SISTEM IRRIGASI Didik Suprayogo Bahan Bacaan: http://www.fao.org/docrep/R4082E/r4082e06.htm
IRRIGASI
Penyiapan tindakan yang memungkinkan petani untuk menyediakan kecukupan air bagi tanamannya yang dikumpulkan dan disalurkan dari tempat lain
FUNGSI IRIGASI Fungsi utama: Memenuhi kebutuhan air tanaman Fungsi spesifik: 1. mengambil air dari sumber (diverting) 2. Membawa/mengalirkan air dari sumber ke lahan pertanian (conveying) 3. mendistribusikan air kepada tanaman (distributing) 4. mengatur dan mengukur aliran air (regulating and measuring)
SISTEM IRRIGASI? The irrigation system consists of: • Diverting: a (main) intake structure or (main) pumping station, • a conveyance system, • a distribution system, • regulating and measuring: • •
a field application system, and a drainage system
SISTEM IRRIGASI
The (main) intake structure, or (main) pumping station, directs water from the source of supply, such as a reservoir or a river, into the irrigation system.
The conveyance system assures the transport of water from the main intake structure or main pumping station up to the field ditches.
The distribution system assures the transport of water through field ditches to the irrigated fields.
The field application system assures the transport of water within the fields.
The drainage system removes the excess water (caused by rainfall and/or irrigation) from the fields.
Pumping station conveyance system
distribution system
field application system
MAIN INTAKE STRUCTURE
The intake structure is built at the entry to the irrigation system (see Fig. 70). Its purpose is to direct water from the original source of supply (lake, river, reservoir etc.) into the irrigation system.
PUMPING STATION
In some cases, the irrigation water source lies below the level of the irrigated fields. Then a pump must be used to supply water to the irrigation system (see Fig. 71).
PUMP
There are several types of pumps, but the most commonly used in irrigation is the centrifugal pump. The centrifugal pump (see Fig. 72a) consists of a case in which an element, called an impeller, rotates driven by a motor (see Fig. 72b). Water enters the case at the center, through the suction pipe. The water is immediately caught by the rapidly rotating impeller and expelled through the discharge pipe.
BENDUNGAN URUGAN TANAH DAN WADUK PERTANIAN (EMBUNG)
Sumber gambar : http://www.flickr.com/photos/erensdh/4025394008/
KEGUNAAN BENDUNGAN URUKAN TANAH DAN WADUK PERTANIAN (EMBUNG) Penyediaan air untuk irigasi Mengendalikan atau mengontrol kelebihan air Rancangan ditentukan integrasi anatara prinsip fisika tanah dan mekanika tanah sebagai rancangan dan penerapan prinsip prinsip konstruksi keteknikan Tinggi konstruksi tidak lebih dari 15 m. Bendungan dikonstruksi dari tumpukan tanah dimana bahan tanah ditimbun merata secara berlapis dan dilanjutkan dengan pemadatan pada kondisi kelembaban yang optimum untuk mencapai kepadatan maksimum yang ditargetkan.
