Effects of Antecedent Precipitation Index on the Rainfall-Runoff Relationship

AHMET ISTANBULLUOGLU1,2, FATIH KONUKCU2, ISRAFIL KOCAMAN2 and FATIH BAKANOGULLARI3
1 Trakya University, Tekirdag Agricultural Faculty, Agricultural Construction and Irrigation Department, TR-59030 Tekirdag, Turkey
2 Trakya University, Tekirdag Agricultural Faculty, Agricultural Construction and Irrigation Department, TR-59030 Tekirdag, Turkey
3 Soil and Water Resources Research Institute, 39030 Kirklareli, Turkey

Abstract

ISTANBULLUOGLU, AHMET, FATIH KONUKCU, ISRAFIL KOCAMAN and FATIH BAKANOGULLARI, 2006. Effects of Antecedent Precipitation Index on the Rainfall-Runoff Relationship. Bulg. J. Agric. Sci, 12: 35-42

The effect of antecedent precipitation index of Soil Conservation Service-Curve Number (SCS-CN) method (SCS, 1956) on the precipitation-runoff relationship was examined. Using long-term measured rainfall data from Istanbul-Catalca Damlica Creek Watershed (ICDC W) located in a semi-arid region, calculated runoff values under both taking 5-day antecedent precipitation amount into account and not taking it into account conditions were compared. There were not any statistically significant differences between the calculated runoff values under both conditions. However, when the calculated runoff values under both conditions were compared with the directly measured runoff values, calculated values were found to be significantly larger, up to 7 folds, than the directly measured ones. Therefore, SCS-CN method was criticised in terms of over-sizing hydraulic structures and increasing the cost.

Key words: Antecedent precipitation index, curve number method, hydrologic modelling, rainfall-runoff, Thrace, Turkey