What constitutes 'design pressure' in irrigation systems?

'Design pressure' in irrigation systems represents the necessary pressure needed to deliver water effectively through the system while accounting for various factors that may impact performance. This includes the required head pressure to achieve the desired irrigation coverage as well as the total pressure losses that occur throughout the system due to friction and other resistances encountered in pipes, fittings, and valves.

By considering both the desired head pressure and the total pressure losses, the design pressure ensures that the system can deliver adequate water to the sprinklers or other distribution points under anticipated operating conditions. This comprehensive approach allows for optimal system performance, ensuring that plants receive the necessary water at the correct rate.

The other options focus on narrower aspects of pressure that do not encompass the broader requirements for operational effectiveness. For example, merely considering the total pressure from the water supply ignores the critical losses that can occur under real conditions. Similarly, solely defining design pressure as the required pressure at the sprinklers fails to take into account the contributing factors like friction losses, and defining it exclusively based on the pump system does not reflect the complete hydraulic profile of the irrigation system needed for effective planning and design.