Water Accounting Plus (WA ) Sheet 1: Resource Base
| Wa+ Sheet 1 Flux | Description | Data used | Calculation approach |
|---|---|---|---|
| Padvection | Precipitation | WaPOR L1_PCP_M | Aggregate by hydrological year |
| Qdesal | The inflow from desalinated water | Input time-series (optional) | Aggregate by hydrological year |
| Qswin | The inflow from surface water (i.e. interbasin surface water inflow) | Input time-series (optional) | Aggregate by hydrological year |
| Qgwin | The inflow from groundwater water (i.e. interbasin groundwater inflow) | Input time-series (optional) | Aggregate by hydrological year |
| Gross Inflow | Total inflow from all sources | - | Padvection + Qdesal + Qswin + Qgwin |
| ΔS | Flow from total water storage change | - | Netinflow - Gross Inflow |
| Rainfall ET | ET that occurs from effective rainfall and canopy interception. Effective rainfall is the part of the rainwater that does not percolate below the root zone, flows away over the soil surface as run-off, or evaporates from canopy interception, thus, available in the root zone and can be used by plants | WaPOR-derived ET rainfall | Aggregate by hydrological year and Landuse Categories |
| Incremental ET | ET that occurs from other sources except effective rainfall and interception. For example, evaporation of irrigation water, evaporation of groundwater through deep-rooted vegetation, water evaporation over a lake or other water surface that exceeds the rainfall on the water body itself. | WaPOR-derived ET incremental | Aggregate by hydrological year and Landuse Categories |
| Landscape ET | ET that occurs naturally, not due to water management (i.e. evaporation on managed reservoirs, or ET from irrigation water). | - | Rainfall ET + Total incremental ET of Protected Landuse, Utilized Landuse, and Modified Landuse |
| Consumed water/ ET | ET occurs as interception, evaporation, soil evaporation, water evaporation, canopy transpiration/ The total Evapotranspiration is evapotranspiration from non-manageable, manageable and managed land uses | WaPOR L2_AETI_M | Aggregate by hydrological year |
| Utilized flow | ET from managed water use (i.e. irrigated crops, managed reservoirs) | - | MWU Incremental ET |
| Exploitable water | The net inflow minus Landscape ET | - | Utilized flow + Outflow |
| Qswoutlet | The river outflow at the outlet of the basin | Input time-series | Aggregate by hydrological year or zero for endorheic basin |
| Qswout | The outflow as surface water (i.e. interbasin surface water outflow) | Input time-series (optional) | Aggregate by hydrological year |
| Qgwout | The outflow as groundwater (i.e. interbasin surface water outflow) | Input time-series (optional) | Aggregate by hydrological year |
| Non-consumed water/ Outflow | Total outflow | - | Qswoutlet + Qswout + Qgwout |
Based on the WA+ sheet 1, a number of key performance indicators, which were developed by Dost et al. (2013) in consultation with the Land and Water Division of FAO, can be calculated to describe the entire system. These indicators help the basin planners to understand the key information on water management in the basin (Karimi, 2014).
The first set of indicators can be related to the Resource Base Sheet:
1. ET Fraction = ETtot / (P + Qin) (%)
o ET fraction indicates which portion of the total inflow of water is consumed and which part is converted into renewable resources. A value higher than 100% indicates over- exploitation or a dependency on external resources.
2. Stationarity Index = ΔStorage / ETtot (%)
o Stationarity Index is an indication of the depletion of water resources. Positive values indicate that water is added to the groundwater and/or surface water storage. Negative values indicate a depletion of the storage.
3. Basin Closure = 1 - Outflow / (P + Qin) (%)
o Basin Closure defines the percentage of total available water resources (Precipitation + basin inflow) that is consumed and/or stored within the basin. A value of 100% indicates that all available water is consumed and/or stored in the basin.
The second set of indicators focuses on the actual amount of water that is currently managed, or is available to be managed:
4. Available Water (AW) = Gross Inflow – Landscape ET – Reserved flow (km3/year)
o Total amount of water that is available to be managed.
5. Managed Water (MW) = Incremental ET of Managed Water Use (km3/year)
o Total amount of water that is abstracted for Managed Water Use.
6. Managed Fraction = Managed Water / Available Water (%)
Percentage of water that is actually managed from the total amount of water that is available.
Dost, R., Obando, E.B., Bastiaanssen, W., Hoogeveen, J., 2013. Water Accounting Plus (WA+) in the Awash River Basin. Coping with Water Scarcity – Developing National Water Audits Africa [WWW Document]. URL https://www.wateraccounting.org/files/projects/awash_basin.pdf (accessed 1.8.19).
Karimi, P., 2014. Water Accounting Plus for Water Resources Reporting and River Basin Planning (PhD thesis). TU Delft, Delft, The Netherlands.