Lower Sutkel Lift Irrigation

Odisha is a landlocked state in India, with a rich variety of Flora and Fauna. Formed in the year 1936, it is a state in India with land area of 155,707 sq. km and, shares its borders with West Bengal, Andhra Pradesh, Chhattisgarh and Jharkhand.

It covers almost 4.87% of total area of india and the coastal line of 450 kms. The population below poverty line is at 32.6% and with majority of the population rural, the government aims to increase agrarian practices.

According to the Indian conglomerate, the irrigation project involves supplying water to irrigate 57,600 hectares of Culturable Command Area (CCA) in the Balangir district of the state by pumping water from the Lower Suktel Dam. Larsen & Toubro won the EPC contract for Right Command of Lower Suktel Irrigation Project in Odisha.

According to the Indian conglomerate, the irrigation project involves supplying water to irrigate 57,600 hectares of Culturable Command Area (CCA) in the Balangir district of the state by pumping water from the Lower Suktel Dam. Larsen & Toubro won the EPC contract for Right Command of Lower Suktel Irrigation Project in Odisha.

The contract includes survey, design, and construction of Lower Suktel Dam. It also calls for the survey, design, procurement, installation, testing, and commissioning intake and intermediate pump houses, MS, DI and HDPE pipeline of different diameters, delivery chambers, and pipeline distribution networks with all associated works.

Larsen & Toubro has stated:

“With this order from the irrigation sector, the Business has reinforced its credentials of possessing the technical and executional capability to deliver the elementary requirement of water to the farmers and drive the growth of agriculture across the state.”

Larsen & Toubro partnered with a dynamic team from Chennai, India – who are pioneers in the field of surveying using drones. The team called Birdscale, was awarded the job to carry out the surveying the entire command area spanning 5 districts with a gross command area of 576 Sq. Km.

The survey was carried out using advanced RTK and PPK enabled long rang autonomous drones. The Birdscale team pre-surveyed several crucial factors such as the environment, weather, logistics for planning the survey process and optimal locations for benchmarks and launch sites for the drone. The flight paths and limits were fed into the Remote controllers for autonomous flying and managed by a well-experienced fleet of DGCA approved pilots from Birdscale, with each over 500 hours recorded in flight. With each flight path covering 5 Sq. Km., for effective data collection, battery life and security, each flight runtime was around 90 mins. Multiple technologies like LIDAR, photogrammetry, SFM, Real-time kinematic, Post processing kinematics, Differential geographic positioning system and Global navigation satellite systems were utilized to achieve desired accuracy standards in surveying.

The data collected from the field survey was transferred securely to the data processing center in Tamil Nadu for post processing and the required outputs were extracted by trained engineers experienced in carrying out similar projects.

A detailed demonstration of the processes and the working timelines were given on site to the government officials on site before and during the survey process for a better understanding and appreciation of the technology. The advantages of the technology over conventional methods such as reduced survey duration, non-intrusion in any activities, data acquisition even in remote and inaccessible locations while still providing a continuous data of density about 700 points/sq.m with an accuracy of about 3 cm to 5 cm were explained during these demonstrations. A demo flight was carried out in the presence of the officials to give them an experience on the process of survey using Drones.

The Nearest GTS Benchmarks value has been obtained from Geodetic and research branch from survey of India and the same value has been validated in field by using static observation system in Differential geographic positioning system. The level from the GTS benchmark was transferred to the Benchmark at the Dam location by 12 hours observation for high accuracy and was found to be consistent with the levels provided by the client.

The levels from the benchmark were then transferred to 9 Base station locations spread evenly across the command area with high precision. The levels for the base stations were transferred through static observations of minimum 4 hours duration. These Base stations act as the benchmark for other points to be transferred within a vicinity of 6 kms from them without any signal interruption. The base station locations are as shown in the image below.

The data from benchmark in dam has been transferred to multiple points in site for data quality check which are called as follows:

1. Ground control Points

The Ground control Points also called as GCP’s are large markings in any permanent and flat structures either marked by paint or an A1 sized also used incase of absence of Permanent structures.  The centre points of GCP’s were validated by DGPS and same has been cross checked for accuracy in ORI images generated by RTK drones. The GCP’s were also used as Tie-points for increasing accuracy of topography and cross verification of LIDAR values.

2. Test Control Points
The Test control Points also called as TCP’s are same as GCP’s which act as cross verification points of LIDAR. The TCP’s are L shaped points with an indication showing numbers and values on them to act as reference points for cross verification. Every LIDAR map is given with two to three TCP’s for each maps.

The GCP’s and TCP’s spread all over the command area will stay as complimentary verification points for topography, Contours and tie points for village maps. These measures increase the accuracy to 2cms for Horizontal and vertical accuracy. Over 400 RTK points were dispersed even across the survey area for improved accuracy.

