Water Resources Natural Resource Economics, (New March 2000) 15 Water management 15 Sustainability 14 Land Resources 12 Meteorology and Climate 12 Pollution and Degradation 12 more ... Water resources 12 Irrigation 9 Policy and Planning 9 Soil Water Management (Irrigation and Drainage), (Revised June 2002) 9 Environmental aspects 8 Environmental impact 8 Land use 7 Plant Production 7 Social Psychology and Social Anthropology, (New March 2000) 7 Soil Chemistry and Mineralogy 7 Water quality 7 Watershed management 7 Watersheds 7 Agricultural Economics 6 Management 6 Water use 6 Aquatic Biology and Ecology 5 Case studies 5 Ecosystems 5 Food Economics, (New March 2000) 5 Hydrology 5 Plants 5 Water conservation 5 less ...