1. Where is Patna?
Patna, which is the capital city of Bihar state in India, is located in the north-east part of India. Geographically, it is about 25.61°N latitude and 85.13°E longitude. Patna is located on the southern bank of the Ganges River and in the broad and fertile Indo-Gangetic Plain. This simple land has been a cradle of agriculture practices for centuries with arable land for agriculture. Being located along the Ganges River, the city forms an important node of the regional network of rivers, and it has influenced its historical growth and economic endeavor.
Patna is historically and culturally one of the oldest continuously inhabited cities in the world. It has a rich heritage dating back over two millennia. hitherto known as Pataliputra, it was the capital city of majestic empires such as Mauryan, Shunga, and Gupta dynasties. Here, at those times, Patna was a center of education, culture, and governance. The city's past grandeur is felt in its ancient ruins, archaeological sites, and the remains of gigantic palaces and stupas. Today, Patna is a thriving metropolis that blends its historic heritage with modern urban life. It is renowned for its colorful festivals, traditional handicrafts, and unique food culture that reflects Bihar's abundance of diversity.
The Ganges River is Patna's primary and most significant river system. The Ganges river originates from the Gangotri Glacier in the Himalayas and runs about 2,525 kilometers through north India before emptying into the Bay of Bengal. The Ganges is a source of life in Patna, providing water for domestic use, agriculture, and industry. Historically, it also used to be an important trade route that was utilized in order to transport goods and bring about cultural exchange. The river is also used in various religious and cultural activities of the people as the Ganges is considered holy in Hinduism. But over the recent decades, the river has been subjected to several issues like industrial effluent, sewerage, and agricultural runoff pollution, which are equally detrimental to the river's environmental health as well as the health of the communities dependent on it.
2. What is River Flow around Patna?
Several factors influence the river flow around Patna. Precipitation and runoff feature at the top of the list. The region experiences a monsoon-type climate, and the monsoon season typically runs from June to September. Heavy and often irregular rainfall follows during this time, especially in the upper reaches of the Ganges in the Himalayan catchment area. The runoff-rainfall creates a steep rise in the stage and velocity of the flow of the Ganges during the period of passage through Patna. On the other hand, from October to May, which is the dry season, the level of water reduces considerably and the flow is considerably less. Climate change has added to the problem with more uneven rainfall patterns, with heavier rains in shorter time spans and longer dry spells, thus increasing the risks of floods and drought.
The topography and river profile also play a fundamental role in determining the flow. The low-gradient Indo - Gangetic Plain allows the Ganges to meander and create shallow and broad sections and deep channels. The sediment forms the majority of the riverbed, and it is under constant erosion and deposition. These aspects of form have a local influence on flow characteristics, sediment transport, and the development of the floodplain. The tributaries that join the Ganges at Patna also influence the dynamics of flow by modifying the volume and velocity of water.
Upstream, there are dams, barrages, and reservoirs on the Ganges and its tributaries that regulate the release of water. Water is stored up during the monsoon period and released slowly during the dry season to allow a minimum flow downstream and supply water for various purposes. But improper handling of water release can lead to sudden increase in water levels in Patna, and thereby flood, or low water levels in the dry season, affecting water supply to different sectors.
Patna has seen big hydrological events of the past affecting the city. Heavy rains of the monsoon year 2019 created a severe Ganges flood, which submerged large parts of Patna. According to the Bihar State Disaster Management Department reports, the flood submerged residential areas, damaged infrastructure, and displaced thousands of people (Source: Bihar State Disaster Management Department, 2019). Observing such activities is essential in designing effective flood - control policies, protecting the lives and properties of the residents, and maintaining sustainable management of water resources within the region.
3. How to Observe the River Flow in Patna?
The anchored boat and the surface drift buoy are the traditional methods of observing river flow.
The surface drift buoy technique is a simple but primitive one. Floats are released on the surface of the river, and their movement along a fixed distance and for a fixed interval is traced. This provides an estimate of surface flow velocity. But this method is restricted. It only measures at the surface, and that does not necessarily indicate the flow through the entire water column. Wind may even have a significant impact on buoy movement, so measurements are not always exact.
