This book is about the finding the revised design of Spillway channel of a hydropower dam in Sweden. (The Dabbsjön spillway). The spillway capacity is believed to be insufficient specially considering large floods.Downstream of the spillway gates the water jet strikes the rock downstream and enters a channel and further downstream the channel turns to the right entering the hydropower plants. The main objective was to study and document the new shape of the spillway channel. The model was constructed and located at the NTNU/SINTEF laboratory in the scale 1:30 and lab test were carried out. Initially the test was carried on the model with original shape and features as in prototype. In this stage observation were made on flow pattern in the spillway and on the channel downstream.On the other hand the model was run for different discharges with the difference of 1 cm opening of the gates to find out the capacity of the both the gates. so this works covers all the finding done under the spillway model to mitigate the problem and the capacity curves for gates in different openings.