TITLE:
Compatibility of Drought Magnitude Based Method with SPA for Assessing Reservoir Volume: Analysis Using Canadian River Flows
AUTHORS:
Tribeni C. Sharma, Umed S. Panu
KEYWORDS:
Extreme Number Theorem, Markov Chain, Moving Average Smoothing, Standardized Hydrological Index, Sequent Peak Algorithm
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.14 No.1,
January
5,
2022
ABSTRACT: The traditional sequent peak algorithm (SPA) was used to assess the reservoir volume (VR) for comparison with deficit volume, DT, (subscript T representing the return period) obtained from the drought magnitude (DM) based method with draft level set at the mean annual flow on 15 rivers across Canada. At the annual scale, the SPA based estimates are larger, on an average of nearly 70%, compared to the DM based estimates. To ramp up the DM based estimates to be in parity with SPA based values, the analysis was conducted through the counting and the analytical procedures involving only the annual SHI (standardized hydrological index, i.e. standardized values of annual flows) sequences. It was found that MA2 or MA3 (moving average of 2 or 3 consecutive values) of SHI sequences was required to match the counted values of DT to VR. Further, the inclusion of mean, as well as the variance of the drought intensity in the analytical procedure, with the aforesaid smoothing led DT comparable to VR. The distinctive point in the DM based method is that no assumption is necessary such as the reservoir being full at the beginning of the analysis—as it is the case with the SPA.