Related by context. Frequent words. (Click for all words.) 63 siltation 59 soil erosion 57 silting 57 saltwater intrusion 56 sedimentation 56 coastal erosion 54 polluted runoff 53 wetlands 53 wetland 52 sewage overflow 52 environmental degradation 52 overexploitation 51 sewage overflows 51 stormwater pollution 51 aquatic habitat 51 eutrophication 50 pollution 50 salinity 50 subsidence 50 fragile ecosystem 49 invasive species 49 algae blooms 49 stormwater runoff 49 overgrazing 49 groundwater recharge 49 desertification 49 aquatic ecosystems 49 sewer overflows 49 flooding 48 habitat degradation 48 algal bloom 48 sewage spills 48 overdevelopment 48 algal blooms 48 inundation 48 arsenic contamination 47 drainage 47 watercourse 47 damming 47 landslip 47 beach erosion 47 landslips 47 wetland habitat 46 groundwater pumping 46 dam 46 nutrient pollution 46 deforestation 46 embankments 46 habitat 46 ecological 46 water hyacinth 46 overfishing 46 insect infestations 46 urbanization 46 rapid urbanization 46 mangrove forests 45 estuary 45 river basin 45 silt 45 invasive weeds 45 floodplain 45 riparian habitat 45 Drainage 45 wetland restoration 45 toxic algae 45 Three Gorges dam 45 hydrological 45 ecological catastrophe 45 erosion 45 freshwater 45 Desertification 45 riparian 44 acidification 44 vector borne diseases 44 mangrove forest 44 Invasive species 44 turbidity 44 schistosomiasis 44 catastrophic wildfires 44 dams 44 Urbanization 44 coastal ecosystems 44 flood mitigation 44 ponding 44 floods 44 floods droughts 44 stormwater drainage 44 invasive weed 44 flashfloods 43 trans boundary 43 overland flooding 43 ecologically sensitive 43 beetle infestation 43 tributaries 43 water borne diseases 43 aquatic vegetation 43 encroachment 43 Japanese knotweed 43 lake 43 floodplains 43 dredging