Introduction:
A core wall is a structural element provided in an earthen dam. It plays a crucial role in enhancing the stability and strength of the dam. In this response, we will explore why a core wall is provided in an earthen dam and understand its significance.

Explanation:
1. Purpose of a core wall:
- A core wall is constructed to prevent the seepage of water through the embankment of an earthen dam.
- It acts as a barrier to control the flow of water through the dam, ensuring its stability and preventing any potential damage.

2. Preventing seepage:
- Seepage is a critical issue in earthen dams as it can lead to erosion of the soil particles, weakening the structure over time.
- The core wall is constructed using impervious materials such as clay, concrete, or asphalt, which significantly reduce the permeability of the dam.
- The impervious nature of the core wall prevents the water from seeping through the embankment, ensuring the stability of the dam.

3. Enhancing stability:
- The presence of a core wall greatly enhances the stability of the earthen dam.
- By reducing seepage, it prevents the erosion of soil particles and the subsequent weakening of the dam structure.
- The core wall also acts as a structural element, providing additional strength and support to the dam.
- It helps to distribute the load of the water evenly across the dam, minimizing any potential stress concentrations.

4. Construction and design:
- The core wall is typically constructed in the central portion of the dam, extending from the foundation to the top of the embankment.
- It is designed to have an adequate thickness and height to effectively resist the hydrostatic pressure exerted by the impounded water.
- The core wall is often made impermeable by using compacted clay or by providing a concrete or asphalt lining.

Conclusion:
In conclusion, a core wall is provided in an earthen dam to prevent seepage, enhance stability, and ensure the long-term integrity of the structure. It acts as a barrier to control the flow of water through the dam and is constructed using impervious materials. The core wall plays a crucial role in safeguarding the structural stability and functionality of the earthen dam.