Table 1 Major flows and storages considered within heritage hydrology, their characteristics and major effects
Category | Name | Magnitude and frequency | Spatial cover | Major effects |
|---|---|---|---|---|
Inputs | Wind-driven rain (WDR) | High magnitude, low frequency (but variable) | General (certain directions favoured) | Water ingress to porous materials, runoff generation |
Capillary rise | Continuous, with high magnitude, low frequency events | Lower parts of structures | Water ingress to porous materials, deep-seated wetness generation | |
Capillary condensation | Continuous | General | Material moisture equilibrium (“ baseline”) | |
Surface floodwater | High magnitude, low frequency | Lower parts of structures | Water ingress to porous materials, deep-seated wetness generation | |
Throughputs | Runoff (down facade) | Low magnitude, low frequency | Patchy | Supports biofilms and chemical transformation on building surfaces |
Ingress (capillary) | Low magnitude, low frequency (corresponds to WDR) | General (certain directions favoured) | From WDR and capillary rise | |
Ingress (cracks) | High magnitude, low frequency | Patchy | Higher velocity flow through cracks and design faults, gravity influenced | |
Storages | Surface wetness | Patchy | Influenced by factors controlling ‘time of wetness’, affects biofilms/chemical reactions | |
Deep-seated wetness | General | Influencing indoor climate, mould etc | ||
Outputs | Splash | Low magnitude, low frequency | Patchy | Driving rain may be splashed away from less porous or saturated surfaces |
Runoff (to ground) | Low magnitude, low frequency | Patchy | Usually controlled by ‘water goods’ (drainpipes etc.) in managed buildings | |
Evaporation | Continuous | General | Encourages internal water movements and transport of soluble salts |