Your search found 5 records
1 Hirpa, F. A.; Dyer, E.; Hope, R.; Olago, D. O.; Dadson, S. J. 2018. Finding sustainable water futures in data-sparse regions under climate change: insights from the Turkwel River Basin, Kenya. Journal of Hydrology: Regional Studies, 19:124-135. [doi: https://doi.org/10.1016/j.ejrh.2018.08.005]
Water scarcity ; Water resources ; Sustainability ; Water allocation ; Climate change ; Drought ; Risk assessment ; Groundwater depletion ; Water demand ; River basins ; Precipitation ; Models / Kenya / Turkwel River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H048915)
https://www.sciencedirect.com/science/article/pii/S2214581818302155/pdfft?md5=36588c83188aeb04b624afbaf6c3fc62&pid=1-s2.0-S2214581818302155-main.pdf
https://vlibrary.iwmi.org/pdf/H048915.pdf
https://vlibrary.iwmi.org/pdf/H048915.pdf
(2.44 MB) (2.44 MB)
Study region: the Turkwel river basin, Kenya experiences a high level of water scarcity due to its arid climate, high rainfall variability and rapidly growing water demand.
Study region: the Turkwel river basin, Kenya experiences a high level of water scarcity due to its arid climate, high rainfall variability and rapidly growing water demand.
New hydrological insights: The results show that climate variability and increased water demand are each important drivers of water scarcity in the basin. Increases in water demand due to expanded irrigation strongly influences on the resilience of the basin’s water resource system to droughts caused by the global climate variability. The climate response surface offers a visual and flexible tool for decision-makers to understand the ways in which the system responds to climate variability and development scenarios. Policy decisions to accelerate water-dependent development and poverty reduction in arid and semi-arid lands that are characterised by rapid demographic, political and economic change in the short- to medium term have to promote low-regrets approaches that incorporate longer-term climate uncertainty.
Study region: the Turkwel river basin, Kenya experiences a high level of water scarcity due to its arid climate, high rainfall variability and rapidly growing water demand.
New hydrological insights: The results show that climate variability and increased water demand are each important drivers of water scarcity in the basin. Increases in water demand due to expanded irrigation strongly influences on the resilience of the basin’s water resource system to droughts caused by the global climate variability. The climate response surface offers a visual and flexible tool for decision-makers to understand the ways in which the system responds to climate variability and development scenarios. Policy decisions to accelerate water-dependent development and poverty reduction in arid and semi-arid lands that are characterised by rapid demographic, political and economic change in the short- to medium term have to promote low-regrets approaches that incorporate longer-term climate uncertainty.
2 Dyer, E.; Washington, R.; Taye, Meron Teferi. 2020. Evaluating the CMIP5 [Coupled Model Intercomparison Project Phase 5] ensemble in Ethiopia: creating a reduced ensemble for rainfall and temperature in Northwest Ethiopia and the Awash Basin. International Journal of Climatology, 40(6):2964-2985. [doi: https://doi.org/10.1002/joc.6377]
Climate change ; Models ; Evaluation ; Rain ; Temperature ; Climatic data ; Trends ; Observation ; Seasonality ; Simulation ; Forecasting ; River basins ; Policies / Ethiopia / Awash Basin
(Location: IWMI HQ Call no: e-copy only Record No: H049591)
https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/joc.6377
https://vlibrary.iwmi.org/pdf/H049591.pdf
https://vlibrary.iwmi.org/pdf/H049591.pdf
(8.09 MB) (8.09 MB)
The purpose of this study was to evaluate the historical skill of models in the Coupled Model Intercomparison Project Phase 5 (CMIP5) in two regions of Ethiopia: northwestern Ethiopia and the Awash, one of the main Ethiopian river basins. An ensemble of CMIP5 models was first selected so that atmosphere-only (Atmospheric Model Intercomparison Project, AMIP) and fully coupled simulations could be directly compared, assessing the effects of coupled model sea surface temperature (SST) biases. The annual cycle, seasonal biases, trends, and variability were used as metrics of model skill. In the Awash basin, both coupled and AMIP simulations had late Belg or March-May (MAM) rainy seasons. In connection to this, most models also missed the June rainfall minimum entirely. Northwest Ethiopia, which has a unimodal rainfall cycle in observations, is shown to have bimodal seasonality in models, even in the AMIP simulations. Significant AMIP biases in these regions show that model biases are not related to SST biases alone. Similarly, a clear connection between model resolution and skill was not found. Models simulated temperature with more skill than rainfall, but trends showed an underestimation in Belg (MAM/April-May (AM)) trends, and an overestimation in Kiremt or July-September (JAS/June-September (JJAS)) trends. The models which were shown to have the most skill in a range of categories were HadGEM2-AO, GFDL-CM3, and MPI-ESM-MR. The biases and discrepancies in model skill for different metrics of rainfall and temperature found in this study provide a useful basis for a process-based analysis of the CMIP5 ensemble in Ethiopia.
