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1. Impacts of Climate Change on the Nile Flows at Dongola Using Statistical Downscaled GCM Scenarios, Mohamed E. Elshamy, Mohamed A.-A. Sayed, Bakr Badawy.

   Abstract

   This study was initiated with the objective of evaluating the relative magnitude of uncertainties across emission scenarios, due to downscaling. The study analyzed the change in Nile flows at Dongola resulting from two emission scenarios (A2 and B2) using the results of 3 GCMs (CGCM2, ECHAM4, and HadCM3).It is to be mentioned here that a GCM is a global circulation model (GCM) that could depict different pictures for the future precipitation over the Nile basin, and consequently could expect the discharge of the river. A 10-member assemblies of statistically downscaled precipitation scenarios for the 2010–2099 period was designed for the whole Nile basin from the output of these experiments. Potential evapotranspiration (PET) were calculated for the base-period (1961-1990) and for three 30-year time slices in the future (2010-2039, 2040-2069, and 2070-2099) using the Penman-Montheith equation. Rainfall and PET scenarios were used to drive a fine-scale hydrological model of the Nile Basin. Observed rainfall from the base-period was used to determine the parameters of the statistical downscaling model (SDM) for the different GCMs. The results showed that the ECHAM4 predicts a steady increase in Nile flows in the future while CGCM2 underestimates the flow in the base-period. On the other hand, an increase was predicted by years 2020 and 2030. The expected flow is similar to the observed mean. It was also predicted that the flow might decrease rapidly in case of the A2 scenario. However, the HadCM3 showed a slight trend of increase to the flood season flows and a slight trend of increase for the base-period flow. This counterbalances each other so that the total annual flow does not change. The results also indicated that the uncertainty range, across the models, is larger than that across the two studied scenarios. The range of differences between the scenarios is model dependent and time dependent. The uncertainty due to downscaling is also large and is proportional to the flow. It was thus concluded that the implications of the changes might be huge for the water resources planning and management within the basin and particularly for Egypt.
   Key words: Nile Basin, Hydrologic Models, Climate Scenarios, Downscaling, Climate Change Impacts

2. Impact Assessment of Future Climate Change for the Blue Nile Basin, Using a RCM Nested in a GCM, Eman S.A. Soliman, M. A. Aty Sayed, and Marc Jeuland.

   Abstract

   This paper establishes a basis for evaluation of climate changes impacts within the Blue Nile River sub-basin, using the RegCM3 Regional Climate Model to simulate interactions between the land surface and climatic processes. The RegCM3 model nested with the ECHAM5 General Circulation Model (Max Planck institute) were applied and the obtained results are presented.. The results were then fed as inputs to the Nile Forecast System NFS) (a distributed rainfall runoff model of the Nile Basin) and the interaction between the climatic and hydrological processes on the land surface was fully coupled. Rainfall patterns and evaporation rates were generated using RegCM3, and the resulting runoff and Blue Nile streamflow patterns were simulated using the NFS. The results, obtained from the RegCM3 climate model, were compared to the observational datasets for precipitation and temperature from the Climate Research Unit (UK) and the NASA Goddard Space Flight Center GPCP (USA) for the period 1985-2000. The validity of the stream-flow predictions from the NFS is assessed using historical gauge records. Finally, the modeling results of the A1B emissions scenario of the IPCC for the years 2034-2055 are presented. The results indicated that the future changes in rainfall might vary over different areas of the Upper Blue Nile catchment in Ethiopia. This suggested that there might be a good reason for developing climate models with finer spatial resolution than the commonly used GCMs.
   Key words: Nile Basin, Hydrological processes, Regional climate modeling, NFS, ECHAM, climate change.

3. Impact of Climate Change and the Human Activities on Land Degradation in Arid and Semi-arid Regions, Muna M. Elhag and Sue Walker.

   Abstract

   This research was initiated with the objective of analyzing the climate change and climate variability in the Butana area, north - eastern part of Sudan, during the period 1940-2004 and to study the interaction between land degradation, climate change and the human activities through the analysis of the vegetative cover and soil degradation. To explore the climate variability and climate change, in terms of rainfall for the period from 1940 to 2004, the annual time series for 4 weather stations (ElGadaref, Halfa, WadMedani and Shambat) across the Butana area, were analyzed, The trend of the rainfall at WadMedani and Shambat showed a significant declination, while that of Halfa and ElGadaref did not show a significant change. Using the Residual Trend Method, the differences between the observed peak NDVI and the peak NDVI predicted by the rainfall was calculated for each pixel. This method identified the degraded areas that exhibit negative trends in NDVI. From the results, it was noticed that the residual effect of the human activities are severe in zones 1 and 2 (-0.17 to -0.5) during 1982-1986, during severe drought. After this period the effect became less during the period of 1992-1996. This indicated a decrease of the human impact and an increase in the observed NDVI. These findings could be interpreted as recovery from the drought years or might be due to the reductions that occurred in livestock numbers. During the period of 1997-2001 the area experienced a drought in 2000 and the human influence increased but still relatively less than during the period 1982-1991.
   Key words: Climate change, Human impact, land degradation, RESTREND, Sudan
   

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