Physical measures are structures built for soil and water conservation. Some principles should be considered. They should aim to

• increase the time of concentration of runoff, thereby allowing more of it to infiltrate into the soil;
• divide a long slope into several short ones and thereby reducing amount and velocity of surface runoff;
• reduce the velocity of the surface runoff;
• protect against damage due to excessive runoff (Tidemann 1996).

In most systems any physical measure can be built – check dams or contour ditches, for example (see figure) (Heathcote 1998).

Soil and Water Conservation Measures in the Gina River catchment

In the Gina River catchment walls and terraces are used. Both serve as control structures to prevent soil erosion processes - a major problem in this drainage basin.

Terraces are explained in more detail on the following learning page.