Factors Affecting Erosion

  Agronomic Measures 1. It is the practices of growing vegetation 2. It is done on mild sloppy land 3. It is used to reduce runoff, enhance infiltration, and dissipate the impact of raindrops due to cover, dissipate the erosive power of erosive agents, and control wind erosion and water erosion. 4. In the soil loss equation, agronomical measure reduces the value of C and P from 1 to 0.2 and 0.5 respectively. Following are the types of agronomical measures for controlling soil and water erosion, Contouring Contour farming The objective of contour cultivation/farming  To reduce the sheet and rill erosion  To reduce the sediment transport and other solids and nutrients  To enhance the infiltration rate. Contour farming involves ploughing, planting, and weeding along the contour, i.e, across the slope rather than up and down. Contour lines are lines that run across a (hill) slope such that the line stays at the same height and does not run uphill or downhill. As contour lines travel...

 Before going for any soil and water conservation measures (agronomical or mechanical), it is important to understand certain things of that area which are cited below, 1. Physiography of the area Size Shape Relief Mean elevation Landslope Drainage Soils Vegetative cover Land use 2. Rainfall Measurement and Analysis 3. Intensity-Duration-Return Period Relationship 4. Theories of Onset Of Runoff 5. Design of Peak Runoff Rate 6. Flood /Drought 7. Strom Pattern 8. Water Flow In a Watershed

 Much of soil erosion in India is caused by faulty practices of farming. The most outstanding among these are faulty ploughing, lack of mulching, cultivation along the steep slope, deforestation, and above all the practice of shifting cultivation. One example of such practices is seen in the form of fields ploughed along the slope and not along the contours. This method of tilling the land provides readymade rills at the time of rain and the flow of water concentrates in the furrows made through ploughing. It increases the velocity of runoff thereby facilitating quick removal of soil. Contour ploughing, in contrast, provides a sequence of ridges and furrows to the water flowing over the surface and the velocity of runoff is thus retarded and a lesser amount of soil is likely to be removed in such a situation.

 Erosion is influenced by a variety of elements including rainfall characteristics, soil factors, topography, climate, and land use. Rainfall Characteristics For erosion to occur, runoff must first be present. Runoff is defined as that portion of rainfall that does not infiltrate nor accumulate on the soil surface but moves downslope. Rainfall rate and duration both influence runoff and erosion. Runoff occurs only when rainfall intensity exceeds soil infiltration rate. Infiltration will decrease with time during the initial stages of a storm. Thus, no runoff may occur from a storm of short duration, while a storm of the same intensity but of longer duration may result in substantial runoff. Rainfall intensity influences both the rate and volume of runoff. During a high-intensity storm, infiltration capacity is exceeded by a greater margin than during a less intense rainfall event. Thus, even though the precipitation amount may be similar for two events, a high-intensity storm will ...