Results of sediment from an area specified flow can be determined by measurement of sediment transport of dissolved (suspended sediment) at the control point of the river flow. Sediment is often found in rivers both soluble and insoluble is a product of weathering of host rock is influenced by environmental factors, especially climate change. The result of weathering of rocks are known as soil particles, therefore the effect of the power of kinetic rainwater and surface runoff, especially in the tropics, soil particles can be chipped and transported to a lower place to then enter into rivers and is known as sediment.
Because of the process of sediment transport caused by the flow of river water will result in silting-silting and the formation of new regional tanahtanah edges of rivers and river deltas. Based on sediment type and size of the soil particles and mineral composition of the parent material of which it is composed are known various types of sediments such as sand, clay and others depending on the size of the particles. According to its size, the sediment can be divided into several types as shown in Table 3 (Dunne and Leopold, 1978 in Asdak C, 2007)
Table 3. Type of sediment by particle size
Free flow of the river is usually greater on river body than in a place close to the cliff face or the bottom of the river, the stream-flow patterns were erratic (turbulance flow) power of momentum caused by the flow speed of uncertainty is moved in the direction of water flow over scrolls slowly by water which starts and ends is uncertain as well.
Rolls of water flow will cause the shape change of the kinetic energy generated by the movement of the river flow to heat energy, which means that no energy is lost due to the roll movement of the water flow. But there are also some kinetic energy that moves to the bottom of the river that allows the movement of large particles of sediment at the bottom of the river and is known as creeping sediments (Asdak C., 2007). The amount of sediment yield estimates by Asdak C.2007 can be determined by the following equation:
Y = E (SDR) Ws
Where
Y = Results of sediment per unit area
E = Erosion Amount
Ws = Area Watershed.
SDR = Sediment Delivery Ratio (Ratio Release of Sediments)
The value of the SDR in the calculation results of sediment a river basin is generally determined using the relationship between the table and the amount of SDR watershed area (Table 1). To calculate the approximate amount of erosion in a watershed can be used USLE method, according Asdak C. (2007) with the formulation:
E = RKLS.CP
Where :
E = estimate of the magnitude of the erosion amount (tonnes / ha / year)
R = factor erosivitas rain
K = soil erodibility
LS = length factor – slope
C = factor of land cover crops or crop management
P = factor of soil conservation measures