Comparison of Run-Off Computed by Strange’s Table and ‘Dry Damp Wet’ Method

Author(s):

Dr. R. Bhavani , JNTUA College of Engineering, Anantapur

Keywords:

Dry Damp Wet method, Monsoon Rainfall, Rain gauge station, Run-off, Strange’s table and Theissen polygon

Abstract:

Run-off calculations are essential for designing any storage structure. Rrun-off can be calculated based on the rainfall data of rain gauge stations influencing the catchment area. In general, empirical methods are being used to compute the runoff. One of the methods of computing run-off is by Strange’s table. The Strange’s table provides the run-off in terms of percentage of the monsoon rainfall for Good, Average and Bad catchments. One more method is Dry Damp Wet method to compute the run-off. In this method, the condition of the catchment can be considered as Dry, Damp or Wet based on the occurrence of daily rainfall. In the present study, an attempt has been made to compare the runoff obtained by these two methods. The influencing zone of Anantapur rain gauge station, determined by Theissen polygon method has been selected for the present study. Rainfall data of Anantapur rain gauge station for the period from 1982 to 2013 has been used to compute the run-off. Monsoon rainfall of corresponding year has been considered for computation of run-off using Strange’s table and daily rainfall data has been used to compute the run-off as per Dry Damp Wet method. Run-off values obtained by Strange’s table and by Dry Damp Wet method have been compared and found that the values are varying. The variation is due to occurrence of rainfall at varied frequencies. As the frequency of rainfall is also taken in to account in addition to the magnitude of rainfall in Dry Damp Wet method, the values obtained by this method can be considered more precise.

Other Details:

Manuscript Id	:	IJSTEV2I10222
Published in	:	Volume : 2, Issue : 10
Publication Date	:	01/05/2016
Page(s)	:	1091-1095

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