This paper and presentation is published at the 6th International RWSN Forum.
Rural Water Supply Network Forum
6th International RWSN Forum
Rural Water Supply in the 21st Century: Myths of the Past, Visions for the Future
Date: 29th November - 1st December 2011
Location: Kampala, Uganda
Presentation: Hydrological reconnaissance for rural water projects using free online information
Hydrological reconnaissance for rural water projects using free online information (SamSamWater Foundation) from SamSamWater FoundationBy Sander de Haas.
Download the Google Earth layer file including all map layers mentioned in the presentation.
Hydrological reconnaissance for rural water projects using free online information
Sander de Haas1,2, Merel Hoogmoed1,3 and Harry Rolf2
1SamSamWater Foundation, The Netherlands
2PWN Water Supply Company North Holland, The Netherlands
3Dunea Water Supply Company, The Netherlands
Free online information can be beneficial in the preparation, design and implementation of rural water projects. Free online sources of meteorological data (rainfall, evaporation), maps (topography, geology), aerial imagery and elevation data are presented together with examples of how this information has been used in rural water projects. This online information can never fully substitute field observations and measurements, but it can provide valuable additional information and make preparation, design and implementation of rural water projects more efficient and successful.
In recent years a lot of free information has become available online which is of great interest to (rural) water supply projects. This online information can be very beneficial in the preparation, design and implementation of water projects, especially in rural areas where information (maps, research reports, etc.) is often missing. When used in the right way, this online information can make rural water projects more efficient and successful.
In this paper we give an overview of some valuable sources of free online information and how to use these to the benefit of rural water supply projects. In the following paragraphs we will give examples of online sources of meteorological data (rainfall, evaporation), maps (topography, geology), aerial imagery and elevation data. Examples are given of their use in rural water projects throughout Africa. This overview doesn’t claim to be complete, we just want to open up the online treasure box hoping the information in it will be of use in the preparation and implementation of your rural water projects.
Meteorological information (rainfall, evaporation, temperature)
Many water projects start with gathering meteorological data, on rainfall and evaporation. Often, general information on the annual amount of rainfall comes from textbooks or online sources, but is generalized at (sub-)country scale. Getting more detailed information can be difficult, especially for non-touristy areas.
The Food and Agriculture Organization (FAO) of the United Nations has collected information on 14 meteorological parameters (including precipitation, evaporation and temperature) from over 28,000 stations worldwide in a database (FAOCLIM). They developed a tool, New_LocClim (ftp://ext-ftp.fao.org/SD/Reserved/Agromet/New_LocClim/), which allows you to access this information. The data is interpolated between the meteorological stations to create climate maps and display graphs showing monthly averages on meteorological parameters. There are many options and features available in the software, which makes it somewhat difficult to use.
The SamSamWater Foundation created an online tool (https://www.samsamwater.com/climate/) where the user can point out a location using a map interface. The tool will then display a table and graph of average rainfall and evaporation amounts for that location (Figure 1). Using this tool, the frequency, duration and intensity of rainy seasons can be found for any given location. This SamSamWater Climate tool uses the same data source as the New_LocClim tool, but is easier to use and can be accessed online without installing software. However it has fewer options on the type of interpolation and parameters then the New_LocClim software.
Figure 1 SamSamWater Climate Tool showing the monthly rainfall and evaporation for Kampala, Uganda
We have been using the climate data for many rural water projects, for example to calculate the amount of potential evaporation from a lake in Burkina Faso (De Haas, 2010) and to determine the optimum dimensions of a roofwater harvestings system in Uganda (De Haas 2011). In Tanzania we used it to identify the nearest location of a meteorological station, which to everyone’s surprise was located right into our research area (De Haas 2007).
Most people are familiar with online maps, Google Maps (http://maps.google.com/)being the most commonly used. These maps are very easy to use, but are often still lacking detail in rural areas of developing countries. Google is encouraging users to improve the maps using their Map Maker program (http://www.google.com/mapmaker). Using this tool, users can edit and improve the online maps and they can download the data to be used in their own GIS software for non-commercial use (https://services.google.com/fb/forms/mapmakerdatadownload/).
