Identify Priorities in Your Community: Additional Information on Water

 

The following page contains a broad array of information about water collected during Phase One (2008-2009) of CBT's Communities Adapting to Climate Change Initiative. Some of the material included herein can be found in the final reports or guidebooks, but some cannot. This webpage is not a formal factsheet; it contains fragments of information and bits of knowledge that we hope will be useful to you.


Elkford consulted water expert Hans Schreier, Professor IRES /UBC and CBT Advisory Committee Member, regarding water issues. Below is a series of questions and answers that provide helpful information regarding stream-flow, storm-water management, and flooding.

Practical Innovations in Stormwater Management 2009 pdf 858KB This paper highlights practical innovations in stormwater management at the property, neighbourhood and watershed scales. It is co-authored by Hans Schreier, UBC Professor and CBT Advisory Committee Members.


Stream-Flow

Q: PCIC doesn’t predict stream-flow as part of their modeling and they do not have an explanation along with the graphs that give us a good understanding about what the monthly changes in stream volume will be. Stream-flow volume is obviously important to determine if there will be issues with flooding for the community. Can you help on this front?

A:The global climate models are not able to predict with any accuracy how the flow of individual streams will change. In general, we expect glacial fed streams to contribute greater stream-flow in mid to late summer during the early phase of melting. However, when the glacier's mass is significantly reduced, a threshold is reached when the contribution from ice melt is no longer visible. This can happen very quickly and will result in lower late summer stream-flows. Determining when that threshold is reach is very difficult and since we have very little information on the status of the glaciers that feed Elk Creek it is prudent to initiate some monitoring.

The other factor that needs to be considered is snowmelt. We expect most snow-fed streams to peak earlier in the spring because temperature increases are highest in late winter and spring. We therefore expect earlier, and in high snowfall years, higher peakflows and significantly reduced base-flow in late summer. The shift in peakflow is already visible in many streams and a two to three weeks advance in peakflow is expected over the next 25 years.

 

Storm-water Management 

Q: We are looking for more information on storm-water management. Do you have a document you could refer us to or could you offer some advice on questions to ask to determine if the district’s storm-water management system/practices merit further investigation as a climate change adaptation priority? The current OCP does contain this information. (Note: For all new development areas, the method of handling storm-water drainage shall be determined in a storm-water management plan prepared by the developer. The plan will propose facilities in order to ensure that the rate of flow does not increase as a result of development.)

A: From my visit it appears that most of the town is on fairly well-drained soils and surficial materials. This has a significant advantage because all new development can easily mitigate storm-water runoff and older properties can be rehabilitated.

The main problem is the amount of impervious surfaces that is being created, because this creates more and faster runoff during intensive rainfall and snowmelt events. The adaptation options are at three scales: 1) the property level, 2) the neighborhood level, and 3) the watershed level.

1. Adaptation techniques at the property level

We are now able to demonstrate that if you choose the right practices, you can design your property to generate zero storm-water runoff. This can be accomplished by:

  • Use roof-water collection tanks (for outdoor use in the summer).
  • Minimize the impervious surfaces using pervious materials or lock type tileor porous asphalt.
  • Make sure you have at least 30 cm of topsoil in your grass and garden area and minimize compaction.
  • Build a 2 x 2 x 2 m hole in the garden, fill it with gravel and direct surface runoff into the rock pit.
  • Maintain trees on your property because they soak up CO2, moderate summer temperatures and act as storm-water retention system. (We have a study going on to measure how effective urban trees are in retaining and evapotranspiring rainfall. Depending on the tree we can absorb and delay rainfall runoff by up to 60% within a tree-covered area.)

If you initiate a combination of these techniques, you should be able to disconnect your property from a storm-water piping system because all rainfall and snowmelt water is stored, detained and infiltrated.

2. Adaptation techniques at the neighborhood level

At this scale we have to be concerned about road runoff, and runoff from industrial and commercial area. The innovative adaptation techniques are to:

  • Build roads without curbs and gutters but build them in such a way as to direct the road runoff into swales at each side of the road. These swales are made up of sand filters and they need to be connected to detention ponds and wetlandsthat work as storage and infiltration systems.

