A piece of land has a drainage coefficient of 20 mm .
Calculate the capacity required at the outlet end of the drainage ditch draining a water
shed of 600 hectares in 24 hours.

To calculate the required capacity at the outlet end of the drainage ditch, we first need to convert the drainage coefficient and the area into compatible units. The drainage coefficient of 20 mm means that for a 600-hectare area (which is 6,000,000 m²), we will experience a vertical drainage requirement of 20 mm over 24 hours.

So, the volume of water to be drained in a day is:
Volume = Area × Drainage Coefficient = 6,000,000 m² × 0.020 m = 120,000 m³.

Now, to find the flow rate required for the outlet over a 24-hour period:
Flow Rate = Volume / Time = 120,000 m³ / 24 h = 5,000 m³/h.

Therefore, the outlet ditch must have a capacity of at least 5,000 m³/h to effectively drain the watershed.

To ensure drainage system efficiency, consider potential variations in rainfall and soil type, which can affect absorption rates. It’s also wise to include a buffer in capacity for unexpected heavy rains. Regular maintenance and cleaning of drainage ditches are essential to prevent blockages and ensure proper function.