2. Spain 2015
Environment Agency North East Thames
Area – ‘my patch’
2
3,500 km sq
Over 6 Million population
Urban: London north of Thames river
Rural: Hertfordshire and parts of Essex,
Bedfordshire, and Buckinghamshire
with larger towns
over 500,000 ML/yr, mainly Public
Water Supply
Chalk Aquifer and Chalk Rivers
3. Spain 2015
Chalk rivers we are protecting
3
March 2013 wet year March 2012 dry year
River Misbourne
Lower Bottom,
looking upstream
River Beane
Frogmore Hall,
looking downstream
4. Spain 2015 4
Why Water Footprint
Assessment?
Abstraction
Effluent
discharge
Regulations /
Management
Water use and
contamination
Water
scarcity
Water
pollution
Cause Effect
WFA
Water
available
5. Spain 2015
Water Footprint Assessment – project plan
5
Water
footprint
sustainability
assessment
Water
footprint
accounting
Water footprint
response
formulation
Setting goals
and scope
Phase 1 Phase 2 Phase 3 Phase 4
Water scarcity
Water pollution
Climate change
Groundwater and
surface water
Quantity and
quality
Domestic
agriculture and
industry
1 Carry out Water
Footprint
Assessment of
SENET with
future outlook
2 Communicate
water scarcity
and pollution
issues
3 Recommend
improvements to
water
management
6. Spain 2015 6
Water Footprint Accounting and Assessment
Surface Water and Groundwater Blue Water Footprint
7. Spain 2015 7
Water Footprint Accounting and Sustainability Assessment
Surface Water and Groundwater Blue Water Footprint
8. Spain 2015 8
Water Footprint Sustainability Assessment
Groundwater Blue Water Footprint
13. 13Spain 2015 www.waterfootprint.org
Zhang et al., 2014
Water footprint response formulation
Quantity and Quality,
license under
conditions
Quantity and Quality
(PS only)
Quantity, license
under conditions
Quality (PS and NPS)
Quality (PS only)
BWS & WPL within
sustainable limit,
license period. review
14. 14Spain 2015 www.waterfootprint.org
Key learnings
Zhang et al., 2014
WFA unifies both quantity and quality aspects in water resources
assessment, planning and management.
WFA finds the links between water use, water management and water
scarcity and pollution levels, thus helping better identify cause-effect
relationships among these elements.
WFA looks at the water quality issue from the pollution load perspective
rather than only the pollutant concentration using the waste assimilation
approach. This highlights where the assimilation capacity has been
exceeded even when the pollutant concentrations meet quality
standards.
WFA is an innovative approach able to support in reforming the current
regulatory system for water abstraction license and discharge permit,
and therefore useful for formulating effective response strategies to
mitigate blue water scarcity and water pollution levels.
Footprint calculation based on CAMS data for water resources and Assessment point from CAMS are base units.
EA regulates water resource to protect the environment. Groundwater in Chalk Aquifer important in for drinking water and environment.
Why this project?
Outline of project
12 APs have blue WF on surface water as a result of industrial water use, all of which are due to the lost return flow. See the red arrows as example.
3 APs have blue WF on surface due to domestic water use, resulting from the lost return flow. See the red arrows as example.
Assessment:
1 = blue footprint is equal to safely available water for environment
3 = blue footprint is three times the safely availabe water.
It changes over the year because of changes in safely required flow
Blue Water Scarcity = Total Blue WF / (Natural Runoff – Environmental Flow Requirements)
Total Blue WF (surface&ground water) = Blue WF_indus + Blue WF_domes + Blue WF_agri, here the distinction is not made between groundwater and surface water.
Environmental Flow Requirements (EFR) usual takes x% of the natural flow. Here 80% (uniform throughout the SENET catchments) is used following the previous literature. Dunbar (CEH) et al. (2004) propsoed an approach to different environmental weighting for England and Walse, in which it suggests percentages of Q95 natural flow that can be abstracted depending on environmental weighting (ecological sensitivity and objectives). The suggested percentages range between 0 – 30%, which is generally in accordance with what we did here.
