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Elfatih A B Eltahir - One of the best experts on this subject based on the ideXlab platform.
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climate change enhances interannual variability of the Nile River flow
Nature Climate Change, 2017Co-Authors: Mohamed S Siam, Elfatih A B EltahirAbstract:Nile basin countries are expected to double their population by 2050. Observations and climate model projections now suggest water resources may be additionally stretched by a 50% (±35%) increase in interannual Nile flow variability in the twenty-first century. The human population living in the Nile basin countries is projected to double by 2050, approaching one billion1. The increase in water demand associated with this burgeoning population will put significant stress on the available water resources. Potential changes in the flow of the Nile River as a result of climate change may further strain this critical situation2,3. Here, we present empirical evidence from observations and consistent projections from climate model simulations suggesting that the standard deviation describing interannual variability of total Nile flow could increase by 50% (±35%) (multi-model ensemble mean ± 1 standard deviation) in the twenty-first century compared to the twentieth century. We attribute the relatively large change in interannual variability of the Nile flow to projected increases in future occurrences of El Nino and La Nina events4,5 and to observed teleconnection between the El Nino–Southern Oscillation and Nile River flow6,7. Adequacy of current water storage capacity and plans for additional storage capacity in the basin will need to be re-evaluated given the projected enhancement of interannual variability in the future flow of the Nile River.
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explaining and forecasting interannual variability in the flow of the Nile River
Hydrology and Earth System Sciences, 2014Co-Authors: Mohamed S Siam, Elfatih A B EltahirAbstract:This study analyzes extensive data sets collected during the twentieth century and defines four modes of natural variability in the flow of the Nile River, identifying a new significant potential for improving predictability of floods and droughts. Previous studies have identified a significant teleconnection between the Nile flow and the eastern Pacific Ocean. El Nino–Southern Oscillation (ENSO) explains about 25% of the interannual variability in the Nile flow. Here, this study identifies a region in the southern Indian Ocean, with a similarly strong teleconnection to the Nile flow. Sea surface temperature (SST) in the region (50–80° E and 25–35° S) explains 28% of the interannual variability in the flow of the Nile River and, when combined with the ENSO index, the explained variability of the flow of the Nile River increases to 44%. In addition, during those years with anomalous SST conditions in both oceans, this study estimates that indices of the SSTs in the Pacific and Indian oceans can collectively explain up to 84% of the interannual variability in the flow of the Nile. Building on these findings, this study uses the classical Bayesian theorem to develop a new hybrid forecasting algorithm that predicts the Nile flow based on global model predictions of indices of the SST in the eastern Pacific and southern Indian oceans.
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Explaining and forecasting interannual variability in the flow of the Nile River
Hydrology and Earth System Sciences Discussions, 2014Co-Authors: Mohamed S Siam, Elfatih A B EltahirAbstract:Abstract. The natural interannual variability in the flow of Nile River had a significant impact on the ancient civilizations and cultures that flourished on the banks of the River. This is evident from stories in the Bible and Koran, and from the numerous Nilometers discovered near ancient temples. Here, we analyze extensive data sets collected during the 20th century and define four modes of natural variability in the flow of Nile River, identifying a new significant potential for improving predictability of floods and droughts. Previous studies have identified a significant teleconnection between the Nile flow and the Eastern Pacific Ocean. El Niño–Southern Oscillation (ENSO) explains about 25% of the interannual variability in the Nile flow. Here, we identify, for the first time, a region in the southern Indian Ocean with similarly strong teleconnection to the Nile flow. Sea Surface Temperature (SST) in the region (50–80° E and 25–35° S) explains 28% of the interannual variability in the Nile flow. During those years with anomalous SST conditions in both Oceans, we estimate that indices of the SSTs in the Pacific and Indian Oceans can collectively explain up to 84% of the interannual variability in the flow of Nile. Building on these findings, we use classical Bayesian theorem to develop a new hybrid forecasting algorithm that predicts the Nile flow based on global models predictions of indices of the SST in the Eastern Pacific and Southern Indian Oceans.
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el nino and the natural variability in the flow of the Nile River
Water Resources Research, 1996Co-Authors: Elfatih A B EltahirAbstract:Natural variability in the annual flow of the Nile River has been the subject of great interest to the civilizations that have historically occupied the banks of that River. Here we report results from analysis on two extensive data sets describing sea surface temperature of the Pacific Ocean, and the flow of water in the Nile River. The analysis suggests that 25% of the natural variability in the annual flow of the Nile is associated with El Nino oscillations. A procedure is developed for using this observed correlation to improve the predictability of the Nile flood. A simple hypothesis is presented to explain physically the occurrence of the Hurst phenomenon in the Nile flow.
