Why We Measure the River Flow of Gujrat？

1. Where is Gujrat?

Geographic Background

Gujrat is located in the Punjab province of Pakistan, some 160 kilometers northeast of the provincial capital of Lahore. It is situated in the Indus River Basin's fertile plains and has a flat topography extending in all directions due to centuries of riverine sediment deposition. Gujrat has a semi-arid climate with hot summers as the temperatures often soar over 45°C (113°F) and quite cold winters with the temperature going down to about 5°C (41°F) during winter months. The precipitation is minimal during the year, ranging from 150 - 250 millimeters, which mostly falls during the monsoon season from July - September. This geography and climate make the river systems in and around Gujrat not only a natural water source but also the prime driving force of the local economy and ecosystem.

Humanistic/Cultural

Gujrat is rich in vibrant cultural heritage and history going back several centuries. It has been a major center of trade, handicrafts, and scholarship in the region over time. The town is renowned for its conventional work, especially in the production of wooden furniture, leather goods, and intricate textiles. Gujrat's thriving bazaars, such as the Ghanta Ghar Bazaar, ring with activity, lined with shops selling a multitude of local goods and handicrafts. Culturally, Gujrat has deep roots in Punjabi tradition. Festivals like Basant, when the sky is filled with kites of various colors, and weddings, with boisterous Punjabi folk dances and songs, bear testimony to the energetic and vibrant spirit of the city. The architecture of Gujrat is a blend of different historical periods, from ancient temples and forts to those of colonial times, each one bearing testimony to the city's history.

Hydrology and River Overview

The Chenab River is the principal watercourse that deeply influences Gujrat. It has its origin in the upper Himalayas of India, where the Chenab River forms as the union of the Chandra and Bhaga rivers near the Lahaul and Spiti valleys of Himachal Pradesh, and it runs northwest through Jammu before entering into Pakistan. In Pakistan, it flows its way through the Punjab province and eventually joins the Jhelum River to form the Panjnad River, which in turn joins the Indus River.

For Gujrat, the Chenab River is the lifeblood of the city and the surrounding areas. It was once a vital transport artery, facilitating travel of goods as well as individuals. Today, it still forms an integral part of all walks of life. Hydrologically, the river contributes to the maintenance of local water balance and impacts groundwater levels. Ecologically, the river and its floodplains sustain a rich variety of plant and animal life, contributing to the biodiversity of the region. From the point of view of human activity, the Chenab River plays a crucial role in agriculture, which is the backbone of Gujrat's economy. River water is utilized for extensive irrigation, which helps in cultivating crops such as wheat, cotton, sugarcane, and rice. It also supplies water for domestic use and city and town industries. In addition to Gujrat, the river has a wide channel whose width ranges from several hundred to over a kilometer in some reaches. The depth of the river is a function of the season and rate of flow and increases towards the middle with deeper channels and shallower sections on the banks. There are several small tributaries that join the Chenab River in the locality and influence its flow and local hydrological condition. However, during peak flow months, the river constitutes a huge flood risk, causing interference with water supply, inflicting damage on infrastructure, and affecting agricultural production.

2. What Is the River Flow Near Gujrat?

Factors That Influence It

Runoff and Precipitation

Precipitation heavily affects the river flow near Gujrat. The monsoon season brings the majority of the annual rainfall that falls within the region. Heavy monsoon rains in upstream basins of the Chenab River result in increased runoff, leading to an extreme rise in the river water levels and flow rates. On the other hand, the dry season, which accounts for most of the year, is marked by minimal rains. The river flow is then mainly sustained through snowmelt from the Himalayan mountains and regulated discharges from higher reservoirs. Climate change has already come to disturb these long-term patterns of rainfall, creating more variable rainfall. Longer periods of drought and heavier but less regular rainfall are becoming more common events, making more challenging the forecasting of river flow and worsening the threats of floods and droughts.