3. Adaptation Measures at the watershed scale

  • Maintain a very good buffer zone (at least 30-60 m) on both side of the stream.
  • Regulate land use within the buffer zone and create artificial wetlands within the buffer zone.
  • Protect your headwater area and maintain good soil infiltration and detention systems in the headwaters.

The only thing that needs to be considered is to make sure that the areas used for storm-water infiltration are not directly connected with the aquifer from which you obtain your drinking water.

* We have organized three big workshops over the past year in Vancouver, Calgary and Toronto on Low Impact Storm-Water Management Innovations and all presentations are available on my website: http://research.ires.ubc.ca/projects/ISM/index.htm.

Practical Innovations in Stormwater Management 2009 pdf 858KB This paper highlights practical innovations in stormwater management at the property, neighbourhood and watershed scales. It is co-authored by Hans Schreier, UBC Professor and CBT Advisory Committee Members.

 

Tips from Elkford's Final Report (pages 51-53)

  • Town of Gibson’s, BC:Implementing a water-metering program, as well as water efficient fixtures and hot water tank replacements. They have a very comprehensive and information website dedicated to water issues:http://www.gibsonswater.ca
  • Many communities in the Okanagan have installed end-use water meters, which have reduced water use by up to 20%. Okanagan Sustainable Water Strategy, Action Plan: http://www.obwb.ca/water_strategy/

 

Q: Do you know if it is possible to include swales, underground lines, stormwater management, etc. into the OCP bylaw, rather than a separate 'Development Standards Bylaw"? Since we are updating the OCP and integrating CCA into it, we are trying to fit as many CCA strategies into the OCP as possible.

A: From George Penfold, CBT Advisory Committee; Selkirk College, Regional Innovation Chair - Rural Economic Development, Castlegar, BC

  • Have a look at the Lantzville OCP. They have the DP policies set up there. The process is usually to include theDP policies in the OCP and the specifics of development standards in the standards by law as all development doesn't happen througha DP process. Laurie Cordell is a good resource as well.
  • You should also be consulting with the municipal solicitor.

 

Flood

Q: Have you done work related to flood plain mapping? I have emailed a couple of people in the Ministry of the Environment asking about the possibility of integrating the PCICmodelinginto theircurrent orfuture mapping, but in general I need more information on determining when their may be red flags for flooding in a community. I want to know when it may be a priority that warrants further investigation.

A: To determine flooding events is a very tricky business. We can probably suggest what the risk will be, a couple of weeks before, but this is highly dependent on the combined effect of rain and snowmelt effects.

There are a number of very good flooding adaptation techniques you can pursue:

1. Map out the floodplain in detail and develop a flood risk map and then regulate the land use. (Note re Elkford: From my visit it appears that the sewage treatment plant and a few buildings are at a relatively high risk.)

2. Select areas that can be designated to be flooded during storm events (e.g. parks, lowland depressed areas, wetlands, agricultural fields, grazing land, forests). This provides temporary storage and the impact on the land after the floods is small. In some places they designate farmland to be deliberately flooded and then compensate the farmer for temporary loss in production. This is far cheaper than building protective structures that need to be maintained. Considerable potential exists to designate flood storage areas upstream of the town by creating more wetland space in the floodplain.

3. Make sure that bridges do not constrict the stream channel and maintain as much of the natural channel as possible.

4. Maintain as wide of a buffer zone on both sides of the Elk River as possible and maintain the wetlands, forests, parks etc.

 

Other Notes:

  • As far as swales, underground lines, and storm water management are concerned, those could all be included in aDevelopment (Green) Standards by-law. The District of Lantzville on Vancouver Island, along with Cumberland and Gibsons, has developed a good bylaw that you might want to consider as a model.

For more information on useful resources pertaining to water, see the Resources section of Kimberley's Case Study or the Resources section of Elkford's Case Study.