What is it about?

Drought is a complex stochastic natural hazard caused by prolonged shortage of rainfall. Several environmental factors are involved in determining drought classes at the specific monitoring station. Therefore, efficient sequence processing techniques are required to explore and predict the periodic information about the various episodes of drought classes. In this study, we proposed a new weighting scheme to predict the probability of various drought classes under Weighted Markov Chain (WMC) model. We provide a standardized scheme of weights for ordinal sequences of drought classifications by normalizing squared weighted Cohen Kappa. Illustrations of the proposed scheme are given by including temporal ordinal data on drought classes determined by the standardized precipitation temperature index (SPTI). Experimental results show that the proposed weighting scheme for WMC model is sufficiently flexible to address actual changes in drought classifications by restructuring the transient behavior of a Markov chain. In summary, this paper proposes a new weighting scheme to improve the accuracy of the WMC, specifically in the field of hydrology.

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Why is it important?

This is a novel way to predict drought classes. This will also help to manage the Markov chain process which has ordinal states.


Prediction and forecasting play a very important role, especially in early warning situations. Consequently, accurate and precise techniques of drought forecasting may reduce their severe effect by making effective drought mitigation policies. In this article, the SPTI drought index being a more comprehensive drought monitoring procedure is used to classify historical monthly drought profile. Outcomes show that by introducing standardized squared weighted Kappa as a weight, the research suggests a new way to get adjusted prediction probabilities under WMC framework. Furthermore, it is observed that the advantage of step forecasting can be achieved by just changing the transition probability vector and rearranging vectors of weights. Therefore, among numerous other studies and forecasting framework, the uniqueness of this research is to introduce ordinal measure of association at various lags in WMC-based prediction method.

Zulfiqar Ali
Quaid-i-Azam University

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This page is a summary of: A New Weighting Scheme in Weighted Markov Model for Predicting the Probability of Drought Episodes, Advances in Meteorology, November 2018, Hindawi Publishing Corporation, DOI: 10.1155/2018/8954656.
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