Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Modelling Hydrological and Hydrodynamic Processes in Lake Tana Basin, Ethiopia
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Hydraulic Engineering.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Lake Tana Basin is of significant importance to Ethiopia concerning water resources aspects and the ecological balance of the area. The growing high demands in utilizing the high potentials of water resource of the Lake to its maximal limit, pictures a disturbing future for the Lake. The objective of this study was to assess the influence of topography, soil, land use and climatic varia-bility on the hydrological and hydrodynamic processes of the Lake Tana Basin. The physically based SWAT model was successfully calibrated and validated for flow and sediment yield. Se-quential uncertainty fitting (SUFI-2), parameter solution (ParaSol) and generalized likelihood un-certainty estimation (GLUE) calibration and uncertainty analysis methods were compared and used for the set-up of the SWAT model. There is a good agreement between the measured and simulated flows and sediment yields. SWAT and GIS based decision support system that uses multi-criteria evaluation (MCE) was used to identify the most vulnerable areas to soil erosion in the basin. The results indicated that 12 to 30.5% of the watershed is high erosion potential. Pro-jected changes in precipitation and temperature in the basin for two seasons were analyzed using outputs from fifteen global climate models (GCMs). A historical-modification procedure was used to downscale large scale outputs from GCM models to watershed-scale climate data. The results showed significant changes in streamflow and other hydrological parameters in the period between 2045-2100. SWAT was combined with a three dimensional hydrodynamic model, GEMSS to investigate the flow structure, stratification, the flushing time, lake water balance and finally the Lake‘s water level response to planned water removal. We have found an alarming and dramatic fall of the water levels in Lake Tana as response to the planned water withdrawal. The combination of the two models can be used as a decision support tools to better understand and manage land and water resources in watersheds and waterbodies. The study showed that the Lake Tana Basin may experience a negative change in water balance in the forthcoming decades due to climate change as well as over abstraction of water resources.

Place, publisher, year, edition, pages
Stockholm: KTH , 2010. , viii, 66 p.
Series
Trita-LWR. PHD, ISSN 1650-8602 ; 1057
Keyword [en]
Lake Tana, Climate Change, SWAT, Hydrological Modeling, Hydrodynamic, GEMSS, MCE, Streamflow, Sediment yield
National Category
Oceanography, Hydrology, Water Resources Water Engineering
Identifiers
URN: urn:nbn:se:kth:diva-12024ISBN: 978-91-7415-558-7 (print)OAI: oai:DiVA.org:kth-12024DiVA: diva2:295181
Public defence
2010-03-05, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Note
QC 20100720Available from: 2010-02-17 Created: 2010-02-17 Last updated: 2011-05-24Bibliographically approved
List of papers
1. SWAT model application and prediction uncertainty analysis in the Lake Tana Basin, Ethiopia
Open this publication in new window or tab >>SWAT model application and prediction uncertainty analysis in the Lake Tana Basin, Ethiopia
2010 (English)In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, no 3, 357-367 p.Article in journal (Refereed) Published
Abstract [en]

Lake Tana Basin is of significant importance to Ethiopia concerning water resources aspects and the ecological balance of the area. Many years of mismanagement, wetland losses due to urban encroachment and population growth, and droughts are causing its rapid deterioration. The main objective of this study was to assess the performance and applicability of the soil water assessment tool (SWAT) model for prediction of streamflow in the Lake Tana Basin, so that the influence of topography, land use, soil and climatic condition on the hydrology of Lake Tana Basin can be well examined. The physically based SWAT model was calibrated and validated for four tributaries of Lake Tana. Sequential uncertainty fitting (SUFI-2), parameter solution (ParaSol) and generalized likelihood uncertainty estimation (GLUE) calibration and uncertainty analysis methods were compared and used for the set-up of the SWAT model. The model evaluation statistics for streamflows prediction shows that there is a good agreement between the measured and simulated flows that was verified by coefficients of determination and Nash Sutcliffe efficiency greater than 0.5. The hydrological water balance analysis of the basin indicated that baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. More than 60% of losses in the watershed are through evapotranspiration. Copyright (C) 2009 John Wiley & Sons, Ltd.