The anchored boat method uses a boat and anchors it at one spot in the river. A current meter is submerged in the water at several depths to measure the velocity of the flow. This method gives a clearer picture of the flow at the site in question. It is labor - intensive, time - consuming, and poses safety risks to the crew, especially in turbulent or high - velocity waters. Repeated measurement at several sites by this method requires a lot of resources and personnel.
Acoustic Doppler Current Profilers (ADCPs) offer a more advanced and efficient option. ADCPs are able to quantify water velocity at numerous levels across the entire water column without touching the water, so they do not physically invade the body of water. They are able to quickly generate extensive flow profiles, surveying huge areas of the river within a very limited amount of time. This makes them highly appropriate for monitoring the complex and dynamic river flows in the area around Patna.
4. How Does ADCP, Which Operates on the Doppler Principle, Work?
ADCPs operate based on the Doppler principle. They project acoustic pulses into the water. Along their path, these pulses travel through moving particles, such as suspended sediment, plankton, or little animals. When the signals bounce off such particles in motion, the frequency of the bounced signals changes in relation to the speed of the particles relative to the ADCP. By measuring these frequency shifts, the ADCP is able to calculate the water speed at different depths, creating a comprehensive profile of river flow. This enables accurate measurement of flow rates, direction, and general river dynamics, which are valuable information in hydrological studies and water resource management.
5. What is Required for Quality Measurement of River Flow in Patna?
For reliable measurement of river flow using ADCP at Patna, some equipment features are necessary. Material reliability is of top concern. The ADCP should be capable of withstanding the hostile river environment, e.g., contact with sediment - laden water, varying water temperature, and potential effects from floating vegetation material. High - quality corrosion - resistant materials, such as titanium or proprietary polymers, give the instrument durability and prolonged operation.".
Size and weight also matter. A lighter and smaller ADCP is easier to handle and deploy, especially in the sometimes difficult river conditions near Patna. Ease of deployment allows for more convenient data taking over different river sections.
Cost-effectiveness is also a top priority. A good quality performing ADCP at an economical price is most desirable for Patna's large-scale or extended monitoring projects. This ensures quality monitoring of the river flow without over-budgeting.
6. How to Choose the Right Current Measurement Equipment?
Deployment Methods
- Boat-mounted (mobile boat) ADCP: Ideal for conducting surveys, river discharge measurement, and creating accurate flow maps. It can survey long stretches of the Ganges along Patna at a quick rate, which can be useful in comprehending the general river flow regime.
- Fixed (bottom - mounted) ADCP: Best suited for long - term continuous monitoring. Fixed on the river bed, it can subsequently measure data over long periods, which proves extremely helpful to determine long - term trends and alterations in the flow of the river.
- Cableway ADCP: Wherever there is a cableway in a river reach, a cableway ADCP may be used to get accurate and consistent flow measurements at exact locations, useful for calibration and verification of other measurement techniques.
Working Frequency
The working frequency of an ADCP decides its range and resolution. A 600 kHz ADCP with up to 70 meters range can be employed in rather shallow sections of the Ganges or for high-resolution measurements in deeper sections. A 300 kHz ADCP with a capability to measure up to 110 meters is more suitable for deeper sections of the river. The frequency of selection depends on the specific situation of the river and measurement needs, e.g., the amount of detail desired and the maximum depth of the water column to be measured.
Brand Recommendations
Renowned ADCP brands all over the world include Teledyne RDI, Nortek, and SonTek, which are renowned for their best quality products, advanced technology, and reliable performance. If an affordable option is considered, then the ADCP manufacturer Chinese company "China Sonar Panda ADCP" stands out. Made of all - titanium alloy material, this "economy ADCP" offers better toughness and corrosion resistance, hence extremely well-suited for the harsh conditions of Gujranwala's Chenab River. Its remarkable cost - effectiveness makes it accessible to a wide range of users, from small research studies to city - wide water schemes. For more information, visit their website at https://china-sonar.com/.
Why We Monitor the Patna River Flow？