Roads account for a bulk of all public infrastructure investment. This perhaps explains the strong association between the very term ‘infrastructure’ and images of highways, bridges, flyovers, etc.
This investment is, for instance, way more than the volume of investment in water resource management. Nevertheless, there is a huge potential to connect and complement road building with water harvesting. Apart from benefits achieved in terms of water harvesting, this would go a long way towards reducing water-related damage to roads which represents a substantial cost (for example, The World Bank (2011) estimates that 35% of all road damage in Ethiopia is caused by run-off).
That development of roads improves access, stimulates the economy and hence reduces poverty is a widely acknowledged and reflected by most empirical work done in this area. While true at the regional level of analysis, this correlation dilutes considerably at more local levels. Road building is typically done without considering the effects on local hydrology, including the recharge of shallow aquifers or the retention of subsurface flows. This invariably leads to water logging in upstream sides of new roads and drying up of wells downstream. Additionally, prevalent road drainage arrangements could cause gullying, depletion of soil moisture and lowering of shallow groundwater tables. This obviously can have negative economic effects and cause much dissatisfaction amongst affected communities.
This applies in particular to national highways: these are tarmacked and by their very nature they dissect watersheds and block run-off patterns, as they follow the escarpments.
Nevertheless, as mentioned above, the threats posed by roads can be turned around. Roads can rather be an asset facilitating water harvesting and groundwater research. Based on research/ practical experiences, here are some of the opportunities that present themselves:
- Carefully planned road alignments can moderate the speed of run-off and direct it towards specific infiltration/recharge zones
- Smart road foundation/compaction techniques reduce interference with the base-flow to shallow wells
- Carefully constructed road crossings (low causeways/Irish Bridges) help retain groundwater upstream
- Water capture from springs
- Roadside plantations that slow down runoff and capture sediment
Key to harnessing all these opportunities (and possibly many others; this is a fast emerging field of study) is the engagement of communities in the planning and implementation process. Unless that is done, the plans cannot achieve the much-needed high resolution in terms of mapping local hydrology, water-use, social considerations and points of conflict.
This page is a plea to systematically combine water harvesting and road building in order to harness the potential for multiple, multi-sectoral benefits that it offers. As mentioned earlier, this approach is as nascent as it is novel, and any developments made in this direction would depend heavily on networking and experience sharing.
MetaMeta (The Netherlands), Mekelle University (Ethiopia) and Institute of Development Studies (UK) are jointly working on re-evaluating over 100 kilometres of planned rural roads in Tigray and Oromiya, Ethiopia, optimizing them for maximum groundwater recharge potential in each area they cross. The following video lays out the basic approach and strategy behind the effort.
And here is a practical video on how to harvest water from existing roads:
- (2009, van Steenbergen and Tuinhof) ‘Making the most of road infrastructure for recharge, retention and reuse: Kenya, China, Brazil;’ Chapter 3.19 in Managing the Water Buffer for Development and Climate Change Adaptation; 3R Consortium, The Netherlands
- (2009, Kubbinga, B.) Road Runoff Harvesting in the Drylands of Sub-Saharan Africa Free University, the Netherlands
- (2012, Neal, I.) The potential of sand dam road crossings Research4Development, UK
- (2006, Bill, S) Water Harvesting from Low-Standard Rural Roads Quivira Coalition, UK
Please use the Comments section to below to share your thoughts and comments. It would be especially helpful if you could share your knowledge about this approach, related resources or specific projects that you might know of.