American Society of Civil Engineers

Development of a Hybrid Index for Drought Prediction: Case Study

by Mohammad Karamouz, (corresponding author), (Prof., School of Civ. Engrg., Univ. of Tehran, Enghelab Ave., Tehran, Iran E-mail:, Kabir Rasouli, (Engrg. Dept., Islamic Azad Univ. Sci. & Res. Branch of Tehran, Tehran, Iran. E-mail:, and Sara Nazif, (Ph.D. Candidate, School of Civ. Engrg., University of Tehran, Tehran, Iran. E-mail:

Journal of Hydrologic Engineering, Vol. 14, No. 6, June 2009, pp. 617-627, (doi:

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Document type: Journal Paper
Abstract: Drought is a natural phenomenon that occurs in many places on the planet and may cause considerable damage. Selection of an integrated index for quantifying drought severity is a challenge for decision makers in developing water resources and operation management policies. In this study, the standardized precipitation index, water surface supply index, and Palmer drought severity index have been combined to develop an integrated index, called the hybrid drought index (HDI), using associated damage of drought events. Application of the HDI in drought severity prediction has been examined using two different types of artificial neural networks, namely, a probabilistic neural network and a multilayer perceptron network. These models have been selected due to their special characteristics that are suitable for prediction schemes. The proposed algorithm for developing HDI and drought prediction has been applied to the “Gavkhooni/Zayandeh-rud” basin in the central part of Iran. The results show the merits of each model in prediction of drought severity and model adaptation. The results also show the significant value of the proposed algorithm in formulation of a combined index for drought prediction.

ASCE Subject Headings:
Neural networks
Hybrid methods