Description

Regional Analysis of Flow Duration Curve for Ungaged Sub-Basins (Case Study: Fomanat plain, Gilan, Iran) 

In Persian 

Objects: Hydrologists around the world widely use the flow duration curve (FDC) in diverse applications. The FDC gives information on the water regime providing critical information to manage the river’s water resources optimally. Unfortunately, the scarcity of streamflow data enables the use of these instruments only for gauged basins.

Method: For this purpose, 21 hydrometric stations having adequate data in the Fomanat plain (Gilan, Iran) were selected. Then, index discharges of flow duration curve thresholds (Q10, Q20,…., Q95) were extracted. The next step uses a linear technique for dimensionality reduction (PCA) to select variables. Furthermore, using the hierarchical clustering analysis, the homogeneous groups were identified, and the optimal number of homogeneity groups was determined based on different clustering scenarios, including the dependent variable, independent parameters, and combined variables. Finally, Multi regression was performed to identify the contribution of each variable based on their cluster. The performance of the models was evaluated using the Dunn and Silhouette indicators.

Results: As a result, the regression equations were established based on the stepwise method, between the index discharge values of flow duration curves and the selected variables, including physiographic factors, precipitation as a climatic factor, and land use. Based on the significance of relations at the 95% threshold level and having the values of these variables, the obtained relations could be used as a regional index in drawing and establishing flow duration curves for ungauged basins. The results showed, by identifying optimal clusters and increasing the number of variables, the regression models respond more accurately.

3rd National Conference on Water Resources Management in Coastal Plains

Authors

M. Jafari Ashourabadi ¹

R. Fazloula¹

M. Effati²

A. Jamali³

1; Department of Water Engineering, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.

2; Department of Civil Engineering, Faculty of Engineering, The University of Guilan, Rasht, Iran.

3; Department of Mechanical Engineering, Faculty of Engineering, The University of Guilan, Rasht, Iran

Keyword

• Flow Duration Curve
• Principal component analysis (PCA)
• multiple regression
• Ungaged sub-basin
• Clustering