"Nature quality" in brooks, ditches and pools
In the last 50 years, the intensification of agriculture has led to a dramatic decline in the "nature quality" (this term is explained in the Technical note) of streams, ditches and pools.
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Pools, brooks and ditches are a characteristic component of the Dutch landscape. In 2000, however, their "nature quality" in terms of their macrofauna and aquatic plants, was half what it had been in 1950. This was true for all water types and all regions.
The most important reason for the decline in "nature quality" is the intensification of agriculture in the second half of the 20th century. Nutrients applied to farmland have ended up in surface water via runoff or leaching, causing water quality to deteriorate. Furthermore, in order to be able to regulate the water levels in the agricultural area, many stream courses have been straightened, dams and weirs have been constructed and the banks of ditches and pools have been steepened. The result is that the gradual transitions from land to water so important as a habitat for many plants and animals, have disappeared.
