ADCP in The Liard River Flood Management

1. Where is The Liard River?

The Liard River is one of the greatest rivers in North America.

Geographical Location and Course It is found in the Yukon Territory of Canada and the northern part of British Columbia. Its source is in the Mackenzie Mountains, and from there, it runs southwesterly for about 1,115 kilometers (693 miles). The river stands out as a large and important tributary of the Mackenzie River system.

Cities and Settlements Along the River There are numerous small communities and aboriginal settlements along the Liard River banks. The communities depend entirely on the river for transport, catching fish, and water supply. In addition, the river plays an important role in the local economy because of fur trading and guiding services provided to tourists that arrive with the intent of seeing the beautiful scenes. As a result, no one interferes with the Lia River watercourse.

Rainfall and Water Conditions The Liard River basin lies in the subarctic climate. For its wet season, although short, could receive a considerable amount of rainfall between June and August. Annual rainfall also ranges from 300 to 600 millimeters throughout the basin. Aside from rain, the snowmelt during spring also supplies volume to the river. Its water level may reach various maximums within the year, peaking at its spring runoff and wet season.

2. What causes flooding in The Liard River?

Heavy Rainfall during the Wet Season Heavy rainfall associated with the wet season is the most common cause of floods in the Liard River. It is important to mention that even small events of rainfall might be very intense and thus easily raise the volume of water within the river and its tributaries. Probably, soil cannot absorb all the water input, and the result is surface runoff which leads to rapid rise of water level in the river.

Spring Snowmelt Apart from that, another major contribution to the flow is due to the melting of the snowpack in the Mackenzie Mountains and surrounding catchment area. So in case snowmelt happens very fast with a sudden increase in temperature, more volumes of water contribute to the Liard River. It is during the transition of spring to summer that the most lethal combination sets in with the combined action of snowmelt and rainfall, which more often than not causes flooding.

Blockage and Ice Jams With the spring breakup of ice, there can be ice jams in the Liard River. In situations where ice jams block the usual flow of the river, water can be impeded and force flood conditions onto the land located upstream of the blockage. Debris of trees and branches that fall can also accumulate and impede the river's flow, promoting flooding.

Considering these flood-related challenges, ADCP profiler offers a more advanced and convenient measurement method to cope with floods.

3. How do ADCPs using the principle of the Doppler work?

Acoustic Doppler Current Profiler(ADCP) work by utilizing the Doppler effect. This device sends acoustic pulses into the water at a known frequency. The choice of the transmitting frequency depends on the depth of the water and also on certain requirements related to the measurement, often 300 kHz or 600 kHz.

Transmission and Reception of Signals The acoustic pulses are transmitted in a fan-shaped pattern. As the pulses move through the water, they encounter moving water particles and any suspended sediment. As these pulses strike these moving objects, some of the energy is scattered back to the ADCP meter .

Detection of the Doppler Shift Due to the Doppler effect, reflected signals have a different frequency from the ones transmitted. In case the water particles or sediment move towards the ADCP flow meter, this frequency will be higher than the original frequency at which transmission took place. If they are moving away, it is lower. The sensors on the ADCP doppler are designed to detect these changes in frequency with very high precision.

Calculating Velocity and Other Parameters The ADCP internal algorithms calculate the velocity of water currents at various depths in the water column from the detected Doppler shifts. Integrating this velocity information over the cross-sectional area of the river, it also can develop the flow rate of water at any given point in time. An ADCP has also been used to provide information on the movement and concentration of suspended sediment in the water.

4. What are the applications of ADCP in floods of The Liard River?

Velocity Measurement

In cases of flooding of the Liard River, the ADCP current profiler become very significant while determining the speed of water flow. In fact, they are able to measure, in real time, the speed at which water travels at any given depth. It helps in the realization of dynamic behavior such as whether the current is strong near the water surface or on the ground. These velocity data are able to indicate time and space variations of current, which is an important aspect in the prediction of spread and impact of flood.

Flow Measurement Application

ADCP current meter can be used to calculate flow rates of the Liard River during floods with accuracy. They combine the measured velocities with the determined cross-sectional area of the river at the measurement point, hence an approximation of the volume of water flowing downstream is obtained. The latter information is quite valuable in flood forecasting and analysis of the flood magnitude. It approximates how much water will arrive at different zones along the riverbanks and the proportion of damages.

Sediment Translocation Research Application

Most floods in the Liard River result in the translocation of sediment. ADCP current can be used to study the translocation of sediment by detecting the Doppler frequency shift caused by suspended sediment particles. This allows the analysis of sediment transport patterns during floods, such as how floods alter the distribution of sediment on the bed and banks. It also gives good insight into the possible morphological changes to be expected in this river over long periods of time and the impact of sedimentation on infrastructure like bridges and dams.