Michael Ghil - One of the best experts on this subject based on the ideXlab platform.
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Oscillatory modes of extended Nile River records (A.D. 622–1922)
Geophysical Research Letters, 2005Co-Authors: Dmitri Kondrashov, Yizhak Feliks, Michael GhilAbstract:[1] The historical records of the low- and high-water levels of the Nile River are among the longest climatic records that have near-annual resolution. There are few gaps in the first part of the records (A.D. 622–1470) and larger gaps later (A.D. 1471–1922). We apply advanced spectral methods, Singular-Spectrum Analysis (SSA) and the Multi-Taper Method (MTM), to fill the gaps and to locate interannual and interdecadal periodicities. The gap filling uses a novel, iterative version of SSA. Our analysis reveals several statistically significant features of the records: a nonlinear, data-adaptive trend that includes a 256-year cycle, a quasi-quadriennial (4.2-year) and a quasi-biennial (2.2-year) mode, as well as additional periodicities of 64, 19, 12, and, most strikingly, 7 years. The quasi-quadriennial and quasi-biennial modes support the long-established connection between the Nile River discharge and the El-Nino/Southern Oscillation (ENSO) phenomenon in the Indo-Pacific Ocean. The longest periods might be of astronomical origin. The 7-year periodicity, possibly related to the biblical cycle of lean and fat years, seems to be due to North Atlantic influences.
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oscillatory modes of extended Nile River records a d 622 1922
Geophysical Research Letters, 2005Co-Authors: Dmitri Kondrashov, Yizhak Feliks, Michael GhilAbstract:[1] The historical records of the low- and high-water levels of the Nile River are among the longest climatic records that have near-annual resolution. There are few gaps in the first part of the records (A.D. 622–1470) and larger gaps later (A.D. 1471–1922). We apply advanced spectral methods, Singular-Spectrum Analysis (SSA) and the Multi-Taper Method (MTM), to fill the gaps and to locate interannual and interdecadal periodicities. The gap filling uses a novel, iterative version of SSA. Our analysis reveals several statistically significant features of the records: a nonlinear, data-adaptive trend that includes a 256-year cycle, a quasi-quadriennial (4.2-year) and a quasi-biennial (2.2-year) mode, as well as additional periodicities of 64, 19, 12, and, most strikingly, 7 years. The quasi-quadriennial and quasi-biennial modes support the long-established connection between the Nile River discharge and the El-Nino/Southern Oscillation (ENSO) phenomenon in the Indo-Pacific Ocean. The longest periods might be of astronomical origin. The 7-year periodicity, possibly related to the biblical cycle of lean and fat years, seems to be due to North Atlantic influences.
Seliem M Elsayed - One of the best experts on this subject based on the ideXlab platform.
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evaluation of surface water quality and heavy metal indices of ismailia canal Nile River egypt
The Egyptian Journal of Aquatic Research, 2014Co-Authors: Mohamed E. Goher, Ali M Hassan, Ibrahim A Abdelmoniem, Ayman H Fahmy, Seliem M ElsayedAbstract:Ismailia Canal is one of the most important branches of the Nile River in Egypt. It is the main source of drinking and irrigation water for many cities. Weighted arithmetic method of water quality index (WQI) was used to evaluate the water quality of Ismailia Canal according to drinking, irrigation and aquatic life water utilizations. The objective of the index is to transform complex water quality data into understandable and usable information by the public. The WQI values of Ismailia Canal are good to poor for drinking and aquatic life utilizations, and excellent for irrigation utilization. Metal index (MI) and pollution index (PI) were calculated to assess the contaminations of the canal water with the metals (Al+3, Cd+2. Cu+2, Fe+2, Mn+2, Ni+2, Pb+2 and Zn+2). MI and PI values denote the dangerous pollution of the canal water, which is described as seriously at most sites along, in particular for drinking and fisheries utilizations. It may be attributed to the effluents of different industrial wastes arriving at the canal water. Law 48/1982 for the protection of the Nile River and its waterways against pollution must be enforced to prevent the obvious deterioration of the canal water and to improve its quality.
P. Douglas Curtis - One of the best experts on this subject based on the ideXlab platform.
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Water Balance of Blue Nile River Basin in Ethiopia
Journal of Irrigation and Drainage Engineering-asce, 1994Co-Authors: Peggy A. Johnson, P. Douglas CurtisAbstract:The Blue Nile River in Ethiopia has a drainage area of approximately 324,530 km2 and supplies nearly 84% of the water to the Nile River during high‐flow season, making it the main source of water for Ethiopia, Sudan, and Egypt. Relatively few analyses have been conducted on the Blue Nile River basin largely due to the lack of hydrologic data. The objective of this paper is to present existing stream‐flow data for the Blue Nile River and its tributaries within the Blue Nile River basin in Ethiopia and to use that data to provide insight into the River's hydrology in Ethiopia. A monthly water‐balance model was developed for this purpose. Comparisons of the predicted and observed monthly hydrographs are provided for selected subwatersheds within the Blue Nile basin. Spatial distribution of the calibrated coefficients is also discussed. Results will be useful in forecasting flows along the Blue Nile and Nile Rivers and in determining the effect of global climatic changes on continental hydrology.