The level of detail of the maps is improving over time, but they are still lacking the detail of real topographic maps. Also, the maps are mainly focused on roads and are often lacking information on water related features such as rivers, dams, etc. In many African countries it is very difficult (if possible at all) to obtain hard copies of topographic maps. There are however some good online sources for topographic maps. From the 1950’s to 1990 the former Soviet Union Army created a set of beautiful and quite detailed maps covering the African continent (and most of the rest of the world). Besides roads, these maps show rivers, dams, contour lines and other objects useful in the preparation of water projects. The U.S. government also created several map series (ONC, JPG, TPC map series) which can be useful, but these maps contain fewer details on hydrologically interesting objects.
Most of the Soviet and U.S. maps range in scale from 1:200,000 to 1:1,000,000. The maps thus don’t show minor details, but are still very suitable to get an overview of an area and have much more detail compared to Google Maps (see Figure 2).
Figure 2 Sample from Google Maps (left) and 1:500,000 Soviet topographic map (right) of Mount Kilimanjaro, Tanzania
The Center for Geographic Analysis of the University of Harvard created AfricaMap (http://africamap.harvard.edu/), an online map viewer where you can access both the Soviet and U.S. army maps very easily (click the appropriate checkboxes under ‘Map Layers’, ‘Base Mapping’). Another great source for online maps on (mainly) soils and geology is ‘The soil maps of Africa’ (http://eusoils.jrc.ec.europa.eu/esdb_archive/eudasm/africa/index.htm) where over 2,000 digitized high resolution maps are available.
We have been using these maps in the preparation and design of rural water projects and during field visits. Every time they have been very useful basemaps for planning and navigation. More than once our local counterparts were surprised we were aware of local roads they thought only locals knew about.
Aerial imagery (photographs captured by satellites or airplane) can be found online at several websites. A good source to view these images is trough Google Maps (select ‘Satellite’ in the top-right corner), but more advanced options and additional information is accessible through the Google Earth software (http://earth.google.com). Google Earth shows you a 3D globe where you can zoom in and view detailed aerial imagery and other map layers such as roads, borders, place names and photographs taken in the area you are viewing (use the ‘Layers’ window in the lower-left corner to activate the map layers). A package of additional layers that are useful for water projects (including the Soviet and U.S. army topographic maps mentioned under ‘maps’) can be downloaded from:
One of the hidden gems of Google Earth is the option to display historical aerial imagery (click the ‘clock’ icon in the toolbar on the top). By default the software shows you the most recent image, but by using this feature you can view older imagery captured from the same location. This is a great way to determine for example the rate of deforestation, land use changes and to show differences between the rainy and dry season. Historical imagery is not yet available at every location, but the amount of images is growing rapidly.
Sometimes you are lucky and satellite images are available at exactly the right moment. This was the case for a research project on micro-dams in Burkina Faso. A very detailed satellite image of the dam was available at the end of the dry season and another image of the same area was taken only two weeks later after the first rains (Figure 3). Using these images we were able to determine accurately the volume of water stored behind the dam (De Haas, 2010).
Figure 3 Satellite image of a micro-dam in Sanga, Burkina Faso just before the first rains (left image captured at 25 May 2009) and shortly after the first rains (right image captured at 5 June 2009)
Elevation data and maps
Elevation data is crucial for many water projects, for example for the design of pipelines, to determine catchment boundaries, runoff, etc. But it can be very difficult to measure the elevation in the field. Again, there are some practical online resources available.
Google Earth displays the elevation of the location under your mouse pointer in the toolbar at the bottom of the screen (if there is no toolbar, select ‘View’, ‘Toolbar’ from the menubar at the top). This will give you a quick impression of the elevations in the area. Google Earth can also be used to display an elevation profile (with inclinations) of any given transect (draw a ‘path’, right click on it in the ‘Places’ window and choose ‘Show elevation profile’), see Figure 4 for an example.
