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News Link • Environment

The science that transformed a dry streambed into an oasis

• By Communications and Publishing

Laura Norman stood by the trickling stream and let the enchantment of her surroundings wash over her. The landscape was verdant, lush even, but Norman wasn't standing in a tropical paradise. In fact, her oasis was in one of the driest, hottest regions in the world, and only a handful of years ago, this gully was virtually barren of plants.

In the arid and semi-arid southwestern United States, where Norman has studied watersheds for over 20 years, land use changes and climate change are causing increasing desertification. And yet where she stood, as if by magic, permanent wetlands had sprung up.

But it wasn't a spell or a massive feat of engineering that caused moisture to seep into the land, allowing plants to grow and creating habitat for aquatic animals. It was simple technology that when carefully applied, allowed the laws of nature to transform the land.

The simple technology Norman and her team used was a type of nature-based solution they call Natural Infrastructure in Dryland Streams, or NIDS. Essentially, NIDS are structures made of rock, wood or mud that people or reintroduced beavers construct across the flow of water in a gully, creek or stream.

The NIDS structures she studies seem like dams, but they don't retain water, they merely slow it down. They are basically detention structures, not impoundments.

Norman studies these detention structures as part of her long-term Aridlands Water Harvesting Study. While simple, they have many benefits.

Slowing the flow decreases erosion and allows the water time to seep into the ground where it can recharge underground reservoirs, or aquifers. Although they slow the flow, counterintuitively they increase downstream water levels.

These detention structures also trap sediment, improving downstream water quality and creating substrate in which plants can take root. Once in place, the wetland ecosystems that form around NIDS further decrease erosion and support wildlife.


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