AI SearchDevelopment of type curves for flow forecasting
Call Number: AIT Thesis no. WA-90-27 Material type:
TextSeries: Asian Institute of Technology. Thesis ; no. WA-90-27Publication details: Bangkok : Asian Institute of Technology, 1990Description: 103 pSubject(s): Online resources: Dissertation note: Thesis (M.Eng.) - Asian Institute of Technology, 1990 Summary: The present study deals with the development of Type Curves using historical streamflow data and for short-term flow forecast based on those curves. Building of streamflow models from historical sequences and use of those model for forecasting is very important for water resources system development, multiple purpose water resources planning, evaluating and constructing, effective usage and distribution of water resources short period forecast based on type curve is a new approach in this field and demands careful study. Streamflow sequences were spitted for a length double that of forecasting period. With providing an allowable limit of sum of squared residual from a given series, Several series under that limit were grouped together and subjected to multiple regression analysis assuming some form of polynomial equations. The best fit equations were selected depending on few statistical criteria such as t-test, R-squared values. Curves which exhibited similar trend in the first period (first 7-days) and also similar in shape were grouped together. They are called Type curves. By interpolating between type Curves, flows for the second period (second 7-days) sere calculated. The streamflow of two big river of Asia namely, the Brahmaputra (Jamuna) and the Ganges (Padma) were use for the development of the Type curves. Flows ranging from 1974-1988 were used for development and that from 1960-1973 for verification. The curves were tested taking random samples from streamflow sequences not used for their development. Results were found acceptable with relative error varied from 0.64% to 4.4%. The weekly volume calculated from the predicted flows using type curves and that obtained from Box-Jenkin ARIMA Modelling was compared and found satisfactory. If the first 7-days trend were not clearly defined Type Curves produce misleading results. These curves may give better result if the flow in a year is divided into rising, recession and fluctuating parts to develop them.
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A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology
Thesis (M.Eng.) - Asian Institute of Technology, 1990
The present study deals with the development of Type Curves using historical streamflow data and for short-term flow forecast based on those curves. Building of streamflow models from historical sequences and use of those model for forecasting is very important for water resources system development, multiple purpose water resources planning, evaluating and constructing, effective usage and distribution of water resources short period forecast based on type curve is a new approach in this field and demands careful study. Streamflow sequences were spitted for a length double that of forecasting period. With providing an allowable limit of sum of squared residual from a given series, Several series under that limit were grouped together and subjected to multiple regression analysis assuming some form of polynomial equations. The best fit equations were selected depending on few statistical criteria such as t-test, R-squared values. Curves which exhibited similar trend in the first period (first 7-days) and also similar in shape were grouped together. They are called Type curves. By interpolating between type Curves, flows for the second period (second 7-days) sere calculated. The streamflow of two big river of Asia namely, the Brahmaputra (Jamuna) and the Ganges (Padma) were use for the development of the Type curves. Flows ranging from 1974-1988 were used for development and that from 1960-1973 for verification. The curves were tested taking random samples from streamflow sequences not used for their development. Results were found acceptable with relative error varied from 0.64% to 4.4%. The weekly volume calculated from the predicted flows using type curves and that obtained from Box-Jenkin ARIMA Modelling was compared and found satisfactory. If the first 7-days trend were not clearly defined Type Curves produce misleading results. These curves may give better result if the flow in a year is divided into rising, recession and fluctuating parts to develop them.
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