Fraser Aquifer System

Aquifer System

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Fraser Lowlands

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Fraser Aquifer System unit description

Update:2014-03-03

Physiography
The regional aquifer system is composed of two main types of aquifers: fractured bedrock and granular aquifers. In ascending order, the stratigraphy of the area shows a glaciofluvial sand and gravel unit which is exposed and overlies fine sediments (clay and silt) of Fort Langley and Capilano Formations which overlie till discontinuous unit. Marine sediments, overlying the bedrock are found under the till unit. The bedrock of Fraser Lowland and Fraser River delta consists of three, fundamentally different tectono-stratigraphic units: 1) plutonic rocks and subordinate metasedimentary and metavolcanic rocks; 2) formations of sandstone, conglomerate and mudstone and 3) contact between the Paleogene-Neogene succession and Quaternary deposits. The glaciofluvial sediments comprise the granular aquifers. There are many aquifers in the glaciofluvial sediments; mapping has identified more than 200 aquifers in the region. Informations on granular aquifers are from Brookswood and Abbotsford-Sumas aquifers. Granular aquifers are separated from the roc aquifer by aquitard units, which limited the interaction between the aquifers. Water percolates through the glaciofluvial sediments or fractures of coastal mountains. In the granular aquifer, it flows through the voids. In the rock aquifer, the intergranular porosity is very low thus water flows through complex fracture systems. It mostly discharges by submarine seepage. Considering that it is covered by multiple sediments units, the bedrock aquifer has low vulnerability. However, the granular aquifers are very vulnerable to contaminations. Those aquifers are characterized by good aquifer potential and are exploited for commercial, municipal and domestic uses and for irrigation. The rock aquifer has low aquifer potential. It is less exploited than the granular aquifers, but it represents the source of ground water for areas north of the Fraser River sediments. In general, records of ground water quality analyses reviewed for the Fraser Basin show the groundwater is usually high in dissolved mineralization and also hard.
Hydrogeological region	Cordillera
Hydrogeological context
Relief	North and south of the Fraser River, the Fraser Lowland consists mainly of gently rolling and flat-topped uplands, with elevation less than 175 m and separated by wide flat-bottomed valleys.
Area	2006.00 km2
Lithology
Description	In descending order, the glaciofluvial sand and gravel unit (unit C) is exposed and overlies fine sediments (clay and silt) of Fort Langley and Capilano Formations (units A and B) which overlie till discontinuous unit (unit D). Marine sediments, overlying the bedrock is found under the till unit. The bedrock of Fraser Lowland and Fraser River delta consists of three, fundamentally different tectono-stratigraphic units: 1) plutonic rocks and subordinate metasedimentary and metavolcanic rocks; 2) formations of sandstone, conglomerate and mudstone and 3) contact between the Paleogene-Neogene succession and Quaternary deposits.
Source
Aquifer
Aquifers	List of aquifer regional bedrock aquifer sedimentary Brookswood aquifer sedimentary Abbotsford-Sumas aquifer many other granular aquifers

Unit properties

Surficial aquifer media


Typical value:	porous
Description	Glaciofluvial sand and gravel
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Bedrock aquifer media

Typical value:	fractured
Description	Plutonic rocks; sedimentary rocks and high relief erosion surface in the contact area between the Paleogene-Neogene succession and Quaternary deposits.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Confinement

Typical value:	confined - unconfined
Description	Granular aquifers : Mostly unconfined Rock fractured aquifer : confined
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Surficial sediment thickness

Description	Generally, the sediments thickness is above 300 m.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Regional precipitation
1200 mm/y
Description	Annual precipitation over most of the aquifer averages 1200 mm/yr.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Regional recharge

Description	Granular aquifer are directly recharge by precipitations or by rivers. Rock aquifer is recharged by the coastal mountains.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Regional discharge

Description	At regional scale, the main discharge is submarine seepage.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Hydrogeological unit yield

Description	Individual well yields in the rock aquifer rarely exceed 1 l/s. Granular aquifers are characterized with much more important yields.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Hydrogeological unit potential

Typical value:	medium regional
Description	Granular aquifers have a good aquifer potential while rock aquifer is characterized by low aquifer potential.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Groundwater usage

Typical value:	domestic - industrial
Description	The granular aquifers are exploited for commercial and domestic uses and for irrigation. The rock aquifer is exploited for domestic use.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Aquifer vulnerability

Description	Granular aquifers are exposed and present moderate to high vulnerability. The fractured rock aquifer is protected by sediments cover and has low vulnerability.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.

Groundwater Quality

Typical value:	fresh - hard
Description	In general, records of ground water quality analyses reviewed for the Fraser Basin, show the ground water is usually high in dissolved mineralization and also hard.
Source	Chapter 9 -- Ground Water Resources of the Basins, Lowlands and Plains 9.1 COASTAL BASINS, LOWLANDS AND PLAINS. 9.1.1 FRASER LOWLAND.