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Monthly Water Balance for Blue Nile River Basin in Ethiopia
1993Co-Authors: Peggy A. Johnson, P. Douglas CurtisAbstract:The objective of this study was to present existing stream flow data for the Blue Nile River and tributaries within the Blue Nile River basin in Ethiopia and to use that data to provide some insight on the temporal and spatial variation of the hydrology of the Blue Nile in Ethiopia through a monthly water balance.
Assefa M. Melesse - One of the best experts on this subject based on the ideXlab platform.
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Hydrological Variability and Climate of the Upper Blue Nile River Basin
Nile River Basin, 2020Co-Authors: Assefa M. Melesse, Wossenu Abtew, Shimelis Gebriye Setegn, Tibebe DessalegneAbstract:This chapter discusses the hydrometeorology, land use, soils, topography, agroecological zones, extreme flows, climatic variability and climatic teleconnections of the upper Blue Nile River basin. The basin has a varied topography, rainfall and temperature resulting in different agroclimatic zones. Spatial distribution of annual rainfall over the basin shows high variation with the southern tip receiving as high as 2,049 mm and the northeastern tip as low as 794 mm annual average rainfall. The analysis of the basin’s River flow and El Nino Southern Oscillation (ENSO) index connectivity indicates that the upper Blue Nile River basin rainfall and flows are teleconnected to the ENSO index. Based on event correspondence analysis, high rainfall and high flows are likely to occur during La Nina years and dry years are likely to occur during El Nino years at a confidence level of 90%. Low and high flow analysis for selected tributaries and flow at the Blue Nile River flow shows different recurrence intervals of the high and low flows.
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Upstream–Downstream Linkages of Hydrological Processes in the Nile River Basin
Springer Geography, 2015Co-Authors: Belete Berhanu, Yilma Seleshi, Melkamu Amare, Assefa M. MelesseAbstract:The various used of water in large transboundary River basins like the Nile River will require an understanding of the upstream–downstream hydrological linkages and impacts for better planning and management of the shared resources . Related to this understanding, the hydrological processes in the three broadly classified zones (headwaters zone, transitional zone and depositional zone) have paramount importance in the decision-making process of basin-wide water uses. Particularly, changes in the headwater zone at the Ethiopian highlands (the Blue Nile sub-basin) will have the most significant connectivity to the downstream water uses and hydrological regimes. If we compare the combination effects of the rainfall amount received by in three sub-basins (Bahr-EL-Ghazal Blue Nile and Equatorial Lakes Basin), and their larger drainage area, the two sub-basins (Bahr-El-Ghazal and Equatorial Lakes Basin) receive much greater than that of the Blue Nile sub-basin. But the contribution of flow by the western basins is comparatively low. This study uses Geographical Information System (GIS) as the base tool and 30 m SRTM Digital elevation model, high resolution mean monthly rainfall, and multi-stations (226) mean monthly potential evapotranspiration data for analysing the hydrological upstream–downstream connectivity. With these input data, the analysis has confirmed that the upstream and downstream linkages in the Nile River Basin is largely dependent on the extent of the transitional zone, in which the releasing function is more characterised by the evaporation process than runoff. Thus, under the current setting, the dependency of the hydrological system for the downstream reach/zone of the Nile River basin on the processes of the Blue Nile sub-basin is more significant due to the short extent of the transitional zone in this sub-basin.
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the Nile River basin
2014Co-Authors: Wossenu Abtew, Assefa M. MelesseAbstract:The Nile River basin is one of the transboundary River basins that is in the forefront of water resource challenges of the century. As the basin’s population is growing, water demand is increasing. Focus on basin hydrology, climate change, and water management is critically needed. The Blue Nile subbasin is relatively more efficient in generating runoff contributing most of the flow to the Nile compared to the White Nile. This makes flows susceptible to changes in the watershed. The basin’s high rate of population growth is putting stress on natural resources including water. In 25 years, the population of the 11 Nile countries is projected to reach 726 million. A 64 % increase in water demand is projected in the Nile basin countries without factoring increase in per capita water demand. The link between River and watershed is becoming vivid as demand for water and power grows and becomes a source of conflict.