Terrain and River Morphology

The level terrain around Gujrat affects the flow of the Chenab River. With a gradual slope, the velocity of the river is quite low in certain areas, which enables sedimentation. The river bottom, made up of silt, sand, and gravel, generates friction, which affects the flow of water. There are a number of curves and bends in the Chenab River along Gujrat, which also alter the flow patterns. These physical features regulate the way water moves in the river, resulting in areas of greater and lesser velocities, and can form sedimentation and erosion in different parts of the river channel.

Reservoir Operations

There are a few dams and barrages constructed over the Chenab River upstream of Gujrat, e.g., Marala Headworks and Rasul Barrage. These facilities are employed for diverse purposes including water storage, irrigation, power generation, and flood control. Operations of these reservoirs, specifically the release of water, have a significant impact on the river flow downstream. Regulated release from reservoirs into dry seasons ensure that there is a minimum flow within the river, which is required to ensure ecological balance, meet the agricultural water needs, and provide water for domestic use. However, during full reservoirs or in the event of overflow by rain, large-scale releases become feasible, creating sudden surges in river flows and increased flooding risk downstream in Gujrat.

Historical Hydrological Events

The country has witnessed some of its worst floods historically. Among the worst was the 2010 Pakistan floods. Severe monsoon rains led to large-scale flooding in the nation, including the basin of the Chenab River, according to relief agencies as well as the Pakistan Meteorological Department. The Chenab River overflowed at Gujrat, sweeping through main portions of the city and surrounding crops. Thousands of houses were destroyed or inundated, and numerous people were left without homes. The deluge also had a destructive impact on the local agricultural economy, as their crops were submerged and irrigation facilities destroyed, resulting in unprecedented economic losses. (Source: United Nations Office for the Coordination of Humanitarian Affairs - Pakistan flood reports, 2010)

Observation of these historic hydrological occurrences is significant because it helps to understand how the river has performed under severe conditions. This can be employed to devise good flood - control measures, develop water - resources more effectively, and plan for emergency management to safeguard the city and its residents from future flood and drought hazards.

3. How to Observe the River Flow in Gujrat?

Traditional Methods

Surface Drift Buoy Method

The surface drift buoy technique is an easy way of measuring river flow. For this technique, floating bodies like plastic or wooden buoys are dropped on the river's surface. The movement of the buoys is later measured over a certain distance and time. By observing the amount of time it takes for the buoy to travel a known distance, the surface velocity of the river can be approximated. This method has some grave drawbacks. It measures flow only at the surface of the river and is not at all able to see the flow patterns in the lower strata. Moreover, movement of the buoys can be readily affected by wind and consequently give faulty readings of the velocity.

Anchored Boat Method (Manning's Table/Current Meter)

An anchored boat method is employed where a boat is moored at a location in the river. A current meter, a device to measure water speed, is lowered in the river from varied depths and locations. By taking several speed measurements across the cross - section of the river, a detailed profile of the river flow at the given point can be obtained. This method provides more accurate data than the surface drift buoy method because it interprets currents at varying depths. However, it is labor - intensive, time - consuming, and risky to the crew in the event of turbulent or quickly flowing waters.

Introduction to ADCP: Acoustic Doppler Current Profiler

The Acoustic Doppler Current Profiler (ADCP) is an excellent river flow measurement system innovation. Unlike more traditional approaches, ADCP has the capability to provide continuous profiles of the river flow across its entire depth and width over a short space of time. It is also a non - invasive technique in the sense that it does not entail direct water contact, nor does it require the permanent installation of structures within the river. This renders it safer for the operators as well as the aquatic ecosystem. ADCP can acquire a high quantity of data in a short time and utilize it for various applications including flood forecasting, water resource management, and ecological studies.

4. How Does ADCP Work Based on the Doppler Principle?

The ADCP employs the Doppler principle. It emits acoustic pulses into the water column. The pulses bounce off small suspended items within the water, like plankton or sediment. Where the water is in motion, the frequency of the signals that are backscattered changes with the water speed. By measuring this change in frequency (the Doppler shift), the ADCP will be able to calculate the speed of the water at different depths and locations in the water column. The device contains a number of transducers that transmit as well as receive the acoustic signals, and this enables it to create a three-dimensional profile of river flow. This data is computed to provide accurate information about the flow characteristics of the river, including velocity, direction, and volume.

