Determining minimal residual flow at waterfalls used for hydropower

While hydropower is considered a promising energy source to achieve climate protection goals, there can be conflicts between the attractive appearance of waterfalls and diverting water to produce power. In a European case study, seven waterfalls were observed, and a discharge-related picture series shows the interaction between the flow and the appearance of waterfalls. On the basis of this study, a methodology to determine minimal flow requirements at waterfalls has been developed. Based on the area covered by water and the time of water extraction, the extent of the impact is determined. The extent and value of the waterfall are then combined in a consequence matrix. The methodology is approved on a Norwegian and an Austrian waterfall.