Fishway (Tangga Ikan)

Definisi Fishway

Fishway atau tangga ikan atau jalur ikan adalah gabungan elemen (struktur, fasilitas, perangkat, operasi pemeliharaan, dan upaya atau tindakan) yang diperlukan untuk memastikan pergerakan ikan yang aman, tepat waktu, dan efektif melewati penghalang. Contohnya termasuk, tetapi tidak terbatas pada, tangga ikan yang dapat diatur, lift ikan, jalan pintas, perangkat pemandu, zona lintasan, aliran operasional, dan penghentian suatu unit bangunan.
Istilah "fishway," "fish pass," atau "fish passageway" (dan juga "eelway," "eel pass," atau "eel passageway") dapat dipertukarkan. Namun, Rekayasa (Engineering) merekomendasikan penggunaan istilah "fishway" atau "eelway" karena istilah tersebut konsisten dengan 16 U.S.C. § 811 (1994), yang berbunyi:
“Bahwa hal-hal yang dapat menjadi ‘tangga ikan’ berdasarkan pasal 18 untuk tangga ikan yang aman dan tepat waktu di hulu dan hilir harus dibatasi pada struktur, fasilitas, atau perangkat fisik yang diperlukan untuk memelihara semua tahap kehidupan ikan tersebut, dan operasi serta tindakan proyek yang terkait dengan struktur, fasilitas, atau perangkat tersebut yang diperlukan untuk memastikan efektivitas struktur, fasilitas, atau perangkat tersebut untuk ikan tersebut.”
Istilah " tangga ikan " atau " tangga sidat" mengacu pada tindakan, proses, atau ilmu pengetahuan untuk memindahkan ikan (atau sidat) melewati penghalang aliran sungai, misalnya bendungan.

Zona Lintasan

Zone of Passage (ZOP) atau zona lintasan tangga ikan harus berada di area yang berdekatan yang berupa bentangan alam, baik lateral, longitudinal, dan vertikal yang cukup luas, di mana kondisi hidraulik dan lingkungannya memadai untuk dipertahankan guna menyediakan lintasan melalui aliran sungai yang dipengaruhi oleh bendungan atau penghalang aliran sungai.

Aman, Tepat Waktu, dan Efektif

Elemen tangga ikan dirancang dan dibangun untuk menyediakan tangga ikan yang aman, tepat waktu, dan efektif.
Ketiga karakteristik didefinisikan seebagai berikut :

-   Jalur Aman: Pergerakan ikan melalui ZOP harus tidak mengakibatkan stres, cedera , atau kematian ikan  (misalnya, karena tarikan turbin, benturan, dan bertambahnya pemangsa atau predator). Jika pergerakan melewati penghalang mengakibatkan kematian atau kondisi fisik yang mengganggu perilaku migrasi, pertumbuhan, atau reproduksi,  hal ini tidak boleh dianggap sebagai jalur yang aman untuk tangga ikan.

-  Jalur Tepat Waktu: Pergerakan ikan melalui ZOP harus berlangsung tanpa penundaan atau dampak yang signifikan secara material terhadap pola perilaku penting atau persyaratan riwayat hidup ikan.

-  Jalur Efektif: Pergerakan target spesies yang melalui ZOP harus menghasilkan keselarasan yang menguntungkan antara desain struktural, operasi dan pemeliharaan, dan kondisi lingkungan selama satu atau beberapa periode utama. Efektivitas mencakup penilaian kualitatif (misalnya, integritas papan penahan kayu, pengaturan waktu siklus hopper) dan pengukuran kuantitatif. Istilah "efisiensi" (dan hiponimnya yaitu efisiensi lintasan dan efisiensi tarikan) dicadangkan untuk elemen kuantitatif efektivitas.

=   Efisiensi: Ukuran kuantitatif dari proporsi populasi yang termotivasi untuk melewati penghalang (yaitu, populasi yang termotivasi) yang berhasil bergerak melalui seluruh ZOP; biasanya dinyatakan sebagai produk dari efisiensi tarikan dan lintasan.

=  Efisiensi Tarikan: Ukuran proporsi populasi (yang termotivasi) yang berhasil tertarik ke jalur ikan; biasanya diukur sebagai persentase dari populasi termotivasi yang menemukan dan memasuki jalur ikan.

= Efisiensi Lintasan: Ukuran proporsi ikan yang memasuki jalur ikan yang juga berhasil melewati jalur ikan; keberhasilan melewati jalur ikan biasanya diukur di pintu keluar jalur ikan; juga disebut sebagai "efisiensi jalur ikan internal."

Sumber United States Fish and Wildlife Service Region 5 FISH PASSAGE ENGINEERING DESIGN CRITERIA, Juni 2019, Manual ini menggantikan semua edisi sebelumnya dari Fish Passage Engineering Design Criteria yang diterbitkan oleh U.S. Fish and Wildlife Service Region 5)

Catatan Fishway Groundsill K. Progo
 

Kontruksi groundsill Kali Progo
Foto kontruksi grounsill Kali Progo
Design fishway in Progo River
Design fishway in Opak River
Sabo & Groundsill


Adachi’s formula
On the artificial strip roughness
On grain roughness in rivers and streams
Effect of macrorough sidewalls on flow resistance
Effect boulders arrangement
Fishways in Japan
Fishways in Indonesia
 
 

  
ature like fishways 

 

  
 

  

Location of Fishways

  

 General Consideration of Fishways
 

  
more
 
How to Design Artificial Roughness of the Water Channel 
 

Designing artificial roughness in a water channel involves strategically creating surface irregularities to modify flow characteristics. This is often done to reduce velocity, increase mixing, or improve heat transfer. The design process typically involves selecting appropriate roughness elements, determining their size, shape, and spacing, and considering the impact on the overall hydraulic performance of the channel. 
Here's a more detailed breakdown of the design process:

1. Defining the Purpose and Objectives:

Reduce Velocity:

Artificial roughness can be used to decrease water velocity, which is helpful in areas where high velocities can cause erosion or damage. 

