THIS PPT COVERS ABOUT EROSIVITY OF RAINFALL ,FACTORS AFFECTING EROSIVITY AND ESTIMATION OF EROSIVITY WHICH IS DONE BY 2 METHODS 1EI METHOD AND KE>25 METHOD.

1. EROSIVITY OF RAINFALL
PRESENTATION BY
UTKARSH JAIN

2. INTRODUCTION
• IS POTENTIAL ABILITY OF RAIN TO CAUSE EROSION.
• HIGHLY RELATED TO SOIL EROSION.
• POWER OF OVERLAND RUNOFF FLOW TO ERODE SOIL IS:
1.PARTLY A PROPERTY OF RAINFALL &
2.PARTLY OF SOIL SURFACE.

3. FACTORS AFFECTING RAINFALL EROSIVITY.
I.RAINFALL INTENSITY.
• IS RATE OF RAINFALL OVER LAND SURFACE.
• KINETIC ENERGY IS RELATED TO RAINFALL.
• EQUATION. KE=210.3 + 89 Log10I
• HERE: KE= KINETIC ENERGY
& I = RAINFALL INTENSITY

4. II. DROP SIZE DISTRIBUTION.
• INFLUENCES:
1. ENERGY MOMENTUM &
2. EROSIVITY OF RAIN.
• BOTH INFLUENCES ARE IN CUMULATIVE WAY.
• RELATION B/W DROP SIZE AND INTENSITY.
0.182
• D50 =2.23(I)
• HERE D50 IS MEDIAN DROP SIZE.

5. III. TERMINAL VELOCITY.
• IS FUNCTION OF DROP SIZE.
• HAS FOLLOWING RELATIONSHIP WITH RAINFALL ENERGY
2
• RELATION : EK =I(V) / 2
• HERE EK =RAINFALL ENERGY
& V = TERMINAL VELO.
EMPERICAL REL. B/W TEMINAL VELO. DROP DIA.&
INTENSITY.
4.33 1.07 0.65
E = K (V) (d) (I)

6. IV. WIND VELOCITY.
• AFFECTS RAINFALL INTENSITY BY INFLUENCING K.E.
• EFFECT OF WIND VELOCITY ON SOIL DETATCHMENT.
• V. DIRECTION OF SLOPE.
• INCREASES IMPACT FORCE OF RAINDROP.
WIND VELOCITY INTENSITY OF RAINFALL.
1.6 2.84 5.61
% SOIL DETATCHMENT
0
6.7
13.4
56 93 97
95 98 100
97 100 100

7. ESTIMATION OF EROSIVITY
• IT IS DONE BY TWO METHODS
1. E I30 INDEX METHOD.
11. KE>25 INDEX METHOD.

8. EI3 0 INDEX METHOD
• PRODUCT OF K.E AND 30 MIN MAX. INTNSITY RAIN.
EQUATION:
EI30 = K.E * I30
LIMITATION:
• NOT SUITABLE FOR TROPICAL AND SUBTROPICAL ZONES

9. KE>25 INDEX METHOD
• SUITABLE WHERE RAINFALL INTENSITY>25.
• USED IN SAME MANNER AS EI30 INDEX METHOD.