Table 1.
Water availability and residence times in glacial/ice sheet compartments.
| Location | Water Presence in Accumulation Season | Residence Time and Water Flow | Important References |
|---|---|---|---|
| Ice-lidded cryoconite holes | Yes, but some can completely freeze during accumulation season | Years, but occasionally connected to the rest of the system during accumulation season. Estimates say that ~50% of the cryoconite holes hydrologically connect to the supraglacial system every accumulation season. | [61,91] |
| Open cryoconite holes | No | During accumulation season, they have a higher connectivity to the glacial system than ice-lidded cryoconite holes, showing lower permanence times. | [39,63] |
| Weathering crust | Yes, if insulated by a snowpack. | Several days, water is released to the glacial when the system is saturated. Water flow is slow in the interstitial space. | [55,58,60] |
| Supraglacial streams | No | Depending on the ablation stage of the system, water can flow at different rates. | [64] |
| Supraglacial ponds and lakes | Yes. Lakes can form ice lids and maintain water during accumulation season. | Years; water is released to the glacial when the system is saturated. Smaller ponds can be drained by meltwater streams. | [39,50,61,64] |
| Firn aquifer | Yes | Perennial; water is released to the glacial when the system is saturated. | [52,92,93,94,95] |
| Englacial conduits | Yes, when the presence of solutes and particles lowers water freezing temperature. | Fast-flowing systems with permanence of hours up to a day. However, water can be present all year round and even for multiple years if water pockets are formed by collapsed conduits. Depending on the ablation stage of the system, water can flow at different rates. | [88,96,97] |
| Ice veins | Yes | Residence times in the ice veins are unknown. However, due to the low water flowing rate, we assume it to be in the order of years (at the very least). | [98] |
| Subglacial cavities | Yes | Days to months, and water is usually present all year round. | [99,100,101] |
| Subglacial channels | No | Hours, water is usually present only during peak ablation season. | [99,100,101] |
| Subglacial till | Yes | Potentially all-year round. | [36,78] |
| Subglacial lakes | Yes | Years; some systems have estimated water residence times of millions of years. | [79,80,102] |