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. Almighty than with the man with the silver iodide Just as we might set out to establish that society could generator. make a profitable investment in improving our capa- Given the diversity of interests and also the accept- bilities, a good case can be made for our having the ance of weather as an unmanageable variable, I have tools to make effective use of increased investments. had occasion recently to witness the conservatism of In ancient times past, the telescope and the barometer agricultural leaders in the eastern United States toward were critical instruments that opened up new vistas embracing weather modification. For so long, weather for science. We have modern counterparts in the form has been accepted by them as a given to be reconciled by of computers and modeling technology, in satellites and climatic statistics and experience that it is difficult to other platforms for remote sensing, in radar, and in consider that it could be a management variable like high-speed data communications. These are some of fertilizer. the important tools available to us, but as yet they are Practitioners on the water resources side of hydro- only partially exploited. meteorology have increasingly been faced with the same Earlier I spoke of the several steps of scientific kind of challenges from doubting Thomases and di-

Unauthenticated | Downloaded 10/04/21 12:22 AM UTC 986 Vol. 57, No. 8, August 1976 vergent interests. It is not clear to many of these people tire operation is the determination of flood discharges, that a reservoir for flood control, hydro power, water flood heights, and area flooded. Emphasis is on the once- supply, or recreation is preferable to a wild river. The in-100-year flood, but attention is given to floods of other diverse interests are also revealed by the people in an frequencies as well. Such flood frequency determinations upstream area who wonder why they should be perma- are somewhere between the hydrometeorological process nently flooded out of existence for the benefit of those and the wide blue yonder. Only the larger streams have who live downstream. lengths of record approaching 100 years, most have no Our recent laws, and particularly the interpretations records at all, and so regional transpositions as well as of the courts, have made it clear that the burden of extrapolations are involved. The program should also proof will be upon him who would modify and manage. bring to bear rainfall as the basic source of storm fre- Unfortunately, the social sciences, which deal with quency and amounts because those records are longer the responses of people, and the environmental sciences, and can be transposed with fewer constraints. which deal with the impacts on ecology, are far more So although there will be much to do with hearings, primitive and uncertain than the science with which regulations, permits, and insurance rates, I consider we deal. So, as far ahead as I can see, we will have hydrometeorology as central to the effective prosecution to walk down the crooked road leading to manage- of this program. I hope that our governments—federal, ment with a troop of tenderfoots. There will be many a state, and local—give this adequate attention and fund- town meeting and many a formal court proceeding be- ing so that we can do good scientific and professional fore management of the atmosphere and management of work and show substantial progress in our time. the hydrosphere become general realities. A second program that I consider of importance for In the meantime, improved observation, understand- the future attention of hydrometeorology is the safety ing, and prediction in our work will shorten the road by of old dams. Such a program has been started in the improving our credibility. Corps of Engineers but seems to be languishing for What, then, are some of the areas in which hydro- lack of adequate support. A very few states also have meteorology will be concerned? A number of these are such programs, but I have not been able to arouse any well-established areas of activity and, in fact, are repre- support in my State. This seems to be one of those sented on the program here in Ft. Worth. These include program areas where society will only lock the barn dense networks, severe storms, radar meteorology, remote door after the horse is stolen. The present program was sensing, statistical distributions, quantitative precipita- launched in Congress as a reaction to the slag dam wash- tion forecasting, planned and inadvertent weather modi- out and disaster in West Virginia. It is a pity that we fication, and the hydrometeorology of cities. All of these apparently will need a failure every couple years to seem to hold promise for further advances and the im- maintain budgetary interest. provement of our science and its application. However, Heaven knows there is plenty of potential for disaster I will not elaborate on these topics here, believing that because of the untold numbers, certainly many thou- their discussion might be more properly associated with sands, of dams in this country that were designed and the conference papers as they are presented. built without the benefit of our present hydrological But I would like to discuss briefly three program areas skills. Here again other skills are needed as well—partic- that seem to be likely growth areas for us and in which ularly geologic, foundation, and structural engineering some of you may not have become involved. and the closely allied field of hydraulics. But central to The first of these is flood plain management. This the program is a complex hydrometeorology with con- area has come into national focus because our tradi- sideration of return periods of floods and an evaluation tional methods for dealing with floods were not pro- of reasonable risks. ducing results. These traditional methods can be char- A third program area I would like to mention is that acterized as engineering solutions with principal de- of water quality management planning. This program pendence upon flood control dams and levees. The was mandated by the Water Pollution Control Act of results of some 40 years of national experience along 1972 (P.L. 92-500). A feature of this Act was to direct this course are that despite large investments, our annual attention for the first time in any significant way to the flood damages continue to mount. Emphasis has now nonpoint or diffuse sources of pollution. Previously, at- shifted to nonstructural approaches including zoning tention was directed almost entirely to the pollution with controlled land use, flood proofing, and flood in- that came out of pipes from industries and municipali- surance. The last of these, particularly, will be heavily ties. With really very limited experimental or opera- dependent upon satisfactory hydrometeorology. The tional data, it had become increasingly apparent that program is directed by the Federal Insurance Adminis- our national stream pollution problems would never be tration in the Department of Housing and Urban solved without dealing with the diffuse sources. This will Development. bring hydrometeorology into the pollution problem to a The size of that agency's job is immense. There are far greater degree than ever before. It would seem to tens of thousands of cities that are flood prone and have three major dimensions. In the first place, precipi- for which flood plans, regulations, and permits must tation is itself a source of diffuse pollution because it is be developed, issued, and enforced. Central to the en- far from as pure as the proverbial driven snow. In fact,

