ESTIMATION OF RUNOFF FROM SMALL WATERSHEDS OF DOON VALLEY

Abstract

THIS PAPER PRESENTS AN ANALYSIS OF DATA COLLECTED FROM FIVE EXPERIMENTAL WATERSHEDS OF VARYING SIZES (4.4 TO 83.4 ha ) AND LAND USES ( AGRICULTURE , FOREST AND A MIXTURE OF THE TWO ) IN DOON VALLEY. THIS ANALYSIS HAS SHOWN THAT A SIMPLE LINEAR MODEL IS BETTER THAN THE LOGARITHMIC ONE IN PREDICTING BOTH RUNOFF VOLUME AND PEAK INSPITE OF THE FACT THAT RAINFALL RUNOFF RELATIONSHIPS ARE GENERALLY NON-LINEAR. THE MAXIMUM VARIANCE IN THE MODEL FOR RUNOFF PEAK ARE CONTRIBUTED BY THE WATERSHED PARAMETERS LIKE THE AREA OF WATERSHED AND THE LENGTH OF THE MAIN CHANNEL . IN THE CASE OF RUNOFF VOLUME, PARAMETERS LIKE THE RAINFALL AMOUNT AND ITS DURATION CONTRIBUTED MAXIMUM TO THE VARIANCE. TESTING OF THE EXPRESSIONS WITH THE DATA FROM THE FIFTH WATERSHED HAS SHOWN GOOD AGREEMENT BETWEEN THE OBSERVED AND COMPUTED VALUES OF RUNOFF PEAK AND VOLUME