Towards a Water Scarcity & Drought Indicator System (WSDiS) Maggie Kossida – ETC/Water

Presentation Outline Water Scarcity Indicators for Awareness Rising Relevant Water Stress Indicator (RWSI) Storage Indicator (St) Water Use per sector (WUs)

Relevant Water Stress Indicator (RWSI) Key Message Designed to depict the balance between natural renewable water resources and abstraction, in order to assess the prevailing water stress conditions in a catchment. Refinement of the WEI and other relevant indicators (e.g. WAI, WSI etc.) Provides more accurate metrics of evaluating the relevant water scarcity in a catchment, since it considers the “true” volume of water which is available for exploitation accounting for environmental requirements and returned water In line with WFD (The level of stress or relevant water scarcity in a catchment changes if we subtract an amount of water that is not actually available for abstraction since it needs to be left in the catchment to maintain its ecological status)

Relevant Water Stress Indicator (RWSI) RWSI = ABS / RWA Relevant Water Stress Indicator (RWSI) = Percent of Total Freshwater Abstracted over the total Renewable Water Availability Where: ABS = Total Freshwater Abstracted RWA = Renewable Water Availability Metrics: annual (or monthly if available) values should be plotted and compared to the Long Term Annual Average (LTAA) of the last 20 years or the longest timeseries available to assess the trend. Spatial scale: River basin (RB) or WFD River Basin District (RBD) Temporal scale: Annual, monthly if possible

Relevant Water Stress Indicator (RWSI) Methodology a. Calculation of Renewable Water Availability (RWA) RWA = P – Eta + I – EF + R Where: Precipitation (P) = [total volume of all forms of precipitation which falls over the catchments in hm3] Actual Evapotranspiration (ETa) = [total volume of water which evapotranspirates over the whole catchments area in hm3] External Inflow (I) = [total volume of water in hm3 flowing into the catchment from upstream and/or neighboring catchments, refers both too surface and groundwater inflows as a sum] Environmental Flow (EF) = [minimum volume of water in hm3 that needs to be sustained for environmental purposes] Returned water (R) = [volume of abstracted water that is discharged to the catchment’s fresh water resources either before use as losses or after use, e.g. hydropower, in hm3. Discharges to the sea are excluded.)

Relevant Water Stress Indicator (RWSI) Methodology b. Calculation of Freshwater Abstraction (ABS) ABS = ABS_SW + ABS_GW Where: Total Freshwater Abstraction (ABS) = [total volume of all freshwater abstracted regardless of source and type of water supply system from the catchment’s freshwater sources in hm3] Total Freshwater Abstracted from surface water resources (ABS_SW) = [total volume of freshwater abstracted from the catchment’s surface water resources only, regardless of the type of water supply system in hm3] Total Freshwater Abstracted from groundwater resources (ABS_GW) = [total volume of freshwater abstracted from the catchment’s groundwater resources only, regardless of the type of water supply system, in hm3]

Relevant Water Stress Indicator (RWSI) Comments Provides better metrics of the actual water stress conditions in comparison with other relevant indicators/indices The parameters of the RWSI are requested under the WISE-SoE#3 reporting (except the EF) The calculation of environmental flow (EF) is not globally established, and there may be differences in the implemented methodologies, yet member states have calculated EF on the basis of the WFD RBMPs reporting. The indicator is relatively easy to calculate and straightforward to use. The indicator can readily be integrated with other indicators at the same scale and used for water management purposes, or to better assess the drivers and impacts of water scarcity. It is particularly meaningful to evaluate the RWSI together with an indicator on Storage

Storage Indicator (St) Key Message Important for evaluating the total water availability of the catchment, especially during periods where the renewable water availability is low (either due to low precipitation or limited inflows in the catchments). This indicator does not reflect the storage capacity (which may be higher due to infrastructure and related water works), but the actual water stored in the surface and groundwater reservoirs over the previous time step (month or year). Combined with additional indicators on water abstraction and use the St indicator can communicate messages on how much of the stored water is used up and from which economic activity, during which periods and at what rates, thus allowing for proper water management.

