Related Experiment Video
Updated: May 28, 2026
12:50
Continuous Instream Monitoring of Nutrients and Sediment in Agricultural Watersheds
Published on: September 26, 2017
Ambient noise in large rivers (L)
Miodrag S Vračar1, Miomir Mijić
1Military Technical Institute, Ratka Resanovića 1, Belgrade, Serbia. vracarmiodrag@open.telekom.rs
The Journal of the Acoustical Society of America
|October 7, 2011
Summary
This study monitored hydroacoustic noise in European rivers for ten years. River flow dynamics significantly impact low-frequency noise, while human activities dominate higher frequencies.
Area of Science:
- Environmental Science
- Acoustics
- Hydrology
Background:
- Hydroacoustic noise in rivers is a critical environmental factor.
- Understanding noise sources is essential for aquatic ecosystem health.
- Large European rivers like the Danube, Sava, and Tisa face diverse environmental pressures.
Purpose of the Study:
- To investigate the characteristics and sources of hydroacoustic noise in three major European rivers over a decade.
- To analyze the correlation between noise spectra and hydrological/meteorological conditions.
- To differentiate the impact of natural factors versus anthropogenic activities on riverine noise levels.
Main Methods:
- Long-term (10-year) hydroacoustic noise monitoring across the Danube, Sava, and Tisa rivers.
- Analysis of noise spectra, focusing on frequency distributions and spectral levels.
- Correlation analysis between noise dynamics and environmental variables (flow rate, speed, wind).
Main Results:
- Noise spectra exhibit broad peaks between 20-30 Hz with a consistent downward slope at higher frequencies.
- Low-frequency noise (<100 Hz) strongly correlates with water flow and speed dynamics.
- Higher-frequency noise is primarily influenced by human activities on and along the rivers.
Conclusions:
- River flow is a key driver of low-frequency hydroacoustic noise.
- Anthropogenic sources are significant contributors to higher-frequency river noise.
- Wind's influence on river noise is less pronounced than in other water bodies due to annual surface variations.
More Related Videos
Related Concept Videos
01:27Laminar Flow
Laminar flow represents a smooth, orderly fluid motion where particles move along parallel paths, resulting in minimal mixing between layers. Streamlined particle paths characterize this flow regime and occur under conditions where viscous forces dominate over inertial forces. The distinction between laminar, transitional, and turbulent flow is primarily determined by the Reynolds number, a dimensionless quantity calculated as:
01:24Freshwater Microbial Ecology
Freshwater systems such as streams, rivers, and lakes exhibit distinct physical and biological characteristics that influence their microbial communities. These environments are broadly categorized into lotic systems—those with flowing waters like streams and most rivers—and lentic systems, which include still or slow-moving waters such as lakes, ponds, and marshes.In lentic systems, phytoplankton drive primary production, generating autochthonous organic carbon. In contrast, lotic systems...
01:24Rapidly Varying Flow
Rapidly varying flow (RVF) in open channels is characterized by abrupt changes in flow depth over a short distance, with the rate of depth change relative to distance often approaching unity. These flows are inherently complex due to their transient and multi-dimensional nature, making exact analysis difficult. However, approximate solutions using simplified models provide valuable insights into their behavior.Key Features of Rapidly Varying FlowRVF is commonly observed in scenarios involving...
01:17Design Example: Analyzing Capacity Contours for Flood Risk Assessment
Flood risk assessment involves careful planning and analysis to ensure the safety of communities near water retention structures. Capacity contours are a vital tool in this process, as they illustrate the potential spread of water at specific levels in a given area. In the context of building a bund across a small valley, these contours play a critical role in evaluating the safety of nearby residential areas.In this example, the bund is intended to store stormwater in the valley. The engineers...
01:09Deriving the Speed of Sound in a Liquid
As with waves on a string, the speed of sound or a mechanical wave in a fluid depends on the fluid's elastic modulus and inertia. The two relevant physical quantities are the bulk modulus and the density of the material. Indeed, it turns out that the relationship between speed and the bulk modulus and density in fluids is the same as that between the speed and the Young's modulus and density in solids.
The speed of sound in fluids can be derived by considering a mechanical wave propagating...
The speed of sound in fluids can be derived by considering a mechanical wave propagating...
01:06Echo
The human ear cannot distinguish between two sources of sound if they happen to reach within a specific time interval, typically 0.1 seconds apart. More than this, and they are perceived as separate sources.
Imagine the sound is reflected back to the ears. Assuming that the source is very close to the human, the difference between hearing the two sounds—the emitted sound and the reflected sound—may be more than the minimum time for perceiving distinct sounds. If this is the case, then the...
Imagine the sound is reflected back to the ears. Assuming that the source is very close to the human, the difference between hearing the two sounds—the emitted sound and the reflected sound—may be more than the minimum time for perceiving distinct sounds. If this is the case, then the...