Statement 1: Deltas are less satisfactory sites than estuaries for the siting of large ports.
Statement 2: The construction of artificial harbours can overcome this.

Explanation:
Deltas vs Estuaries:
1. Deltas are landforms that are formed at the mouth of rivers where they deposit sediment over long periods of time. They are characterized by their triangular shape and are usually rich in nutrients.
2. Estuaries, on the other hand, are semi-enclosed coastal areas where freshwater from rivers mixes with saltwater from the ocean. They are typically found where rivers meet the sea and are characterized by their brackish water.

Statement 1: Deltas are less satisfactory sites than estuaries for the siting of large ports.
- Deltas are formed by the deposition of sediment carried by rivers. This sedimentation process can result in the formation of shifting sandbars, shallow channels, and unstable landforms, making deltas less suitable for the siting of large ports.
- The shifting nature of deltas can pose challenges for navigation and require constant dredging to maintain navigable channels.
- The presence of shallow channels and sandbars can also hinder the movement of large ships and limit the capacity of the port.

Statement 2: The construction of artificial harbours can overcome this.
- Artificial harbours are man-made structures designed to provide shelter and facilitate the safe docking of ships. They are constructed using breakwaters, jetties, and other engineering techniques.
- By constructing artificial harbours, it is possible to create stable and deep-water port facilities even in areas with challenging natural conditions like deltas.
- Artificial harbours can provide protection against waves, tides, and sedimentation, thereby improving the navigability and safety of the port.
- Dredging can be done to deepen the channels and maintain a sufficient depth for large ships to navigate.
- The construction of artificial harbours can also provide opportunities for land reclamation, which can be used for port infrastructure, storage facilities, or other commercial activities.

Conclusion:
Both statements are correct. Deltas are generally less satisfactory sites for large ports compared to estuaries due to their shifting nature and shallow channels. However, the construction of artificial harbours can overcome these challenges and provide stable and deep-water port facilities even in deltaic regions.