陳蕙雅思閱讀短文 - 邁阿密海灘海沙流失嚴重

您要是想去邁阿密的海灘上曬曬日光浴，那您得趕快了，聽說那邊的海沙流失挺嚴重的。開始我還以為是有人偷沙子，後來才知道是人類對自然環境的破壞造成的。

The beaches in Florida's Miami-Dade and Broward counties, among the most popular, have run out of sand.

The U.S. Army Corps of Engineers is holding meetings this week to figure out where they can get more sand from, according to the Associated Press. They have to work fast to protect the shoreline from erosion during future hurricanes.

Beaches are formed by the erosion of offshore rocks and promontories. The fine size crystals of quartz and other material are carried onshore by waves and deposited on the beach.

Even the material offshore has to come from somewhere, and that source is inland erosion. Rivers carry the sediments and deposit it off the coast.

The problem is we've dammed up rivers and built up harbors, so there's less sediment replenishing the material offshore these days. Humans are now the greatest shapers of landscapes, moving much more Earth than wind or water. At the same time, we have a proclivity for storm-prone coastlines that are increasingly under threat from erosion and climate change.

The Army Corps began intervening in Florida in the late 1970s since without a well-nourished beach, coasts are vulnerable to hurricanes and storm surges.

Typically, the Corps sources the sand for its projects from nearby places, but these have been depleted in the Miami-Dade and Broward counties, the AP reported. The continental shelf is rather narrow off these counties, providing little area for dredging. Coral reefs also hinder removal.

There's enough sand available off southeastern Florida to replenish five counties over 50 years but these reserves are mostly in the waters off St. Lucie, Martin and Palm Beach counties, the AP reported.

And then there's the question of cost. Beach nourishment can be expensive, and the federal government and local entities split the bill for the first 50 years of nourishing a beach. After that, the federal funding falls off. The term is coming to an end for many projects. The Senate just passed a bill that would extend the deadline by 15 years. The House will take up its version of the bill next month.