Precipitation hits the surface of Earth 
• 1.) If Permeable/Pervious Surface = water will
sink in Ex: Sand, Gravel, Dirt
• 2.) If Impermeable/Impervious Surface = water
will not sink in, may be trapped in basin OR may
run off from high  low elevation
• Ex: Red Clay, Cement, Asphalt

26. Water Drainage Patterns
• Divide = high ridge of land from which water will
flow in different directions
• Watershed/River Drainage Basin = drainage
area where all water from one side of a divide
flows, all water flows to one central river based
on the topography (curves/elevation) of the land
• What River Basin do we live in??
• Catawba River Wateree River Santee River
 Atlantic Ocean!

27. Examine A Watershed

28. Possible Water Flow Example
• Precipitation 
• Land 
• Flows Downhill 
• Stream 
• River 
• Larger River OR Lake 
• Estuary = mix of fresh & salt water in a bay 
• Ocean!!...all water ends up here 

29. Groundwater
• Water that seeps into the soil & is pulled down
by gravity
• Can move or sit under the surface if there are
spaces between the rock/soil particles
(permeable)
• Water will seep down until it hits an
impermeable surface, then fill up from there
(like your bathtub with the drain closed!)
• The region filled with ground water = Saturation
Zone
• The top surface of this area = Water Table

30. Water Table & Saturation Zone

31. Aquifers
• Underground permeable rock or sediment that
contains water
• Particles in ground act like filter to water!!

32. Ogallala Aquifer – under U.S.
• Huge source of
freshwater for
drinking & irrigation
in the U.S.
• Depleting at alarming
rate…
• “The average annual
depletion rate
between 2000 and
2007 was more than
twice that during the
previous fifty years!”

33. Groundwater to the Surface Via…
• 1.) Man-made Well – pipe dug into ground to
extract water from aquifer
• 2.) Artesian Well – water flows naturally to
surface because it’s under pressure
• 3.) Spring – water flows to surface because
surface of land dips below water table
• 4.) Hot Spring/Geyser – water heated up by
rocks, pushes up to surface due to pressure

34. Man-Made Well

35. Artesian Well & Spring

36. Distribusi Perairan tawar cont.
• Danau sangat dalam : 20 badan air
• Danau Baikal mengandung volume air sangat besar (20%)
• Danau sangat dalam ( >400 m) umumnya berada di:
a) Amerika Utara
b) Amerika Selatan
c) Afrika tengah
d) Asia

37. Distribusi perairan Tawar Cont.
Sungai di setiap Benua Luas area drainase (103
km 2)
Rata-rata aliran air/tahun
Amerika (Mississippi,
Amazon, Parana)
38.500 527.000
Eropa (Danube,
Rhine,Vistula)
9800 1.000.000
Afrika (Congo, Nile,
Zambezi)
30.300 136.000
Asia (Ob-
Irtysh,Yangtze,Gangga)
45.000 435.000

38. Most Lakes
• Most lakes are much smaller,
shallower (<20 m)
• Lakes can be formed in many
ways
• Two general categories
• Catastrophic
• Non-catastrophic

39. Catastrophic Formation
• Most lakes have catastrophic
origin
• Developed as result of some
violent activity
• Tendency to be clustered together
in lake districts

40. Types of Catastrophic Lakes
• Glacial lakes
• Erosion and deposition by glacial
ice movements
• Most important lake-forming
process
• Most numerous in Northern
Hemisphere

41. Danau dan cekungan danau
Danau :Kumpulan air (tawar/asin) yang terkumpul
pada suatu cekungan dimana aliran air cenderung tenang
Cekungan danau : “mangkuk” atau penurunan permukaan tanah yang
terisi air

42. Sejarah pembentukan dan geologi danau
mempengaruhi
 Area cekungan,bentuk dan kedalaman
 ukuran watershed dan mineral tanah
 Kualitas air dan karakteristik sedimen

43. Sejarah Pembentukan cekungan danau
Berdasarkan sejarah pembentukkan cekungan, danau
terbagi atas:
1. Danau tektonik
2. Danau vulkanik
3. Danau glacial
4. Danau longsoran
5. Danau yang terbentuk dari sungai

44. Danau Tektonik
Danau yang terbentuk karena adanya
penurunan permukaan lapisan bumi
akibat patahan dan pergeseran
http://cuba.ija.csic.es/~danielgc/

45. Jenis danau tektonik: Graben
http://earthquake.u
sgs.gov/learn/glossa
ry/?term=graben
Hasil dari
depresi/penurunan
permukaan bumi yang
terbentuk karena
patahan
Pemukaan cekungan
berbentuk seperti segi-
empat
Contoh:
Lake tahoe
Lake Tanganyika
Lake Baikal

46. Danau Baikal: Danau terdalam
Danau tertua
Kedalaman rata-rata 730
m
Kedalaman maksimum
1620m

48. Jenis danau tektonik : kenaikan dasar laut
• Terjadi karena proses naiknya permukaan dasar laut sehingga
membentuk danau yang dangkal
• Dasar berbahan kapur
L. Okeechobee

49. Danau Vulkanik
Danau yang terbentuk karena aktivitas gunung berapi
Permukaan
Cekungan ber-
Bentuk lingkaran
Air mengisi caldera

