Mussie, Mulugeta (2013) Runoff Estimation by Giuh Based Clark and Nash Models for Shaya River. Masters thesis, Addis Ababa University.
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Abstract
For catchments with stream gauging, the traditional techniques for runoff estimation use historical rainfall-runoff data to derive the unit hydrograph. However, for ungauged catchments some indirect approaches have been used. Due to scarcity of data, more emphasis is being given to the conceptual models which are based on the geomorphological characteristics of the catchment than the physically based models. Geomorphological Instantaneous Unit Hydrograph (GIUH) approach is among the various techniques available for the runoff estimation, especially for ungauged catchments. In this study, the mathematical model developed by other investigators for the estimation of Clark model parameters using the geomorphological characteristics for ungauged basins and GIUH based Nash model have been used to simulate the direct surface runoff (DSRO) hydrographs of Shaya river basin up to Robe gauging site. GIS package Integrated Land and Water Information System (ILWIS) has been used to evaluate the geomorphological parameters of Shaya basin. Arc GIS is used to draw the isochrones maps, of the selected catchment, required to draw the time area diagram for the GIUH based Clark model. Velocity vs. excess rainfall intensity relationship has also been developed based on the stream gauging station data obtained from the Ministry of Water and Energy. The direct surface runoff (DSRO) hydrographs estimated by the two GIUH based approaches have been compared with the direct surface runoff hydrographs estimated by HEC-HMS package Clark and Nash IUH models and also with the observed direct surface runoff hydrographs. Some of the error functions viz. (i) efficiency (EFF), (ii) root mean square error (RMSE), (iii) percentage error in peak (PEP) and (iv) error function (Err), have also been used to evaluate the performance of the GIUH based models. From the models evaluation it is observed that GIUH based Clark approach provided the best estimation in peak discharge, whereas Nash IUH model performed best in estimating the time to peak discharge. It is also observed that the direct surface runoff hydrographs estimated using GIUH based Clark and GIUH based Nash model approaches, are quite accurate. Finally, this paper concludes that GIUH based conceptual models can be used to simulate rainfall-runoff relations with better estimation, especially for ungauged catchments. However, further works are required in implementing the GIUH based approaches in different parts of Ethiopian ungauged catchments, with varying geomorphology. The researcher recommends further investigations on GIUH based models using satellite based data, which can substitute the conventional historical gauging records.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Geomorphologic Instantaneous Unit Hydrograph (GIUH), HEC-HMS, Nash IUH Model, ILWIS (Integrated Land and Water Information System), GIS, Arc GIS, DSRO, rainfall-runoff, Ungauged Catchment. |
| Subjects: | Q Science > QA Mathematics T Technology > T Technology (General) T Technology > TA Engineering (General). Civil engineering (General) T Technology > TC Hydraulic engineering. Ocean engineering |
| Divisions: | Africana |
| Depositing User: | Andriamparany Edilbert RANOARIVONY |
| Date Deposited: | 12 Jul 2018 06:53 |
| Last Modified: | 12 Jul 2018 06:53 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/7337 |
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