RDN Water Budget Project – Phase One:
Gabriola, DeCourcy & Mudge Islands – Electoral Area B
Phase 1 of the Water Budget project is expected to provide preliminary insight into the sustainability of current water use practices in each water region, and will be used to identify areas of concern for further study.
The main Phase 1 report provides overview of the hydrogeology of the Gabriola, Mudge & DeCourcy Islands (RDN Water Region 7), water budget methods and results.
The report is divided into 5 sections:
In addition to this report, the Agriculture Water Demand Model helps us better understand the amount of water required for agriculture throughout the region.
Detailed technical graphs and maps are included in the Appendices and links – see PDF downloads marked
Tips for non-technical readers:
- Improve your understanding with Water 101
- Move your mouse over coloured words for definitions and links to more info
- Consult the Glossary
1.2 Project Scope and Tasks
1.3 Report Organization
2.1 Geological Setting
2.2 Hydrogeological Units and Properties
2.2.1 Fractured Rock Aquifers
2.2.2 Hydraulic Properties
2.2.3 Hydrogeological Units
2.2.4 Well Yields and Aquifer Productivity
2.3 Groundwater Flow System
2.3.1 Average Groundwater Levels
2.3.2 Groundwater Flow
2.3.3 Depth of Freshwater Lens
2.4 Seasonal Groundwater Level Variation
2.4.1 Water Level
2.4.2 Seasonal Change in Volume of Stored Groundwater
2.5 Groundwater Recharge and Discharge
2.5.1 Surface Water on Gabriola Island
2.5.2 Estimating Groundwater Recharge from Precipitation
3. Water Budget
3.1 Water Budget Sub-Regions
3.2 Estimation Method for Pumping Water Demand
3.3 Water Demand Results
3.3.4 Total Pumping Demand
3.4 Water Stress
4. Data Gaps
4.1 Properties of Hydrogeological Units
4.2 Water Levels
4.3 Salt Water Intrusion and Depth of Freshwater
4.4 Water Budget
5.1 Hydrogeological Conceptual Model Assessment
5.2 Water Budget Assessment
5.3 Gaining a Better Understanding for the Future
List of Tables
- Table 1: Monthly water stress by water sub-region on Gabriola, Mudge, and DeCourcy Islands for low and high recharge scenarios.
- Table 2: Recommended data collection.
List of Figures
Most figures presented in the main report are symbolic and designed to visually introduce some sections and to improve understanding of text by non-technical readers. Find detailed technical graphs and maps in the Appendices.
- Figure 1: Regional District of Nanaimo and Electoral Area B.
- Figure 2: Nanaimo Group sequence of formations on Gabriola, Mudge, DeCourcy islands.
- Figure 3: Gabriola syncline and geological units in cross-sections.
- Figure 4: Fractured sandstone, mudstone, and fault zone.
- Figure 5: Ocean tides and water level fluctuations in wells.
- Figure 6: Hydrogeological units on Gabriola Island.
- Figure 7: Flow through fractures in sandstone and mudstone at exposed cut rock slope.
- Figure 8: Water table elevation and assumed flow directions: Gabriola Island.
- Figure 9: Cross-section of the Gabriola Island showing water table, water wells, and geological units.
- Figure 10: Groundwater flow in conceptual model of Gabriola Island.
- Figure 11: Freshwater-saltwater boundary and flow directions.
- Figure 12: Provincial Observation Wells on Gabriola Island.
- Figure 13: Provincial observation wells on Gabriola Island.
- Figure 14: Conceptual drawing describing seasonal change in groundwater level observed on Gabriola Island at a well in fractured rock and stepped water table.
- Figure 15: Water budget sub-regions for Gabriola, Mudge, and DeCourcy islands, showing simplified land use zoning and existing pumping wells (source: RDN, BC MOE).
- Figure 16: Water use type in sub-regions
- Figure 17: Monthly summer and winter pumping water demand for sub-regions.
- Figure 18: Residential pumping water use by use type of fixture and outdoor garden, comparing summer season and rest of year.
- Figure 19: Average monthly pumping water stress in sub-regions.
Details on specific components, methodologies and calculations, and technical references are presented in the appendices, with detailed technical graphs and maps.
Appendix A: Geological Review
Appendix B: Hydrogeological Conceptual Model
Appendix C: Tidal Analysis
Appendix D: Water Budget Data and Calculations