Storage Indicator (St) Storage (St) Total volume of water in hm3 stored in the catchment, both in surface and groundwater reservoirs, during the reference period t Metrics: annual (or monthly if available) values should be plotted and compared to the Long Term Annual Average (LTAA) of the last 20 years or the longest timeseries available to assess the trend. Spatial scale: River basin (RB) or WFD River Basin District (RBD) Temporal scale: Annual, monthly if possible

Storage Indicator (St) Methodology St = St-1 + ΔSt (e.g. S2010 = S2009 + ΔS2010) Where: Storage (St) = [total volume of water in hm3 stored in the catchment, both in surface and groundwater reservoirs, during the reference period t] Difference in Storage (ΔSt) = [the difference in the volume of water in hm3 stored in the catchment between the reference period t and the previous period t-1, in all the surface and groundwater reservoirs] ΔSt = P - ETa + I + R – Abs - O ΔSt, P, ETa, I, R, Abs as mentioned previously (units in hm3) Outflow (O) = [the total outflow from the catchment to a downstream and/or a neighboring catchment in hm3 as measured at the outlets. The total outflow includes the environmental flow releases EF]

Storage Indicator (St) Comments Many MS use this indicator but mostly broke down into surface water storage (lakes and reservoirs, snowpack) and groundwater storage (aquifers). Data for the calculation of the St can be provided by the WISE-SoE#3 reporting The change in storage (ΔSt) which is used to compute the indicator is calculated based on the parameters of the hydrological cycle, thus is supposes that hydrological balance of the area is accuraletly simulated. Yet, it can be measured as well when broken down by components (surface water storage i.e. lakes and reservoirs, groundwater, snowpack storage) Relatively easy to calculate and straightforward to use Can readily be integrated with other indicators at the same scale and used for water management purposes, or to better assess and impacts of water scarcity It is particularly meaningful to evaluate the Storage together with an indicator on water exploitation and renewable water availability.

Water Use per sector (WUs) Key Message Designed to depict the volume of water that is actually used by end users for a specific purpose within a territory, such as for domestic use, agriculture or industrial processing. Provides accurate metrics of evaluating the water allocation between the different economic activities and their water use intensity Provides useful information to be considered in the design of economic and policy response measures which cut across all sectors, e.g. cap and trade, voluntary trading of water rights etc.

Water Use per sector (WUs) Indicator Water Use per sector (WUs) Where: Water Use per sector (WUs) = Total Volume of all Freshwater Used from a specifc user sector Metrics: annual (or monthly if available) values should be plotted and compared to the Long Term Annual Average (LTAA) of the last 20 years or the longest timeseries available to assess the trend. Spatial scale: River basin (RB) or WFD River Basin District (RBD) Temporal scale: Annual, monthly if possible

Water Use per sector (WUs) Methodology Total Freshwater use (WU) can be divided based on the actual economic sectors that use the resource (based on NACE classes). Therefore, six sub-indicators may be introduced that have the same assessment, units, and spatial and temporal scale characteristics with the main freshwater use indicator: Total Volume of Domestic freshwater use Total Volume of Agricultural freshwater use (NACE A) Total Volume of Mining & Quarrying freshwater use (NACE B) Total Volume of Manufacturing freshwater use (NACE C) Total Volume of Energy freshwater use (NACE D) Total Volume of Services freshwater use (NACE I) Total Volume of Other freshwater use (Other) The SUM of the above six sub-indicators is ≤ of the Total Volume of freshwater used

Water Use per sector (WUs) Comments Water Use data are collected through the WISE-SoE#3 and Eurostat JQIWA. Water use data are often at a different aggregation level (NUTS) and available by the statistical services, which may cause some problems of comparability. Yet, these data have been reported in the RBMPs of the WFD and thus it should be easy to obtain them It is an open question whether these data are actually measured (by the water services and then disseminated) or calculated based on proxies. The indicator is relatively easy to calculate and straightforward to use The indicator can readily be integrated with other indicators at the same scale and used for water management purposes, or to better assess the drivers and impacts of water scarcity Evaluation of water used by the different economic activities along with additional supporting socio-economic data is strongly related with issues of: Water allocation and equity, Prioritisation of conflicting water uses, Environmental cost recovery, Water pricing, Water efficiency

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