Table 2 Parameters, class/rating, and weight factors for the DRASTIC-P and DRASTIC indexes and SI (adapted from [5, 69]

D

The depth to water table (m)

0–1.5

10

5

5

0.186

1.5–3

9

3–4.5

8

4.5–9

7

9–15

5

15–22.5

3

22.5–30

2

Up to 30

1

R

Net recharge (mm)

 > 250

9

4

4

0.212

180–250

8

100–180

6

50–100

3

0–50

1

A

Aquifer media

Karst limestone

10

3

3

0.259

Basalt

9

Sand and gravel

8

Massive sandstone and limestone

7

Bedded sandstone and limestone

6

Glacial

5

Weathered metamorphic/igneous

4

Metamorphic/igneous

3

Massive shale

2

S

Soil media

Thin or absent, gravel

10

5

2

–

Sandstone and volcanic

9

Peat

8

Shrinking/aggregate clay/alluvium

7

Sand loam, schist, sand, karst volcanic

6

Loam

5

Silty loam

4

Clay loam

3

Muckacid, granitoid

2

Non-shrink and nonaggregate clay

1

T

Topography (slope) (%)

0–2

10

3

1

0.121

2–3

9

3–4

8

4–5

7

5–6

6

6–10

5

10–12

4

12–16

3

16–18

2

 > 18

1

I

Impact of the unsaturated zone

Karst limestone

10

4

5

–

Basalt

9

Sand and gravel

8

Gravel, sand

7

Limestone, gravel, sand clay

6

Sandy silt

5

Metamorphic gravel and sandstone

4

Shale, silt, and clay

3

Silt clay

2

Confining layer, granite

1

C

Hydraulic conductivity

\(>6.5{e}^{-4}\)

10

2

3

–

\(5{e}^{-4}-9.5{e}^{-4}\)

8

\(33{e}^{-5}-5{e}^{-4}\)

6

\(15{e}^{-5}-33{e}^{-5}\)

4

\(5{e}^{-5}-15{e}^{-5}\)

2

\(1.5{e}^{-7}-5{e}^{-5}\)

1

LU

Land use

–

–

–

–

0.222