soil basics*

For starters, this graph from left to right:

Before European settlement, all of these lands were covered in dense forests and rain water either moved into the air (evapotranspiration) or into groundwater/interflow. As the forests were cleared, the amount of groundwater began to decrease significantly depending on land use--until where land has been totally covered over with impervious surface, there is none filtering through to replenish groundwater supplies! Easy to see the impact our new subdivisions with huge houses on small lots or the mushroom-style smaller detached houses with a handkerchief lawn on tiny 29 foot lots have on our shrinking groundwater supply. With all that runoff, no wonder the Region is proposing a stormwater tax to cover the increasing infrastructure costs!

Soil stores & regulates water flow, thus naturally maintaining flow rates and water cycles year round. The uppermost soil layer traps most of the rainfall. When this layer becomes saturated, some of the moisture works its way through the more porous sections of the lower soil layers. This process filters rainfall and stores water for long periods of time.

Traditional suburban development has a negative impact on the natural hydrologic cycle. When the initial soil and vegetation layers are replaced by impervious surfaces, moisture flows immediately off-site and into storm-water retention ponds and storm drains. Very little water flows into underground reservoirs (aquifers). Because rainfall flows off-site so quickly, there is no chance of rainwater sinking deeper into the aquifers..

Development on Waterloo moraine involves smoothing out the most extreme hills & removing the till cap (cf. photo of grading operation above). Inherent danger is that there will be holes left that will allow contamination (road salt) to seep into the aquifer.

2006 proposal re storm tax: user fee to cover cost of diverting stormwater into area creeks and rivers; rates based on area of property that is paved or occupied by buildings. More of either impervious surface increases the amount of runoff that goes into the stormwater system.

Need to determine the ideal amount of development that can be built on the land while sustaining the natural environment. The maximum amount of development is expressed as the percent of the watershed that can be covered by impervious surfaces. Essentially this is the development capacity of the watershed. (City of Hamilton Planning and Development).

Rapid population growth puts extra pressure on municipal supply systems (water source and storage capacities).

"A generation ago, many of us had a direct connection to a farm, but
today's generation is disconnected from farms and farming.
We've lost touch with out roots,
in a literal and figurative sense."
-- Carl Hiebert, author of Gift of Wings (1986)

* Photos L to R: soil being removed from top of moraine and moved elsewhere in process of grading a subdivision; Baden farmer's field that has been turned into subdivision since that photo was taken; Wilmot upland woodlot still relatively untouched although the woodlot is not large enough to shelter forest interior breeding species.

* originally posted to Shirt Tails II 08 May 2006 to which
Anonymous said... I say briefly: Best! Useful information. Good job guys.