VARUN
VARUN - Virtual Acoustic Reality for Underwater Noise is an operational program developed by Awareocean that can simulate various underwater noise pollution, transmission and impacts on marine animals.
VARUN Briefing
VARUN provides various underwater noise simulation and visualization effects, such as piling, ships, sonar, wind turbune, etc. It can be used for environmental impact assessment, marine space planning and utilization, sonar performance prediction, etc.
Scenario
01
Pile-driving Noise
VARUN simulates impact piling power from 60 to 4,000 kJ, vibratory hammer piling, bubble curtain noise reduction and damping noise reduction, etc.
05
Wind Turbine Operated Noise
Based on initial conditions such as wind turbine installed capacity and wind speed, the cumulative distribution of underwater noise generated by large numbers of wind turbines is estimated.
04
Sonar Signal
VARUN simulates the transmission of continuous wave (CW) sonar and frequency/amplitude modulation wave (FM/AM/Chirp) sonar to predict the sonar performance.
02
Ship Underwater Radiated Noise (URN)
The underwater radiated noise from construction vessels, commercial ships and research vessels is simulated.
06
Cetacean Hearing Weight
Underwater noise values weighted by simulated cetacean hearing, e.g., low/mid/high frequency cetecean.
08
Wind-driving Wave Noise
VARUN simulates different wind speeds or wave heights to produce changes in ambient noise.
03
Ambient Noise from Shipping
The distribution of low-frequency environmental noise is estimated based on the ships density of AIS data.
07
Fish Hearing Weight
Underwater noise values weighted by simulated fish hearing, e.g., Sciaenidae.
09
Noise Cumulative Impact Prediction
The noise from multiple maritime projects during the same period was estimated together, including piling, construction vessels, and wind turbine operation at nearby wind farms.
Application on EIA
Estimation of the worst impact of pile-driving noise
Simulate an offshore wind farm using impact piling with a power of 3,000 kJ.
Underwater noise maps show the maximum impact area and estimated measurement values.
Cumulative impact of simultaneous piling at nearby wind farms
Simulate two nearby offshore wind farms driving piles at the same time with 3,000 kJ power.
Big bubble curtains (BBC) are used to reduce noise and prevent underwater noise from exceeding the warning value.
Use underwater noise maps to show the overall noise increase and spread.
Ship URN
Simulate the underwater noise emitted by a research vessel at a speed of 10.2 knots.
The underwater noise map shows the results after adding the weighting of cetacean hearing.
Estimating Ship Noise from Ship Density
The ship density value is estimated from the ship automatic identification system (AIS) data.
Underwater noise maps show how ship noise is distributed differently in space.
Successful Cases
VARUN has been successfully used in environmental impact assessment (EIA), ship underwater radiated noise (URN) and marine spatial planning.
Outstanding Paper Award
Impact-driven piles are often used in subsea foundation installation in offshore wind farms. The underwater noise generated by piling is quite loud, which may cause auditory effects and injury to cetaceans. Therefore, in the environmental impact assessment (EIA), it is necessary to simulate the forecasting such as the impact range of piling noise, the occurrence of hearing threshold shift, and the effect of mitigation measures. In this study, the numerical model, Virtual Acoustic Reality of Underwater Noise (VARUN) is used. The received sound pressures at the depths and azimuths are superpositioning and converted into sound waves for underwater noise calculation, which can be calculated in accordance with the underwater noise indicators required by the standards, such as Leq, Lss, LE30s, Lpk and L5s. Since the cumulative impact of underwater noise on cetaceans during the whole process of piling is complex, this study further proposes a piling scenario analysis, and calculates the cumulative pressure of underwater noise on cetaceans based on the conditions of strike intervals and strike numbers, and includes the cetacean hearing weighting as well. Hearing threshold weighting is used to present and analyze the noise impact ranges and the distance of hearing threshold shift in the underwater noise map. The cumulative impact of simultaneous piling in multiple wind farms will be discussed in the conclusions.
