GEOTECHNICAL DESKTOP STUDY: GA-MATHIPA DAM PROJECT
2. INTRODUCTION
This report presents a geotechnical desktop study for the proposed construction
of a small dam and reservoir in the Ga-Mathipa/Ragopola area, Limpopo
Province. As a dam is a high-risk structure with significant engineering
complexity, this project is classified under Geotechnical Category 3. The
objective is to evaluate the geological and climatic conditions of the site to
provide preliminary engineering recommendations for the dam wall foundation
and reservoir basin.
3. SITE DESCRIPTION
Location: The site is situated in the Fetakgomo-Tubatse Local Municipality,
within a tributary valley of the Steelpoort River.
Coordinates:
• • Dam Wall (Point A): 24°32'00"S; 30°10'12"E
• • Reservoir Basin (Point B): 24°31'36"S; 30°10'30"E
Topography: The site exhibits a typical valley morphology. Point A is located at a
narrow topographic "pinch point," suitable for a dam wall, while Point B is
situated in a broader upstream basin.
4. CLIMATIC DATA AND TOPOGRAPHY
4.1 Weinert N-value
The climatic conditions significantly influence the weathering of the parent rock.
The Weinert N-value is calculated using the formula:
N = (12 * Ej) / Pa
Where Ej is the evaporation in January and Pa is the total annual precipitation.
Assumptions:
Based on regional data for the Steelpoort area, Pa is assumed to be ~550mm
and Ej is assumed to be ~250mm. This results in a calculated N-value of
approximately 5.45.
2. INTRODUCTION
This report presents a geotechnical desktop study for the proposed construction
of a small dam and reservoir in the Ga-Mathipa/Ragopola area, Limpopo
Province. As a dam is a high-risk structure with significant engineering
complexity, this project is classified under Geotechnical Category 3. The
objective is to evaluate the geological and climatic conditions of the site to
provide preliminary engineering recommendations for the dam wall foundation
and reservoir basin.
3. SITE DESCRIPTION
Location: The site is situated in the Fetakgomo-Tubatse Local Municipality,
within a tributary valley of the Steelpoort River.
Coordinates:
• • Dam Wall (Point A): 24°32'00"S; 30°10'12"E
• • Reservoir Basin (Point B): 24°31'36"S; 30°10'30"E
Topography: The site exhibits a typical valley morphology. Point A is located at a
narrow topographic "pinch point," suitable for a dam wall, while Point B is
situated in a broader upstream basin.
4. CLIMATIC DATA AND TOPOGRAPHY
4.1 Weinert N-value
The climatic conditions significantly influence the weathering of the parent rock.
The Weinert N-value is calculated using the formula:
N = (12 * Ej) / Pa
Where Ej is the evaporation in January and Pa is the total annual precipitation.
Assumptions:
Based on regional data for the Steelpoort area, Pa is assumed to be ~550mm
and Ej is assumed to be ~250mm. This results in a calculated N-value of
approximately 5.45.
