Land surveying can be a complex field that involves a variety of intricate concepts. Here are 10 of the most challenging concepts that new surveyors might find difficult to grasp:

1. Geodetic Datum and Coordinate Systems: Understanding different geodetic datums, coordinate systems (e.g., latitude and longitude, UTM), and their transformations can be daunting for new surveyors.

2. Map Projections: Grasping the various map projection methods, their distortions, and when to use each projection can be challenging due to the mathematical complexities involved.

3. Error Propagation: Dealing with error propagation and understanding how measurement errors accumulate through different surveying processes and calculations can be confusing.

4. Geoid and Ellipsoid: Comprehending the difference between the geoid (the Earth's actual shape) and the ellipsoid (a simplified mathematical model) is essential but can be difficult due to the three-dimensional nature of the Earth.

5. Least Squares Adjustments: Mastering the principles of least squares adjustments used to refine survey measurements and minimize errors requires a solid understanding of statistics and matrix mathematics.

6. Cadastral Surveying: Navigating the legal intricacies of cadastral surveying, property rights, boundaries, and the associated laws and regulations can be overwhelming for new surveyors.

7. GPS/GNSS Technology: Understanding the principles of Global Positioning System (GPS) and Global Navigation Satellite System (GNSS) technology, along with factors influencing accuracy, can be complex.

8. Remote Sensing and LiDAR: Grasping remote sensing techniques like LiDAR (Light Detection and Ranging), aerial imagery interpretation, and their applications in surveying demands knowledge of sensor technology and data analysis.

9. Survey Adjustments: Learning to perform adjustments on survey data to minimize errors and improve accuracy involves both mathematical concepts and a deep understanding of survey methodologies.

10. Vertical Datums and Leveling: Comprehending different vertical datums, leveling techniques, and the intricacies of transferring height measurements accurately can be challenging due to the complexities of Earth's shape and gravity field.

Keep in mind that while these concepts may be challenging initially, with continuous study, practice, and real-world experience, new surveyors can gradually gain a better understanding of these complex concepts and become proficient in the field.