This is a two part Earthcache with a bit of distance between the two stages. The second stage is located in Mud Bay Park and the gates to this park close at 8 pm so no night caching.
SERPENTINE AND NICOMEKL LOWLANDS
Surrey’s lowland are low elevations areas that are influenced by ocean and river tides and are protected through river and shoreline dykes. The catchment area for the Serpentine and Nicomekl Rivers is 334 square km of which 59 square km is considered part of the lowland floodplain area for the river.
The land was inter tidal until the late 1800's when farmers started to reclaim the land with the use of dykes and canals. In 1910, Surrey built sea dams which consists of gates to control the flow of water. During low tides the gates open to allow fresh water to flow into Mud Bay and at high tides the gates close to prevent salt water to flow upriver to the farm lands.
In 1920 dyking of the rivers started and it wasn't until the 1950's that mechanical dredging helped build up the dykes along the rivers. In December 1951, high tides up the Nicomekl and Serpentine rivers combined with gale-force winds to flood 490 hectares of farmland under 1.5 meters of salt water. Repairs cost about $20,000 and the salt residue affected farm production for a few years. In 1997 the City of Surrey implemented a full dyke strategy which includes building up the dykes and pump stations.
Climate change is likely to increase the tidal level and storm surges that come up this estuary. The mouth of the Serpentine river is about 2 km from the sea dam and onshore winds get funneled into the mouth of the river which can cause the onshore tide to be higher than one would expect. The other challenge with climate change is more runoff from upstream. The gates would open during low tides on the sea side to allow the water to come out from the upstream lands and flow downstream to prevent flooding from rainfall and snow melt from upstream. With continued climate changes the dykes may have to be significantly raised and the sea gate rebuilt.
MUD BAY FLOODPLAIN
Mudflats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. Tidal flats, along with inter-tidal salt marshes are important ecosystems. They usually support a large population of wildlife, and are a key habitat that allows tens of millions of migratory shorebirds to migrate from breeding sites in the northern hemisphere to non-breeding areas in the southern hemisphere.
The northern tip of Boundary Bay is known as Mud Bay and is locally influenced by freshwater through the discharge of the Serpentine and Nicomekl rivers into the enclosed bay area which creates a strong brackish influence. Both the Serpentine and the Nicomekl rivers are tidally influenced and have dykes, floodgates and sea dams installed along portions of them to mitigate flooding and facilitate farming. It is also an important stop for birds migrating along the Pacific Flyway, particularly for western sandpiper and dunlin, and has been designated a Hemisphere Reserve by the Western Hemisphere Shorebird Reserve Network and a Canadian Important Bird Area. The mudflats, extensive eel grass beds and salt marshes support a rich population of marine invertebrates which are an important source of energy for migrating shorebirds. During migration times the bird count in the bay may exceed 100,000.
From the posted waypoint you can look out over Mud Bay. If you visit at low tide you will see the vast inter tidal mud flats that are created by the sediment from the Serpentine and Nicomekl rivers. Looking south you follow the coast line along the BNSF train tracks. The train tracks were built in 1907 with upgrades over that last 110 years.
To claim this earthcache, please email me the answers to these questions via my profile page. Answers should be sent in at time of logging, if not before, thank you. Unfortunately, any logs that do not meet the requirements will be deleted
Stage #1Sea Gate N 49° 05.191 W 122° 49.146
1. At the time of your visit is it a low tide or high tide? Is the sea gate opened or closed? How high or low is the tide according to the gauge?
2. Do you think this is an effective way to control the water flow of the river?
Stage #2 Mud Bay N 49° 05.191 W 122° 51.600
1. Do you think that the train dyke has effected the natural flow of the river?
2. Do you think the tides have helped keep the sediment from the rivers close to the shoreline as it stands now.
Many thanks to Catapult Jeff for his assistance in creating this Earthcache.
The placement of this cache is Authorized by the City of Surrey
