International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 6, Issue 4, April (2015), pp. 39-45 © IAEME 39 WATERSHED MODELING USING ARTIFICIAL NEURAL NETWORKS Dr Saman H. Al-Hamawandi Faculty of Engineering, University of Sulaimani, Kurdistan of Iraq Dr Abdul-Ilah Y. Mohammed Professor, University of Baghdad, Iraq Dr Rafa H.Al-Suhaili Professor, University of Baghdad, Iraq ABSTRACT Artificial Neural Networks analysis was used for modeling rainfall-runoff relationship. A new Instantaneous ANN watershed model was built and tried herein using Walnut Gulch watershed (catchment) area. For modeling the instantaneous response of a catchment to a rainfall event an ANN model was built shown herein. The built model can represent the actual response using descritized rainfall-runoff values, over a selected time interval (∆t). As this time interval decreases the actual response is more accurately modeled. This model was applied to one of the sub-catchment of Walnut Gulch watershed (sub-catchment No.9 (flume 11)). The model was found successful to represent the lag-time and time of runoff related to the hyetograph properties. The obtained correlation coefficient between observed and predicted runoff values were found to be (0.999), with mean square error equal to (1.02E-06) and the required hidden nodes were (13). The instantaneous ANN model was applied also for Goizha-Dabashan watershed area located north Sulaimaniyah city north-east Iraq. The results indicate the capability of the model to simulate the runoff-rainfall relationship with correlation coefficient (0.9987) and mean square error (9.74E-06) and the required hidden nodes were (8). Keywords: Rainfall, Raunoff, Watershed, Time Interval, Lag Time, Hydograph. INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY (IJCIET) ISSN 0976 – 6308 (Print) ISSN 0976 – 6316(Online) Volume 6, Issue 4, April (2015), pp. 39-45 © IAEME: www.iaeme.com/Ijciet.asp Journal Impact Factor (2015): 9.1215 (Calculated by GISI) www.jifactor.com IJCIET ©IAEME