Regionalization of flow duration curve for Abbay Basin using GIS technique
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Date
2007-02
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Addis Ababa Universty
Abstract
Water resource development planning is usually referred as the
process to define how to utilize the available water resource to
meet the desired objectives. In order to compensate for the
scarcity of data for the available water resource, regionalization
is found to be one of the best methods of transferring
information from the gauged station to ungaged sites.
The purpose of this paper is to develop regionalized Flow
Duration Curve for Abbay Basin. Based on similarity of
standardized rainfall patterns eight regions were identified and
Flow Duration Curves of each region are developed.
For the development of reliable flow duration curve, daily flow
distribution from the mean monthly stream flow is derived. Flow
Duration Curve based on the estimated daily flow is developed
and an equation for each region is determined.
The regional equations were developed using regression
analysis. These equations relate discharges of 70 and 80
percent of exceedance for ungauged watershed in the basin, or
for short record length stations and catchment characteristics.
Estimation of low flow for ungaged sites (below 50% of
exeedance) can be obtained using regional regression method
and subsequently Flow Duration Curve for each regions.
For the evaluation of hydropower potential sites requires
knowledge of the time availability of flow at a certain point in a
river as described in Flow Duration Curve. It is also useful in
other hydrologic investigations where knowing the average time availability of flow is required, such as for irrigation projects and
others.
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Keywords
Regionalization