The benefits of creating small earth dams for retaining water, both surface and subsurface, are multiple. The reserved water can be used for domestic and agri- cultural applications. Natural ecosystems will benefit as a result of the improved hydrological conditions, often helping to halt or reverse desertification by slowing down the large water cycle and preventing water runoff in the rainy season. Im- proved water retention improves conditions in drought-affected ASAL regions and lifts the burden of water carrying from women, allowing more time for family and education. (Holzer 2012; Ulbig 2014; Stephens 2010).
This research examines the application of the geographical sciences and GIS as a methodology for assessing models of small earth dams with regard to their utility in retaining water for community use and conservation. Building on the work of a number of researchers, it proposes a GIS-based solution for estimating the scale of earthworks, reservoir volumes, watershed extent and dam construction risk. By formulating these concerns into a single procedural model, it is hoped that students and designers can use this work to accompany the decision making process during site selection and cost/benefit analysis. By comparing this GIS-based model with prior research and guideline formulae from the literature, the accuracy and effectiveness of this model can be evaluated.
Additionally, this paper is intended to be of use as a manual to students who wish to learn more about the development of the tool, with a view to enabling further research and understanding of the spatial analysis procedures described therein. Attention is given to the process of acquiring and preparing source data, with the intention that local elevation data can be sourced and imported into the solution. By utilising open source GIS technologies such as PostGIS, Mapnik and Leaflet, it is demonstrated how such a tool can be developed for the open web, and the output of this project includes a working, open sourced web based tool for designing landscapes of small earth dams.
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