In answer to the question on another thread, the NCRS dam book is very comprehensive and provides research answers, in a READABLE manner for most of the questions we have here. As it is copyrighted, I cannot re-distribute, but look for:
Agriculture Handbook 590
Ponds -- Planning, Design, Construction.
http://www.in.nrcs.usda.gov/pdf%20files/PONDS.PDF Available from your local DoA/NCRS guy/gal and of course on the internet as pdf.
lots of color charts, maps, graphics, isoclines, tables, and cross references.