Watersheds and Landforms

No matter where you live, the land area is divided into sections according to an interconnected system of creeks, streams, and rivers.  These provide water for drinking, irrigation, and industry.  The area of land (essentially a basin) that drains into a particular watercourse is called a watershed.  Therefore, the entire land on which we all live is a series of interconnected watersheds. If you were to look at a cross section of a particular watershed, it can be described by the main regions as indicated on the illustration below. 

Ideal home sites are generally located in upland areas, whereas terraces and floodplains are prone to flooding.  You should be aware of land uses above and below your location, even in upland areas.  For example, you may be affected by erosion or changes in water drainage from construction sites or pollution sources above you.  Likewise, you may be liable if your land uses adversly affect runoff for neighbors located below you in the watershed.  You should learn where the water comes from above you, and where it goes when leaving your property.

The water table is the uppermost level of the water which flows through underground aquifers.  This level changes throughout the seasons, being higher usually in the spring. If the water table is too close to the surface, water from rain or septic system leach fields will not infiltrate very well into the ground.  This can cause maintenance problems with your septic system, or health hazards from sewage pooling on the surface or contaminating ground water. 

Another factor of concern is depth to bedrock.  If bedrock is too close to the surface, special and expensive methods are required both for basements and for septic systems.