India, Jan. 8 -- Every time the hills of Kerala slipped, cracked or came rushing down as mud and water, one name returned to public conversation with unsettling regularity. It surfaced in newspaper columns, television debates, official committee reports and private conversations among administrators and activists. Often it was spoken with irritation, sometimes with anger, increasingly with a quiet sense of regret. Madhav Gadgil.

He did not belong to Kerala by birth. A Marathi from Pune, trained far from the humid southern slopes of the Western Ghats, Gadgil nevertheless became one of the most consequential public figures in Kerala's environmental and political life. Over four decades, the state argued with him, resisted him, occasionally...