Keyword
SWAT, Lake Tana, hydrological modelling, SUFI-2, GLUE, ParaSol, WATER-QUALITY MODELS, BLUE NILE RIVER, CHAOHE BASIN, FLUCTUATIONS, CALIBRATION, PARAMETERS, HYDROLOGY, RAINFALL, BALANCE, FUTURE
National Category
Oceanography, Hydrology, Water Resources Water Engineering
Identifiers
urn:nbn:se:kth:diva-12019 (URN)10.1002/hyp.7457 (DOI)000274048300010 ()2-s2.0-77949580283 (Scopus ID)
Note
QC20100719Available from: 2010-02-17 Created: 2010-02-17 Last updated: 2017-12-12Bibliographically approved
2. Spatial delineation of soil erosion vulnerability in the Lake Tana Basin, Ethiopia
Open this publication in new window or tab >>Spatial delineation of soil erosion vulnerability in the Lake Tana Basin, Ethiopia
2009 (English)In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 23, no 26, 3738-3750 p.Article in journal (Refereed) Published
Abstract [en]

The main objective of this study was to identify the most vulnerable areas to soil erosion in the Lake Tana Basin, Blue Nile, Ethiopia using the Soil and Water Assessment Tool (SWAT), a physically based distributed hydrological model, and a Geographic Information System based decision support system that uses multi-criteria evaluation (NICE). The SWAT model was used to estimate the sediment yield within each sub-basin and identify the most sediment contributing areas in the basin. Using the NICE analysis, an attempt was made to combine a set of factors (land use, soil, slope and river layers) to make a decision according to the stated objective. On the basis of simulated SWAT, sediment yields greater than 30 tons/ha for each of the sub-basin area, 18.4% of the watershed was determined to be high erosion potential area. The NICE results indicated that 12-30.5% of the watershed is high erosion potential area. Both approaches show comparable watershed area with high soil erosion susceptibility. The output of this research can aid policy and decision makers in determining the soil erosion 'hot spots' and the relevant soil and water conservation measures. (C) Copyright 2009 John Wiley & Sons, Ltd.

Keyword
soil erosion, Lake Tana, SWAT, MCE, GIS, hydrologic modeling, NONPOINT-SOURCE POLLUTION, WATER ASSESSMENT-TOOL, SWAT MODEL, MULTICRITERIA EVALUATION, CALIBRATION, PARAMETERS, HYDROLOGY, TRANSPORT, CRITERIA
National Category
Water Engineering Oceanography, Hydrology, Water Resources
Identifiers
urn:nbn:se:kth:diva-12020 (URN)10.1002/hyp.7476 (DOI)000273438100011 ()2-s2.0-76149099237 (Scopus ID)
Note
QC20100719Available from: 2010-02-17 Created: 2010-02-17 Last updated: 2017-12-12Bibliographically approved
3. Modeling of Sediment Yield From Anjeni-Gauged Watershed, Ethiopia Using SWAT Model
Open this publication in new window or tab >>Modeling of Sediment Yield From Anjeni-Gauged Watershed, Ethiopia Using SWAT Model
2010 (English)In: Journal of the American Water Resources Association, ISSN 1093-474X, E-ISSN 1752-1688, Vol. 46, no 3, 514-526 p.Article in journal (Refereed) Published
Abstract [en]

The Soil and Water Assessment Tool (SWAT) was tested for prediction of sediment yield in Anjeni-gauged watershed, Ethiopia. Soil erosion and land degradation is a major problem on the Ethiopian highlands. The objectives of this study were to evaluate the performance and applicability of SWAT model in predicting monthly sediment yield and assess the impacts of subbasin delineation and slope discretization on the prediction of sediment yield. Ten years monthly meteorological, flow and sediment data were used for model calibration and validation. The annual average measured sediment yield was 24.6 tonnes/ha. The annual average simulated sediment yield was 27.8 and 29.5 tones/ha for calibration and validation periods, respectively. The study found that the observed values showed good agreement with the simulated sediment yield with Nash-Sutcliffe efficiency (NSE) = 0.81, percent bias (PBIAS) = 28%, RMSE-observations standard deviation ratio (RSR) = 0.23, and coefficient of determination (R superset of) = 0.86 for calibration and NSE = 0.79, PBIAS = 30%, RSR = 0.29, and R superset of = 0.84 for validation periods. The model can be used for further analysis of different management scenarios that could help different stakeholders to plan and implement appropriate soil and water conservation strategies.

