3. Supply – use balance
This section is based on a comparison of runoff estimates by the SWY InVEST model and data on water consumption from ArmStat regional statistics.
Water use in marzes in 2023, mln m3
| Marzes | Drinking, domestic | Industry, communal, building | Agriculture, fish breeding, forestry | Total use |
| Aragatsotn | 3.7 | 1.3 | 226.3 | 231.3 |
| Ararat | 6.7 | 6 | 799.3 | 812 |
| Armavir | 10.2 | 13.5 | 514.1 | 537.8 |
| Gegharkunik | 24.5 | 0.8 | 29 | 54.3 |
| Kotayk | 8.6 | 8.6 | 147.1 | 164.3 |
| Lori | 9.3 | 5.7 | 3 | 18 |
| Shirak | 7.9 | 2.2 | 53 | 63.1 |
| Syunik | 16.3 | 57.1 | 6 | 79.4 |
| Tavush | 8.1 | 1.7 | 11.1 | 20.9 |
| Vayots Dzor | 2.4 | 0.5 | 21 | 23.9 |
| Yerevan city | 59.8 | 40.6 | 156.5 | 256.9 |
Ararat, Armavir and Yerevan city are water-deficient marzes. The discharge from their territory is significantly less than the water consumption. The total flow from the territories of other marzes provides the total water consumption.
Baseflow is most important for agricultural water use because it provides flow during the hot summer months when water demand is greatest. Baseflow residence time spans months to years and the baseflow is distributed throughout this period, not just in the summer months. However, the comparison of baseflow and agricultural water use can be useful for assessing the water deficit in marzes. In these terms, the Ararat and Armavir marzes become even more water-deficient. Baseflow is less than agricultural water use also in Yerevan city and marzes Aragatsotn and Kotayk.
In the Aragatsotn, Ararat, and Armavir and marzes baseflow provides 5-7% of agricultural water consumption, in Kotayk 95% (it should be remembered that this figure does not include the flow from Sevan), in other marzes the baseflow is several times higher than water consumption.
| Baseflow, mln m3 | Quick flow, mln m3 | Total flow, mln m3 | Water use in agriculture, fish breeding, forestry, mln m3 | Total water consum-ption, mln m3 | Difference between total runoff and total water consumption in marzes, 2023 | Difference between baseflow and agricultural water consumption in marzes, 2023 | Share of baseflow in agricultural consumption, % | |
| Vayots Dzor | 91 | 152 | 243 | 21 | 24 | 220 | 70 | 434 |
| Tavush | 100 | 233 | 333 | 11 | 21 | 312 | 89 | 898 |
| Syunik | 139 | 357 | 496 | 6 | 79 | 417 | 133 | 2323 |
| Shirak | 228 | 337 | 565 | 53 | 63 | 502 | 175 | 431 |
| Lori | 281 | 440 | 721 | 3 | 18 | 703 | 278 | 9369 |
| Kotayk | 139 | 189 | 328 | 147 | 164 | 164 | -8 | 95 |
| Gegharkunik | 222 | 615 | 838 | 29 | 54 | 783 | 193 | 766 |
| Armavir | 27 | 58 | 85 | 514 | 538 | -453 | -487 | 5 |
| Ararat | 59 | 104 | 162 | 799 | 812 | -650 | -741 | 7 |
| Aragatsotn | 168 | 249 | 418 | 226 | 231 | 186 | -58 | 7 |
The boundaries of marzes largely coincide with the boundaries of large basins
| Basins | Marzes |
| Aghstev | Tavush |
| Akhuryan | Shirak |
| Arpa | Ararat and Vayots Dzor |
| Debed | Lori |
| Hrazdan | Gegharkunik, Kotaik and Erevan city |
| Metsamor | Armavir and Aragatsotn |
| Vorotan | Syunik |
If errors caused by discrepancies between watershed and marz boundaries are disregarded, it is possible to roughly estimate the ratio of provided to utilized services in the basins. According to this rough estimate, water consumption exceeds flow in Arpa and Metsamor watersheds, which means that the population and economy in these basins consume underground waters or surface water from other watersheds.
