THE SCIENCE OF S.L. DINGMAN: THE APPLICATION OF PHYSICAL PRINCIPLES TO HYDROLOGIC PROBLEMS AT ITS BEST

Through my association with S.Lawrence (Larry) Dingman over the years I have come to the conclusion that his ability to explain and apply, in simple terms, physical principles to problems in the hydrologic sciences is unique and of great value to the practicing hydrologist. He has produced, in my opinion, the two best contemporary hydrology text books available – Physical Hydrology (Prentice-Hall Publishers), and Fluvial Hydrology (Freeman Press) - the best because they are comprehensive yet simple, and present theory and practice as lucidly as anything I have ever studied short of Ven Te Chow's classic books.

Examples of his ability to summarize, apply physical principles and explain using mathematical reasoning the key hydrologic processes are apparent throughout Physical Hydrology in Box inserts located in virtually every chapter of the book. Many times I have referred to these concise descriptions in order to better understand and use hydrologic models and for deriving estimates of various quantities and rates of movement through the hydrologic cycle. I have also found rich content within Larry's research papers going back to his days at Harvard and CRREL.

I present here a concept that Larry never had the chance to explore while at UNH, but which was written on the white board in his office for at last two years, that I think deserves attention by fluvial morphologists: The application of Hamilton's Principle, stating that the difference between potential and kinetic energy within a dynamic system should be minimized such that Int(PE - KE)=( Min. Value) where the minimum value is a characteristic of the system, may be a productive approach to looking at flow resistance and downstream hydraulic processes in river systems.