Intelligent estimation of flood hydrographs using an adaptive neuro–fuzzy inference system (ANFIS)

Abstract

Intelligent computing tools such as artificial neural networks (ANNs) and fuzzy logic approaches are proven to be efficient when these are individually applied to variety of problems. Recently, there has been a growing interest in combining both of those approaches, and as a result, neuro–fuzzy computing technique has been evolved. This approach has been tested and evaluated in the field of signal processing and related areas. But researches have only begun evaluating the potential of this hybrid approach to hydrologic modeling studies. This paper presents the application of an adaptive neuro–fuzzy inference system (ANFIS) to flood hydrograph modeling, and it is demonstrated by modeling the flood hydrograph flowing to the Shirindarreh Reservoir dam located in the northern Khorasan Province, Iran. This was carried out using 24 flood hydrographs recorded in Barbarqaleh river gauging station. From this dataset, 15 flood hydrographs were chosen to train the model and 6 flood hydrographs to test the model. The different architectures of neuro–fuzzy model according to the membership function and learning algorithm were designed and trained with different epochs. The results were evaluated in comparison with the observed hydrographs and the best structure of model was chosen according the least RMSE in each performance. To evaluate the efficiency of neuro–fuzzy model, various statistical indices such as Nash–Sutcliff and flood peak discharge error criteria were calculated to show the level of agreement between observed and calculated hydrographs. In this simulation, the coordinates of a flood hydrograph including peak discharge were estimated using the discharge values occurred in the earlier time steps as input values to the neuro-fuzzy model. The amount of Nash–Sutcliff criterion for the input patterns of P1, P2, P3 and P4 were 0.82, 0.81, 0.62 and 0.45, respectively. These results indicate the satisfactory efficiency of neuro–fuzzy model, especially in P1, P2 and P3 for flood simulating. This performance of the model demonstrates the suitability of the implemented approach to flood management projects.