Molla, Tegegne (2009) Estimation of Evapotranspiration for Irrigation Performance Assessment Using Satellite Remote Sensing at Kobo Valley Irrigation Project, Northern Ethiopia. Masters thesis, Addis Ababa University.
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PDF (Estimation of Evapotranspiration for Irrigation Performance Assessment Using Satellite Remote Sensing at Kobo Valley Irrigation Project, Northern Ethiopia)
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Abstract
This paper describes the use of a remote sensing technique, the Surface Energy Balance Algorithm for Land (SEBAL), to assess actual evapotranspiration across Kobo valley irrigation project. The SEBAL model was applied to the Landsat 7 ETM+ image corresponding to December 05, 2003 to produce estimates of ET at 30×30m resolution. The actual evapotranspiration (ETa) was integrated for 24 hours on a pixel-by-pixel basis from the instantaneous evapotranspiration (ET). SEBAL ETa estimates vary from 0 to 4.86 mm/day over the image. Lowest ETa was observed for barren fields and highest for water bodies. ETa for vegetative areas ranges 3.5 to 4 mm/day. Irrigated areas, drip and sprinkler irrigation systems, appear to evaporate with average rate of 1.8 mm/day. Penman-Monteith reference crop evapotranspiration ET0 on the same day was found to be 4.5 mm/day at the meteorological station. During the dry season, actual evapotranspiration increases with the availability of moisture in the soil instead of the temperature gradient. The performance of the irrigation system for the command area (September to January) was determined according to 5 indicators, namely overall consumed ratio (OCR), relative water supply (RWS), depleted fraction (DF), crop water deficit (CWD), and relative evapotranspiration (RET). Potential and actual evapotranspiration parameters used in determining these indicators were estimated according to the SEBAL (Surface Energy Balance) method using Landsat ETM+ image. Seasonal averages of the irrigation project calculated from the results were 0.55, for OCR; 1.23 for RWS; 0.29 for DF; 42.44mm/month for CWD; 0.43 for RET. According to the seasonal average values of all the performance indicators, the irrigation performance of the area is usually poor and only the overall consumed ratio indicator is within the range of acceptability. Thus, performance indicators showed that less irrigation water was supplied to the area than was needed.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Performance indicators, performance assessment, evapotranspiration, SEBAL, remote sensing |
| Subjects: | G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > Q Science (General) Q Science > QD Chemistry Q Science > QE Geology |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 24 May 2018 12:37 |
| Last Modified: | 24 May 2018 12:37 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/4082 |
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