Abstract:
The effect of length of streamflow records on truncation level (TL) and consequent drought characterization using streamflow data
for a 50 year period at Banda (Ken river) and Nandghat (Seonath river) sites in India are studied. The study demonstrates the divergence in
estimates of TL from different sets of data of various assessment lengths of duration and severity of independent streamflow drought events.
TL for each 10-day (sum of 10 days streamflow volume) period during the year have been estimated as 75% of dependable flow value from
corresponding flow duration curves prepared for datasets of various lengths and periods. A pooling procedure has been used to identify
independent streamflow drought events. The study revealed that the estimation of TL using data covering fewer than 30 years shows considerable
variations and may lead to biased estimates in TL values in the study basins. However, the estimates of TL derived from datasets
covering 30 years or more are reasonably close to that of TL derived from 50 years of data, and the assessment for duration and severity of
drought events are comparable. Therefore, data spanning 30 years or more should be used for realistic stream flow drought characterization.
