Watersheds

Understanding how watersheds are affected by human development and climate change is essential to protect them and reduce risks to future water security.  

Climate change affects watersheds in many significant ways including:

1. Changes in precipitation patterns:

• More intense and heavy rainfall which increases erosion and carries pollutants and sediments into water bodies.

• Prolonged periods of drought leads to less runoff, decreased groundwater recharge, and reduces lake levels.

2. Reduced snowpack and snowfall:

• Although not many places on Salt Spring Island have prolonged periods with snow, it can still play an important role in groundwater recharge.  Snow remains on the ground for a longer period of time than rain, by melting slowly, it allows water to infiltrate into the ground and recharge groundwater, runoff will also slowly travel to water bodies refilling lakes.

3. Increased evaporation:

• Higher temperatures can cause increased evaporation from water bodies and land.  This can lead to drier soils, making it more difficult for plants to survive.  This will lead to drier conditions, further exacerbating drought conditions.

Human development and activity can also affect watersheds through:

1. Altering natural flow:

• Building dams or diverting rivers can change the natural flow of water in a watershed, affecting ecosystems, and reducing water availability downstream.

2. Increased water demand:

•  Human development increases water consumption for domestic, industrial, and agricultural use.  This can strain water sources such as groundwater and lakes, reducing water flow in rivers and lake levels. 

3. Pollution:

• Runoff from roads, industrial sites, residential areas, and agricultural lands can carry fertilizers, heavy metals, microplastics, and other pollutants into streams in lakes.  This degrades water quality and aquatic habitats.  

4. Urbanization and impervious surfaces:

• Building roads, sidewalks, parking lots, and buildings increases impervious surfaces preventing water from soaking into the ground.  This leads to increased runoff which can cause erosion and reduced groundwater recharge.

5. Deforestation and land clearing:

• Logging and removal of vegetation affects the ability for soil to absorb water leading to increased runoff and sedimentation.  Vegetation also plays a key role in filtering pollutants from runoff, therefore its absence can lead to a decline in water quality.