Keyword
SWAT, SUFI-2, sediment yield, soil erosion, watershed modeling, Anjeni, hydrology, streamflows
National Category
Oceanography, Hydrology, Water Resources
Identifiers
urn:nbn:se:kth:diva-12021 (URN)10.1111/j.1752-1688.2010.00431.x (DOI)000278522700006 ()2-s2.0-77954615297 (Scopus ID)
Note
QC 20100719 Uppdaterad från in press till published (20101123).Available from: 2010-02-17 Created: 2010-02-17 Last updated: 2017-12-12Bibliographically approved
4. Impact of Changing Climate on Water Resources Variability in the Lake Tana Basin, Ethiopia
Open this publication in new window or tab >>Impact of Changing Climate on Water Resources Variability in the Lake Tana Basin, Ethiopia
Show others...
(English)Manuscript (preprint) (Other academic)
Keyword
Climate Change, Lake Tana, SWAT, GCM, Hydrological modeling, Downscaling, SRES
National Category
Oceanography, Hydrology, Water Resources Water Engineering
Identifiers
urn:nbn:se:kth:diva-12022 (URN)
Note
QC 20100719 Manuskriptet har uppdaterats och publicerats som "Impact of climate change on the hydroclimatology of Lake Tana Basin, Ethiopia".Available from: 2010-02-17 Created: 2010-02-17 Last updated: 2011-05-24Bibliographically approved
5. Combined 3D Hydrodynamic and Watershed Modelling of Lake Tana, Ethiopia
Open this publication in new window or tab >>Combined 3D Hydrodynamic and Watershed Modelling of Lake Tana, Ethiopia
2011 (English)In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 398, no 1-2, 44-64 p.Article in journal (Refereed) Published
Abstract [en]

 The growing high demand for lake Tana water portends a disturbing future. The main objective of this paper is to make a contribution to the development of a sustainable use of the water of Lake Tana. A fully three-dimensional hydrodynamic model was combined with a watershed model and together, these models were successfully validated for the year 2006. The flow structure is characterized by large recirculation and secondary flow regions. Secondary flows are induced by hydrodynamic instabilities occurring at the interfaces of layers with a velocity gradient and the interaction with the irregularities of the bed. The weak stratification process in Lake Tana is characterized by a classic summer profile, which is more pronounced during January-February. Mixing processes in the lake are controlled by wind, the mixing energy induced by both river inflows and the lake outlet, and convective mixing due to the negative buoyancy. An alarming fall of the water levels in Lake Tana was found in response to the planned water withdrawal. The long flushing time (19 months) will not allow a fast decay of contaminated materials released into the lake. The flow structure will not be significantly modified by the planned water withdrawal but the flushing time will decrease. The hydrodynamics of Lake Tana resemble a closed system similar to a shallow reservoir with an overflow type outlet. The implication is that the lake is vulnerable to changes in external conditions and sustainable use of the water resource of the lake will require awareness of this vulnerability. The combined watershed and hydrodynamic models would be effective tools to achieve this awareness. It is also necessary to address the impact of climate change on the fate of the lake. These are all difficult challenges that need to be addressed to safeguard the sensitive eco-system of the area.

National Category
Geophysical Engineering Water Engineering
Identifiers
urn:nbn:se:kth:diva-12023 (URN)10.1016/j.jhydrol.2010.12.009 (DOI)000287267600005 ()2-s2.0-78951473738 (Scopus ID)
Note
QC 20110307 Ändrad från submitted till published 20110307Available from: 2010-02-17 Created: 2010-02-17 Last updated: 2017-12-12Bibliographically approved

Open Access in DiVA

fulltext(3915 kB)4952 downloads
File information
File name FULLTEXT01.pdfFile size 3915 kBChecksum SHA-512
bd53b59287baa02cc243efba7c570c667ddc384f4bbc9f585d42ada6846d0cf4564035d8cf797c627ca3d49306a0efb1d0b72001175eba79f62f94689d29f930
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Setegn, Shimelis Gebriye
By organisation
Hydraulic Engineering
Oceanography, Hydrology, Water ResourcesWater Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 4952 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1337 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf