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

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