Erosivity of rainfall

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 Log 10 I HERE: KE= KINETIC ENERGY & I = RAINFALL INTENSITY

4. II. DROP SIZE DISTRIBUTION. INFLUENCES: ENERGY MOMENTUM & EROSIVITY OF RAIN. BOTH INFLUENCES ARE IN CUMULATIVE WAY. RELATION B/W DROP SIZE AND INTENSITY. 0.182 D 50 =2.23(I) HERE D 50 IS MEDIAN DROP SIZE.

5. III. TERMINAL VELOCITY. IS FUNCTION OF DROP SIZE. HAS FOLLOWING RELATIONSHIP WITH RAINFALL ENERGY 2 RELATION : E K =I(V) / 2 HERE E K =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 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 I 30 INDEX METHOD. 11. KE>25 INDEX METHOD.

8. EI 30 INDEX METHOD PRODUCT OF K.E AND 30 MIN MAX. INTNSITY RAIN. EQUATION: EI 30 = K.E * I 30 LIMITATION: NOT SUITABLE FOR TROPICAL AND SUBTROPICAL ZONES

9. KE>25 INDEX METHOD SUITABLE WHERE RAINFALL INTENSITY>25. USED IN SAME MANNER AS EI 30 INDEX METHOD.