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

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4.2.6 Post Processing of Output DataThe result at this stage contains numerous potential sites for small-scale hydropowerthat, for different reasons, are inaccessible or unusable. To exclude these areas weapplied a mask-grid on the algorithm-output by using the ArcGIS raster calculatorfunction. The mask-areas are:o National Parks – derived from the Land use layer. The national parks areprotected areas, mostly containing tropical rainforests.o Electrified areas – derived from the Administrative layer. These areas arerepresented of major towns. They are already connected to the existing grid andare therefore in no need of small-scale hydropower.o Surrounding Countries – derived from national borders in the Administrativelayer. A number of potential sites are situated in the neighboring countries,because the geographical input data exceeds the borders of Uganda.4.3 Evaluation of Potential SitesWhen the GIS-analysis was finished, the result had to be evaluated in order to determinethe quality. The evaluation was performed during three weeks in the study area, coveringapproximately 3000 square kilometres. Due to the inability to unhindered visit all sites inthe terrain, we decided to evaluate sites in vicinity of roads and smaller villages. Weestimated to be able to evaluate at least 25 sites. Due to our economic situation, thepossibility to travel with a 4X4-car was excluded; instead we used a small Chinese-mademotorcycle.The purpose of the evaluation was to validate that the result coincides with reality. Thiswas done by controlling a) that the stream had a head of at least 20 meters over adistance of 100 meters and b) that there was a permanent flow in the stream. To furtherestimate the power potential of the site, we measured the flow of the stream.4.3.1 Head MeasurementsTo validate the required head of 20 meters over a distance of 100 meters, we used ahand-held sighting meter (see Figure 4.11). They are often called inclinometers or Abneylevels and can be accurate if used by an experienced person, but it is easy to makemistakes and double-checking is recommended. Because they are small and hand-held,the error will depend on the skill of the user, but will typically be between 2% and 10%.44
To measure the slope of a potential site one of us walked 100 meters either up-river ordown-river, depending on our start point. To measure the distance we used a 20-metertape measure. When reaching the 100-meter point, one of us used the inclinometer andtook sight on the other person’s eyes. The angles are then put into Equation 4.2 tocalculate the height difference between us. At sites with very difficult terrain, we had todivide the measurements into steps, as can be seen in Figure 4.11.h=nL nsinαn(4.2)where h n is head, L n is distance between measuring points and α n is the angle ofinclination (Fraenkel et al., 1991).Figure 4.11 Inclinometer and measuring technique. Source:Fraenkel et al., 1991.4.3.2 On-Site Measurements of FlowWhen measuring the flow of the rivers in our evaluation, we used the principle of lettinga cross-sectional profile of the streambed be charted for a known length of the stream(see Figure 4.12). We used a slightly modified approach compared to the describedmethod, because of limited resources and time. Instead of charting the complete profileof the streambed, we let one measurement in the middle of the stream represent theheight of a triangle-shaped cross-section (see Equation 4.3).45
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Seminar series nr 121Finding Potent
Page 5: AbstractOver 2 billion people, most
Page 9: AcknowledgmentsFirst of all, we wou
Page 12 and 13: 5 Result ..........................
Page 14 and 15: For the specific case of Uganda, a
Page 17 and 18: 2 Study AreaThe main reason for us
Page 19 and 20: In the 1960’s Uganda was one of t
Page 21 and 22: 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 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 74 and 75: UTM Zone 36N projection. The study
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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