Related by context. Frequent words. (Click for all words.) 59 environmental degradation 59 groundwater recharge 57 saltwater intrusion 57 salinity 57 siltation 56 groundwater pumping 56 groundwater 55 nutrient runoff 55 polluted runoff 55 soil erosion 55 rapid urbanization 55 species extinctions 55 glacial melt 54 habitat fragmentation 54 frequent droughts 54 aquifers 53 prolonged drought 53 sedimentation 53 overexploitation 53 irrigated agriculture 53 hydrological cycle 53 ocean acidity 53 pollution 52 scanty rainfall 52 arsenic contamination 52 urbanization 52 habitat degradation 52 overgrazing 52 eutrophication 51 Severe drought 51 silting 51 arid regions 51 underground aquifers 51 El Niño phenomenon 51 glacier melt 51 acidification 51 hydrologic 51 hydrological 50 aquatic ecosystems 50 shoreline erosion 50 Urban sprawl 50 subsidence 50 drylands 50 floods droughts 50 Droughts 49 harmful algal blooms 49 Urbanization 49 droughts 49 irrigated crops 49 desertification 49 algal blooms 49 oxygen depletion 49 aquifer 48 ecologically fragile 48 ecological 48 dissolved oxygen levels 48 crop yields 48 deficient rainfall 48 coastal erosion 48 sewage discharges 48 melting permafrost 48 aquatic ecosystem 47 deforestation 47 monsoon rainfall 47 nutrient pollution 47 depletion 47 watersheds 47 groundwater basin 47 aridity 47 freshwater ecosystems 47 underground aquifer 47 seagrasses 47 rainfall 47 Salinity 47 Desertification 47 aquatic habitat 46 Groundwater 46 semi arid 46 Polluted 46 algal bloom 46 Tibetan Plateau 46 sewage overflows 46 Overpopulation 46 rapid industrialization 46 transboundary 46 El Nino phenomenon 46 melting glaciers 46 winterkill 46 algae blooms 46 pollutions 46 stormwater runoff 46 contaminate groundwater 46 water 46 air pollution 46 Pollution 46 fragile ecology 46 hydrology 45 atmospheric circulation 45 fragile ecosystem 45 freshwater 45 drought