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| DOI：10.13522/j.cnki.ggps.20180327 |
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| Classifying Drought in Heihe Basin Using SRI Index and Copula Function |
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ZHANG Xiangming, SU Xiaoling*, ZHANG Gengxi
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College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China
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| Abstract: |
| 【Objective】 The purpose of this paper is to present a method to classify drought based on the measured data in Heihe basin.【Method】Two methods based on runoff-frequency classification were used to realize probabilistic statistical analysis of the runoff data at the Yingluoxia hydrological station in the Heihe River Basin. The SRI-based hydrological drought classification standard (Standard 1) was proposed. The Standard 1 and drought standardization criteria (Standard 2) based on the standardized precipitation index (SPI) were used to identify three drought characteristic variables of hydrological drought, including duration, intensity, and peak intensity. The Copula function was used to study the multivariate joint distribution of hydrological drought, the RMSE, AIC, and BIC criteria was selected as the discriminant basis for the joint distribution goodness of fit test to optimize the Copula function type and then calculated the return period for different drought events.【Result】The classification of hydrological drought grade based on Standard 1 is more consistent with the real drought situation than Standard 2. The univariate return period is between the joint return period and the cooccurrence return period, it therefore is possible to estimate the return period of the drought events. A severe drought lasing for 2.68 months occurs about every three years in the basin.【Conclusion】The SRI-based classification of drought in the multivariable hydrological drought study improves the joint distribution function, and the calculated drought characteristics marched historical data. |
| Key words: SRI; drought; grade division; Copula function; return period |
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