RANCANGAN BENDUNGAN URUKAN TANAH DAN WADUK PERTANIAN (EMBUNG) Rancangan untuk mengontrol air diprediksi atas dasar:
Sifat pondasi, yaitu: stabilias, kedalaman pada lapisan yang kedap air, permiabilitas tanah, dan kondisi drainase Kondisi setempat dan ketersediaan bahan konstruksi
Macam Konstruksi:
Embung sederhana Lapisan kedap air terpusat (core / Zoned type) Tipe diafragma / pancang
Dasar waduk: 70% pasir, 20 s/d 25 % liat, dan cukup debu, Tanah diurug 0.3 m di padatkan Paling tidak 0,6 m harus ada tanah diatas batuan
Bila tidak ada bahan tsb, dapat dilakukan campuran bentonit dg tanah dengan minimum mengandung 10 s/d 15% pasir, Atau dg polyphosfate, atau bahan kimia lainnya, atau film plastic atau butyl
Blanket di perpanjang = 8 s/d 10 kali kedalaman waduk Tebal Blanket = 10% kedalaman waduk, minimum 1m
Dari bahan plastik, butyl, beton, logam, kayu
PERSYARATAN PONDASI
Untuk bendung kecil cukup dengan bor tanah bila lebih besar perlu mengkaji kondisi bawah tanah dan kondisi geologi, untuk uji mekanika tanah:
Distribusi ukuran partikel tanah Indek plastis dan cair Kekuatan geser tanah, Kompressibilitas Permiabilitas
Macam Pondasi:
Batuan pejal; kadang ada malahan bahaya bocor, untuk itu perlu sementasi / injeksi bahan semen Pasir halus yang seragam, bila dibawah “kepadatan kritis” (void ratio dimana tanah mengalami deformasi walupun tanpa merubah volume), maka pondasi ini harus dikonsolidasi untuk mencegah aliran akibat beban penggenangan Pasir kasar dan kerikil, pada saat penggenangan akan mengaalami konsolidasi, pelapisan bahan kedap air di bagian muka diperlukan untuk mencagah kebocoran, Liat yang plastis, tekanan geser yang diakibatkan oleh berat bendungan harus lebih kecil dari pada ketahanan geser bahan pondasi, side slope yang lebih mendatar diperlukan untuk mengurangi tekanan geser
RANCANGAN YANG DISESUAIKAN BAHAN YANG TERSEDIA Ranacangan ditetapkan pada keguanaan secara ekonomis yang paling murah yang didasarkan dari bahan yang tersedia di tempat bangunan Rancangan Penampang melintang tergantung kondisi pondasi dan ketersediaan bahan urukan, contoh: kombinasi lapisan kedap air dan Lapisan kedap air terpusat dilakukan untuk pondasi yang tidak kedap air yang dalam. Untuk pemadatan dan kapasitas penahanan air:
Kerikil : pasir: debu: dan liat untuk kepadatan maksimum = < 20% kerikil, 2050% pasir, < 30% debu dan 15-25% liat Tanah yang mudah mengembang dan mengkerut hanya di gunakan pada yang tergenang, Bahan organik tanah harus di kelupas dari konstruksi
AIR REMBESAN MELALUI BENDUNGAN Air rembesan tergantung pada karakteristik bahan tanah baik untuk pondasi dan urukannya. Pemahaman dan pengetahuan posisi garis rembesan penting untuk mengontrol rembesan. Garis rembesan adalah garis diatas rembesan: diatas garis ini tidak ada tekanan hidrostatis, dibawah garis ini ada tekanan hidrostatis Garis rembesan dipengaruhi: (1) permebilitas bahan urukan dan pondasi, (2) posisi dan aliran air bawah tanah, (3) tipe dan rancangan bendungan, (4) penggunaan perangkat drainase untuk menampung rembesan dibagian bawah bangunan.
e =h/3 q = (K(h – e)/L)*((h + e)/ 2) = (K/2) * ((h2 – e2)/L) = (4Kh2/9L) q max
q = (4Kh2/9L) e = 23/3 = 7.6 m L = (2Z + h – e/2) cot α + W + 0.3M L = (2X3 +23 – 7.6/2) x 1 +6+6.9 = 38.1 m q = (4 x 0.0176 x 23 x 23)/ (9X 38.1) q = 0.1086 m3/ d per lineal meter of length
PERLAKUAN PONDASI Macam pondasi: (1) batu, (2) material bertekstur halus (liat dan debu), material bertekstur kasar (pasir dan kerikil). Bahan batu harus hati hati melihat sambungan, patahan geologi, lapisan permiabel. Bahan bertekstur halus: penglupasan bahan organik, buat galian profil sedalam 0.6 s/d 1 m dengan lebar bawah 4 s/d 6 m Bahan bertektus kasar: dibuat profil hingga kedalaman lapisan kedap air, atau batuan, lebar bawah minimum 3 m s/d 6 m
Tinggi minimum lapisan kedap air sebagai penyumbat air adalah setengah dari tinggi bendungan, side lope kurang dari 1:1, Minimum lewbar bagian atas lapisan kedap air 1.2 m
Drainase:
SIDE SLOPE AND BERMS, TOP WIDTH Kurang 15 m < tajam dari 3:1 bagian depan dan 2:1 bagian belakang, Bahan urukan kasar 3:1 atau 4:1 Top width bendungan < 5 m = 2.4 m, Top width > 5 m W = 0.4 H + 1
Freeboard
h = 0.014 (Df) 1/2
Net and gross freeboard embung 0.6 ha, dimana panjang permukaan air = 183 m, asumsi frost depth = 0.15 m, dengan periode ulang 25 th Q max = 4.00 m3/detik, dengan kedalaman aliran spillway =0.3 m H = 0.014 (183)1/2 = 0.19 m, flood storage depth = 0.6m Net freeboard = 0.15 + 0.19 = 0.34 m Gross freeboard = 0.34 + 0.3 + 0.6 = 1.24 m
Mechanical Spillways
CONVEYANCE AND DISTRIBUTION SYSTEM
The conveyance and distribution systems consist of canals transporting the water through the whole irrigation system. Canal structures are required for the control and measurement of the water flow.
