To ensure safe operation of hydropower plant (HPP) in all conditions, every HPP has to have
defined operation concept. Operation concept is always defined for starting conditions in
which HPP and its reservoir starts to operate. Based on the selected operation concept a set of
operating rules is applied. As a result of the selected operating concept and designed set of
operation rules a water level pivot point appears in HPP reservoir. Pivot point represents the
point in the reservoir, where the water level remains constant, regardless the increase or.
decrease of the flow in the river. Pivot point appears only at times, when HPP operates in
accordance with designed set of operation rules. But with the construction of HPP, hydraulic
conditions of the river are altered. Consequently of that a process of sedimentation begins in
the reservoir. In this assignment the impact of sedimentation on the initial location of water
level pivot point and thus on starting operation concept is analyzed with methods of hydraulic
modeling. Hydraulic calculations are performed for theoretical example of HPP in a reservoir
with simplified geometry. Changes in reservoir's bottom and hydraulic roughness are
observed and their impact on the starting operating concept is investigated. By performing
calculations for this example, we obtaine basic knowledge regarding how the various changes
influence the water level pivot point and the level of impact on operation concept. The results
are later validated with calculations for the hydraulic model of HPP Boštanj. Based on the
results from both calculations, the analysis were made. The analysis explains the impact of
sedimentation on the location of water level pivot point, the implications on operation concept
and how the effects can be mitigated.
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