If possible the water should be taken so far above the meadows as to have sufficient fall without damming up the river.
The space for the site was gained by pulling down the old houses composing the Schlossfreiheit and damming the Spree.
The islands of Schouwen and Duiveland are united owing to the damming of the Dykwater; St Filipsland, or Philipsland, and South Beveland are connected with the mainland of North Brabant by naturally formed mud banks.
Some are contained in alluvial depressions in the river valleys; others have been formed by volcanic eruptions, the ejecta damming the rivers until exits were found over cliffs or through gorges.
The idea was even mooted of damming up the river near Hauconcourt, and thus, flooding out the whole of the civil population of Metz; but expert civil engineers, who were sent for from Germany, reported against the proposal.