OPEN CANALS An open canal, channel, or ditch, is an open waterway whose purpose is to carry water from one place to another. Channels and canals refer to main waterways supplying water to one or more farms. Field ditches have smaller dimensions and convey water from the farm entrance to the irrigated fields.
CANAL CHARACTERISTICS According to the shape of their cross-section, canals are called rectangular (a), triangular (b), trapezoidal (c), circular (d), parabolic (e), and irregular or natural (f) (see Fig. 73).
CANAL CHARACTERISTICS The most commonly used canal cross-section in irrigation and drainage, is the trapezoidal cross-section. For the purposes of this publication, only this type of canal will be considered. The typical cross-section of a trapezoidal canal is shown in Figure 74.
CANAL CHARACTERISTICS The freeboard of the canal is the height of the bank above the highest water level anticipated. It is required to guard against overtopping by waves or unexpected rises in the water level. The side slope of the canal is expressed as ratio, namely the vertical distance or height to the horizontal distance or width. For example, if the side slope of the canal has a ratio of 1:2 (one to two), this means that the horizontal distance (w) is two times the vertical distance (h) (see Fig. 75).
A BOTTOM SLOPE OF A CANAL
EARTHEN CANALS Earthen canals are simply dug in the ground and the bank is made up from the removed earth, as illustrated in Figure 77a. The disadvantages of earthen canals are the risk of the side slopes collapsing and the water loss due to seepage. They also require continuous maintenance (Fig. 77b) in order to control weed growth and to repair damage done by livestock and rodents.
LINED CANALS Earthen canals can be lined with impermeable materials to prevent excessive seepage and growth of weeds (Fig. 78). Lining canals is also an effective way to control canal bottom and bank erosion. The materials mostly used for canal lining are concrete (in precast slabs or cast in place), brick or rock masonry and asphaltic concrete (a mixture of sand, gravel and asphalt). The construction cost is much higher than for earthen canals. Maintenance is reduced for lined canals, but skilled labour is required.
CANAL EROSION Canal bottom slope and water velocity are closely related, as the following example will show. A cardboard sheet is lifted on one side 2 cm from the ground (see Fig. 79a). A small ball is placed at the edge of the lifted side of the sheet. It starts rolling downward, following the slope direction. The sheet edge is now lifted 5 cm from the ground (see Fig. 79b), creating a steeper slope. The same ball placed on the top edge of the sheet rolls downward, but this time much faster. The steeper the slope, the higher the velocity of the ball. Water poured on the top edge of the sheet reacts exactly the same as the ball. It flows downward and the steeper the slope, the higher the velocity of the flow. Water flowing in steep canals can reach very high velocities. Soil particles along the bottom and banks of an earthen canal are then lifted, carried away by the water flow, and deposited downstream where they may block the canal and silt up structures. The canal is said to be under erosion; the banks might eventually collapse.
DROP STRUCTURES AND CHUTES Drop structures or chutes are required to reduce the bottom slope of canals lying on steeply sloping land in order to avoid high velocity of the flow and risk of erosion. These structures permit the canal to be constructed as a series of relatively flat sections, each at a different elevation (see Fig. 80). Drop structures take the water abruptly from a higher section of the canal to a lower one. In a chute, the water does not drop freely but is carried through a steep, lined canal section. Chutes are used where there are big differences in the elevation of the canal.
DISTRIBUTION CONTROL STRUCTURES Distribution control structures are required for easy and accurate water distribution within the irrigation system and on the farm: 1. Division boxes 2. Turnouts 3. Checks
DIVISION BOXES Division boxes are used to divide or direct the flow of water between two or more canals or ditches. Water enters the box through an opening on one side and flows out through openings on the other sides. These openings are equipped with gates (see Fig. 81).
