Appendix 2 147
Sanitation Services The lack of sanitation presents a challenge in that it impacts both human health, and water and environmental quality in growing cities. We therefore sought some reliable indicators to measure the lack of sanitation at household (primary) level as well as municipal (secondary) level in the cities surveyed. This corresponds to indicators 28 and 29 respectively. The first limitation is that these indicators come from a variety of sources, which has implications on definition, reliability, and consistency across the cities surveyed. Secondly, it must be emphasized that access to improved sanitation does not in itself indicate that sewage is disposed of in a safe manner. As we had difficulties isolating an indicator for the disposal of all sewage, we decided to look at cholera prevalence as an indicator of poor sewage disposal (indicator 30). Again, sources are disparate and not consistent, and cholera is not only an indicator of extremely poor sewage disposal, but also of other factors including the resilience and efficiency of the health system, which we did not intend to capture here. Nevertheless, for the cities in consideration, it is the most representative indicator available. Flood Hazards in River Basins Indicator 31 selected for this variable was calculated for this study. It presents an estimate of flood frequency based on the United Nations Environment Programme (UNEP)/Global Resource Information Database-Europe (GRID) PREVIEW flood data set. The unit is the expected average number of events per 100 years (hydrological model of peak-flow magnitude). The methodology and sources used to create this indicator come from a variety of studies. City basin summary statistics are derived from the basin definition used by Strzepek et al., 2011. The frequency of flood events was created through a three-step process: 1. Use of GIS modeling using a statistical estimation of peak-flow magnitude and a hydrological model using HydroSHEDS data set and the Manning equation to estimate river stage for the calculated discharge value. 2. Observed flood events from 1999 to 2007, obtained from the Dartmouth Flood Observatory. 3. The frequency was set using the frequency from UNEP/GRID-Europe PREVIEW flood data set. In areas where no information was available, it was set to a 50-year returning period. The data set was designed by UNEP/GRID-Europe for the Global Assessment Report on Risk Reduction. It was modeled using global data.