This post is a reflection following up a recent article.

From a computational hydrologist’s perspective, one limitation in hydrology is how to connect the water cycle with both natural and anthropogenic processes in the Earth system model.

It is generally easy to focus on one process or term, such as runoff or ET. However, it is challenging to link ET with runoff in different landscapes.

In the Earth system model framework, we need to consider all the water cycle processes. For example, how does water flows from land to river, then to lake or ocean? And how does ET come from land or lake into the atmosphere?

The first challenge in ESM is how to represent land, river, and lake appropriately so that they can communicate. For example, the Antarctic and Greenland are considered masses of glaciers, but many other hydrologic processes on them are ignored.

The second challenge is how to consider the vegetation and animal feedback with the water cycle. This is also important for the carbon cycle.

The last challenge is how to consider the human factor, including agriculture, and dam operation.

There is also a dependency relationship between these challenges. For example, without improving the representation of the natural system, there will be large uncertainty in the human factor.

In ESM, we need to consider all the above three challenges all together to have a better understanding of the water cycle.