1. Loading of different kind of substances to watercourses
2. Hydro-morphological changes

Before any human actions on the river basins, nutrients, suspended solids and organic matter have always been transported from soil to waters. This is called natural leaching. Especially the river drainage basins are characterised by this constant material transport, the biota of the river ecosystems being dependent on this transport. For example, organic detritus particles, which derive from the soil ecosystems of the drainage basins, are important food sources for the river biota, for the so called detritus food chain composed of benthic invertebrates, fungi and bacteria. Any leaches of any substances to watercourses higher than the natural leaching can be called loading. The loading can end up to waters either with run-off waters from the drainage basin or through the atmospheric fall-out.

 

Many human actions may have effects on the hydrology of the water, like draining and regulation of water level. Some actions may directly change the natural morphology of the watercourses, like dredging or channelisation. All these kind of actions can be called hydro-morphological pressures.