TURNOUTS Turnouts are constructed in the bank of a canal. They divert part of the water from the canal to a smaller one. Turnouts can be concrete structures (Fig. 82a), or pipe structures (Fig. 82b).
CHECKS To divert water from the field ditch to the field, it is often necessary to raise the water level in the ditch. Checks are structures placed across the ditch to block it temporarily and to raise the upstream water level. Checks can be permanent structures (Fig. 83a) or portable (Fig. 83b).
CROSSING STRUCTURES It is often necessary to carry irrigation water across roads, hillsides and natural depressions. Crossing structures, such as flumes, culverts and inverted siphons, are then required. 1. Flumes 2. Culverts 3. Inverted siphons
FLUMES Flumes are used to carry irrigation water across gullies, ravines or other natural depressions. They are open canals made of wood (bamboo), metal or concrete which often need to be supported by pillars (Fig. 84).
CULVERTS Culverts are used to carry the water across roads. The structure consists of masonry or concrete headwalls at the inlet and outlet connected by a buried pipeline (Fig. 85).
INVERTED SIPHONS When water has to be carried across a road which is at the same level as or below the canal bottom, an inverted siphon is used instead of a culvert. The structure consists of an inlet and outlet connected by a pipeline (Fig. 86). Inverted siphons are also used to carry water across wide depressions.
WATER MEASUREMENT STRUCTURES
The principal objective of measuring irrigation water is to permit efficient distribution and application. By measuring the flow of water, a farmer knows how much water is applied during each irrigation.
In irrigation schemes where water costs are charged to the farmer, water measurement provides a basis for estimating water charges.
The most commonly used water measuring structures are weirs and flumes. In these structures, the water depth is read on a scale which is part of the structure. Using this reading, the flow-rate is then computed from standard formulas or obtained from standard tables prepared specially for the structure.
WEIRS In its simplest form, a weir consists of a wall of timber, metal or concrete with an opening with fixed dimensions cut in its edge (see Fig. 87). The opening, called a notch, may be rectangular, trapezoidal or triangular.
PARSHALL FLUMES The Parshall flume consists of a metal or concrete channel structure with three main sections: (1) a converging section at the upstream end, leading to (2) a constricted or throat section and (3) a diverging section at the downstream end (Fig. 88). Depending on the flow condition (free flow or submerged flow), the water depth readings are taken on one scale only (the upstream one) or on both scales simultaneously.
CUT-THROAT FLUME The cut-throat flume is similar to the Parshall flume, but has no throat section, only converging and diverging sections (see Fig. 89). Unlike the Parshall flume, the cutthroat flume has a flat bottom. Because it is easier to construct and install, the cut-throat flume is often preferred to the Parshall flume.
PENGUKURAN DEBIT AIR
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Pengertian Dasar • Debit air adalah Jumlah air yang mengalir pada suatu luasan persatuan waktu tertentu misalnya: (liter/detik) atau (liter/menit), (liter/detik) atau (m3/menit)
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Peralatan Pengukuran Peralatan yang dapat digunakan untuk mengukur debit air harus disesuaikan dengan kondisi aliran air yang akan diukur Debit aliran yang kecil (1 s/d 5 lt/dt) cukup digunakan alat sederhana misalnya ember untuk mengukur volume dan arloji, jam tangan untuk mengukur waktu
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Untuk debit yg sedang dan besar ( > 5 lt/det) maka diperlukan alat ukur yang lebih baik dan lebih teliti Peralatan tersebut antara lain dinamakan current meter, yakni alat yang berfungsi mengukur kecepatan aliran air dg sangat teliti.
