GENERAL CLASSIFICATION 1. Surface-water hydrology 2. Groundwater hydrology 3. Vadose-zone hydrology

TEMPORAL SCALE 4. Flood hydrology 5. Drought hydrology 6. Yield hydrology 7. Baseflow hydrology 8. Low-flow hydrology

CLIMATIC REGIONS 9. Arid-land hydrology 10. Tropical hydrology 11. Nordic hydrology 12. Polar hydrology

ECOLOGICAL REGIONS 13. Forest hydrology 14. Rangeland hydrology 15. Wildland hydrology 16. Agricultural hydrology 17. Urban hydrology 18. Rural hydrology 19. Regional hydrology

GEOMORPHIC REGIONS 20. Catchment hydrology 21. Watershed hydrology 22. Basin hydrology 23. Snow hydrology 24. Glacier hydrology 25. Mountain hydrology 26. Hillslope hydrology 27. Karst hydrology 28. Hard-rock hydrology 29. Alluvial-fan hydrology 30. Floodplain hydrology 31. Stream hydrology 32. Lake hydrology 33. Wetland hydrology 34. Peatland hydrology 35. Coastal/deltaic hydrology 36. Estuarine hydrology 37. Island hydrology 38. Endorheic hydrology 39. Global hydrology 40. Prairie-pothole hydrology 41. Spring hydrology

METHODOLOGIES 42. Deterministic hydrology 43. Stochastic hydrology 44. Statistical hydrology 45. Parametric hydrology 46. Conceptual hydrology 47. Analytical hydrology 48. Numerical hydrology 49. Theoretical hydrology 50. Applied hydrology 51. Experimental hydrology 52. Scientific hydrology 53. Engineering hydrology 54. Computational hydrology 55. Synthetic hydrology 56. Kinematic hydrology 57. Dynamic hydrology 58. Physical hydrology 59. Spatial hydrology 60. Systems hydrology 61. Field hydrology 62. Operational hydrology 63. Online hydrology 64. Soft computing hydrology

TOPICAL 65. Environmental hydrology 66. Agronomic hydrology 67. Water-quality hydrology 68. Contaminant hydrology 69. Drainage hydrology 70. Mining hydrology 71. Reservoir hydrology 72. Road/bridge hydrology 73. Navigational hydrology 74. Nuclear/isotope hydrology 75. Military hydrology 76. Economic hydrology 77. Socioeconomic hydrology 78. Historical hydrology 79. Archaeological hydrology 80. Medical hydrology 81. Political hydrology 82. Forensic hydrology 83. Ecohydrology 84. Geohydrology 85. Paleohydrology 86. Transboundary hydrology 87. Space hydrology 88. Microscale hydrology 89. Mesoscale hydrology 90. Disturbance hydrology 91. Disaster hydrology

RELATED FIELDS 92. Hydrogeology 93. Hydroecology 94. Hydrometeorology 95. Hydroclimatology 96. Ecohydroclimatology 97. Dendrohydrology 98. Dendroclimatology 99. Hydrosedimentology 100. Hydroarchaeology 101. Hydrochemistry 102. Hydrobiology 103. Hydrogeography 104. Hydroinformatics 105. Sedimentology 106. Fluvial geomorphology 107. Deltaic geomorphology 108. Potamology 109. Water law