Assessment of the dry and wet period severity with hydrometeorological index

Fatih Keskin¹* and Ali Unal Sorman²*

¹State Hydraulic Works, Investigation and Planning Department, Inonu cad. No: R-7 Yucetepe/Ankara/Turkey.

²Middle East Technical University, Civil engineering Department, Water Resources Laboratory Ankara/Turkey.

*Corresponding author. E-mail: fatihk@dsi.gov.tr.

Accepted 28 December 2009

   Abstract

The paper examines the existing condition of water resources for the basin of Çamlidere dam in the vicinity of capital city of Ankara, Turkey and highlights the hydrological elements that are mostly prone to the change of atmospheric conditions. After the evaluation of environmental conditions, the standardized precipitation index (SPI), standardized runoff index (SRI) and standardized potential evapotranspiration index (SEI) have been calculated with monthly air temperature, precipitation and stream runoff records in and around the basin. The calculated index values are used for defining the hydrometeorological dryness and wetness severity in the basin named as Aggregated Drought Index (ADI). The aggregated drought index was able to clarify the long wet and dry periods with a high correlation between the North Atlantic Oscillation (NAO) and El-Nino Southern Oscillations (ENSO) indices. The determined monthly ADI values provide an indication to predict wet or dry conditions in advance for the study basin.

Key words: Drought, wetness, north Atlantic oscillation, southern oscillation, aggregated drought index, camlidere dam, Turkey.