Andrew’s work tends towards the hard science approach – measuring water flows in the dry season, comparing it to forest catchement systems and hydrology regimes, and making measured conclusions. All good stuff, and desperately needed in a period where we tend (myself included) to go all Henny Penny about the environment.
I have reservations about the argument being advanced here, but no justification or qualification to oppose them. For the most part I’m simply glad that people are doing this work. I would like to see future work on forests and hydrology regimes take on some larger regional questions, however.
For instance, when Andrew writes that decreased forests do not necessarily equal decreased dry-season flows (as you would expect, given the traditional understanding of forests as water-retention devices, which expend their wet-season accumulations during the dry), we are not given any real understanding for what actually accounts for this. (Again, not his point in the paper – but an important project for the future perhaps). He says that dry season flows may actually increase! Where is all this water coming from?
One possible source is hinted at, but not connected in the post or the paper itself – deforestation has not resulted in lowered rainfall. But rainfall is not (especially in monsoon Asia) merely the result of forest hydrology, right? (right?) Are we dealing here with a much larger cycle that is potentially fouling up the local data on forest hydrology and dry-season water flows?
Anyway, you’d do a lot worse than taking a careful read of Andrew’s excellent work.