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Dasar Perhitungan • Rumus dasar: • Q=AxV Dimana : Q = debit aliran (m3/det) A = Luas penampang aliran (m2) V = Kecepatan aliran air (m/det)
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PENGUKURAN AIR DI PIPA
FAKULTAS PERTANIAN UNIVERSITAS BRAWIJAYA
Debit Aliran Melalui Pipa Debit aliran yang melalui pipa dapat diukur debitnya dengan cara meletak suatu alat yang disebut meter air. Q =C A (2gh)1/2 C= 0.6 Prinsip kerja alat ini adalah merubah kecepatan aliran air menjadi putaran baling-2 (propeller) dan kemudian dirubah dalam satuan debit. Alat elektrik, singnal listrik, solar panel, transmisi radio Meteran air
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Mengukur debit air yang keluar dari Pipa
Untuk debit kecil dapat diukur dg peralatan ember dan jam tangan Q = A x V atau Q = Vol / waktu
Ember
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Contoh perhitungan • • • •
Volume ember 6 liter: Waktu pengambilan air = 2 detik Maka debit aliran adalah Q = 6/2 = 3 liter/detik Pengambilan air harus dilakukan minimal 5 kali agar didapatkan hasil yg cukup teliti, dengan cara diambil harga rata-rata dari semua nilai yg didapat 57
Memperkiraan debit yg lewat Pipa tertutup Q =AxV A = Luas penampang pipa (cm2 atau inc2) V = Kecepatan aliran lewat pipa (m/dt) Contoh perhitungan : Kondisi Pipa dianggap penuh air, maka A = ¼ µ d2, , d = diameter pipa ( 4 inci=10 cm) A = ¼ x3,14 x(10) 2 = 78,5 cm2 V = kecepatan air misal = 1 m/det=100 cm/dt, maka Q = 78,5 x 100 = 7850 cm3/det= 7,85 lt/dt 1 hari = 24 jam=60 menit=86400 detik Q = 7,85 x 86400 =678240 lt/dt=678,24 m3/hari • Harga 1 m3=Rp 100,- = 67800,-/hari • Harga 1 bln=30 hari = 30 x 67800 = Rp. 2.034.000,-/bln
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PENGUKURAN AIR DI SALURAN TERBUKA
FAKULTAS PERTANIAN UNIVERSITAS BRAWIJAYA
Debit Air pada Saluran Irrigasi / Sungai Untuk debit pada saluran irrigasi /sungai kecil dapat diukur dengan cara sbb: • Dengan menggunakan pelampung/gabus yang diletakkan pada permukaan air yg sedang mengalir dan dicatat waktunya menempuh jarak tertentu • Mengukur kedalaman air dan lebar saluran /sungai dengan meteran
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Contoh Gambar 2
1
10 m, t =…..det? Misal t = 10 det V = 10 m/10 det = 1 m/det b=2m
Bila rata aliran = 80% aliran pelampung
h = 0,5 m
A = b x h = 2 x 0,5 = 1 m2, maka Q = A x V = 1 x 1 x 0.8 = 0.8 m3/det
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Gambar Current Meter
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PERSYARATAN PENGUKURAN DEBIT DI SUNGAI
Persyaratan yang di maksud antara, lain meliputi : 1. Lokasi pengukuran; 2. Jumlah dan waktu pengukuran; 3. Peralatan, tenaga pelaksana dan dana.
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1. Lokasi Pengukuran Mempunyai pola aliran yang seragam, kecepatan alirannya tidak terlalu lambat atau terlalu cepat. Pengukuran yang baik pada lokasi yang mempunyai kecepatan aliran mulai dari 0,20 m/det sampai dengan 2,50 m/det; kedalaman aliran pada penampang pengukuran harus cukup, kedalaman aliran yang kurang dari 20 cm biasanya sulit diperoleh hasil Yang baik.
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Jangan Pada aliran turbulen/bergolak Yang disebabkan oleh batu-batu, vegetasi, penyempitan lebar alur sungai dilakukan pada alur sungai yang stabil atau lurus, lokasi pengukuran debit mudah didatangi, tidak tergantung dari keadaan cuaca khususnya pada musim penghujan atau pada saat terjadi banjir;
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2. Jumlah dan waktu pengukuran; • Pelaksanaan pengukuran debit, hasilnya harus dapat menggambarkan sebuah lengkunng debit untuk sebuah penampang basah yang tidak tetap, • Jumlah pengukuran debit minimal 10 buah untuk sebuah lengkung debit yang datanya tersebar mulai keadaan aliran terendah sampai tertinggi 67
• Sedangkan periode pelaksanaannya tergantung daripada musim. • Pada musim kemarau pada umumnya cukup satu sampai dua kali selama keadaan aliran masih tetap rendah. • Pada musim penghujan memerlukan frekuensi pengukuran Yang lebih banyak, yaitu minimal 3 kali
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Lengkung Debit
1,4 Tinggi air (m)
1
0
2 Debit air (m3/det)
5
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3. Peralatan, tenaga pelaksana dan dana • Gabus, curret meter, arloji, meteran dll • Mininal 1 -2 orang • Tergantung situasi
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Bangunan Pengukur Debit pada Saluran Irigasi 1.Bangunan Cipoletti Berbentuk Segi empat 2.Bangunan Thomson
H B
Berbentuk setitiga H
Q = a Hb 71
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• Pintu Sorong
H
B
Bila sungainya besar? Bagaimana cara mengukurnya?