50. Danau Toba
Danau vulkanik terbesar di
dunia
Terbentuk karena proses
supervolcanic 69000-
77000 tahun yang lalu

51. Danau Glacial
Danau yang terbentuk karena adanya pencairan es
Jumlah sangat banyak
Menghasilkan danau
yang berukuran besar

52. Danau longsoran (landslide)
• Danau terbentuk karena materi longsor (batu, pasir, lumpur)
memblok pinggiran lembah
Mountain lake, Virginia (6000 tahun)

53. Danau yang terbentuk dari sungai
Danau yang terbentuk
karena penumpukan
materi bawaan sungai
mengakibatkan bagian
sungai terpisah
Permukaan cekungan
berbentuk bulan sabit

54. Solution Lakes
• Bodies formed when water
dissolves soluble rock formations -
karst
• Limestone sinks
• FL, MI, KY, IN, TN
• Cenotes
• Yucatan Peninsula

55. Danau larutan
• Cekungan danau terbentuk ketika mineral yang tersimpan di bawah
permukaan bumi terlarut menciptakan lubang cekungan
• Cekungan berbentuk corong
• Permukaan cekungan berbentuk lingkaran

56. Danau Buatan (Bendungan)
• Genangan air berukuran besar yang diciptakan untuk memenuhi
kebutuhan manusia
• Membendung lembah sungai

57. Lakes formed by Organisms
• Beaver dams
• Human reservoirs
• Sphagnum dams

58. Sungai
• Ekosistem air mengalir
• 0,1% dari seluruh permukaan air dibumi
• Residence time air relatif lebih cepat dari danau
• Gerakan air satu arah

59. Masukan air ke sungai
Sumber masukan air ke sungai:
Aliran air diatas permukaan tanah
Aliran air dibawah permukaan tanah

60. Masukan air ke sungai
Presipitasi
Watershed
Terserap tanaman
Terserap permukaan
tanah
Aliran permukaan
Aliran lateral Water table
Mata air

61. Kanal
• Kanal: cekungan atau lembah yang berisi air mengalir
• Variasi volume aliran air pada kanal sungai dipengaruhi oleh:
a. Musim
b. Intensitas hujan
• Volume air sungai>kapasitas kanal sungai = banjir

62. Struktur danau
PROFUNDAL
SUPRALITTORAL
EULITTORAL
UPPER LITTORAL
MIDDLE LITTORAL
LOWER LITTORAL
LITTORIPROFUNDAL
EPILITTORAL
PELAGIC

63. Struktur danau
• Epilittoral : diatas level air, tidak dipengaruhi percikan air
• Supralittoral:diatas level air, terkena percikan air
• Eulittoral: diantara gelombang tertinggi dan terrendah
• Upperlittoral:makrofita berakar
• Middlelittoral:makrofita mengapung
• Lowerlittoral: makrofita terbenam
• Littoprofundal:cahaya matahari sangat rendah

64. Zonasi Biota

65. Reservoir (Waduk)
• Diciptakan dengan membendung lembah sungai
• Diciptakan untuk tujuan khusus
Cadangan air
Kontrol banjir
Energi listrik

66. Karakteristik waduk
• Kecepatan air mengalir pada saluran waduk dipengaruhi oleh:
a. Masukan air dari watershed
b. Pemanfaatan air
• Keberadaan waduk mempengaruhi perubahan ekosistem di sekitar
waduk

67. Morfologi waduk
RIVERINE
TRANSISI LACUSTRINE

68. Zonasi waduk
Zona Riverina
1. Dangkal
2. Air tercampur sempurna
3. Air kaya material terlarut (lumpur, tanah liat dan bahan organik)
4. Keruh
5. Produktivitas rendah

69. Zonasi waduk
Zona Transisi
1. Arus air melemah
2. Kekeruhan menurun
3. Produktivitas primer meningkat

70. Zonasi waduk
Zona lacustrine
1. Ada stratifikasi suhu
2. Sifat seperti danau

71. Perbandingan karakteristik danau,
sungai dan waduk
Karakteristik Sungai Waduk Danau alami
Watershed Banyak cabang anak
sungai, posisi
watershed curam
Sempit, panjang,
mencakup area
yang luas
Melingkar
mengelilingi
cekungan danau,
area sempit
bentuk Panjang, berkelok-
kelok, bagian sungai
yang lurus
berukuran besar
Beragam, lojong-
segitiga
Bulat-lonjong
Kedalaman rata-
rata
Dangkal di hulu
dalam di hilir
Kedalaman
meningkat dari
zona riverine-
lacustrin
Sedang-sangat
dalam
kemiringan Meningkat dari
hulu ke hilir
Meningkat dari
zona riverine-
lacustrin
Bagian terdalam
berada di tengah
cekungan

72. Perbandingan karakteristik danau, sungai dan
waduk
Karakteristik Sungai Waduk Danau
Erosi Manyeluruh,
disebabkan oleh
arus air, gaya
gravitasi
Menyeluruh pada
zona riverine
karena arus air,
melemah pada
zona lacustrin
Pada lokasi
tertentu,
disebabkan oleh
gelombang dan
arus
kekeruhan Tinggi, berubah-
ubah
Tinggi, berubah-
ubah, kandungan
tanah liat dan
lumpur tinggi
rendah
Fluktuasi level air Tinggi, tidak teratur,
banjir
Tinggi, tidak teratur Rendah, stabil
Wetzel 1990