Finding Potential Sites for Small-Scale Hydro Power in Uganda: a ...

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UTM Zone 36N projection. The study area is located in UTM zone 35, but is in all mapsextrapolated to be in same zone as the rest of the country. When using a GPS in thestudy area, you will receive coordinates in zone 35, which therefore differs from thecoordinates in the maps. The knowledge about this was received later and therefore weabandoned the use of GPS, which reduced the pace of our evaluation.The fact that the use of GPS no longer was an alternative to find the potential sites andthe inability to unhindered visit all sites in the terrain, we decided to evaluate sites invicinity of roads and smaller villages. This was done despite the knowledge that a certaindegree of tarmac bias could occur, which would make the selection of evaluation sitesstatistically incorrect. On the other hand, there is no interest in potential sites far awayfrom roads, since it will make transportation of construction material more complicatedand expensive.The reason to why not more than three sites fulfilled the required criteria of head andpermanent flow, at the evaluation, was not our algorithm, but incorrect input data. Whenperforming the evaluation we found that all watercourses, except these three, wereseasonal and not permanent as supposed to in the input data. This probably arose as aclassification error when digitizing the watercourse layer. Despite that we did not findpermanent watercourses, every visited site clearly showed signs from water activity,which means that the data is correct regarding location. Of course this should have beencritically questioned before performing the analysis. We should also have asked the NFAwhat the requirements are for a watercourse to be classified as permanent. None of thiswas done, instead we committed the mistake of assuming that the data was correct.We interpreted the conditions in the study area mentioned earlier, regarding precipitationand topography to be favorable for watercourses suitable for small-scale hydropower.The result from the evaluation showed the opposite since we hardly found anywatercourses at all in the area, which surprised us. The reason for this is partly because ofthe incorrect classification but also because of the properties of the volcanic geology.According to Nyiraneza and Hoellhuber (2002) the absence of surface water is caused byhigh and inhomogeneous permeability of soil and underlying geological formations.Something we came across when evaluating the potential sites, which also can explain theabsence of surface water, is the construction of subsurface water pipes. The water is ledthrough pipes from springs down to the village center, where it supplies the villagers withdrinking water.62
From this we can draw the conclusion that the quality of watercourses as input data is ofmajor importance. As the result from the evaluation show, almost 80 percent of the sitesdo not qualify to be a potential site for small-scale hydropower, because of low quality ofinput data. There are two different errors that can contribute to the low quality of data.The first and most obvious is the classification error mentioned above, but also theaccuracy that the watercourses have been digitalized with can be of importance. If thewatercourses have been imprecisely digitized, this can result in rivers located at thewrong position in the DEM, when making the overlay. This can result in loss of potentialsites or gain of false sites.6.6 Lesson LearnedFrom our study we conclude that the result is largely dependent on the quality ofwatercourse input data. In order to avoid errors such as incorrect classification and lowdigitalization precision and to receive a more accurate result, one option is to use self-input data over rivers and streams. This can be attained by using the producedproducedDEM to calculate catchment area and flow accumulation. To make the input data evenmore reliable, factors concerning precipitation, infiltration and evaporation can be takeninto consideration. This is an extensive task, which demands a thorough investigation ofthe geology and climatology of the area. Although this is time consuming, the resultshould be rivers at exact position and also knowledge about its volume flow rate andtemporal variation. A better, faster and more reliable approach would be to use ourmethod with available watercourse data and perform a field survey in the area of interestin order to ensure which sites that really have a potential for small-scale hydropower.6.7 End DiscussionAs mentioned, there were only three sites in the evaluation that fulfilled the criteria of asuitable small-scale hydropower site. To put these into context, the site with smallestpotential electrical output of 1.9 kW would according to Fraenkel et al. (1991) be suitablefor a battery charging station, as it is not economic to transmit electricity over longerdistances because the cost of the cables will be out of proportion to the value of thepower. Further Maher and Smith (2001) argues that a small-scale hydropower stationwith a potential electrical output equal to the site in Nyambare (4.8 kW) is enough tosupply a village of up to 100 households with common devices such as; light bulbs,radios, televisions, refrigerators and food processors. The largest potential site found inthe evaluation, with a capacity of 48.4 kW, would be suitable for income generatingbusinesses, such as small-scale industries or workshops as well as for household energy.63
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Seminar series nr 121Finding Potent
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AbstractOver 2 billion people, most
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AcknowledgmentsFirst of all, we wou
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5 Result ..........................
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For the specific case of Uganda, a
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2 Study AreaThe main reason for us
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In the 1960’s Uganda was one of t
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2.1.3 TopographyMost of Uganda is s
Page 23: Figure 2.4 The highest volcano in K
Page 26 and 27: e able to manually write the data,
Page 28 and 29: Depending on the appearance of the
Page 30 and 31: o Then the water flows from the for
Page 32 and 33: and generator is 65% and 80% effici
Page 34 and 35: Table 3.2 Capacity and production o
Page 36 and 37: Table 3.5 Small-scale hydropower ca
Page 38 and 39: technology was supplied to an area
Page 40 and 41: component to all of these issues, g
Page 42 and 43: The Rural Electrification project t
Page 44 and 45: The closer the interviewer is to th
Page 46 and 47: Over this area we bought the follow
Page 48 and 49: The primary erosive force determini
Page 50 and 51: There are a set of tolerances used
Page 52 and 53: ivers are seasonal, since the hydro
Page 54 and 55: (a) (b) (c)Figure 4.8 An example sh
Page 56 and 57: 4.2.6 Post Processing of Output Dat
Page 58 and 59: A = ( b ⋅ h)2(4.3)Where A equals
Page 60 and 61: elinquish because of too expensive
Page 62 and 63: The first step when performing the
Page 64 and 65: more obvious in their geographic co
Page 66 and 67: By using a smaller area it is possi
Page 68 and 69: 5.3 Summary of Resultso The general
Page 70 and 71: projects are supposed to be finance
Page 72 and 73: Sinks are a reoccurring problem whe
Page 76 and 77: As described in chapter 3.3.3 all r
Page 78 and 79: and if good financing possibilities
Page 80 and 81: Hutchinson M. F., Dowling T. I., 19
Page 83 and 84: 9 Appendix9.1 Interview: Rural Elec
Page 85 and 86: 9.3 Digital DataAll data layers are
Page 87 and 88: Frame creationThis is made in order
Page 89 and 90: time2=clock;%starts timer on clock
Page 91 and 92: next(1,2)=(y-1);cell_height=(highes
Page 93 and 94: endendif height>=20;%if the accumul
Page 95: Site 16 (147486,78619)Site 20 (1560
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