The cause of soil erosion, among others:
1. Land bald or absence of plants;
2. Land not made sloping terraces – terraces and ridges as a buffer water and soil are straight;
3. Land is not made dike couples as barriers to erosion;
4. On forest land damaged by trees – trees cut illegally to become bald;
5. On the muddy ground surface used for grazing wild that land on getting damaged.
Erosion and Sedimentation is the process of soil particle detachment from its parent somewhere and terangkutnya the material by the movement of water or wind, followed by deposition of material contained elsewhere (Suripin, 2002). Erosion and sedimentation according Suripin (2002) depends on several factors: the characteristics of rainfall, slope, plant cover and the soil’s ability to absorb and release water into a shallow layer of soil, the impact of soil erosion may cause sedimentation in the river so as to reduce capacity river.
Figure 4. Deforestation
A number of materials that can undergo erosion in full from its source to the point of control is called the result of sediment (sediment yield). The results of these sediments are expressed in units of weight (tonnes) or unit volume (m3) and is also a function of the area of flux. It can also be the result of sediment is the amount of sediment derived from erosion in the catchment area were measured at certain periods of time and place (Asdak C., 2007).
Of the sedimentation process, only a portion of the flow in the river sediment is transported out of the watershed, while others settle in certain locations of the river (Gottschalk, 1948, in T Ven Chow, 1964 Suhartanto, 2001). Foster and Meyer (1977) found erosion as the cause of sedimentation caused by water mainly includes the release process (detachment), washout (transportation), and precipitation (depotition) of soil particles caused by the collision of rainwater and water flow.
Materials sediment erosion results often move short distances before being deposited. These sediments remain in soil or deposited elsewhere flatter or partially into the river. The general equation for calculating sedimentation of a watershed is not yet available, to further facilitate development approach based on the area. The ratio of the overall material transported sediment soil erosion called Sediment Discharge Ratio (Sediment Delivery Ratio / SDR) that is a function of the area.
Sedimentation geologically is a process of soil erosion is running normally, it means that the deposition process that takes place still within the limits permitted or in the natural balance of the degradation process and agradasi on flattening the earth’s crust due to weathering. Sedimentation process accelerated sedimentation deviate from geological processes and takes place in a time of rapid, destructive or harmful and can disrupt the balance of nature or environmental conservation. These events are usually caused by human activities in cultivating the land. How to cultivate land that one can lead to soil erosion and high sedimentation.