Terrestrial Hydrology

TERRESTRIAL HYDROLOGY

by Antonio C. Antonio

February 11, 2014

The image included in this article will give us an idea on the important functions involved in Terrestrial Hydrology which are as follows:

1.     The forest canopy intercepts rainfall, protects soil and provides shade;

2.     The forest canopy promotes transpiration, nutrient storage and trapping of air pollutants;

3.     The forest floor functions as a filter for sediment and other chemicals;

4.     The forest floor promotes infiltration and water and nutrient storage; and,

5.     Ground soil functions as a filter to remove biological nutrients and pollutants.

QUESTION:  If our watershed management objective is to produce as much water as possible, do you think reducing the number of trees and replacing them with small trees and bushes will help?  Why or why not?

ANSWER:

My answer to this question is based largely on the experiences of the forest management company I worked for. 

Part of sustainable forest management is a program called “Timber Stand Improvement” or TSI.  In the company I used to work for, I would often grill our technical staff (our foresters) on the benefits and cost justification of this program.  I always argue that “we should not fix anything that is not broken” as I (from a layman’s viewpoint) didn’t see anything wrong with the forest within our area of operation.  It was in one of these meetings with the foresters that one of them mentioned that “TSI will improve terrestrial hydrology”… a term strange to me then as it was the first time I heard of it.  They went on to say that TSI will increase the water-bearing capacity of the ground which will guarantee continuous growth of trees even during the dry season.  

TSI, I should also mention, does not necessarily mean felling or harvesting of trees.  It only entails clearing of unwanted branches (the canopy) through pruning and brushing of the forest floor… but, none-the-less, an expense item which was my only concern (from the purely business management standpoint) considering the wide area where TSI would have to be implemented.  But, then, who am I to argue on the merits of the forester’s professional opinion… when my job was to make sure that the necessary funds are made available for the TSI program.

Using the borrowed knowledge I have, I should say that replacing trees with smaller ones and bushes will not support a watershed management plan to possibly produce as much water.  The TSI program specifically calls for canopy clearing and forest floor clearing as well.  Replacing trees with smaller ones is not also part of the deal.  I will just have to trust our foresters on this one (their contention that this will increase the water-bearing capacity of the forest) as I cannot intelligently justify my argument for now.  In the meantime, I really should indulge in more research and study of terrestrial hydrology.

Just my little thoughts…

REFERENCES:

·         Hydrology (http://en.wikipedia.org/wiki/Hydrology)

·         Transpiration (http://en.wikipedia.org/wiki/Transpiration)

·         Evaporation (http://en.wikipedia.org/wiki/Evaporation)

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