Monitoring of variations in water for lakes and reservoirs is a requirement for meeting human needs and assessing ongoing climatic changes. However, regular gauging networks fail to provide the information needed for water volume data. The aim of this study is to evaluate an approach to estimate water volume variation for the southern part of Lake Nasser in Egypt without in-situ gauge measurements and bathymetry maps. Combination of both Hydroweb satellite altimetry and Landsat 8 satellite imagery data was used. As compared to in-situ water levels, satellite altimetry provided accurate water levels variations for Lake Nasser; the RMSE was 0.28 m, with excellent agreement (R 2 is 0.98). The lowest water level of altimetry database i.e. 174.57 m was used as a reference level for estimating water volumes variations for the study duration 8/2014-6/2015. All water altimetry levels were converted to differences of recorded water level above the lowest altimetry Level (∆WL). Series of Landsat 8 imagery data were selected to extract surface areas corresponding to radar altimetry water levels dates. Areas-∆WL relationship model was established as a polynomial function: A = f(∆WL), and therefore, the relationship of the water volume above the lowest water level for the study time (∆V) and ∆WL was obtained through the analytical integration of (Area-∆WL) model. Another approach (Heron method) was also applied for estimating water volume variations. Validation of these two approaches showed that estimated water volume variations above reference water level using both methods i.e. integration and Heron agreed well with in-situ measurements of volume variation deduced from recent bathymetry map and in-situ water levels (R 2 for both methods = . Another byproduct for these approaches was the modeling for a remote detecting water level. Once the F(L) relationship is set up for a given region, future Landsat images can be utilized to track water levels freely of radar altimetry. Finally it can be concluded that remote sensing resources (satellites radar altimeters and optical satellite images) that are openly accessible these days represent a great opportunity to remotely monitor reservoir water capacity and help in examining and observing hydrological and water driven procedures.
A significant decrease in the pH of saliva has been detected in patients with recurrent aphthous ulcers (RAU). The decreae in pH was more prominent at night than between meals, and some persistent decrease was noticed even after recovery. The total proteins of saliva in RAU were also significantly decreased.These findings were similar to those observed in patients complaining of petic ulcers, so it is recommended that patients with RAU should be treated with antacids as well as anticholinergic drugs, and that the possibility of concomitant peptic ulceration should also be investigated.
The High Aswan Dam is one of the largest dams in the world. Completion of the dam in 1970 resulted in the formation of Lake Nasser/Nubia (LNN). LNN has a highly irregular shape and dimensions. Its total length is about 500 km (335 km in Egypt, known as Lake Nasser; 165 km in Sudan, known as Lake Nubia). It has an average width of 12 km, an average depth of about 25 m and a maximum depth of 90 m. Large quantities of sediment are deposited in the lake, which complicates accurate knowledge of its navigational routes. Moreover, the sediment deposition and lowering of water levels has resulted in the creation of shallow areas that navigation bottlenecks. Furthermore, this problem is expected to increase in the future because of climate change impacts, and the effects of upper Nile River projects. The objective of this study was to identify a sustainable channel for navigation purposes in Lake Nasser/Nubia. A numerical model (Delft‐3D) was used to simulate the navigation waterway along Lake Nasser/Nubia. Calibration and verification of the model for flow and sediment deposition were performed during the period of 2009–2012. There was a good agreement between the observed and modelled results for the whole domain. The model was used to evaluate the designed navigation waterway, based on different scenarios. The calculated volume of the needed dredging, based on time series for the years 2002–2006 (‘which represents a minimum flood’), was 5.94 million m3 (mcm); the calculated volume of the dredging using time series for the years 1992–1996 (‘which represents an average flood’) was 6.64 mcm; and the calculated volume of the dredging using time series for the years 1996–2000 (‘which represents a maximum flood’) was 8.46 mcm. The modelling approach proved to be a useful tool for monitoring the future navigation waterway in Lake Nasser/Nubia.
Modern technologies are becoming very essential tools for water resources and environmental studies analysis. One of these modern technologies is using the remote sensing for water resources and environmental studies. This study aims to monitoring, detecting, and investigating environmental changes in Fayoum region, which consists of 5 districts. Different change detection techniques; Delta Cue, Unsupervised classification differencing, Spectral Indices, and Multi temporal remotely sensed data (Landsat ETM+ 1999 and2003) were adopted in this research. Different change detection algorithms are utilized in this study as unsupervised classification images differencing, Magnitude Diff, Tasseled Cap, Single band, Normalized Difference Vegetation Index (NDVI), the Normalized Differential Water Index (NDWI), and Tasseled Cap transformation Wetness indicator (TCW). Changed water bodies surface areas, vegetation, bare difference areas, areas changed from vegetation to bare and the opposite were all detected using the above mentioned techniques and quantified to district levels using ArcGIS methodologies. Results showed that water bodies have increased of about 10.6 km 2 in Lake Karon, 0.078 km 2 in Wadi Rayan 1, and decreased for about 3.6 km 2 in Wadi Rayan 2 during the study period. The vegetation cover has increased by 6.25%, and 11.17% in Fayoum, and Senores districts respectively and decreased by 6.63%, 8%, and 2.04 in Tamay, Ibshoy, and Itsa respectively. The bare and built up areas for Fayoum and Senores were decreased by 0.011% and 10.1% respectively, while Tamay, Ibshoy, and Itsa were increased by 12%, 11.2%, and 11.74% respectively. Results of the statistical analysis showed that there was significant correlation between the change values resulted from tested change detection techniques. The outcome of this study represents a valuable resource for decision makers to guard against the environmental changes, and for future development projects.
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