• Misal lebar sungai = 20 meter • Kedalaman air 2 meter • Berapa debit nya? b=
m?
h =…m?
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FIELD APPLICATION SYSTEMS
There are many methods of applying water to the field. The simplest one consists of bringing water from the source of supply, such as a well, to each plant with a bucket or a water-can (see Fig. 90). This is a very time-consuming method and it involves quite heavy work. However, it can be used successfully to irrigate small plots of land, such as vegetable gardens, that are in the neighbourhood of a water source. More sophisticated methods of water application are used in larger irrigation systems. There are three basic methods: Surface irrigation Sprinkler irrigation Drip irrigation
SURFACE IRRIGATION Surface irrigation is the application of water to the fields at ground level. Either the entire field is flooded or the water is directed into furrows or borders. Furrow irrigation Border irrigation Basin irrigation
FURROW IRRIGATION
Furrows are narrow ditches dug on the field between the rows of crops. The water runs along them as it moves down the slope of the field. The water flows from the field ditch into the furrows by opening up the bank or dyke of the ditch (see Fig. 91a) or by means of syphons or spiles. Siphons are small curved pipes that deliver water over the ditch bank (see Fig. 91b). Spiles are small pipes buried in the ditch bank (see Fig. 91c).
BORDER IRRIGATION
In border irrigation, the field to be irrigated is divided into strips (also called borders or borderstrips) by parallel dykes or border ridges (see Fig. 92). The water is released from the field ditch onto the border through gate structures called outlets (see Fig. 92). The water can also be released by means of siphons or spiles. The sheet of flowing water moves down the slope of the border, guided by the border ridges.
Perkiraan aliran (l/detik) pada siphons H H (cm)
Diameter siphons (mm) 27
34
42
53
63
76
5
0.3
0.6
0.9
1.5
2.1
3.1
7
0.4
0.7
1.1
1.8
2.5
3.7
10
0.5
0.8
1.3
2.1
3.0
4.5
15
0.6
1.0
1.6
2.6
3.7
5.5
20
0.7
1.1
1.8
3.0
4.3
6.3
30
0.8
1.4
2.2
3.6
5.2
7.7
50
1.1
1.8
2.8
4.7
6.8
10.0
PANJANG MAKSIMUM IRRIGASI ALUR (m) Q max (l/s)
S (%)
Rata-rata kedalaman air yang diterapkan (m) 75
150
225
30 0
50
Liat
100
150
200
50
75
Lempung
100
125
Pasir
6.0
0.1
340
440
470
50 0
180
340
440
470
90
120
190
220
1.2
0.5
400
500
560
75 0
280
370
470
530
120
190
250
300
0.3
2.0
220
270
340
40 0
180
250
250
340
60
90
150
190
BASIN IRRIGATION
Basins are horizontal, flat plots of land, surrounded by small dykes or bunds. The banks prevent the water from flowing to the surrounding fields. Basin irrigation is commonly used for rice grown on flat lands or in terraces on hillsides (see Fig. 93a). Trees can also be grown in basins, where one tree usually is located in the centre of a small basin (see Fig. 93b).
SPRINKLER IRRIGATION
With sprinkler irrigation, artificial rainfall is created. The water is led to the field through a pipe system in which the water is under pressure. The spraying is accomplished by using several rotating sprinkler heads or spray nozzles (see Fig. 94a) or a single gun type sprinkler (see Fig. 94b).
