“But, you know, if we don't pay attention to the hyporheic zone, then it's going to be a sick system. “A biologist working for the city named realised that ok, we can put back some S curves, we can put back some trees and logs and rocks and kind of make it look habitaty. Thornton Creek in Seattle had been engineered to death, she says straightened, built over and diverted into pipes. “It’s not going to be able to support diverse life and spread its sediment in a way that helps reduce flooding and provide water through the dry season.” If the stream doesn't have a healthy hyporheic zone, then it's also going to be a sick system, she says. It's serving as the base of the food web, and it's a highly oxygenated area so fish like salmon lay their eggs there.” “And there are many critical things that happen here in terms of nitrogen, phosphorus and carbon cycling - so that's cleaning pollutants. “It's basically part of the stream or the river that is also moving downstream, but much, much more slowly, because it's moving through rock and soil. The hyporheic zone is between the aquifer and the surface water, she says. But in fact, that's not the case at all, surface water and groundwater are connected, they're effectively the same water.”Ī creek in Seattle has been brought back to life by restoring its hyporheic zone. “In California, we've done a lot of over-pumping of groundwater, we've tended to use that as extra water when surface water runs low. “The water can then go underground very quickly, and then it will seep into the surrounding clays, which are less permeable over a longer period of time and raise the groundwater table for quite a large area. They are like the ancestors of today’s rivers, she saysĪ hydrogeologist in California named Graham Fogg had the idea to find these underground rivers and to direct water into the valley during flood. These ones in California are special, because they were made by the last ice age.” “A lot of places have ancient rivers and streams that are buried underground. In California, they are making use of ancient, hidden underground waterways to manage high water flows. Just as hard engineering has worsened urban flooding, it is possible to restore water systems she says. “We're blocking water from those slow phases on the land where it can absorb floods, filter underground to supply water in the dry season, store carbon dioxide three to five times as much as forests and provide really important habitat for all kinds of plants and animals that also help to sustain these systems.” These interventions prevent water from behaving in the way it wants, she says. And just since 1992 the land area covered by cities has doubled.” “We've intervened with dams and diversions on two thirds of the world's big rivers. “Humans have actually filled or drained as much as 87 percent of the world's wetlands. “And so, if you're just focused on one thing, then you're causing a lot of unintended consequences.”Īs cities have expanded, and we pave over more land, we have also been draining wetlands, the natural sponges which regulate water, she says. “Water has relationships with soil and rock and microbes, and beavers and plants and humans even.
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