Why Do We Measure the River Flow in Sargodha?

1. Where is Sargodha?

Geographic Background

Sargodha is located within Pakistan's central region, in Punjab province. Positioning some 240 kilometers southwest of provincial capital Lahore, the city is located on the Indus River Basin's fertile alluvial plains. The topography of the city is largely flat as a result of centuries-long deposition by rivers in the region. Sargodha is situated in a semi-arid region with extremely hot summer seasons where temperatures typically reach more than 45°C (113°F) and relatively cold winters, where temperatures can fall to around 5°C (41°F) during winter months. The annual rain is scarce, varying from 150 - 250 millimeters, so the regional river systems are not just crucial for water supply but also crucial for the maintenance of the regional ecosystem as well as the sustenance of many human activities.

Humanistic/Cultural

Sargodha is also rich in cultural and historical heritage. It has long been an important center for trade, agriculture, as well as education in the region. Traditional handicrafts of the city, including intricate woodwork and pottery, bear evidence of the ingenuity and imagination of the local artisans. The bazaars of Sargodha are bustling trade centers filled with all manner of products from fruits and vegetables to traditional clothing and jewelry. The city is Punjabi in its deep-rooted tradition. Festivals such as Basant, when the sky is dominated by colorful kites, and weddings, with their follow-up Punjabi folk music and dance, also symbolize the welcoming nature of the locals. Also, Sargodha boasts a military base, where the Sargodha Air Base is among the most powerful air bases in the country, further increasing the strategic and cultural significance of the city.

Hydrology and River Overview

The main river system influencing Sargodha is the Jhelum River, which is among the biggest tributaries of the Indus River. The Jhelum River originates in the Pir Panjal Range of the Indian state of Jammu and Kashmir. The Jhelum River flows northwest through the Kashmir Valley and then into Pakistan, meandering along the Punjab province. Subsequently, the Jhelum River joins the Chenab River, which further gets added to the Indus River system.

For Sargodha, the Jhelum River is of utmost importance. It used to be a vital means of transport previously, with goods and human beings being transported along it. Currently, the river is still vital to the area's water supply, agriculture, and ecosystems. Hydrologically, the Jhelum River supports the regional hydrological balance and regulates ground-water levels. Ecologically, the Jhelum River and its associated floodplains are sources of a diverse range of flora and fauna, such as various fish, birds, and mammals, which serve to uphold biodiversity within the area. From the perspective of human activity, the Jhelum River is essential for the purpose of agriculture, which serves as the backbone of the Sargodha economy. The water of the river is used for irrigation, and it helps in the cultivation of crops such as wheat, cotton, sugarcane, and rice. It supplies water to be used for urban needs and industry in the city and surrounding suburbs.

The Jhelum River, which is near Sargodha, is a wide channel that is between a few hundred meters and over a kilometer in width in certain areas. The river varies in depth according to the season and the flow rate. There are quite a few minor tributaries that flow into the Jhelum River in the neighborhood and contribute to the overall flow of the river and the formation of the hydrological character of the region. The connection between the river and the city's water system is complex. The river is the primary source of water to the treatment plants of the city, which subsequently supply clean water to the industrial and domestic sectors. However, under high-flow conditions, there is a high risk of flooding, which can potentially damage the water supply system, buildings, and agriculture.

2. How is the River Flow Near Sargodha?

Influencing Factors

Precipitation and Runoff

River runoff in the vicinity of Sargodha is significantly influenced by precipitation patterns. Monsoon, typically from July to September, is responsible for most of the rainfall during the year in the region. High monsoon precipitation in the upper catchment areas of the Jhelum River causes higher runoff, leading to considerable rise in the water levels and flow rates of the river. On the other hand, during the dry season, lasting the rest of the year, precipitation is scarce. River flow is then primarily supplied by snowmelt from the Himalayas and managed releases from the upstream reservoirs. Climate change has already started impacting the rainfall pattern again in the basin, leading to more intermittent rain. More intense but less frequent rainfalls and longer dry spells make river flow prediction more difficult and intensify the risks of floods and drought.

