MILESTONES OF HYDROLOGY 200 YEARS OF HYDROLOGIC THOUGHT   [200604] Antoine Chézy
NUMBER	AUTHOR	SUBJECT	MILESTONE	COUNTRY	YEAR
01	Chezy	open-channel flow	First to express the mean flow velocity in terms of channel roughness, hydraulic radius, and bed slope.	France	1776
02	Lagrange	unsteady flow	Developed the equation for relative celerity of small waves in open-channel flow.	France	1788
03	Dalton	evaporation	Developed the general formula for mass-transfer evaporation rate.	United Kingdom	1802
04	St. Venant	unsteady flow	Formulated the equations of unsteady flow in open channels.	France	1848
05	Mulvany	flood hydrology	Developed the concept of runoff concentration, which is the basis of the rational method.	Ireland	1851
06	Stokes	sedimentation	Formulated the terminal fall velocity of a particle in still water.	United Kingdom	1851
07	Darcy	groundwater flow	Developed the law of flow through porous media.	France	1856
08	Breton	unsteady flow	First to formulate the concept of flood wave celerity.	France	1867
09	Froude	open-channel flow	Formulated the dimensionless number which characterizes a flow regime as subcritical, critical, or supercritical.	United Kingdom	1871
10	Reynolds	open-channel flow	Formulated the dimensionless number which characterizes a flow regime as laminar, transitional, or turbulent flow.	United Kingdom	1883
11	Kuichling	flood hydrology	Developed the rational formula to calculate peak flow from small catchments.	USA	1889
12	Manning	open-channel flow	Expressed the mean flow velocity in terms of channel roughness, hydraulic radius (to the 2/3 power), and bed slope.	Ireland	1891
13	Seddon	flood wave celerity	Formulated the flood wave celerity as the slope of the discharge-stage rating divided by the stream's top width.	USA	1900
14	Green and Ampt	infiltration	Developed the first physically based model of infiltration.	Australia	1911
15	Bowen	evaporation	Expressed the ratio of sensible heat to latent heat in terms of climatological variables.	United Kingdom	1926
16	Courant, Friedrichs, and Lewy	computational hydraulics	Developed the numerical stability condition defined as the ratio of physical wave celerity to grid celerity.	Germany	1928
17	Pearson	flood frequency	Developed the widely used Log Pearson III method for flood frequency analysis.	United Kingdom	1930
18	Sherman	flood hydrology	Developed the unit hydrograph, a conceptual model to convert rainfall into runoff in midsize to large catchments.	USA	1932
19	Horton	infiltration	Formulated the conceptual model of infiltration rate in terms of an exponential decay.	USA	1933
20	Snyder	flood hydrology	Developed the first synthetic unit hydrograph.	USA	1938
21	McCarthy	flood routing	Developed the Muskingum method of flood routing.	USA	1938
22	Horton	overland flow	Formulated the conceptual model of overland flow.	USA	1938
23	Theis	groundwater flow	Formulated the Theis method for well hydraulics.	USA	1940
24	Kirpich	flood hydrology	Developed a formula for time of concentration based only on catchment slope and length.	USA	1940
25	Gumbel	flood frequency	Developed a widely used method for flood frequency analysis.	Germany/USA	1941
26	Creager, Justin, and Hinds	flood hydrology	Plotted flood peak per unit of drainage area as a function of drainage area, quantifying runoff diffusion for the first time.	USA	1945
27	Vedernikov	roll waves	Developed the criterion for the instability of free-surface flow.	Soviet Union	1945
28	Clark	flood routing	Routed the unit increment of effective rainfall, first through a time-area histogram, and then through a linear reservoir.	USA	1945
29	Izzard	overland flow	Formulated the conceptual model of overland flow under laminar flow conditions.	USA	1946
30	Penman	evaporation	Developed a formula for evaporation rate which weighs energy-budget and mass-transfer evaporation rates.	United Kingdom	1948
31	Thornthwaite	evaporation	Developed a formula for potential evapotranspiration based on mean monthly temperature and latitudinal data.	USA	1948
32	Blaney and Criddle	evaporation	Developed a formula for consumptive use of water by crops.	USA	1950
33	Hayami	flood routing	Pioneered the mathematical treatment of flood waves as diffusion waves, which led to the concept of channel hydraulic diffusivity.	Japan	1951
34	Craya	unsteady flow	Explained the Vedernikov criterion for roll wave formation, based on the Seddon celerity exceeding the Lagrange celerity.	France	1945/ 1952
35	Budyko and Drozdov	hydrologic cycle	Developed a conceptual model of a coupled land surface-atmosphere system, which substantially improved our understanding of the hydrologic cycle.	Soviet Union	1953
36	Mockus	hydrologic abstraction	Developed the NRCS runoff curve number method to abstract total rainfall into effective rainfall.	USA	1954
37	Lighthill and Whitham	unsteady flow	Formulated the mathematical theory of kinematic waves.	United Kingdom	1955
38	Mockus	flood hydrology	Developed the NRCS synthetic unit hydrograph.	USA	1957
39	Cooper and Rorabaugh	baseflow	Formulated the theory of baseflow recession in terms of physically based parameters.	USA	1963
40	Wooding	overland flow	Pioneered the calculation of overland flow with an open-book schematization.	New Zealand	1965
41	Monteith	evaporation	Improved the Penman formula by expressing the mass-transfer evaporation on a physical basis.	United Kingdom	1966
42	Woolhiser and Liggett	overland flow	Developed the criterion for the applicability of kinematic waves to overland flow in terms of the kinematic flow number.	USA	1967
43	Cunge	flood routing	Explained the Muskingum method in terms of the numerical diffusion of the discrete analog of the kinematic wave equation.	Poland/France	1969
44	Dooge	unsteady flow	Expressed the channel hydraulic diffusivity in terms of the Froude number, extending Hayami's diffusion analogy of flood waves to the realm of dynamic waves.	Ireland	1973
45	Shuttleworth and Wallace	evaporation	Developed an evaporation equation in terms of resistances associated with the plants, soil, and water.	United Kingdom	1985
MILESTONES OF HYDROLOGY 200 YEARS OF HYDROLOGIC THOUGHT   [160531] Robert Manning