The design discharge for intake structures is the maximum daily demand. This refers to the amount of water that the intake structure is designed to handle on a daily basis. It is an important parameter in the design of intake structures, which are typically used to withdraw water from a natural source such as a river, lake, or reservoir for various purposes such as drinking water supply, irrigation, or industrial processes.

Intake structures are designed to have a certain capacity to meet the water demand of the intended application. The design discharge is determined by considering factors such as the maximum daily water demand, population served, and any future growth in water demand.

Here is why the design discharge is the maximum daily demand:

1. **Water demand fluctuation**: The water demand for different applications can vary throughout the day. It is generally higher during certain periods such as mornings and evenings when people are using water for daily activities like bathing, cooking, and washing. Therefore, the maximum daily demand is considered to account for these fluctuations and ensure that the intake structure can handle the peak water demand.

2. **Storage capacity**: Intake structures often include storage facilities such as reservoirs or tanks to store water and ensure a continuous supply during periods of low demand or when the natural water source is not available. The design discharge is used to determine the storage capacity required to meet the maximum daily demand.

3. **System reliability**: Designing the intake structure based on the maximum daily demand ensures that the system can reliably meet the water demand even during peak usage periods. It provides a buffer to handle unexpected variations in water demand and ensures a consistent supply of water to the users.

4. **Future expansion**: The design discharge also takes into account any anticipated future growth in water demand. By considering the maximum daily demand, the intake structure can accommodate future increases in population or water consumption without requiring significant modifications or upgrades.

In conclusion, the design discharge for intake structures is the maximum daily demand. This parameter ensures that the intake structure is designed to handle the peak water demand, provides storage capacity, ensures system reliability, and allows for future expansion.