Effects of atmospheric stability conditions on heat fluxes from small water surfaces in (semi-)arid regions

Atmospheric stability conditions over the water surface can affect the evaporative and convective heat fluxes from the water surface. Atmospheric instability occurred 72.5% of the time and resulted in 44.7 and 89.2% increases in the average and maximum estimated evaporation, respectively, when compared to the neutral condition for a small shallow lake (Binaba) in Ghana. The proposed approach is based on the bulk-aerodynamic transfer method and the Monin-Obukhov similarity theory (MOST) using standard meteorological parameters measured over the surrounding land. For water surface temperature, a crucial parameter in heat flux estimation from water surfaces, an applicable method is proposed. This method was used to compute heat fluxes and compare them with observed heat fluxes. The heat flux model was validated using sensible heat fluxes measured with a 3-D sonic anemometer. The results show that an unstable atmospheric condition has a significant effect in enhancing evaporation alongside the sensible heat flux from water surfaces.     

Urbanization and its impact on flood hazard: the case of Addis Ababa,Ethiopia

Natural Hazards - Rapid urbanization has become and will continue to be an inevitable and inescapable phenomenon in the developing world. Unplanned expansion of cities and the impacts of climate...     

The Amount of Dust and the Distance of NGC 253

The areas of 267 dark clouds in the galaxy NGC 253 were measured. It is shown that the size distribution of these clouds obeys the same exponential formula found for the galaxies NGC 3031, 5128, 5194, and 5457. From the apparent size distribution of the dark clouds the amount of dust and the distance of NGC 253 is found to 4.4 · 10⁷ M_⊙ and 2.06 Mpc, respectively.     

Spatial modeling of solar photovoltaic power plant in Kabul,Afghanistan

Energy planning and solar plant site selections are vital strategic decisions and one of the most complex executive challenges in the interconnected procedures....     

Determination of sediment deposition of Hasanlar Dam using bathymetric and remote sensing studies

Natural Hazards - Hasanlar Dam and Hydroelectric Power Plant are located on Küçük Melen Creek in the Western Black Sea Basin of Turkey. The dam was constructed in 1974 to provide...     

Hydrological mapping from SPOT imagery

Four SPOT images, one panchromatic and three multispectral, were studied to evaluate their usefulness for hydrological mapping in an arid environment. Simple visual methods of interpretation were used to plot the drainage network independently from each test image. The results were compared with the drainage network shown on the topographic map of the area. Results show that with the panchromatic image, over 90 per cent of the map content could be discerned, identified, and plotted. The accuracy of plotting the drainage system from the multispectral images seems to depend on the season in which data had been acquired. However, in all cases, the success rate is not less than 70 per cent. Comparison with Landsat Thematic Mapper (TM) imagery showed that SPOT system is superior in hydrological mapping.