3 Taye, Meron Teferi; Dyer, E.; Charles, K. J.; Hirons, L. C. 2021. Potential predictability of the Ethiopian summer rains: understanding local variations and their implications for water management decisions. Science of the Total Environment, 755(Part 1):142604. [doi: https://doi.org/10.1016/j.scitotenv.2020.142604]
Rain ; Weather forecasting ; Water management ; Decision making ; Oceanic climate ; Temperature ; Climate change ; El Nino-Southern Oscillation ; Precipitation ; Spatial variation ; River basins ; Case studies / Ethiopia / Awash River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050014)
https://www.sciencedirect.com/science/article/pii/S0048969720361337/pdf?md5=58c744b3a1e31d3bceecd1661ae3f3c3&pid=1-s2.0-S0048969720361337-main.pdf
https://vlibrary.iwmi.org/pdf/H050014.pdf
https://vlibrary.iwmi.org/pdf/H050014.pdf
(4.89 MB) (4.89 MB)
Understanding the influence of large-scale oceanic and atmospheric variability on rainfall over Ethiopia has huge potential to improve seasonal forecasting and inform crucial water management decisions at local levels, where data is available at appropriate scales for decision makers. In this study, drivers of Ethiopia‘s main rainy season, July-September (JAS), are investigated using correlation analysis with sea surface temperature (SST). The analysis showed local spatial variations in the drivers of JAS rainfall. Moreover, the analysis revealed strong correlation between March to May (MAM) SST and JAS rainfall in particular regions. In addition to the influence of SSTs, we highlighted one of the mechanisms explaining the regional pattern of SST influence on Ethiopian rainfall, the East African Low-Level Jet. Moreover, examining the occurrence of large-scale phenomena provided additional information, with very strong ENSO and positive IOD events associated with drier conditions in most part of Ethiopia. A sub-national analysis, focused at a scale relevant for water managers, on the Awash basin, highlighted two distinct climate zones with different relationships to SSTs. June was not included as part of the rainy season as in some areas June is a hot, dry month between rainy seasons and in others it can be used to update sub-seasonal forecasts with lead time of one month for JAS rainfall. This highlights the importance of understanding locally relevant climate systems and ensuing sub-seasonal to seasonal forecasts are done at the appropriate scale for water management in the complex topography and climatology of Ethiopia.
4 Dyer, E.; Hirons, L.; Taye, Meron Teferi. 2022. July–September rainfall in the Greater Horn of Africa: the combined influence of the Mascarene and South Atlantic highs. Climate Dynamics, 59(11-12):3621-3641. [doi: https://doi.org/10.1007/s00382-022-06287-0]
Rainfall patterns ; Precipitation ; Atmospheric circulation ; Subtropical climate ; Models ; Datasets / Africa / Ethiopia / South Atlantic High / Mascarene High
(Location: IWMI HQ Call no: e-copy only Record No: H051082)
https://link.springer.com/content/pdf/10.1007/s00382-022-06287-0.pdf
https://vlibrary.iwmi.org/pdf/H051082.pdf
https://vlibrary.iwmi.org/pdf/H051082.pdf
(15.30 MB) (15.3 MB)
July-September rainfall is a key component of Ethiopia’s annual rainfall and is a source of rainfall variability throughout inland Greater Horn of Africa. In this study we investigate the relative influences of the Mascarene (MH) and South Atlantic (AH) highs on July-September rainfall in a covarying region of the Greater Horn of Africa using CHIRPS observed rainfall and the ERA5 reanalysis. We show that a mixed metric using the circulation at 850 hPa of these two subtropical anticyclones (AH-MH), is better correlated with rainfall than individual high circulations. Variations in remote circulation are translated by changes in Central African westerlies and Turkana Jet wind speeds. We apply the AH-MH mixed metric to the CMIP5 and CMIP6 ensembles and show that it is a good indicator of mean July-September rainfall across both ensembles. Biases in circulation are shown to be related to the Hadley circulation in CMIP5 atmosphere-only simulations, while causes of biases in CMIP6 are more varied. Coupled model biases are related to southern ocean warm biases in CMIP5 and western Indian Ocean warm biases in CMIP6. CMIP6 shows an improved relationship between rainfall and Turkana Jet winds and Central African westerlies across the ensemble.
5 Taye, Meron Teferi; Dyer, E.. 2024. Hydrologic extremes in a changing climate: a review of extremes in East Africa. Current Climate Change Reports, 10(1):1-11. [doi: https://doi.org/10.1007/s40641-024-00193-9]
Climate change ; Extreme weather events ; Flooding ; Drought ; Rainfall ; Forecasting / Eastern Africa
(Location: IWMI HQ Call no: e-copy only Record No: H052557)
https://link.springer.com/content/pdf/10.1007/s40641-024-00193-9.pdf
https://vlibrary.iwmi.org/pdf/H052557.pdf
https://vlibrary.iwmi.org/pdf/H052557.pdf
(0.91 MB) (934 KB)
Purpose: Eastern Africa has a complex hydroclimate and socio-economic context, making it vulnerable to climate change-induced hydrological extremes. This review presents recent research on drivers and typologies of extremes across different geographies and highlights challenges and improvements in forecasting hydrological extremes at various timescales. Recent Findings: Droughts and floods remain the major challenges of the region. Recently, frequent alterations between droughts and floods have been a common occurrence and concern. Research underlines the heterogeneity of extremes and the impact of climate change as increased intensity and duration of extremes. Moreover, the importance of local and antecedent conditions in changing the characteristics of extremes is emphasized. Summary: A better understanding of these drivers and how they interact is required. Observational and modeling tools must capture these relationships and extremes on short timescales. Although there are improvements in forecasting these extremes, providing relevant information beyond meteorological variables requires further research.
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