Land Grading Survey and Design

Introduction

Land grading survey and design play a crucial role in irrigation. It involves the process of leveling the land to ensure proper water distribution and drainage. This topic explores the fundamentals of land grading survey and design, different methods used, earthwork quantities computation, equipment used, and their real-world applications.

Land Levelling Methods

Land levelling is the process of creating a smooth and even surface on the land. There are several methods used for land levelling:

1. Contour Bench Levelling: This method involves creating a series of level benches along the contour lines of the land. It helps in preventing soil erosion and conserving water.

2. Cut and Fill Method: In this method, the land is cut from higher areas and filled in lower areas to create a level surface.

3. Laser Levelling: Laser technology is used to accurately level the land by adjusting the height of the equipment based on laser measurements.

Each method has its advantages and disadvantages. Contour bench levelling is effective in hilly areas, while the cut and fill method is suitable for flat terrains. Laser levelling provides precise results but requires specialized equipment.

Contour Bench Levelling

Contour bench levelling is a widely used method for land grading. It involves the following steps:

1. Surveying the Land: The land is surveyed to identify the contour lines and determine the slope of the land.

2. Establishing Contour Lines: Contour lines are marked on the land to indicate the elevation.

3. Determining Bench Heights: The height of each bench is determined based on the desired slope and water flow requirements.

4. Constructing the Benches: The benches are constructed by cutting into the higher areas and filling in the lower areas.

Contour bench levelling is commonly used in agricultural fields, golf courses, and landscaping projects.

Earthwork Quantities Computation

Computing earthwork quantities is essential for estimating the amount of soil that needs to be moved during land grading. There are two methods commonly used:

1. Cross-Sectional Method: This method involves dividing the land into cross-sections and calculating the volume of soil in each section.

2. Average End Area Method: In this method, the average area of the land at the beginning and end of the section is calculated, and the volume of soil is determined based on the difference in these areas.

Both methods provide accurate results, and the choice of method depends on the project requirements.

Equipment for Land Grading

Various types of equipment are used for land grading:

1. Graders: Graders are machines equipped with a long blade that is used to level the land.

2. Scrapers: Scrapers are used to remove the top layer of soil and transport it to another location.

3. Bulldozers: Bulldozers are powerful machines that can push large amounts of soil and create a level surface.

4. Laser-Guided Equipment: Laser-guided equipment uses laser technology to accurately level the land based on predetermined measurements.

Each type of equipment has its advantages and disadvantages. Graders are versatile and can be used for various grading tasks. Scrapers are efficient in moving large quantities of soil. Bulldozers are powerful but may not provide precise leveling. Laser-guided equipment offers high precision but requires specialized training.

Conclusion

Land grading survey and design are essential components of irrigation theory and practices. It ensures proper water distribution, prevents soil erosion, and improves crop productivity. Understanding the different methods, earthwork quantities computation, and equipment used in land grading is crucial for successful irrigation projects. By implementing effective land grading survey and design techniques, farmers and landowners can optimize water usage and achieve sustainable agricultural practices.

Summary

Land grading survey and design are crucial for irrigation. Different methods like contour bench levelling, cut and fill method, and laser levelling are used for land levelling. Earthwork quantities computation is done using the cross-sectional method or average end area method. Equipment like graders, scrapers, bulldozers, and laser-guided equipment are used for land grading. Understanding these concepts and techniques is essential for successful irrigation projects.

Analogy

Land grading survey and design can be compared to building a sandcastle on the beach. Before starting, you need to survey the area and determine the shape and size of the sandcastle. Similarly, in land grading, the land is surveyed to determine the contour lines and slope. Once the survey is done, you can start building the sandcastle by creating different levels and ensuring a smooth surface. This is similar to constructing benches in contour bench levelling. Finally, just like equipment is used for land grading, you may use tools like buckets and shovels to shape and level the sandcastle.