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

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(a) (b) (c)Figure 4.8 An example showing the matrix “DATA” (a) and the arrays“RIVERCELLS” (b) and “ORDER” (c).To locate these ten in a row connected cells the algorithm is designed to search pixelsdownstream by the use of a “3 x 3 pixel search window”, which is illustrated in theexample in Figure 4.9. It starts searching from the highest ranked pixel in “ORDER”,which is also the cell with highest elevation, which in the example corresponds to the cellin the second row and second column in “DATA”. From here it examines all eightsurrounding cells, starting with the northwest pixel and then continuing clockwise.Figure 4.9 An example of how the ”3 x 3 search window” operation works in a fictitious raster.42
The eight pixels in the “3 x 3 search-window” are all examined to see:o if their value is larger than zero - the algorithm should only examine cellscontaining riverso if the value is lower or equal to the current pixel’s value - the search should notbe able to proceed up-streamo if the pixel has been examined earlier in the ten-pixel loop - in order not to getstuck in a loop between two cells with the same pixel valueThe pixels, which fulfill these criteria, are then examined to calculate the best heightdifference from the current pixel, in order to know which pixel to go next. The calculatedheight difference is saved into a variable, which accumulates for each new cell. As can beseen in Figure 4.9, Iteration 1.2, the new pixel where to start from is at row three andcolumn three. The whole process is repeated until ten connected cells have been visitedor until the “river” ends, which is illustrated in Figure 4.9, Iteration 1.9. If theaccumulated height value is 20 meters or more, the visited cells, which coordinates havebeen stored in a temporary variable, are stored into the matrix “OUTPUT”, which canbe seen in Iteration 1 in Figure 4.9. In the case of Iteration 2 in Figure 4.9, the river-cellsaccumulated height value does not reach the required value of 20 meters and aretherefore not stored in “OUTPUT”. Iteration14 in Figure 4.9 illustrates the course ofevents when the search begins in the last pixel in a river. In this case there is only oneconnecting river cell in the “3 x 3 search window”, but since it is upstream, the searchwill be aborted and no output is stored.Inord er for the algorithm to present a correct result, anassum ption that rivers or streams never branch offdownstream in hilly areas has been made. The reason forthis assumption is that our algorithm in such cases (seeFigure 4.10) is limited since it only chooses the branch withthe best height difference and leaves one branchunattended. If this branch individually has a heightdifference of 20 meter it will also be stored in “OUTPUT”.In cases of same height difference the algorithm choosesthe last found branch.Figure 4.10 The unlikelyphenomenon of downstreambranching off rivers43
Page 1:
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 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 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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