Horton, Robert Elmer

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Robert Elmer Horton


Robert Elmer Horton: 1875 (Parma, Michigan) -1945 (Vorheesville, NY)


1897 BSc, Albion College, Albion, Michigan 1901 Married Ella H. Young (died 1971), no children 1932 Honorary PhD, Albion College, Albion, Michigan

Horton's professional work began under the direction of his uncle, George Rafter, a prominent civil engineer who had earlier worked on the Erie Canal and was at the time concerned with its proposed deepening into a seaway. For better streamflow measurements, Rafter had commissioned Cornell laboratory weir studies for which Horton analyzed and summarized the results. This initial work was then considerably extended upon Horton’s becoming New York District Engineer of the U.S. Geological Survey in 1900. The resulting publications became the standard work on the subject.

Subsequent extensive stream gaging then directly led to his earliest work on the low flow or base flow of New York streams, recognizing that groundwater was the major component of this runoff, but how much incident rainfall could reach the aquifer depended on what Horton termed the infiltration capacity of the soil. Thus began his development and utilization of techniques for systematic separation into the several now familiar components of infiltration, evaporation, interception, transpiration, overland flow, etc., all of which owe their refinement and quantification primarily to Horton.

Throughout his career, Horton was also concerned with maximum runoff and flood generation. Indeed, he is best known to meteorologists as an early advocate of a “maximum possible rainfall,” or limiting storm specific to each region. This results in a maximum flood, as best expressed in his own words: “There is for each drainage basin a certain finite rate of flood discharge which Nature is incapable of transcending…” He went on to show that storms approaching this envelope had already been experienced. Horton’s studies of infiltration and overland sheet flow provided a basis for analyzing soil erosion and for devising strategies for soil conservation. This work led in turn to a long series of investigations concerned with the process of drainage basin development. He had realized very early in his work that physical characteristics were important for determining runoff. He had listed those factors important to runoff and flood discharge, including drainage density, channel slope, overland flow length, and other factors. However, he now proposed the converse idea of “hydrophysical” geomorphologic-erosional processes responsible for these same observed stream patterns and drainage properties.

After two decades of refinement, this masterful idea appeared in final form in a 95-page landmark paper just 1 month before his death on April 22, 1945. Horton summarized his results in four laws: the law of stream numbers, the law of stream lengths, limiting infiltration capacity, and the runoff-detention-storage relation. He showed that the most important factor for aqueous erosion was the minimum length of overland flow required to produce sufficient runoff to initiate erosion. While Horton had always considered himself to be a hydraulic engineer, it is interesting to note that this important paper was in fact published in the Bulletin of the Geological Society of America. However, in the words of a contemporary reviewer: “This important and valuable contribution by Horton could have come only from a man of his varied and extensive experience and with his great breadth of vision.”

Upon reviewing Horton’s accomplishments, one is struck by the gradual evolution of his ideas. Rarely does a novel idea emerge full-blown; instead, most had precursors in discussions of his own earlier papers or the work of his colleagues. Because Horton was very active in several professional societies, many of his important contributions were made in just this way. Furthermore, the ultimate emergence of his seminal ideas was the result of two innate abilities: his continual thinking across disciplinary lines and his continual interplay between engineering practice and scientific curiosity. In recognition of his outstanding effectiveness as an engineer and scientist and to serve as an inspiration to workers in the field, the American Geophysical Union continues to honor Horton through its Robert E. Horton Medal, which recognizes outstanding contributions to the geophysical aspects of hydrology. The first recipient was Walter Langbein in 1976. The Hydrology Section of AGU has attached Horton’s name to its service award and to a generous research grant program for Ph.D. candidates in hydrology or water resources. The American Meteorological Society also honors him by its Horton Lectureship, first given by Luna Leopold in 1974.

Horton was a prolific author, known not only for the impressive volume of his work (his contributions did not cease with his death—posthumous papers continued to be published until 1949) but also for its high quality and authority. He could address diverse fields—hydraulics, meteorology, soil physics, and geomorphology—with equal skill. He even published a volume of short stories. He is remembered first, however, as a scientist of great vision, originality, and curiosity.

Hydrological Achievements[edit]

Robert F. Horton is often called the father of American hydrology because of the breadth and interdisciplinary nature of his contributions. He was a practical man who spent his professional life working as a hydraulic engineer for various government agencies and then as a private consultant in the northeastern United States. From his problem-solving experience, Horton persistently distilled general principles about processes in the hydrologic cycle. By promoting quantitative and mathematical approaches to the study of processes, and by emphasizing and illustrating the use ofcarefully measured data, he founded by example the science of analytical hydrology. Horton emphasized the need for "research to provide connective tissue between related problems."

Horton is best known for his theory relating the infiltration capacity of soils to the generation of floods by surface runoff. He went on to emphasize the influence of soils and vegetation on runoff processes. His theory also provided a basis for analyzing the mechanics of soil erosion and for devising rational strategies for soil conservation. Throughout his career, Horton returned to the issue of flood generation, analyzing the physics and temporal variability of rainfall, the role of vegetation in controlling interception as well as transpiration and antecedent soil moisture, and the role of stream channels.

