Assess the potential of a weir as mechanism for contributing to a sustainable sand balance on the Volta River
By Jon Arends, with supervisor Prof. dr. ir. Nick Van de Giesen
Tamale, a city in the Northern Region of Ghana is rapidly urbanizing resulting in a large demand for residential and commercial construction, roads and infrastructure to meet the needs of the growing population. This infrastructure is primarily composed of concrete, which requires large volumes of sands and aggregates in its production. These sands and aggregates come primarily from two sources: marine and terrestrial. Terrestrial sand is used which is generally sourced from river channels and flood plains. When sand and aggregates are extracted at volumes that far exceed the rate of replenishment, it often causes grave environmental consequences.
In Tamale, terrestrial sand is used for concrete works. It is estimated that between 50-65% of sand and aggregates is excavated from the river beds and walls of the Volta River with volumes expected to grow to meet the cities demands. Without proper guidance to maintain a sustainable sand balance, the Tamale region of the Volta River may experience habitat transformation, erosion, channel incision, decreased water supply and increased flood risk.
Weirs are being explored to regulate the water supply for the city. Consequently, sand and aggregates will settle upstream of the weir. Can these weirs be used to sustainably remove sand from the Volta River without long term damage? How much sand could safely be removed? Questions like these hope to be answered in this research.