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[PANEL] 0610 RECENT STUDIES ON ENERGY, WASTE, SEDIMENTATION, EROSION
Organizers:
TSEGAY Aregawi, Institute of Geo-information and Earth Observation Sciences, Mekelle University, Ethiopia
Paper presenters:
TSEGAY Aregawi; AMANUEL Zenebe; DUGUMA Erasu; TESFAYE Feye; RAHWA Gebre Tesfahuney; HENOK Kassa;
Jan NYSSEN; GETACHEW Dagnew
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ASSESSING RUNOFF AND SOIL EROSION BY WATER USING GIS AND RS TECHNIQUES AT MIDMAR CATCHMENT, NORTHERN ETHIOPIA [Abstract ID: 0610-04]
Soil erosion in Midmar watershed is a widespread problem causing loss of soil and organic matter and hence adversely affecting fertility and reduction in crop yield. The root causes for this problem are degradation of natural resources, intensive soil erosion, deforestation, poorly developed infrastructure, impact of farmers to the dam and intensive cultivation. This research has therefore, been carried out to evaluate runoff and soil erosion risk in the watershed. Rainfall data, soil data, DEM data and satellite image were used as input data sets to generate RUSLE factor values. Raster calculator was used to interactively calculate soil loss and derive soil erosion risk map. The result showed that the estimated annual soil loss of the watershed ranges from 0.00 to 122 t/ha/yr and the mean annual soil loss rate is 23.7t/ha/yr. Of the 11 sub-watersheds, nine (67.3%) were predicted to experience annual soil loss of more than the watershed’s average (23.7t/ ha/yr) whereas two sub-watersheds experienced estimated annual soil losses than the average (32.7%). The average soil loss of Midmar watershed is also 23.7t/ha/yr. Among all the sub-watersheds the highest soil loss is contributed by 4 sub-watershed and hence should be given priority during intervention planning.
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DISCLOSING THE DILEMMA OF MUNICIPAL SOLID WASTE MANAGEMENT IN ROBE TOWN [Abstract ID: 0610-02]
The purpose of this study is to assess the existing municipal solid waste management service in Robe town. Its specific objectives are to estimate the quantity of solid waste generated per household, determine the amount of solid waste disposed of properly from individual households, identify the determinants of household solid waste production, identify the stakeholders involved in the management of municipal solid waste, describe the organizational arrangements for municipal solid waste management, and describe current solid waste management practices in Robe town. The researchers used systematic sampling techniques to select sample households, resulting in the selection of 372 respondents and 10 key informants. To achieve the objectives of the study, the researchers used both primary and secondary data sources. The primary data were gathered through questionnaires, interviews and field observations, while secondary data were extracted from different published and unpublished documents and analyzed using both qualitative and quantitative techniques. The findings of this study indicate that Robe municipality provides solid waste management services such as collection, transportation and disposal. These services are provided by Robe town and MSE (micro and small enterprises). However the solid waste management service is not sufficient and handles no more than 30% of the waste. As a result, solid waste management in the town is inadequate, with some 70.7% of households reporting dissatisfaction with current practice. The study reveals that the solid waste generation rate is 0.261kg/person/day making a daily total of approximately 20,000 kg per person generated from households in Robe town. Of the solid waste generated, only 57.5% is properly disposed of at the landfill site while 42.5% is illegally dumped around the town. This is because household education and awareness of municipal solid waste management is lacking. Community participation is poor, there is limited involvement by MSE, poor waste handling by households, lack of standardized landfill sites, weak municipal supervision, lack of stakeholder participation in municipal planning. The absence of public skips and bins, together with the lack of vehicles to transport solid waste, add to the problem. In addition, the failure to separate biodegradable and nonbiodegradable waste, the absence of reuse and recycling, or compost preparation from solid waste, contribute to the problem in Robe town.