The command area was divided into 3 zones namely West, North and South zones for ease of monitoring. Further the zones were sub-divided into areas of up to 5 sq.km for Drone surveying based on several factors such as accessibility, drone battery duration, security, terrain features etc. The Drone survey for the command area was carried out with 3 teams each with a RTK and PPK enabled autonomous drone covering a total area of about 20 skims per day on an average. The GCPs and TCPs in the particular flights were checked for visibility and clarity before the flight. The RTK base station used by the drone to receive signals about its location data real time during the flight were setup at a predetermined location for which the coordinates were noted earlier using DGPS rovers. The flights were carried out autonomously while still being continuously monitored by the team of DGCA approved pilots. The flights were carried out only during optimal weather conditions to avoid inaccuracies in the survey data. The survey was carried out in the most non-intrusive manner without disturbing the local people.

In 20 days from the date of commencement of data capturing , the data over the entire command area was captured and uploaded the remote servers for processing.       The data was downloaded at the data processing center with heavy data processing capacities. The raw data then was checked for quality and used for data processing. Any discrepancy in the quality of the data captured found were intimated to the field team immediately and the data was recaptured.

The Post production works were carried out by a team of dynamic professionals with experience in similar projects with the help of robust processing workstations. Various modules of Data processing were automated through RPAs to improve accuracy and efficiency while still be monitored by experienced professionals. The control points and check points marked on the site using DGPS rovers with an accuracy of 5mm were used for optimizing during photogrammetry and to verify the point cloud data produced by the lidar data processing. The data from photogrammetry and lidar processing were combined to create multiple outputs such as Orthorectified images, Digital elevation models, Point clouds etc. The combination of Lidar and Photogrammetric data have some unique advantages in terms of accuracy and sophistication. The data can be more clearly visualized and required data can be extracted with accuracy.

High Resolution Orthorectified images (ORI) thus created have a ground sampling distance (GSD) of 5cm meaning that the location of any feature in the image can be marked with an accuracy of about 5cm. The ORI images were used for feature extraction process to extracted various features such as village settlements, BT road, cart roads, waterbodies, streams, powerlines, religious landmarks etc. ORI images were also used to extract Land use Land cover (LULC) data.

With LIDAR in combination with photogrammetry, denser, richer, more accurate point clouds were produced. The point cloud thus created will have accurate points with actual colour shading which is very useful in classification of ground points from other points such as trees, structures, etc. The point cloud produced will have almost no erroneous points thereby helping in capturing the actual ground data after removing all the other structures in the Digital Elevation model produced. The DEM can be used directly in a lot of design software used in the market to understand the terrain and design the infrastructure accordingly. This helps in better design and avoids inaccuracies.

The Digital Elevation Model (DEM) created can be used to generate contour and spot levels at any desired intervals. The contour thus produced will be very rich and dense in data as it models the terrain continuously unlike sparsely acquired data in the case of conventional methods such as DGPS or Total station survey.

The high resolution ortho-rectified images were used to geo-reference the cadastral maps. The Cadastral maps were scanned and overlaid on the ORI images. The survey stone marked in the cadastral maps were used as the reference for geo-referencing. The GCPs placed on the survey stones at the site makes it clearly visible in the ortho-rectified images. This helped in aligning the cadastral map to the ORI images. The plots and village boundaries were then digitized to create geo-referenced data. The geo-referenced cadastral maps are provided in multiple formats such as CAD, Shapefile, Kmls etc. for better usage. This will help in easy identification of plot details for design and land acquisition.

The survey data was delivered in multiple formats compatible across most renowned visualization and design softwares. The cadastral maps provided in the shape file format contains survey numbers of every individual plot thus aiding in analyzing the land type and land ownership details with ease. The Data was delivered in both secured hardware device and as secured cloud link for easy data transmission. The data has been made future-proof and hence becomes a highly valuable asset to the entire community aiding in any references for future projects.

The project was completed in 45 days.

• Assigned, 13 10 2022
• 3 days of planning,
  • Site inspection, collected existing survey records and environmental study.
• 30 days of flight,
  • DGCA approved pilots, LIDAR & photogrammetry with average of 19.2 sq. kms per day delivering raw data of 60GB per day.
• 26 days of data processing,

Orthomosaic Maps which include, topographical, contours and elevations and cadastral maps.

Larsen & Toubro, with the dynamic team of Birdscale and its young fleet of highly skilled pilots, managers and the extensive data processing team has successfully completed the survey for Right Command of Lower Suktel Irrigation Project with all required data, mapping and information processing.

This is connected with existing ground data, and made the valid as reference for the upcoming years, for planning infrastructure, agriculture and other community projects.