Figure 4 Example of an elevation profile over mount Kilimanjaro, Kenya
Most of this elevation data is based on SRTM DEM (Shuttle Radar Topography Mission Digital Elevation Model) data with a horizontal resolution of 90 meter (every square of 90 x 90 meter has one elevation). In 2009 the NASA and Japanese government jointly published a 30 m resolution DEM: ASTER GDEM (METI & NASAS, 2009). This data can be downloaded from the ASTER website (http://www.gdem.aster.ersdac.or.jp/). However, the data has to be processed using GIS (Geographical Information System) software. But if you don’t have access to GIS software, the Center for Spatial Information Science and Systems (CSISS) of the George Mason University created DEM Explorer (http://ws.csiss.gmu.edu/DEMExplorer/). This tool allows the user to select a certain area and view or download colour relief maps, contour lines, etc. The tool also includes options to perform hydrological analysis, such as the calculation of drainage basins and streams.
In Kajiado district, Kenya we used the ASTER GDEM elevation data to identify potential sites for the construction of sand storage dams based on the catchment areas (Figure 5). During the field visit we could easily navigate to these potential sites and determine if local (geological and topographical) conditions were suitable for the construction of sand storage dams. The online data doesn’t replace field visits, but greatly increases the efficiency of the siting process.
Figure 5 Land surface elevation (green is low, red is high) and drainage system in the Kajiado District, Kenya derived from the 30 m resolution ASTER GDEM
Conclusions and recommendations
The successful implementation of a rural water project requires a lot of information which is often unavailable or difficult to obtain, because it is either expensive, hard to get or difficult to measure. This is especially true for rural water projects, since data is even more scarce for the rural parts of developing countries and the total budget involved is often small, so it’s not possible to acquire detailed information or set up an extensive field campaign. There are many free online resources available which can provide valuable information and make preparation, design and implementation of a rural water project more efficient and successful.
Some of the online information can also be measured in the field, but doing that will require a lot of time (e.g. rainfall distribution measurements), effort (e.g. elevation measurements) or money (e.g. topographical mapping). While other information is often impossible to acquire within the scope of a rural water supply project (e.g. satellite imagery of the catchment). However, gathering information online can never fully substitute observing and measuring data in the field. Nevertheless, the online information will give valuable additional information and will save a lot of time, effort and money because a field visit can be better prepared and more focused.
There is a huge amount of information available online which can be used in the preparation, design and implementation of (rural) water supply projects. However, a lot of knowledge, data and information is not yet published (online) at all. Organisations (both NGO and governmental) who are involved in (rural) water supply projects should publish much more information on their projects online. By doing this, communities and other organisations working in the same area or in different areas with similar problems, can benefit from the outcomes of these projects. Therefore we encourage everyone involved in (water) development projects to share their information by putting it online and making it accessible to everyone. To set a good example, this paper and all information which is mentioned in this paper (links, references, and additional information) can be accessed online on our website: https://www.samsamwater.com/rwsn.
Food and Agriculture Organization of the United Nations (2005) ‘New_LocClim: Local Climate Estimator’. Environment and Natural Resources, Working paper No. 20 (CD-ROM). Available at http://www.fao.org/nr/climpag/pub/en3_051002_en.asp
Haas, S.A. de (2007) Chamavita water schemes, Usambara Mountains, Tanzania: Mission report 18-07-2007 – 22-07-2007. Available at https://www.samsamwater.com/projects/47/data/Chamavita_-_Mission_report_18-07-2007_-_22-07-2007_-_Sander_de_Haas.pdf
Haas, S.A. de (2010) Hydrogeology and siting of micro-dams around Léo, Burkina Faso: Mission report 10-02-2010 – 23-02-2010. Available at https://www.samsamwater.com/projects/58/data/Hydrogeology_and_siting_of_micro-dams_around_Leo_Burkina_Faso_-_20100614_-_compressed_-_Sander_de_Haas.pdf
Haas, S.A. de (2011) Construction and maintenance of roof water harvesting system. Available at https://www.samsamwater.com/projects/62/data/62-1_Construction_and_maintenance_of_roof_water_harvesting_system.pdf
METI & NASA (2009), METI and NASA Release ASTER Global DEM. Available at http://www.ersdac.or.jp/GDEM/E/4.html
Overview of links mentioned in the paper
New_LocClim climate tool
SamSamWater Climate Tool
Google Maps Mapmaker
Download Mapmaker data
The soil maps of Africa
Google Earth software
SamSamWater collection of Google Earth layers
For more information please contact us
Sander de Haas
+31 (0)6 44 988 559