Ånund Killingtveit

Rainfall distribution on the slopes of Mt Kilimanjaro

Abstract Observations from new precipitation gauges on the southern slopes of Mt Kilimanjaro are used together with observations from the regular network to establish an elevation function for the precipitation on the southern hillside of Mt Kilimanjaro. A third-order polynomial function is found to best describe the distribution of precipitation with elevation for the lower half of the hillside. On the upper half of the hillside, an exponential function is found to best describe the precipitation distribution with elevation. The availability and quality of the precipitation records is often a limiting factor for analyses and may influence the results. A reference precipitation series for the area is established through thorough screening and quality checks of the available data. The elevation function is compared with an isohyetal map for the area. The findings indicate that the maximum precipitation on the southern hillside of Mt Kilimanjaro takes place at about 2200 m a.s.l. which is 400–500 m higher than assumed previously.

Water balance investigations in Svalbard

This paper reviews and summarizes all known previous water balance studies in Svalbard. An updated water balance computation was then done for the three water catchments with the best data: Bayelva, De Geerdalen and Isdammen/Endalen for 10 hydrological years 1990-2001. The computations were based on the best available data and correction methods. Special emphasis was put on correction of precipitation data, both for catch errors and gradients in precipitation. Areal precipitation in the three catchments is more than two times the measured precipitation at the closest meteorological station: 548 mm/year in De Geerdalen, 486 mm/year in Endalen/Isdammen and 890 mm/year in Bayelva. Compared to this, average measured precipitation is only 199 mm/year at Svalbard Airport, close to Endalen/Isdammen and De Geerdalen, and 426 mm/year in Ny-Ålesund, close to Bayelva. Evaporation is not well understood in Svalbard; the best estimates indicate an average annual evaporation of ca. 80 mm/year from glacier-free areas, and no net evaporation from glaciers. Glacial mass balance has in general been negative in Svalbard during the last 40 years, leading to a significant contribution to the water balance, on the order of 450 mm/year on average. Annual runoff ranges from 545 mm in Endalen/Isdammen, 539 mm/year in De Geerdalen up to 1050 mm/year in Bayelva. Runoff computed from water balance compares well with observed runoff, and average error in water balance is less than ±30 mm/year in all three catchments.

The Water Footprint of Hydropower Production—State of the Art and Methodological Challenges

This paper reviews published estimates of water consumption from hydropower production and the methodologies applied. Published values range from negative to more than 115 000 m3 MWh−1. Most gross water consumption rates are in the range 5.4–234 m3 MWh−1, while most net values are in the range 0.2–140 m3 MWh−1. Net values are often less than 40% of the gross values, sometimes only 1% of the gross water consumption estimates. The extremely wide range in estimates is explained by an inconsistent methodology and the very site‐specific nature of hydropower projects. Scientific challenges, such as allocation from multipurpose reservoirs, and spatial assignments in river basins with several hydropower plants, affect the results dramatically and remain unresolved. As such, it is difficult to propose “typical values” for water consumption from hydropower production. This paper points out directions of research in order to prepare a consistent and improved methodology for the calculation of water consumption from hydropower projects. This should take into account the role of reservoirs in the provision of a large range of water services, as well as providing regulated power to the energy system.

A GUIDED SWAT MODEL APPLICATION ON SEDIMENT YIELD MODELING IN PANGANI RIVER BASIN: LESSONS LEARNT (doi: 10.4090/juee.2008.v2n2.053062)

Accra has a population of about 2.3 million and is supplied with water from both the Kpong and Weija Water Works. Water from the Weija treatment plant is taken from the Weija Reservoir which is fed by Rivers in the Densu River Basin (DRB) that flow into the Reservoir at Weija. With increasing annual population growth of Accra at 4.4% and inadequate water supply to it, this study has examined the hydrological data available on the Weija Reservoir from 1980 to 2007 in an attempt to estimate runoff into the Reservoir with the view of determining whether water is available to meet its present and future demands. Results show that even though water abstraction from the Reservoir has increased almost four times since 1980, to more than 67 million m3/year in 2007, and a maximum runoff of 7.97 ± 0.21 × 10-2 km3/year was estimated in 2005, this value is less than the true runoff into the Reservoir. It was also observed that potential evapotranspiration has increased by 0.14% while precipitation has decreased by 0.93% in the DRB, indicating that runoff from the Basin into the Reservoir is probably decreasing, albeit slowly. Additionally, fishing and waste disposal methods are poor; land use practices and other anthropogenic activities in the DRB pose a threat to the sustainability of the Reservoir. Serious educational programmes and enforcement measures need to be urgently adopted to safeguard continuous water flow into the Reservoir. Proper hydrological data collection and data management practices are recommended for the Reservoir and Densu River Basin if detailed planning of the water resources of the Reservoir are to be achieved.Land use and changes in land cover play an important role in local and regional climatic conditions, especially in tropical regions. Piracicaba, a city in southeastern Brazil, has an economy that is based primarily on sugar cane cultivation. The seasonality of this crop means that there are marked annual fluctuations in land use and cover in this municipality. In this work, we investigated the seasonal variation in urban heat-islands and local climatic variations by using remote sensing data, geographic information system (GIS) and atmospheric modeling. The urban heat-islands were analyzed by using Landsat 7 (Enhanced Thematic Mapper+) images for the sugar cane crop (January to March) and non-crop (August to November) periods, and these images were subsequently converted to land surface brightness temperature. The average temperature in the non-crop period was 3.5°C higher than in the crop period, which suggested that heat-island intensity may be linked to the seasonality of sugar cane cultivation. In order to examine the influence of urban areas on regional temperature changes and heat fluxes, numerical simulations were done with the Brazilian Regional Atmospheric Modeling System (BRAMS). Overall, the results obtained suggested that local and regional climatic dynamics were related to land use and changes in land cover.The environmental conditions in Brazil have been contributing to the development of anaerobic systems in the treatment of wastewaters, especially UASB reactors – Up flow Anaerobic Sludge Blanket. The classic biological process, for removal of nutrients, use three reactors - Bardenpho System, therefore, this work intends an alternative system, where the anaerobic digestion and the denitrification happen in the same reactor, in this system, is reduced for two, the number of reactors. The experimental system was constituted by two units: first was a nitrification reactor with 35L volume and 15 days of sludge age. This system was feed with raw sanitary waste. Second unit was an Up flow Anaerobic Sludge Blanket (UASB), with 7.8 L and 6 hours of hydraulic detention time, feed with ¾ of effluent nitrification reactor and ¼ of raw sanitary waste. This work had as objective evaluates the performance of the UASB reactor, in terms of removal efficiency, of bath COD and nitrogen. It was verified that the anaerobic digestion process was not affected, the removal efficiency of organic material expressed in COD, was 71%, removal already expected for a reactor of this type. It was also observed that the denitrification process happened; the removal nitrate efficiency was 90%. Therefore, the denitrification process in reactor UASB is viable