Industry and mining, urban waste-water and water related health hazards in the Andean region Mark Mulligan King’s College London, Andes Basin Focal Project Leader. Data on the locations and outputs from industry, mining and urban centres and their potential impacts on water quality and its effects downstream are very lacking in the Andes. Whilst the UNEP-GEMS database contains many stations for the Amazon, it has very few stations in the Andes. In order to better understand the potential quality of water and impacts upon it, we therefore look more broadly at the origins of water arriving at major dams and cities. We first examine the proportion of water arriving at dams and major cities that has originated from protected areas upstream. The impact of different land covers on watershed services is a highly debated topic. On the basis of the literature to date we can identify the following rules of thumb:
Water quantity services: Protected ecosystems do not necessarily generate more rainfall than agricultural land uses and protected ecosystems may have higher evapotranspiration and thus lower water yields. Thus quantity benefits difficult to prove.
Water regulation services: Protected ecosystems do not protect against the most destructive floods. For ‘normal’ events they do encourage more subsurface flow and thus more seasonally regular flow regimes. Therefore benefits are likely especially in highly seasonal environments.
Water quality services (where quality is quantity for a purpose). Protected ecosystems encourage infiltration leading to lower soil erosion and sedimentation. Unprotected land will tend to have higher inputs of pesticides, herbicides, fertilizers etc. There are thus clear quality benefits of protected areas: generation of higher quality water than non-protected areas.
Assuming that protected areas have a positive impact of water (especially water quality) the proportion of streamflow at a point that is derived from protected areas upstream is thus an indicator of the potential quality of water received and lack of impacts from industry and mining as well as urban waste-water. This was calculated by combining 1km resolution gridded datasets for rainfall (Hijmens et al., 2004), protected areas (WDPA, 2007) flow direction (HydroSHEDS, Lehner et al., 2008), urban areas (CIESIN et al., 2008) and population (Landscan, LandScanTM Global Population Database, 2007). Annual total rainfall (long term mean) was multiplied by a binary value representing the protected area status in each pixel and summed along the flow network from source to mouth to give RfC. The rainfall falling on all areas was also calculated and summed along the flow network to give RfA. (RfC/RfA) * 100 is then the percentage of flow in a given pixel that fell as rain on an upstream protected area. This is shown for part of Colombia/Ecuador in Figure 16. Clearly the influence of protected areas declines significantly downstream of their areas.
Figure 16 Percentage of water derived from protected areas upstream (extract for Colombia/Ecuador)