africa
barrier
blue
bulgaria
clouds
concrete
construction
countryside
dam
electricity
energy
engineering
environment
environmental
europe
flood
flow
flowing
hydro
hydroelectric
hydropower
industrial
industry
iskar
lake
landscape
midmar
mountain
natal
nature
overflow
power
rare
release
reservoir
resource
river
sky
sofia
south
spillway
splash
spray
structure
technology
turbine
wall
water
waterfall