In the last two posts here (one of which you got twice, my apology), I’ve been trying to ‘revision’ the Colorado River as the classic desert river that it is. All rivers are composed of runoff – water from precipitation that did not soak into the ground, collecting in streams that ‘run off’ to the next lower watershed. Humid-region rivers receive new water from unused precipitation all the way along their course to the sea, but a river in the arid lands obtains nearly all of its water as runoff from a highland area high enough to force water vapor to condense into precipitation. The resulting runoff from that precipitation then flows down into the arid lands where it receives very little additional moisture and thus starts to diminish through natural processes on its way to the sea – evaporation under the desert sun, riparian vegetation use, absorption into low desert water tables. When the deserts are large enough, and … Read More
The Water: Where does it all go?
The previous post here ended with the observation, from the 2020 Western Water Assessment Colorado River science study, that around 170 million acre-feet of water fall on the Colorado River Basin – but only 14-17 million acre-feet end up in the actual river. Where does the other 90 percent go? And a corollary question: for such a water-stressed river basin, is there any way to get some of that lost water in the river? We observed earlier that Planet Earth is at just the right distance from the sun for water to exist as a solid, liquid and vapor; recall too that virtually all land-based life depends on it vaporizing from the salty ocean (leaving the salts behind), and then falling over the land as freshwater precipitation, liquid and solid. And the transformations between states are a function of temperature, solar intensity and wind – which means that in a time of rising ambient temperatures, water’s predilection for the vaporous … Read More