Increase Mixing:

Introducing roughness can improve mixing of the water, which can be beneficial for certain processes like heat transfer or aeration. 

Improve Heat Transfer:

Roughness can enhance heat transfer by increasing the surface area and disrupting the boundary layer, leading to more efficient heat transfer in solar collectors or other applications. 

Specific Application:

The design must be tailored to the specific application. For instance, a stilling basin requires a different roughness design than a solar air collector. 

2. Choosing Roughness Elements:

Types of Roughness:

Artificial roughness can take many forms, including granular roughness (e.g., stones, pebbles), discrete roughness elements (e.g., cubes, plates), or geometric features (e.g., corrugations, fins). 

Materials:

The roughness elements should be made of durable materials that are resistant to water flow and erosion. 

Geometry:

The shape and size of the roughness elements will affect their impact on flow. For example, cubic roughness elements will behave differently than T-shaped roughness elements. 

 3. Determining Roughness Size and Spacing:

Roughness Height (e):

This refers to the height of the roughness elements relative to the channel bed. 

Spacing (s):

The distance between the roughness elements can be expressed in terms of the roughness height (e/s) or the hydraulic radius (R/s). 

Spacing Influence:

Different spacing configurations can affect the flow regime, with different spacing ratios leading to different hydraulic behaviors. 

4. Hydraulic Calculations and Modeling:

Manning's Equation:

This equation can be used to estimate the flow velocity and discharge in the channel with artificial roughness. 

Froude and Reynolds Numbers:

These dimensionless numbers can be used to characterize the flow regime and determine whether it is laminar or turbulent. 

Computational Fluid Dynamics (CFD) Simulations:

CFD can provide detailed simulations of flow behavior over artificial roughness, allowing for a more precise design. 

5. Experimental Validation:

Laboratory Experiments:

Conducting laboratory experiments with scaled models can help validate the design and refine the roughness parameters. 

Field Testing:

Full-scale field testing can be used to verify the design and assess its performance in real-world conditions. 

6. Optimization and Refinement:

Iterative Design:

The design process can be iterative, with adjustments made based on experimental results and simulations. 

Multi-objective Optimization:

In some cases, it may be necessary to optimize the design based on multiple objectives, such as minimizing erosion and maximizing heat transfer. 

 7. Specific Considerations:

Stilling Basins:

Stilling basins require a careful design of artificial roughness to dissipate energy and prevent erosion. 

Solar Air Collectors:

Artificial roughness can be used to enhance heat transfer in solar air collectors, with different roughness geometries leading to different performance. 

By carefully considering these factors and using appropriate design tools, it's possible to create artificial roughness that effectively modifies flow characteristics in water channels for various applications. 

Reference;   

 
 Theory of Laminar and Turbulence Flows 


Calculate the energy dissipation of a fish against turbulent flow (W/m3)

To calculate the energy dissipation of a fish against turbulent flow (in W/m³), you need to determine the rate at which kinetic energy is converted into heat due to turbulent friction. This can be estimated by analyzing the turbulent flow field and applying the principles of energy conservation. The dissipation rate, often denoted by ε (epsilon), represents the energy loss per unit mass and time. 

Here's a breakdown of the process and relevant concepts:
Understanding Energy Dissipation in Turbulent Flow:
Turbulence is characterized by chaotic, swirling motions of fluid. 
These swirling motions create shearstresses within the fluid, leading to energy transfer and dissipation. 
The energy dissipation rate (ε) quantifies how quickly this kinetic energy is converted into heat. 
In the context of fish swimming,this energy dissipation represents the force the fish needs to overcome to navigate turbulent waters. 

Key Parameters and Calculations:

Turbulent Kinetic Energy (TKE):

TKE (k) is the kinetic energy associated with the turbulent fluctuations, calculated as k = 1/2 (u'^2 + v'^2 + w'^2), where u', v', and w' are the fluctuating velocity components in x, y, and z directions, respectively. 

Dissipation Rate (ε):

The dissipation rate can be estimated from TKE and the turbulent length scale (L) using the formula ε ≈ (k^(3/2))/L, according to some researchers. 

Volumetric Dissipation Rate (E):
To get the energy dissipation in W/m³, you need to multiply the dissipation rate (ε) by the fluid density (ρ): E = ρ * ε. 

Experimental Measurement:
Measuring the velocity field (instantaneous and average velocities) and using it to calculate TKE and subsequently ε is crucial, says a study on turbulent flow. 

Practical Considerations for Fish Swimming:
Fish Swimming Speed and Behavior:
The fish's swimming speed and how it interacts with the turbulent flow structures (vortices, etc.) will influence the energy it needs to expend. 

Fish Body Shape and Propulsive Efficiency:
The fish's body shape, fin movements, and how efficiently it propels itself through the water also play a role in energy expenditure. 

Fishway Design:
Fishways (structures designed to help fish migrate upstream) are designed with specific energy dissipation limits to ensure fish can navigate them successfully. 

Example:
Let's say you're studying a fishway with a volumetric energy dissipation rate of 200 W/m³. This means that for every cubic meter of water in the fishway, 200 Joules of energy are being dissipated as heat per second. If a fish is swimming in this area, it needs to expend energy to overcome this dissipation. 

































 

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