Engineering conservation

My morning walk today took me up the north bank path of the rio Aguas nature reserve, curious to see how much progress had been made in clearing vegetation from the river bed since I last went up there, exactly a month ago. I was astonished by what I saw.

Not only had another half a kilometre of cane and bushes been cleared from the watercourse, but several large earth moving vehicles were excavating the soil and adding it to the existing dykes, established as a flood prevention measure years ago. There are places on the north side where flood water erosion last winter swept away soil and vegetation, scouring three metre high precipices in places next to the dirt road. All this needs repairing, making stable and safe, and with vast amounts of alluvial soil and stone to draw upon, it will be possible to improve greatly the protection needed whenever there is catastrophic flooding and rio Aguas threatens to burst its banks.

Needless to say, the riverbed environment, stripped of its five metre high cane forest, looks ravaged and desolate, a conservationist's nightmare on a par with images of amazonian despoilation. But, the banks are not being heaped high with stone and the riverbed paved, as is often the case in cities having to cope with the disruptive effect of occasional deluges. There will be a dramatic effect on riverbed wildlife and ecosystems with such environmental disruption, but similar things happen if there is a big flood also, or a toxic incident. The soil here is rich and fertile and the impact of this remodelling of the riverbed won't be permanent. Vegetation will return and quickly re-grow, and the wildlife will return spreading from wherever it now takes refuge.

It was interesting to observe several Great Egrets accompanying the excavators, dicing with death in close proximity to tracks or giant wheels. Wherever the earth is broken open, a feast of seeds and insects is released, and keen eyed birds benefit. A short term gain for them, maybe, a treat in the never ending hunt for food. It was hard to get decent photographs, as the excavators are so big and the bird so tiny in comparison.

Stripped of vegetation, it's possible to see where the river used to meander and maybe still does if there is enough rain for water to appear at ground level. The core route of the river is also being excavated, it's definition being restored, so that it can more effectively take rain water running from the surface either side of the channel. On the north side of the valley, half way down is an artificial plastic lined pond, perhaps collecting spring water from the cliff above. This drains into a channel that connects to the central river bed, feeding the charco which at this point is a few hundred metres lower down toward the sea. All this must be carefully engineered to ensure the right balance between saline and fresh water for the vegetation around the charco to flourish.

How good it is that the municipality and regional government are willing to invest thought, time and money in large scale conservation project of this kind. Nobody wants floods, so managing the landscape is vital. Perhaps those involved have also noticed how many visitors are attracted by the very fact that an otherwise unremarkable coastal valley has retained its bio-diversity and made it into an attractive place to visit. I was passed on the dusty track by a couple of golf carts from the neighbouring Marina Playa course laden with passengers, curious like me to take a look at work in progress. I wonder what the watercourse will look like in a couple of years from now.