Publications Details
Publications Details

Back

Title: HYDROLOGICAL DROUGHT DETECTION USING A WATER BALANCE DERIVED DROUGHT INDEX AND METEOROLOGICAL DROUGHT INDICES

Author: A. Loukas, L. Vasiliades and G. Liberis

Year: 2009

Publisher: European Water Resources Association (EWRA)

Description:

This study estimates hydrological drought characteristics using a water balance derived drought index and meteorological drought indices in Pinios river basin, Thessaly, Greece. Thessaly is an agricultural plain region surrounded by mountains and is traversed by Pinios River, which has a basin area of about 9500 Km2. Fourteen (14) sub-watersheds of Pinios river basin were delineated according to the major tributaries of Pinios river using GIS. For the assessment of hydrological drought, because none of the sub-watersheds have flow gauge stations at their outlets, the following procedure was followed: A 6-parameter monthly conceptual water balance model (UTHBAL model), which uses as inputs areal precipitation, temperature and potential evapotranspiration, was calibrated with the available observed runoff data to optimize model parameters. Monthly precipitation from 66 stations and temperature data from 26 stations were used for the estimation of the basin-wide precipitation and temperature. Then, the water balance model was applied regionally to simulate runoff from the 14 major sub-watersheds of Pinios River basin for the period October 1960 - September 2002. The synthetic runoff was normalized through Box-Cox transformation and standardized to the mean runoff to produce the water balance derived drought index for the assessment of hydrological drought. The basin-wide precipitation and temperature data for the 14 sub-watersheds were used for the calculation of meteorological drought indices. The Standardized Precipitation Index (SPI) at multiple time scales and four indices of the Palmer method (i.e. PDSI, WPLM, PHDI and the Palmer moisture anomaly Z-index) were used as indicators of meteorological drought severity. The hydrological drought index was statistically compared with the meteorological drought indices for the study watersheds. The results showed that the water balance derived drought index is a good indicator of hydrological drought in all watersheds, since is capable to quantify drought severity and duration identified by meteorological drought indices.