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Irigasi dalam budidaya tanaman tebu di GMP : tujuan
•
Menekan kejadian defisit air yang dialami oleh tanaman tebu : durasi, intensitas, dan luasan tanaman yang menderita
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Menekan kehilangan hasil pasca musim kemarau yang ekstrim hingga sekecil mungkin
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Memantapkan tingkat produksi dari tahun ke tahun dan mening-katkan produktivitas secara sinambung
Irigasi dalam budidaya tebu di GMP : pendekatan •
Pengembangan potensi sumber-daya air : pengukuran dan peme-taan; identifikasi karakter sumber air; reklamasi sumber/badan air
•
Pemeliharaan dan pelestarian sumberdaya air : penghijauan DAS; pengendalian erosi; pengendalian gulma air dan gulma terestrial
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Penguasaan teknik aplikasi irigasi : pengetahuan dasar, perhitungan, pemilihan sistem, penyediaan prasarana dan sarana
•
Penyesuaian budidaya : bulan tanam, block system
Irigasi dalam budidaya tebu di GMP : pilihan sistem aplikasi •
Perhitungan kebutuhan air tanaman
•
Penentuan prioritas stadia pertumbuhan tanaman yang diirigasi
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Irigasi curah vs irigasi tetes vs irigasi alur
•
Irigasi curah : big-gun mobile sprinkler vs travelling irrigator
DRIP IRRIGATION
In drip irrigation, also called trickle irrigation, the water is led to the field through a pipe system. On the field, next to the row of plants or trees, a tube is installed. At regular intervals, near the plants or trees, a hole is made in the tube and equipped with an emitter. The water is supplied slowly, drop by drop, to the plants through these emitters (Fig. 95).
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DRAINAGE SYSTEM
(A drainage system is necessary to remove excess water from the irrigated land. This excess water may be e.g. waste water from irrigation or surface runoff from rainfall. It may also include leakage or seepage water from the distribution system.
Excess surface water is removed through shallow open drains (see Surface drainage, Chapter 6.2.1). Excess groundwater is removed through deep open drains or underground pipes (see Subsurface drainage, Chapter 6.2.2).
TUGAS KUALITAS AIR IRIGASI 1. Pemerintah telah mengeluarkan standar kualitas Air Irigasi, untuk itu dari standar tersebut, melalui studi literatur deskripsikan teknik mengukur masing-masing standar kualitas air irrigasi tersebut. Mengapa kualitas tersebut penting bagi pertanian. 2. Kualitas Air di sepanjang Sungai Brantas telah di lakukan monitoring secara periodik oleh Perum Jasa Tirta, tetapkan wilayah pengairan yang memenuhi standar air irrigasi dan wilayah pengairan yang tidak memenuhi standar air irrigasi, dari waktu kewaktu. 3. Melalui kajian literatur, beri rekomendasi bagaimana cara agar wilayah pengairan yang tidak memenuhi standar kualitas air irigasi menjadi air irigasi yang memenuhi standar kualitas air irigasi bagi usaha pertanian.
STRATEGI KONSERVASI AIR (1) REDUCE PLANT WATER DEMAND
A. Plant selection B. Site landscape design C. Plant cultural practices D. Root zone depth E. Mulching F. Soil amendments
(2) MAXIMISE IRRIGATION APPLICATION EFFICIENCY (3) PRECISE CONTROL OF IRRIGATION
(4) ADOPT NEW TECHNOLOGIES (5) OPERATOR SKILLS
STRATEGI KONSERVASI AIR (1) REDUCE PLANT WATER DEMAND (2) MAXIMISE IRRIGATION APPLICATION EFFICIENCY
A. High uniformity B. Optimise hydraulic operating conditions for outlets C. Correct outlet selection D. Effective outlet coverage E. Effective functioning of equipment F. Low head drainage
(3) PRECISE CONTROL OF IRRIGATION
(4) ADOPT NEW TECHNOLOGIES (5) OPERATOR SKILLS
STRATEGI KONSERVASI AIR (1) REDUCE PLANT WATER DEMAND (2) MAXIMISE IRRIGATION APPLICATION EFFICIENCY (3) PRECISE CONTROL OF IRRIGATION
A. Match irrigation to plant water demand B. Correct depth of irrigation C. Hydrozones
(4) ADOPT NEW TECHNOLOGIES
A. Weather stations B. Soil moisture sensors C. Smart controllers D. Alternative method of irrigation - Subsurface drip
(5) OPERATOR SKILLS
TERIMAKASIH