Unauthenticated | Downloaded 10/04/21 12:22 AM UTC t^r r O JQQ Bulletin American Meteorological Society some of the troublesome pollutants such as nitrates may new generation of research effort in our field before be more concentrated in precipitation than in stream satisfactorily accurate and efficient data and understand- flow. This suggests that hydrometeorologists should be- ing will evolve in the field of nonpoint sources of come much more concerned with the quality aspects of pollution. precipitation and runoff than we have tended to be in The third aspect of this pollution field is hydromete- the past. Second, the precipitation excess or runoff is orologic modeling, and here there have been consider- the vehicle that dissolves or dislodges and carries sur- able attention and progress. The principal problem is to face pollutants such as sediments, nutrients, pesticides, have the appropriate numbers to insert—for precipita- and a whole host of residuals, particularly from our tion and the parameters that will consider geology, soils, cities. This process of erosion and transport is one in slope, land use, and season to convert precipitation into which we and everyone else are particularly weak. But the quantity and quality of runoff. the authors of this federal Act seemed to have no ap- So without having been exhaustive, and recognizing preciation of the weakness or absence of data and skills that we will need to share the management of our re- and have required that essentially the entire country be sources with numerous other interests and skills, it is analyzed and plans prepared by the end of 1977. No clear that there is much to be done. Realizing, also, that funds are provided for research, but of course there everything is connected to everything else, we have al- would not be time for that in any case. So, in the mean- ready in place, both scientifically and institutionally, time there will be a great many rough estimates. Surely, one of the most important natural resources, cause and though, the importance of the problem will require a effect linkages—meteorology and hydrology.

William C. Ackermann, Chief of the Illinois State Water Survey since 1956 and Professor of Civil Engineering at the University of Illinois since 1958, began his career in hydrology as a river forecaster with the Tennessee Valley Authority after receiving the B.S. in civil engineering from the University of Wisconsin in 1935. From 1942 to 1954 he was head of the TVA Hydrology Section. After two years with the U.S. Department of Agriculture as head of the Watershed Hydrology Section, he was named Chief of the Illinois Water Survey Division in 1956. In this capacity he directs a broad program of research in hydrology, meteorol- ogy, hydraulics, water chemistry, and water resources systems and plan- ning. A consultant on water resource problems in the United States and abroad, he has also been a frequent adviser to the Presidential commissions on water resources policy. Dr. Ackermann's professional activities have also included membership in the National Advisory Committee on Oceans and Atmosphere (1974-); the National Academy of Engineering (and its Council); the Commission on Natural Resources, National Research Council (1973-); and on many NAS/NAE advisory boards and committees. He has been extremely active in both national and international professional societies, including the American Geophysical Union (Past President and Fellow), American Society of Civil Engineers, International Union of Geodesy and Geophysics (Member of Bureau), International Council of Scientific Unions, and International Association of Scientific Hydrology (President). Dr. Ackermann is the recipient of the Fuller Award of the American Water Works Associa- tion, a Special Achievement Award from the University of Wisconsin, the Collingwood Award of the ASCE, and honorary degrees from Northwestern University and Southern Illinois Uni- versity. He has published extensively in scientific journals.

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