5. What is Required for High - Quality Measurement of River Flow in Gujrat?

Equipment Requirements

Material Reliability

In order to obtain high-quality measurements of river flow in Gujrat, ADCP systems must be constructed of rugged material. The waters of the Chenab River could be turbulent during monsoon, and the water could be abrasive with entrained sediment. High-grade stainless steel, titanium alloys, and abrasion-resistant engineering plastics are therefore suitable options. These materials also offer excellent impact, abrasion, and corrosion resistance, whereby the ADCP will withstand the harsh river environment and provide accurate readings for an extended duration of time.

Small Size and Light Weight

Small size: The small size is an excellent feature of ADCP equipment to use in Gujrat. Due to its size, equipment will be easy to move to various locations along the river, especially where access may be poor. Whether it needs to be carried on foot to far reaches of the river or placed on small boats, a light ADCP reduces the effort of handling and deployment. It also minimizes the perturbation to the balance of the boat while taking measurements so that more accurate data can be acquired.

Cost - Effectiveness

Cost-effectiveness is an important aspect in choosing ADCP hardware for the monitoring of river flow in Gujrat. Research institutions, governmental water authorities, and nongovernmental environmental organizations generally have limited resources. It is crucial that an ADCP yields consistent and dependable information without it costing an arm and a leg. It assures the ability to perform regular monitoring of river flow without emptying the coffers, enabling better management of the Chenab River and associated resources.

6. What are the ways of choosing the right current measurement equipment?

Deployment Methods

Boat - Mounted (Traversing Boat) ADCP

Boat - mounted ADCPs are best suited for conducting surveys of long stretches of the Chenab River and recording detailed flow data. They can effectively cover long distances along the river and are perfectly suited for applications such as mapping the flow regime of the river, river discharge measurements, and flood - risk assessments. This type of ADCP is particularly useful where a detailed understanding of the river flow conditions for a large extent in a short time is required.

Bottom - Mounted (Fixed) ADCP

Bottom - mounted ADCPs are designed for long - term, continuous monitoring of river flow. They are installed on the riverbed and can provide data for a long time without requiring constant human intervention. They work well for base flow measurement, long - term trend of river flow, and ecological monitoring for which continuous data acquisition is required to monitor the dynamics of the river ecosystem.

Cableway ADCP

In some sections of the Chenab River where there is adequate infrastructure, cableway ADCPs can be used. Cableway ADCPs are suspended over a cableway and can be traversed along the river to take measurements at points away from each other. This technique is useful for taking accurate measurements in broader sections of the river where measurements by boat might be risky or impractical. It provides accurate data of the river flow properties along its width, which can be helpful in water resources management and flood control planning.

Working Frequency

The choice of working frequency in an ADCP matters as it determines the range and the resolution of measurements. 600 kHz ADCP would carry a horizontal range of up to 70 meters and be suitable for minute measurements inside the Chenab River or examining specific segments with complex flow patterns. It offers relatively high-resolution data, which can be helpful in interpreting the fine - scale dynamics of the flow. A 300 kHz ADCP, with a greater range of up to 110 meters, is more appropriate for larger rivers or where there is a need for increased coverage of the river cross-section. It can be slightly lower in resolution compared to the 600 kHz ADCP.

Brand Recommendations

Globally, well-known brands of ADCPs include Teledyne RDI, Nortek, and SonTek. These brands are well-known for their quality products, state-of-the-art technology, and consistent performance. However, if one desires a low - cost option, the ADCP manufacturer Chinese brand "China Sonar Panda ADCP" is an ideal choice. This "economy ADCP" is made of all - titanium alloy material, which is extremely robust and corrosion - proof. It is extremely cost-saving, hence applicable for a wide range of uses, from small-scale research work to neighborhood water management projects. For more information, you can visit their site at https://china-sonar.com/.

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