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Assessing climate change effects on water resources is the first step in preparing climate change adaptation measures. However, this is often clouded by the large range of uncertainty resulting from a long chain of modeling activities. Despite progress made to improve climate models, downscaling methods, and hydrological models, uncertainties will remain. This paper proposes a framework to propagate and quantify the uncertainty from the different sources that can be applied at the full cascade but focuses on the climate-modeling component, i.e., different climate models and emissions scenarios. This framework is based on the generalized likelihood uncertainty estimation (GLUE) methodology, which is widely used in the hydrologic community but has not been applied as such to climate impact modeling. This paper presents a preliminary application of the proposed framework to the flow of the main Nile at Dongola. [ABSTRACT FROM AUTHOR]

Lake Victoria, the second largest freshwater lake in the world, is one of the major sources of the Nile river. The outlet to the Nile is controlled by two hydropower dams of which the allowed discharge is dictated by the Agreed Curve, an equation relating outflow to lake level. Some regional climate models project a decrease in precipitation and an increase in evaporation over Lake Victoria, with potential important implications for its water balance and resulting level. Yet, little is known about the potential consequences of climate change for the water balance of Lake Victoria. In this second part of a two-paper series, we feed a new water balance model for Lake Victoria presented in the first part with climate simulations available through the COordinated Regional Climate Downscaling Experiment (CORDEX) Africa framework. Our results reveal that most regional climate models are not capable of giving a realistic representation of the water balance of Lake Victoria and therefore require bias correction. For two emission scenarios (RCPs 4.5 and 8.5), the decrease in precipitation over the lake and an increase in evaporation are compensated by an increase in basin precipitation leading to more inflow. The future lake level projections show that the dam management scenario and not the emission scenario is the main controlling factor of the future water level evolution. Moreover, inter-model uncertainties are larger than emission scenario uncertainties. The comparison of four idealized future management scenarios pursuing certain policy objectives (electricity generation, navigation reliability and environmental conservation) uncovers that the only sustainable management scenario is mimicking natural lake level fluctuations by regulating outflow according to the Agreed Curve. The associated outflow encompasses, however, ranges from 14m³ day-1 (-85%) to 200m³ day-1 (C100%) within this ensemble, highlighting that future hydropower generation and downstream water availability may strongly change in the next decades even if dam management adheres to he Agreed Curve. Our results overall underline that managing the dam according to the Agreed Curve is a key prerequisite for sustainable future lake levels, but that under this management scenario, climate change might potentially induce profound changes in lake level and outflow volume. [ABSTRACT FROM AUTHOR]

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This paper describes the application of hydrologic models of the Blue Nile and Lake Victoria sub-basins to assess the magnitude of potential impacts of climate change on Main Nile discharge. The models are calibrated to simulate historical observed runoff and then driven with the temperature and precipitation changes from three general circulation model (GCM) climate scenarios. The differences in the resulting magnitude and direction of changes in runoff highlight the inter-model differences in future climate change scenarios. A 'wet' case, 'dry' case and composite case produced +15 (+12), -9 (-9) and + 1(+7) per cent changes in mean annual Blue Nile (Lake Victoria) runoff for 2025, respectively. These figures are used to estimate changes in the availability of Nile water in Egypt by making assumptions about the runoff response in the other Nile sub-basins and the continued use of the Nile Waters Agreement. Comparison of these availability scenarios with demand projections for Egypt show a slight surplus of water in 2025 with and without climate change. If, however, water demand for desert reclamation is taken into account then water deficits occur for the present-day situation and also 2025 with ('dry' case GCM only) and without climate change. A revision of Egypt's allocation of Nile water based on the recent low-flow decade-mean flows of the Nile (1981-90) shows that during this period Egypt's water use actually exceeded availability. The magnitude of 'natural' fluctuations in discharge therefore has very important consequences for water resource management regardless of future climate change. [ABSTRACT FROM AUTHOR]

The Nile is one of the world's major rivers; its basin is shared by 11 countries and is home to some 300 million people. This article reviews the multidisciplinary literature on the Nile to understand more about the outlook for this geopolitically significant river basin. I start by synthesizing the key results from recent climate change modeling studies, which show a warming trend for the basin, but considerable uncertainty regarding the direction of precipitation and streamflow change. I explore how different actors within the Nile Basin are perceiving and responding to climate change. Second, I look at the significance of land use, both to basin hydrology and as a driver of water demand. I highlight contemporary land use changes that could impact flows within the Nile Basin. Third, I examine the role of infrastructure in influencing the magnitude and temporality of flows along the river. I focus, in particular, on the Grand Ethiopian Renaissance Dam, its projected impacts, and the concerns it has generated. Finally I explore the geopolitical context of the basin, and the ongoing conflict over water sharing agreements. I look at the treaty currently on the table, the Cooperative Framework Agreement, and the political issues it has raised. In bringing together this diverse literature, the article offers a timely and multifaceted insight into the varied factors that will shape the future of the Nile. WIREs Clim Change 2017, 8:e449. doi: 10.1002/wcc.449 For further resources related to this article, please visit the . [ABSTRACT FROM AUTHOR]

The article discusses the possibility that climate change affected the rise and fall of the Roman Empire, using both historical and scientific evidence. It is said that the earth's climate was stable during the rise of the Empire, with the Nile River flooding in an optimal manner for Egypt's agriculture. Also noted are the possible effects of cooling around 260, warmer weather and a severe drought during the fourth century, and cooling following a possible volcanic eruption around 536. The authors note a probable link between temperature and precipitation patterns.

Like many delta systems, the coastal zone of the Nile delta has been designated as a vulnerable zone to a rising sea level as a consequence of expected climate changes combined with geological and human factors. In view of the understanding of these factors, a degree of vulnerability analysis has been carried out to better locate which sectors need to be assessed and adapted to possible sea level rise (SLR) for the Nile delta-Alexandria region of Egypt. Results reveal that not all of the coastal zones of the Nile delta are vulnerable to accelerated sea-level rise at the same level. Based on multiple criteria the Nile delta-Alexandria coast can be categorized into vulnerable (30%), invulnerable (55%) and artificially protected coastal stretches (15%). These criteria include: local subsidence or uplifting, relative sea-level rise (RSLR), land topography, width of lagoon barriers, beach-face slope, high-elevated features such as dunes and ridges, eroding and accreting coastlines and protection works. Moreover, this study evaluates the long-term relative sea-level rise and subsidence rates along the Nile delta and Alexandria coasts. Statistical analysis of long-term tide gauge data recorded at Alexandria, Burullus and Port Said yields values of 1.6, 1.0 and 2.2 mm/yr, respectively. These values of relative sea-level rise and long-term subsidence rate obtained from age-dated sediment core sections are inconsistent: long-term subsidence appears to be larger (maximum of 7 mm/ yr). This discrepancy might be explained if the subsidence is episodic, and occurs rather abruptly during major earthquakes that occur every few hundred years associated with fault trend lines. Rising sea levels could have significant longterm impacts on the Nile delta, including the distribution of ground water salinity and erosion of the narrow and low-lying barriers of the Burullus and Manzala lagoons. Adaptive measures along the study area particularly those related to coastal protective structures are also evaluated. [ABSTRACT FROM AUTHOR]