The River Waal in the Netherlands is naturally broad and shallow. Meanders along the river have been straightened through channelisation. Dykes have been built along the bank to encourage the water to flow faster in the middle of the channel, enabling better navigation. The river used to flood, which created alluvium-rich floodplains for farming. River defences were built to contain the river, but these were breached when the flooding problem became much more severe.
Can be used to debate whether natural river systems should be changed by humans. Pupils will look at the advantages and disadvantages of human intervention on rivers.