I receive a lot of textbooks in the mail.  If you teach a first year geography class, as I do, publishers will hope to convince you that their textbook is the one for your students.  There is a lot of money to be made.  I don’t use a textbook, but I do look at the many on offer.  One that has recently crossed my desk deserves mention for its unusual inclusion of an historical perspective in a work dealing primarily with water management, Thomas V. Cech’s Principles of Water Resources.  This is not simply policy history.  Cech actually spends two pages explaining the historical development of the qanat system in the Middle East.  Have a look!