Table 1.
Response and predictor variables. Time periods for the mean variables are described in electronic supplementary material, table S2.
| response/predictor variable | category of variable | variable | unit |
|---|---|---|---|
| response | EC | electrical conductivity (EC) | mS cm−1 |
| ion concentration | Ca2+ | mg l−1 | |
| Mg2+ | mg l−1 | ||
 |
mg l−1 | ||
| predictor | geology | catchment mean CaO | % |
| catchment mean MgO | % | ||
| catchment mean S | % | ||
| catchment mean unconfined compressive strength | MPa | ||
| catchment mean log geometric mean hydraulic conductivity | 10−6 m s−1 | ||
| climate | catchment mean annual temperature | °C | |
| catchment mean annual precipitation | mm | ||
| catchment mean number of freeze days | days | ||
| soil | catchment mean available water capacity | dimensionless | |
| catchment mean bulk density | g cm−3 | ||
| catchment mean organic matter content | % | ||
| catchment mean soil erodibility | dimensionless | ||
| catchment mean soil permeability (kf) | m s−1 | ||
| catchment mean soil depth | m | ||
| catchment mean water table depth | m | ||
| topography | catchment area | km2 | |
| catchment mean elevation | m | ||
| vegetation | catchment mean enhanced vegetation index (EVI) | dimensionless | |
| groundwater | catchment mean recharge speed | mm year−1 |