Factors affecting the water cycle

1. THE WATER CYCLE

2. EVAPORATION
• IS THE TYPE OF VAPORAZATION THAT OCCURS ON THE
SURFACE OF A LIQUID AS IT CHANGES INTO THE GAS
PHASE.

4. • EVAPORATION IS AN ESSENTIAL PART OF THE WATER
CYCLE.
• THE SUN (SOLAR ENERGY) DRIVES EVAPORATION OF WATER
FROM OCEANS, LAKES, MOISTURE IN THE SOIL, AND OTHER
SOURCES OF WATER.
• EVAPORATION OF WATER OCCURS WHEN THE SURFACE OF
THE LIQUID IS EXPOSED, ALLOWING MOLECULES TO ESCAPE
AND FORM WATER VAPOR; THIS VAPOR CAN THEN RISE UP
AND FORM CLOUDS. WITH SUFFICIENT ENERGY, THE LIQUID

5. TRANSPIRATION
• TRANSPIRATION IS THE PROCESS BY WHICH MOISTURE IS
CARRIED THROUGH PLANTS FROM ROOTS TO SMALL
PORES ON THE UNDERSIDE OF LEAVES, WHERE IT
CHANGES TO VAPOR AND IS RELEASED TO THE
ATMOSPHERE.

7. • TRANSPIRATION IS ESSENTIALLY EVAPORATION OF WATER FROM
PLANT LEAVES. TRANSPIRATION ALSO INCLUDES A PROCESS
CALLED GUTTATION, WHICH IS THE LOSS OF WATER IN LIQUID
FORM FROM THE UNINJURED LEAF OR STEM OF THE PLANT,
PRINCIPALLY THROUGH WATER STOMATA.
• IN HYDROLOGY, EVAPORATION
AND TRANSPIRATION (WHICH INVOLVES EVAPORATION WITHIN
PLANT STOMATA) ARE COLLECTIVELY
TERMED EVAPOTRANSPIRATION.

8. ATMOSPHERIC FACTOR AFFECTING
TRANSPIRATION
THE AMOUNT OF WATER THAT PLANTS TRANSPIRE VARIES GREATLY
GEOGRAPHICALLY AND OVER TIME. THERE ARE A NUMBER OF FACTORS THAT
DETERMINE TRANSPIRATION RATES:
• TEMPERATURE
• RELATIVE HUMIDITY
• WIND AND AIR MOVEMENT
• SOIL-MOISTURE AVAILABILITY
• TYPE OF PLANT

9. INTERCEPTION
• INTERCEPTION REFERS TO PRECIPITATION THAT DOES NOT REACH
THE SOIL, BUT IS INSTEAD INTERCEPTED BY THE LEAVES,
BRANCHES OF PLANTS AND THE FOREST FLOOR.

11. CONCEPT OF INTERCEPTION:
• INTERCEPTION DEALS WITH THE AMOUNT OF WATER THAT IS CAUGHT AND
STORED ON THE LEAVES AND STEMS OF VEGETATION.
• THE TERM VEGETATION INCLUDES FOREST TREE COVER, CROPS AND LOW LEVEL
VEGETATION LIKE UNDER-BUSH, GRASS ETC.
• PART OF THE PRECIPITATION WHICH FALLS EITHER AS RAINFALL OR SNOWFALL
IS CAUGHT BY VEGETATION COVER BEFORE IT REACHES THE GROUND.

12. FACTORS AFFECTING INTERCEPTION:
THE AMOUNT OF WATER INTECEPTED IS GREATLY VARIABLE AND DEPENDS ON MANY
THINGS. SINCE THE INTERCEPTION AFFECTS THE DISTRIBUTION OF RAINFALL OR
SNOWFALL AND SUBSEQUENT RUN-OFF, IT IS NECESSARY TO UNDERSTAND THE
FACTORS WHICH AFFECT INTERCEPTION.
• TYPE OF VEGETATION
• WIND VELOCITY
• DURATION AND INTENSITY OF THE STORM
• CLIMATE OF THE AREA

13. DEPRESSION STORAGE
• THE VOLUME OF WATER CONTAINED IN NATURAL DEPRESSIONS IN THE LAND
SURFACE, SUCH AS PUDDLES. WATER TEMPORARILY RETAINED IN PUDDLES,
DITCHES, AND OTHER DEPRESSIONS IN THE SURFACE OF THE GROUND, AND
EVENTUALLY EVAPORATED OR INFILTRATED; THE SMALL-SCALE COUNTERPART
OF CLOSED DRAINAGE.

15. • DEPRESSION STORAGE REFERS TO SMALL LOW
POINTS IN UNDULATING TERRAIN THAT CAN
STORE PRECIPITATION THAT OTHERWISE WOULD
BECOME RUNOFF. THE PRECIPITATION STORED IN
THESE DEPRESSIONS IS THEN EITHER REMOVED
THROUGH INFILTRATION INTO THE GROUND OR
BY EVAPORATION.