William C. Ackermann forecasting ires, Chief, Illinois State Water Survey management maybe Urbana, 111. 61801 The Robert E. Horton Lecture, presented at the AMS first conference on hydrometeorology, Ft. Worth, Tex., 20 April 1976 Abstract I am glad that Dr. Luna Leopold in delivering the First Horton Lecture in 1974 devoted much of his Events are recalled in the life and influence of this great man, Robert E. Horton, who founded by example the field paper to the professional career of Dr. Horton, and he of hydrometeorology. drew some valuable lessons for us all. He showed that a Forecasting in hydrometeorology, or any area of science, is man can be outstanding in more than one scientific declared the highest form of pure science. It follows logically discipline, can relate and bridge these disciplines, and after observation and understanding. To proceed into man- agement of the elements whose behavior we forecast will at the same time be a distinguished practicing engineer require association with many other elements of society who and successful entrepreneur. insist upon sharing the decision to manage. Along with the two previous Horton lecturers, Luna Growth areas for hydrometeorological attention are flood Leopold and Max Kohler, we can all be proud to honor plain management, safety of old dams, and water quality management. this man, and to enhance the field of hydrometeorology, which Dr. Horton can be said to have founded. I would also like to express recognition to the World The first, and as far as I can recall, only time I ever Meteorological Organization, which has done much to saw Robert E. Horton was about 1940 when he came to foster hydrometeorology over the years, and to the visit the Tennessee Valley Authority (TVA). I was then American Meteorological Society, among many other ac- a lowly, junior river forecaster and therefore did not tivities, for organizing this first national conference on rate an opportunity to meet this distinguished visitor. the subject. But as he discussed scientific matters with senior staff, Most of us are interested in prediction or forecasting I walked past the open office door a few times to see this hydrometeorological phenomena, and I would char- great man, and I got an impression of a slim, older acterize forecasting as the highest form of pure science. person with an electric personality who dominated the But science does not start with forecasting—it is the meeting. final stage in a learning process that formerly required Robert Horton was a great man to me because we thousands of years and more recently, at least decades. were using his publications on infiltration theory and The process begins with observations of sequences or other pioneering hydrologic methods in developing and associations of events such as the sun rising in the east, applying river forecasting methodology for TVA. or the seasons progressing in a regular fashion, or that Some 20 years later after this man had died, I had dark clouds are the precursor of rain. Typically, in another occasion to admire him. He left a will ultimately ancient times, man's observations of the weather were bequeathing a large sum of money to the Hydrology explained by a mythology that could indeed contain Section of the American Geophysical Union (AGU). The truths but generally was a scientific dead end. only problem was that a condition specified in the will Understanding of natural phenomena only came after was that so long as Mrs. Horton lived, the money would more formal observations, measurements, and the formu- be held in escrow with the income provided to her. lation of a rational theory. Adoption of such scientific Well, Mrs. Horton lived to an extraordinary age. During theories often came into acceptance only after painful that long waiting period, we officers of the Section of confrontation with the established mythology, which was Hydrology were anxious to establish a fund to launch by then usually cloaked in religious beliefs. Sometimes a new journal to be called Water Resources Research. progress depended upon the discovery of a new device I am rather proud of having talked the AGU Council like the telescope or upon necessity such as the events into loaning us $25 000 for that successful venture by that led to the development of the Norwegian school of mortgaging our future inheritance from the Horton meteorology during World War I, which gave us modern estate. theories of air masses and fronts. Robert E. Horton was a great man, and not only a In the field of hydrometeorology it is remarkable hydrologist as some of us were then inclined to think, how long the truth escaped detection, and it is only but also a meteorologist as well, and was President of some 300 years ago that the association of precipita- AMS in 1938-39. tion and runoff was established. Most of the progress in 984 Vol. 57, No. 8, August 1976 Unauthenticated | Downloaded 10/04/21 12:22 AM UTC Bulletin American Meteorological Society 985 this field has taken place in the present century. Our evaluation from observation to understanding and understanding did not flow entirely from the ivory eventually to prediction or forecasting, which I called towers but largely from practicing civil engineers who the highest form of pure science. You may have had a need to know for building dams, irrigation works, wondered why I stopped there instead of going on to and navigation projects. mention management, which is a driving desire of man. Forecasting becomes possible only when a science is Wonderful as the world may be, we are not content with sufficiently well understood that models can be con- nature and regularly see means for improvements, which structed and future behavior predicted. are suggested by our degree of understanding of the To the man on the street, forecasts almost universally natural system. mean weather forecasts, and although this activity is The truth of the matter is that prediction is the end the butt of many jokes, most of us find that it pays of the line that science travels alone. Beyond that point off to take the umbrella when the morning advisory calls we will be joined by numerous other interests that do for rain. Actually, weather forecasts are pretty good, not trust science to go it alone. Thus the title of my are improving, and could be much better if we were lecture, "Forecasting Yes, Management Maybe." willing to pay the price. Perhaps a few examples will help to make the point. Of course the progression from observation to under- An example close at hand, and the subject of papers at standing to forecasting does not proceed entirely in this conference, is hurricanes. We have been forecast- discrete steps, as my remarks may imply. We are almost ing their movement, severity, and effects of winds and invariably attempting to forecast with less than ade- tides for a long time. The benefits of these predictions quate observations and understanding. This explains are strongly positive with a benefit-cost ratio so high why our forecasts are sometimes less than perfect. in lives and property that no rational person would chal- Society has been willing to pay a rather minimal price lenge their importance or the desirability of their being to maintain our hydrometeorological enterprise. I think improved. But modification of hurricanes is another it receives a good return on its investment. It seems to story. When we practiced such modification in the south- me that the time may be appropriate for us to make the ern Atlantic area, it was with extreme caution, and as case that high stakes are involved in which improved hy- a result, very few such storms were available for ex- drometeorological forecasting can bring a much greater perimental modification. A sound scientific decision to return on mankind's investments and concerns. move such modification to the western Pacific, where a In three major foci of national concern—food pro- larger number of tropical storms would be available, duction, energy, and the environment—what might it has been rebuffed by the governments of Japan and be worth toward meeting our national objectives for a China, who will not permit such experimentation in high standard of living, for efficiency of resource utiliza- their spheres. The obvious conclusion is that they do tion, and improvement of the environment if we had not entirely trust the certainty of our scientific under- the capability to forecast weather and water supplies a standing. season in advance? The matter of hurricane modification can be extended Our needs for forecasting are not only long range and to weather modification in general. It is frequently large area but are also short range and mesoscale, as our opposed by environmentalists who, even if they were concentrations of population and development in flood- to accept our meteorological premises, have serious reser- prone and drought-prone areas mount. What would it vations about the terrestrial consequences to plants and be worth to operate our flood control projects with good animals and the entire ecological web. quantitative precipitation forecasts? What would it be Weather modification may also be opposed because of worth in the design of our regulating water works to divergent interests, as when one farmer needs rain on have adequate records of rainfall frequencies? I think his corn fields and another is drying hay. Thus people it would be worth many times what it would cost if may curse their bad luck with the weather, but they our intelligence in foresight approached our intelligence would rather leave decision making in the hands of the of hindsight. That's what good forecasting means to me.