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

METHODOLOGIES 40. Deterministic hydrology 41. Stochastic hydrology 42. Statistical hydrology 43. Parametric hydrology 44. Conceptual hydrology 45. Analytical hydrology 46. Numerical hydrology 47. Theoretical hydrology 48. Applied hydrology 49. Experimental hydrology 50. Scientific hydrology 51. Engineering hydrology 52. Computational hydrology 53. Synthetic hydrology 54. Kinematic hydrology 55. Dynamic hydrology 56. Physical hydrology 57. Spatial hydrology 58. Systems hydrology 59. Field hydrology 60. Operational hydrology 61. Online hydrology 62. Soft computing hydrology

TOPICAL 63. Environmental hydrology 64. Agronomic hydrology 65. Water-quality hydrology 66. Contaminant hydrology 67. Drainage hydrology 68. Mining hydrology 69. Reservoir hydrology 70. Road/bridge hydrology 71. Navigational hydrology 72. Nuclear/isotope hydrology 73. Military hydrology 74. Economic hydrology 75. Socioeconomic hydrology 76. Historical hydrology 77. Archaeological hydrology 78. Medical hydrology 79. Political hydrology 80. Forensic hydrology 81. Ecohydrology 82. Geohydrology 83. Paleohydrology 84. Transboundary hydrology 85. Space hydrology 86. Microscale hydrology 87. Mesoscale hydrology 88. Disturbance hydrology 89. Disaster hydrology

RELATED FIELDS 91. Hydrogeology 92. Hydroecology 93. Hydrometeorology 94. Hydroclimatology 95. Ecohydroclimatology 96. Dendrohydrology 97. Dendroclimatology 98. Hydrosedimentology 99. Hydroarchaeology 100. Hydrochemistry 101. Hydrobiology 102. Hydrogeography 103. Hydroinformatics 104. Sedimentology 105. Fluvial geomorphology 106. Deltaic geomorphology 107. Potamology 108. Water law