Table 4 Continuous variables derived from VHR imagery, with suggested open alternatives, and knowledge relating to their influence on larval habitat suitability (from literature and experts)
Continuous variables from VHR imagery | Alternative existing open product(s) | Larval habitat suitability—Sub-Saharan African cities | Larval habitat suitability—Dakar |
|---|---|---|---|
Topographic Wetness Index (TWI) | Global SRTM mTPI (Multi-Scale Topographic Position Index) | TWI is a steady-state predictor of local wetness that is positively associated with the density of breeding sites [80] | Lowlands are prone to flooding during the rainy season, due to the shallow water table. Puddles can subsist in the dry season in such areas [28] |
Distance to human habitations (proxy: distance to buildings) | Calculate distance to buildings from Open Buildings | The An. gambiae complex of sub-Saharan Africa characteristically breeds in small collections of water close to human habitations [20, 64] | The probability of larvae presence increases when water bodies are located within 10Â m of human habitations [28] |
Distance to trees | Calculate distance to trees extracted from Esri 2020 Land Cover or WorldCover | Trees can provide refuge for digesting/resting mosquitoes [81] | Leafy vegetation is likely to provide resting sites to adults [10, 34] |
Water pollution (proxy: distance to dumpsites) | Calculate distance to dumpsites extracted from OSM | An. gambiae is adapting to polluted waters in urban settings, but its preference goes to clear waters for breeding [9, 12, 82, 83] | Around the main city landfill, traditional wells ('céanes') are polluted at least up to a distance of 350 m [84]. Water pollution in drains does not affect larvae abundance [85] |
n/a | iSDAsoil: Soil pH (proxy for water pH) | A high pH (e.g., due to pollution) is not favourable for breeding and survival, natural pH is preferred [12] | An increase in pH from 7.4 to 8.2 is associated with an increase in larvae abundance [85] |