5. How can the data measured by ADCP be utilized for flood warning and risk management of The Liard River?

Flood Warning

Velocity and Flow Data Monitoring: Velocity and flow rate data in real time from ADCPs are valuable in flood warning systems. By continuously monitoring the parameters, the authorities can know instantly if there is a sudden surge in the speed or volume of water flowing in the river. In case the flow rate crosses the threshold value recorded in previous flood events, an early warning can be issued as a result. It allows the evacuation of people residing in the flood-prone areas and also to prepare all kinds of emergency response measures beforehand.

Water Level Prediction and Warning: The acoustic doppler velocity meter data can be used for the prediction of water level because the velocity and flow rate is related interdependent to the level of water. Analysing the trends of measured data allows forecasting how the water level will change in the near future. This enables the issuance of water levels warnings well in advance to the communities along the river, giving ample time for precautionary measures such as relocating valuable belongings to higher grounds or strengthening flood defenses.

Risk Management

Water Conservancy Engineering Scheduling Decision Support: Data obtained from ADCPs are useful in arriving at decisions regarding the scheduling of water conservancy engineering operations.For example, the rate of flow and velocity may indicate the imminence of a large flood, which, to the concerned agencies managing the dams, would immediately act to reduce or increase the water discharged from the dams to minimize the impact on the area downstream. They can retain more water, if possible, to reduce the peak flood flow, or they can release the water slowly so as not to cause sudden surges that might destroy some highly sensitive infrastructures downstream.

Flood Disaster Assessment and Emergency Response: Further, acoustic doppler flow meter data post-flood would help assess the destruction created by a flood. By analyzing the flow pattern and the velocity during flood flow, one can find where exactly the flooding is very much intense and which area is most affected. This information is very important in giving the necessary insights into the appropriate emergency responses, such as the deployment of rescue teams to areas of greatest need and provision of relief supplies to the victims.

6. What’s needed for high - quality measurement of The Liard River currents?

Material Reliability

The equipment to be utilized shall be made of reliable materials for the accurate and continuous measurement of currents in the Liard River. Particular attention must be given to the casing of the ADCP, which will be subjected to harsh conditions in the river, especially being submerged in the water with possible sediment and impacts.

Small in Size, Light in Weight, and Low in Power Consumption

The ADCP to be used should be of small size, light weight, and with low power consumption to easily deploy and use along the Liard River for large-scale measurements. A small-sized and lightweight device is easy to install on boats, buoys, or other measurement platforms. This contributes to the essentiality of low power consumption for longer-term operation without frequent changing of batteries or access to a continuous power source. It is highly needed in areas where the power supply is not sufficient.

Low Cost for Large-Scale Measurement The cost of ADCPs has to be reasonable to allow their widespread deployment for large-scale monitoring of the Liard River currents. Very high costs will limit the number of devices that can be deployed, thus limiting comprehensive data coverage.

Advantages of Using Titanium Alloy for Casing

This will make the Titanium alloy an excellent material choice for the casing of ADCPs in the Liard River environment, as it contains high corrosion resistance, important because it may contain several corrosive species in the water of rivers. It is also strong and durable to take up the physical stresses and impacts that the device may go through during deployment and operation.

Besides, its relatively low density helps to maintain the overall weight of the device low for the satisfaction of another critical criterion: being lightweight for easy deployment .

7. How to Choose the right equipment for current measurement?

Based on Measurement Orientation If the measurement is desired to be performed for horizontal cross - sectional currents, HADCP (Horizontal ADCP) shall be selected. HADCPs are designed to measure the flow of water in a horizontal plane across the river with accuracy.On the other hand, for measurement related to vertical cross-sectional currents, a Vertical ADCP should be used. Whereas Vertical ADCPs can give one detailed velocity profile from the surface to the bottom of the water column.

Based on Frequency Selection Secondly, the frequency used is determined by the specific measurement needs concerning the depth of the water. For example, a 600 kHz ADCP would be useful in water whose depth is up to 70 meters. This kind of frequency has good resolution and accuracy for shallower waters.

The ADCP of 300 kHz will be better for deeper waters, such as those to be found in parts of the Liard River where the depth is in excess of 70 meters, because it manages to penetrate deeper into the water column and yield reliable measurements of the currents. A number of well - renowned brands of ADCPs in the market include Teledyne RDI, Nortek, and Sontek. However, for those looking for a cost - effective option with high quality, the China Sonar PandaADCP is a great choice. It is made of all - titanium alloy material, which ensures its durability and performance in various river environments. It also offers an incredible cost - performance ratio.

You can learn more about it on its official website: https://china-sonar.com

Here is a table with some well known ADCP instrument brands and models.