Topography and River Morphology

The flat topography around Sargodha impacts the course of the Jhelum River. With a mild gradient, the velocity of the river is relatively low in some locations, facilitating deposition of sediment. The sand, silt, and gravel riverbed exerts friction that influences the flow of water. The Jhelum River, along with a series of bends and meanders near Sargodha, also varies the flow patterns. These physical characteristics determine how the water flows through the river, creating areas of rapid and slow flow, and may cause sedimentation and erosion in different reaches of the river channel.

Reservoir Operations

There are several dams and barrages constructed on the Jhelum River above Sargodha, such as Mangla Dam and Rasul Barrage. These are constructed for different purposes such as storage of water, irrigation, production of power, and protection against floods. The operation of these reservoirs, especially the release of water, has a large impact on the downstream river's flow. During the dry season, the controlled release of water from the reservoirs creates a minimum flow in the river that is essential for maintaining ecological stability, meeting agriculture's water requirement, and supplying water for domestic use. But during periods of heavy rain or when reservoir levels are full, mass releases can occur, leading to instantaneous rises in river discharge and possibilities of downstream flooding at Sargodha.

Historical Hydrological Events

Among the significant floods to affect the area in the past were those of 2010. Torrential monsoon rains led to enormous flooding in Pakistan and areas around Sargodha, according to the Pakistan Meteorological Department and relief agencies. The Jhelum River overflowed, inundating vast areas of irrigated land, causing homes to be destroyed, and forcing thousands to be displaced. The local economy was especially affected by the flood, with enormous losses in agriculture as crops were submerged and irrigation networks were destroyed. (Source: United Nations Office for the Coordination of Humanitarian Affairs - Pakistan flood reports, 2010)

Aside from floods, the area has also been plagued by droughts. Periods of low rainfall and reduced river flow have caused irrigation and domestic water deficits, burdening local water resources and livelihoods. Recreating these earlier hydrological events is significant since this facilitates understanding the action of the river when faced with extreme weather. This information is required for the design of effective flood-control structures, the improvement of water-resource management, and the formulation of emergency response plans to safeguard the city and its inhabitants against potential flood and drought disasters.

3. How to Measure the River Flow in Sargodha?

Traditional Methods

Surface Drift Buoy Method

Surface drift buoy method is a simple method of river flow measurement. In this method, floating materials such as wooden or plastic buoys are released onto the river surface. The movement of these buoys is tracked for a certain distance and time interval. By calculating the time taken by the buoy to travel a specified length, the river's surface velocity can be estimated. This method has severe limitations, however. It will only record the surface flow of the river and fail to consider the flow pattern in the deeper layers. Further, the movement of the buoys is also subject to wind, resulting in erroneous readings of velocity.

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

The anchored boat method involves anchoring a boat in a location in the river. A current meter, a device that takes readings of water velocity, is then released into the river at various positions and depths. By taking a number of velocity readings across the river cross-section, an accurate profile of the river flow at that location can be obtained. The technique provides more accurate information than the surface drift buoy method because it measures the flow at different depths. However, it is time - consuming, labor - intensive, and takes a risk to the safety of the people involved, particularly in turbulent or fast - flowing waters.

Introduction to ADCP: Acoustic Doppler Current Profiler

The Acoustic Doppler Current Profiler (ADCP) is a major step forward in river flow measurement technology. Unlike other methods, ADCP has the capacity to give continuous profiles of the river flow throughout its width and depth within a relatively short period of time. It is an invasive technique, i.e., it entails no immediate contact with the water or with permanent installations introduced in the river. This decreases its risk to both operators and the aquatic ecosystem. ADCP can derive massive amounts of data in a very short time, which can be used for a large array of applications, ranging from flood prediction to planning for water resources and research in ecology.

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

The ADCP operates based on the Doppler principle. The ADCP emits acoustic signals into the water column. The signals bounce off small particles suspended in water such as sediment or plankton. Since water is in motion, the frequency of the backscattered signals changes with the water velocity. By measuring this frequency change (the Doppler shift), the ADCP can calculate the velocity of the water at different depth and location in the water column. It contains several transducers for transmitting and receiving the sound pulses, therefore it can calculate a three-dimensional picture of the river flow. This data is accessed through processing data and giving detailed information of the river flow characteristics, including velocity, direction, and volume.

