Parameter

Range

Rating

Relative weighting

Depth to water (D)

0 - 2 m

7

5

2 - 5 m

6

5 - 9 m

5

9 - 15 m

4

15 - 23 m

3

23 - 30 m

2

>30 m

1

recharge by rainfall

3

1

4

4

2

5

3

6

4

7

5

8

6

9

7

Aquifer media (A)

Massive shale

2

3

Metamorphic/igneous

3

Weathered met./igneous

4

Bedded sandstone, limestone

6

Shale sequences

6

Massive sandstone

6

Massive limestone

6

Sand and gravel

8

Basalt

9

Karst limestone

10

Soil media (S)

Soil thin or absent

10

2

Gravel

9

Sand

8

Peat

7

Shrinking and/or aggregated clay

4

Sandy loam

5

Loam silty loam

4

Clay loam

3

Muck

2

Non-shrinking and non-aggregated clay

1

Topography (T)

0% - 2%

7

1

2% - 6 %

6

6% - 10%

5

10% - 16%

3

16% - 25%

2

>25%

1

Impact of vadose zone

Confining layer

1

5

Silt/clay

3

Shale

3

Limestone

6

Sandstone

6

Bedded limestone, sandstone shale

6

Sand and gravel with significant silt & clay

6

Metamorphic/igneous

4

Sand and gravel

8

Vesicular basalt

9

Karst limestone

10