In a 1945 landmark paper, Horton provided a synthesis of the relations between runoff processes (as influenced by precipitation, soil, and vegetation) and the mechanics of hillslope and channel erosion, and thus of drainage basin development. That paper, summarizing the significance of his career-long scientific interest, continues to provide an inspiration for much of hydrology and geomorphology.

Reference Material[edit]

Anon, 1949. Horton hydrologic papers filed with Archivist of the United States. Trans. Am. Geophys. Union 30(2), 319.

Bernard, M., 1945. Robert E. Horton. Bull. Am. Meteorol. Soc. 26, 242.

Beven, K J, 2004, Surface runoff at the Horton Hydrologic Laboratory (or not?), J. Hydrology, 293, 219-234.

Beven, K J, 2004, Robert Horton's perceptual model of infiltration, Hydrological Processes, 18, 3447-3460.

Beven, K J, 2004, Robert Horton and abrupt rises of groundwater, Hydrological Processes, 18, 3687-3696.

Dooge, J.C.I., 1992. Sensitivity of runoff to climate change: a Hortonian approach. Bull. Am. Meteorol. Soc. 73, 2013–2025

Hall, F R, 1987, Contributions of Robert E. Horton, History of Geophysics, 3: 113-117, AGU: Washington

Langbein, W.B., 1976. Acceptance and response to award of first Robert E. Horton Medal. Trans. Am. Geophys. Union 57, 572.

Paynter, H, Robert E Horton, https://honors.agu.org/robert-e-horton-1875–1945/

Committee on Opportunities in the Hydrologic Sciences, 1991, Opportunities in the Hydrologic Sciences, Water Science and Technology Board, National Research Council, http://www.nap.edu/catalog/1543.html

Major Publications[edit]

Horton, R.E., 1905, Snowfall. freshets. and winter flow of streams in the State of New York. In U. S. Dept. Agr. Mo. \Veath. Rev., 33: 196~202. [includes first snow density measurement to get water equivalent]]

Horton, R.E., 1915. The melting of snow. Mon. Weath. Rev. 43, 599–605.

Horton, R.E., 1916. Some better Kutter’s formula coefficients. Engng News-Rec. 75, 373–374.

Horton, R.E., 1919. Rainfall interception. Mon. Weath. Rev. 47, 603–623.

Horton, R.E., 1933. The role of infiltration in the hydrologic cycle. Trans. Am. Geophys. Union 14, 446–460.

Horton, R.E., 1935, Surface runoff phenomena. Part 1. Analysis of the hydrograph. Horton Hydrological Laboratory, Publication 101. Edward Bros. Ann Arbor, Michigan.

Horton, R.E., 1936. Maximum groundwater levels. Trans. Am. Geophys. Union 17(2), 344–357.

Horton, R.E., 1937. Determination of infiltration capacity for large drainage basins. Trans. Am. Geophys. Union 18(2), 371–385.

Horton, R.E., 1938. The interpretation and application of runoff plat experiments with reference to soil erosion problems. Proc. Soil Sci. Soc. Am. 3, 340–349.

Horton, R.E., 1939. Analysis of runoff-plat experiments with varying infiltration-capacity. Trans. Am. Geophys. Soc. 20, 693–711.

Horton, R.E., 1940. An approach towards physical interpretation of infiltration-capacity. Proc. Soil Sci. Soc. Am. 5, 399–417.

Horton, R.E., 1941. Flood-crest reduction by channel storage. Trans. Am. Geophys. Union 22(3), 820–835.

Horton, R.E., 1942a. Simplified method of determining an infiltration-capacity curve from an infiltration experiment. Trans. Am. Geophys. Union 23(2), 570–574. þ discussion.

Horton, R.E., 1942b. Simplified method of determining the constants in the infiltration-capacity equation. Trans. Am. Geophys. Union 23(2), 575–577. þ discussion.

Horton, R.E., 1942c. Remarks on hydrologic terminology. Trans. Am. Geophys. Union 23(2), 479–482.

Horton, R.E., 1945a. Erosional development of streams and their drainage basins: hydrophysical to quantitative morphology. Bull. Geol. Soc. Am. 56, 275–370.

Horton, R.E., 1945b. Infiltration and runoff during the snow-melting season, with forest-cover. Trans. Am. Geophys. Union 26(1), 59–68.

Horton, R.E., 1948a. The physics of thunderstorms. Trans. Am. Geophys. Union 29(6), 810–844.

Horton, R.E., 1948b. Statistical distribution of drop sizes and the occurrence of dominant drop sizes in rain. Trans. Am. Geophys. Union 29(5), 624–630.

Horton, R.E., 1949. Convectional vortex rings-hail. Trans. Am. Geophys. Union 30(1), 29–45.

Horton, R.E., van Vliet, R., 1940. Determination of areal average infiltration-capacity from rainfall and runoff data, USDA, SCS (mimeo) (cited in Linsley, Kohler and Paulhus, 1949, p311).


Source: AGU Obituary by Henry M. Paynter

Source: AGU Virtual Hydrologist Site with full publication list

A slideshow about the impact of Robert Horton has been put together as part of the AGU Centennial Celebrations and may be found here