5. What Does It Require to Measure River Flow High-Quality in Sargodha?

Equipment Requirements

Material Reliability

For high-quality river flow measurement in Sargodha, equipment has to be manufactured with reliable materials. The Jhelum River experiences turbulent water during the monsoon season, and the water may contain abrasive sediment. Therefore, high-grade stainless steel, titanium alloys, and high-strength engineering plastics are employed. These provide high impact, abrasion, and corrosion resistance, thereby ensuring that the ADCP is able to withstand the harsh river environment and make accurate measurements for a prolonged period of time.

Small Size and Light Weight

Light and compact is a desirable aspect of ADCP gear in Sargodha. The compactness of the gear makes it easier to transport to various locations along the river, especially in areas access might be challenging. Regardless of whether it has to be hand carried to remote sections of the river or installed on small boats, an ultralight ADCP reduces effort involved with handling and deployment. It also minimizes the impact on the boat's stability when measuring, leading to higher quality data.

Cost - Effectiveness

Cost effectiveness is the most important consideration when choosing ADCP equipment to utilize for river flow measurement in Sargodha. Research institutions, government ministries responsible for water management, and environmental nongovernmental organizations have limited funding. The ADCP must deliver valid and reliable data at an affordable price. This enables frequent measurement of river flow without breaking the bank, enabling proper management of the Jhelum River and its associated resources.

6. How to Choose the Suitable Current Measurement Instrument?

Means of Deployment

Boat - Mounted (Traveling Boat) ADCP

Boat- mounted ADCPs are particularly well suited to conducting surveys across large sections of the Jhelum River and measuring total flow. They are capable of travelling long distances down the river at a high speed and, as such, are especially well suited to applications which include mapping of river current patterns, discharge measurement of rivers, and flood - risk assessment. This ADCP is particularly useful when there is a need for a particular, detailed understanding of the river flow behavior over a wide area during a comparatively short period.

Bottom - Mounted (Fixed) ADCP

Bottom - mounted ADCPs are designed for long - term uninterrupted monitoring of river flows. Fixed on the riverbed, they are able to collect data for long periods of time without any human intervention.

The below illustration depicts a bottom - mounted ADCP. They are therefore best suited to monitor base flow, long-term trends in river flow, and ecological studies involving constant data collection to establish the river's ecosystem dynamics. They can, for example, be used to examine the impact of pollution or changing water management patterns on the flow in a river over time.

Cableway ADCP

In some areas of the Jhelum River where there is appropriate infrastructure, cableway ADCPs can be utilized. They are installed on a cableway and can be pulled along across the river to record at different points. This proves useful in measuring exactly the flow across wider sections of the river where measurement by a boat-based system could be problematic or unsafe. It provides correct information about the river's flow characteristics along its width, which is useful in water resource planning and management and for flood control planning.

Work Frequency

The choice of work frequency in an ADCP is significant as it affects the range as well as the resolution of measurements. A 600 kHz ADCP would be having a horizontal range of approximately 70 meters and be suitable for accurate measurements in small rivers like the Soan River or observation of localized segments with complex flow patterns. It provides relatively high-resolution data, which is good for understanding the fine-scale flow dynamics. A 300 kHz ADCP with greater range up to 110 meters may be more appropriate for large rivers or application where it is desirable to survey the broader portion of the river cross-section, though it will be very slightly less resolved than the 600 kHz ADCP.

Brand Recommendations

World - leading ADCP brands include Teledyne RDI, Nortek, and SonTek, with high - quality products, advanced technology, and excellent reliability. For a cost - effective budget, ADCP manufacturer Chinese brand "China Sonar Panda ADCP" is also very good. Made of all-titanium alloy material, this "economy ADCP" is extremely durable and resistant to corrosion, well-suited to the harsh environment of the Soan River. Its high cost-effectiveness makes it within the budget of a range of users, from small-scale research projects in the vicinity to city-scale water management initiatives. To find out more, visit their website at https://china-sonar.com/.

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