"The Great Deluge: Hurricane Katrina, New Orleans, and the Mississippi Gulf Coast" (William Morrow, 736 pages, $29.95) is the historian Douglas Brinkley's bid for literary and historical greatness. Hoping to follow in the footsteps of David McCullough, whose fine book on the Johnstown flood established his sterling historical reputation, Mr. Brinkley has sought to create an instant epic, parlaying the story of Hurricane Katrina's rampage through the Gulf Coast into a natural and human drama of cosmic scale. This massive book, based mainly on journalistic sources and the author's own interviews, and crammed with an immense amount of detail, is the result.

One can be excused for wondering from the outset whether enough time has passed for anything of this epic scale to be written about these tragic and infuriating events - or whether Mr. Brinkley is the man for the job. Let me confess that I haven't read all of the writings of Douglas Brinkley. I doubt that anyone - perhaps not even Mr. Brinkley himself - has ever done that. He is a veritable ... deluge of literary productivity, with books to his credit on a dizzying array of subjects, ranging from Beat poetry to Jimmy Carter, and from Henry Ford to, most recently, the failed Democratic presidential candidate John Kerry. Indeed, the range of his literary productions is so wide as to seem indiscriminate. But his bestknown writings seem to have three things in common.

First and foremost is their relentless mediocrity. I cannot think of a historian or public intellectual who has managed to make himself so prominent in American public life without having put forward a single memorable idea, a single original analysis, or a single lapidary phrase - let alone without publishing a book that has had any discernable impact. Mr. Brinkley is, to use Daniel Boorstin's famous words, a historian famous for being well-known.

Second is their sloppiness, partly an inevitable product of the haste in their composition, and partly, one suspects, of a mind that becomes easily bored by careful, close analysis. Mr. Brinkley's views may always track the conventional wisdom, but you would never want to rely on his books as sources of accurate detail. Would you trust a writer who trades on his intimate knowledge of the Gulf South, and yet claims at one point (page 548) that a tired-looking President Bush could not have been jetlagged because "Washington was in the same time zone as Mobile"?

Third, and perhaps most important, is their political agenda, although the word "political" does not quite do the matter justice. Better to say that Brinkley always seems to be seeking someone's favor in what he writes.Which is to say that he has the moral instincts of a court historian. And this means that the would-be patron holds the key to the book's real meaning.

In the case of the Kerry biography, that was easy enough to detect. In the case of "The Great Deluge," Mr. Brinkley seems to have three things in mind. First, he clearly is trying to intervene in the New Orleans mayoral race, and more generally in the politics of Louisiana. "The Great Deluge" is notable for its astoundingly nasty and cartoonish treatment of New Orleans Mayor C. Ray Nagin, and its near-hagiographical treatment of Mr. Nagin's electoral rival, Mitch Landrieu - an account whose most colorful stories rely heavily on interviews with such objective sources as ... Mitch Landrieu. As before with John Kerry, so now with Mr. Landrieu, Mr. Brinkley has not done the careful, time-consuming work of testing the veracity of his sources....