1.2 Consideration of the Hydrological Situation
The biggest erosion damages are usually caused by runoff water. Thereby, soil particles are dissolved and moved down the slope, the water acting as transportation medium. Water can act especially agressively in places, where it cannot drain away quickly enough, but flows down the slope and meets easy-to-solve soil particles. This is why coarse-grained soils like e.g. sand and gravel as well as coherent soils (clays) are less endangered by erosion. It is not only precipitation water, but also spring and slope water, which again and again cause slips, massive depression and rift erosion. Such site conditions demand for project-individual and partly very specific measures.
Incidental surface and spring water as well as leaking seepage water ought to be drained off as comprehensively as possible.
The threat of soil erosion is prevented by largely withdrawing the soil's surface from the attacks of water or wind applying appropriate surface forming.
Preconditions for this are, for example
- a flat structuring of slopes and landscape constructions;
- the rounding of slope tops and other hard contours;
- the creation of a rough soil surface with vivid micro-relief;
- the creation of structures parallel to the slope, when preparing the soil (following the principle of "contour farming");
- the elimination of wind cones in areas with sites endangered by winds.
Here the Following Principle Applies:
Only a procedure, where the techniques of earth moving are adapted to the soil conditions, and a correspondingly adjusted reliefing of the problematic area ensures a successful, permanent protection against erosion by establishing vegetation.