We had our kick off meeting in the field yesterday with KWL consulting engineers who have expertise in water resource engineering. The team included a geomorphologist, a coastal engineer, a professional surveyor and a water resource engineer. The size, complexity and type of this assessment is unique. The work at Cowichan Lake will be a challenge but we have the expertise who can tackle it. Consider the variability of a lake of this size with changing beach slope angles, different geology, varying vegetation, changing winds, protected bays, exposed points, creeks and streams of all sizes as well as the work humans.
As we seek to determine the current natural boundary we need to consider a few factors: 1. The presence of water: how often water reaches a certain point on the shoreline influences what types of vegetation can grow at different elevations. 2. The action of water: the energy of waves along the shoreline depends on the exposure of the shoreline to prevailing winds or boat wakes. This wave energy determines how shoreline are eroded and vegetated over time. 3. The character of the current shoreline (slope, substrate type, vegetation) not only influences the location of the current natural boundary but also plays an important role in how the natural boundary could change as a result of the proposed upgrades and operation of the Cowichan Lake Weir.
Over the next several weeks measurements and photographs will be taken to capture existing conditions to ensure we have a solid benchmark from which to start our analyses. Our BC Professional surveyor will be using his years of experience to record the current natural boundary and key access points along the shoreline. Others will record beach substrate such as gravel, sand, mud, rock and vegetation. This new information along with existing photographs, and high resolution LiDar (light detection and ranging using laser light) data and other databases we will create a clear picture of what exists today. This information, along with a new weir design, climactic data, hydrological modelling will help us determine future impacts of raising the weir.
One thought on “Shoreline Assessment Work”
As an ISA Certified Arborist for over 20 years, I should warn you that the shoreline trees, with the exception of Poplar, Aspen and Willow, cannot tolerate flooding when the air temperature is over 10C for two weeks in the spring and until after the air temperature is below 10C for two weeks in the autumn. Flooding of the roots will occur 10-30cm above the standing water level due to what is called the capillary fringe (less for sand/gravel more for silt/clay). Moreover, root drainage problems and subsequent root rot can take up to 10 years to become apparent as serious decline and death. Short-term damage due to lower resistance to wind you are no doubt already aware of. Regardless, I am sure nobody wants to see a fringe of dead conifers around the lake.