Chanba National Wetland Park

This guide to Chanba National Wetland Park in Xi'an opens with a question: how do you turn a garbage dump into a bird sanctuary? It lays out how degraded this stretch of the Chanhe and Bahe rivers had become, with illegal sand pits, hundreds of millions of cubic meters of construction waste, and roughly a fifth of the river's daily flow arriving as raw sewage. It then follows the unusual engineering decision made in 2003, letting river water flood the very craters that illegal digging had gouged into the riverbed. Stand on the boardwalk and picture the sand pits that once lay bare beneath it.