Tributary of Corte Madera Creek Watershed:

This map was made using a digital elevation model developed from LiDAR (light detection and ranging). Streamstats, a website made by USGS, generates a flow accumulation analysis to determine how water runs off across the landscape. By selecting a lowermost point within the tributary of Corte Madera Creek, Streamstats calculates the land area contributing water to the stream. Streams are shown in blue, and this watershed area is highlighted in yellow. All the rain that falls within the highlighted area flows into the tributary and eventually to Corte Madera Creek. 

Some simple statistics based on the basin that Corte Madera Creek resides in. 50-percent AEP flood = when there is a 50 percent chance of a flood occurring every year.

• Ravenswood tidal marsh
  • The Ravenswood tidal marsh was the third location that I studied. It was fairly windy, with the area being cool compared to the surrounding area. It was also low tide, with the tide changing twice in one day. There was no shade on the tidal marsh and the only animals on the marsh were some birds scavenging for food. The tidal marsh is on the shore of the bay, with multiple creeks feeding into the Ravenswood tidal marsh. It receives a part of its water from San Francisquito Creek and the other part from the bay. This creates brackish water with part salty and part fresh water, which creates a new environment compared to just salt/fresh water. Near the tidal marsh was a “plot” of pickleweed. They provide cover and some shade for small animals as well as a way to create fresh water from the saltwater that comes from the bay.
• Pearson-Arastradero grassland
  • The Pearson-Arastradero was the final location that I studied. The grassland is also around the foothills of the Santa Cruz mountains. During my time at the Pond, the first thing I noticed was the lack of shade and how it had sparse foliage apart from the tall grass. The grassland during the summertime is warm and fairly windy. As a habitat, Pearson-Arastradero grassland is a good place for small critters to hide in. This is due to the tall grass providing cover over a large area. There is also a stable water supply nearby in the form of a Pond.

How is each habitat unique? 

Each habitat has unique features that create a unique habitat, which allows different species to live in each habitat. Sausal Pond has dense foliage surrounding it with lots of shade and is a stable water supply, Corte Madera creek is at a low elevation with a cooler and humid climate, the Ravenswood tidal marsh has changing tides which completely change the habitat twice a day, and the Pearson-Arastradero grassland has tall grass that provides cover for small critters to hide in.

How does each habitat change seasonally?

Sausal Pond’s water level would change seasonally, with the water levels becoming lower during the dry seasons and higher during the wet seasons. I believe the plants would still thrive during the dry season as there is still a groundwater supply. I believe that Corte Madera Creek would dry up a bit as its tributaries would also dry up during the dry seasons and would become larger up as its tributaries would become full again while the creek itself gets rainwater directly. Pearson-Arastradero grassland during the dry season would cause dormancy for the grass, while during the wet season the grassland would be lush.

How might each habitat respond to climate changes? 

Each habitat could undergo substantial changes, such as if Sausal Pond dries out completely, due to climate change. Here are some hypotheses on what would happen and potential reasons why such an event would happen.

• Higher temperatures, thus causing higher evaporation rates, could lower water levels faster than in the past. Future rainfall is uncertain but may become increasingly variable and occur over a shorter period each year(with the same amount of rainfall), causing the dry season to become longer and drier.
• Plants that are further away from Sausal Pond would most likely dry up due to water scarcity in the coming dry seasons. Animals that were once used to the seasonal pattern of water availability in Sausal Pond would be forced to find new habitats due to sharper wet seasons. 
• Corte Madera Creek would eventually dry up as well as its tributaries due to longer dry seasons but would have a fast flow of water during the wet season. This will cause erosion and would affect sediment levels in the water. This would also affect other ponds in the area due to Corte Madera Creek feeding into many others, thus causing lower surface water flow into ponds.
• The Ravenswood tidal marsh would be flooded due to it being close to sea level and the rising sea levels caused by climate change. The pickleweed plot near the tidal marsh would also drown due to its close proximity to the tidal marsh.
• Pearson-Arastradero grassland would also eventually dry up due to longer dry seasons and most of the grass in the area would eventually die over a long period of time.

What measurements can we make to evaluate the health of each habitat and identify long-term changes? 

• Water quality:
  • Turbidity
  • Salinity of water
  • pH
  • Algae
  • Oxygen
  • Temperature
• Water quantity:
  • Groundwater concentration
  • Water levels
• Plant biodiversity
  • Section off a plot of plants
  • Identifying individual species
• Animal biodiversity
  • Identifying individual species
• Soil quality
  • Measure the concentration and spatial variability of nutrients

Conclusion:

Through this document, I showed you about how unique these habitats surrounding the Santa Cruz Mountains are, as well as the effects of climate change on these habitats. With this knowledge, I hope to have enlightened you on how delicate these habitats are and how vital they are to the wider ecosystem. I also hope that you become conscious to our own contribution to global warming and strive to make a change for the better of our Earth.