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RURAL POPULATION AND ENERGY: COSTS AND BENEFITS OF BIOGAS PLANTS DEVELOPMENT AT HOUSEHOLD LEVEL IN THREE SELECTED AREAS OF TIGRAY [Abstract ID: 0610-01]
Biogas has micro and macro benefits which require proper investigation. The purpose of this study was therefore to assess the costs and benefits of biogas at household level in three Weredas in Tigray where the use of biogas is widely adopted. The study used both primary sources of information via questionnaires and secondary data from the literature. 150 households were selected via purposive sampling. The collected data were analyzed using cross tab with phi and Cramer’s value and Spearman’s rho correlation. Most of the female household heads who live in rural areas with no access to electricity and other modern alternative sources of energy are using Biogas. The size of the biogas digester ranges from 6 m³ to 8 m³ with 6 m³ common at household level. The total construction costs of biogas range from ETB 12,300 to 14,000, of which ETB 2,300 to 3,500 is covered by the users and the remaining is covered by government organisations and NGOs. Biogas is used in households for lighting, cooking and coffee making. The main reasons why biogas is adopted are location, cattle ownership, cattle feeding method, income source and subsidy. Benefits of adopting biogas include sustainable waste management, reduced cooking and cleaning time, fertilizer production, savings on kerosene and labor. The larger the biogas digester, the greater the benefits. Biogas users obtain benefits but face problems with biogas and its slurry. The views of female household heads in rural areas with regard to the development of biogas plants need to be listened to as they represent their communities. The Government and NGOs need to adjust their incentives and other aspects of finance to cover part of the introduction to Biogas. All stakeholders in Biogas need to focus on the decision-making elements and recognize the benefits of Biogas, which differ according to the size of the biogas digester, and act accordingly.
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SEDIMENT YIELD AT SOUTHWEST ETHIOPIA’S FOREST FRONTIER [Abstract ID: 0610-03]
Deforestation is one of the major factors of soil erosion in tropical regions, but to what extent does crop growth in deforested areas protect the land from erosion? We evaluated the effect of deforestation on suspended sediment yields on the scale of zero-order catchments by contrasting five paired small forest and cropland catchments at Ethiopia’s southwestern forest frontier. Suspended sediment samples were collected from nine San Dimas flumes and one V-notch weir installed in catchments draining the natural forest and cropland, at different altitudes. The suspended sediment data were collected from June 8 to October 30, 2013 and 2014. The suspended sediment yields of both land-use types was strongly correlated with the corresponding discharge. The results show that the average seasonal suspended sediment yields from cropland (17.0 ± 7.6 Mg ha-1) is four times higher than from the paired forests (4.0 ± 1.9 Mg ha-1). High sediment yields from forests are related to livestock grazing, but forests still have an important role in protecting the surface soil from erosion on south-west Ethiopia’s forest frontier. Land management in southwestern Ethiopia’s highlands will need a big change in paradigm, in which the dominant belief in the recently imported mahrasha ard plough is abandoned, oxen and other cattle reduced in number and kept in the homestead, the forests better protected from human and livestock interference, and the open farmlands turned into agroforestry. Such an approach is still possible as all the elements required are available in the landscape.
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WET AIR OXIDATION:IN PERSPECTIVE [Abstract ID: 0610-05]
Wet air oxidation (WAO) is used to degrade organic and inorganic pollutants at high COD concentration (100-1000gCOD/l) as opposed to other advanced oxidation processes (AOPs). WAO operation variables used are mainly catalyst, temperature, and pressure, which affects stabilization time and COD removal efficiency, ranging 60-99.99%. Traditional WAO involves a temperature of 150-3000C and a pressure of 0.5-20 megapascal, whereas supercritical WAO applies a temperature >3740C and a pressure of >22 megapascal. Various studies are underway to enhance the process, such as the application of catalysts to improve performance even at lower temperature and pressure. However catalysts are being compared to one another based on activity, stability, as well as recoverability potential. Given the limits to treating recalcitrant compounds and the remaining organics, WAO is an environmentally friendly and economically feasible technology, especially if the process is catalyzed. Numerous studies have been done on WAO in recent decades, but they were conducted piecemeal, not comprehensively. This simple review paper presents the basics and current state of the art of WAO by reviewing existing papers, including the reaction mechanism, kinetics, catalysis, installed capacity, and reactor modification aspects, with illustrations.