EFR = 60% x Natural Runoff was also applied to assess the blue water scarcity.
This analysis gives a first indicative result, once more accurate/actual data on EFR become available, the assessment can be refined.
Based on the blue WF accounting results and water availability, we can see now the where and when the blue water consumption has exceeded the sustainable level. You can see the sub-catchments with red or redish color are those where the blue WF is larger than the water availability. We call these blue water scarcity hotspots. This is the monthly variation of overall BWS and this is the monthly variation of groundwater BWS. You see mostly the upstream subcatchment has more severe BWS than the downstream ones, that is because the water abstrated from those places after use were transported to the places where swereage treatment works are located resulting in higher BWS.
12 APs have blue WF on surface water as a result of industrial water use, all of which are due to the lost return flow. See the red arrows as example.
3 APs have blue WF on surface due to domestic water use, resulting from the lost return flow. See the red arrows as example.
Assessment:
1 = blue footprint is equal to safely available water for environment
3 = blue footprint is three times the safely availabe water.
It changes over the year because of changes in safely required flow
Blue Water Scarcity = Total Blue WF / (Natural Runoff – Environmental Flow Requirements)
Total Blue WF (surface&ground water) = Blue WF_indus + Blue WF_domes + Blue WF_agri, here the distinction is not made between groundwater and surface water.
Environmental Flow Requirements (EFR) usual takes x% of the natural flow. Here 85% (uniform throughout the SENET catchments) is used following the previous literature. Dunbar (CEH) et al. (2004) proposed an approach to different environmental weighting for England and Wales, in which it suggests percentages of Q95 natural flow that can be abstracted depending on environmental weighting (ecological sensitivity and objectives). The suggested percentages range between 0 – 30%, which is generally in accordance with what we did here.
EFR = 60% x Natural Runoff was also applied to assess the blue water scarcity (not much difference though)
You see mostly the upstream subcatchment has more severe BWS than the downstream ones, that is because the water abstrated from those places after use were transported to the places where swereage treatment works are located resulting in higher BWS.
Assessment:
1 = blue footprint is equal to safely available water for environment
3 = blue footprint is three times the safely availabe water.
It changes over the year because of changes in effective rainfall recharge
Blue Water Scarcity = Total Blue WF / (10% of natural effective rainfall)
Total Blue WF (&ground water) = Blue WF_indus + Blue WF_domes + Blue WF_agri, only groundwater.
This analysis gives a first indicative result based on generally applied sustainability criterion of 10% effective rainfall availabe for abstractions.
The grey water footprint for point sources (57 large STWs and 111 small STWs) were calculated at the monthly time scale. 12 WQ determinants were considered.
Grey WF for groundwater due to point source discharge was estimated. The grey WF for groundwater was evaluated only with respect to NH4-N.
Total Grey WF due to non-point source pollution, WF_grey (agri),resulting from leaching of fertilizers applied in agricultural lands was estimated with respect to nitrogen.
Assessment: Water Pollution Level (WPL) = Total Grey WF (point source_surface + non-point source_surface) / Actual Runoff
Here Actual Runoff = Gauged flow + Return flow (i.e. the lost return flow coming from other APs).
Some of the APs have high WPL (e.g. those in the upstream catchment), due to high grey WF from non-point source (agri.) leaching, in combination of relatively low actual runoff.
The grey water footprint for point sources (57 large STWs and 111 small STWs) were calculated at the monthly time scale. 12 WQ determinants were considered.
Grey WF for groundwater due to point source discharge was estimated. The grey WF for groundwater was evaluated only with respect to NH4-N.
Total Grey WF due to non-point source pollution, WF_grey (agri),resulting from leaching of fertilizers applied in agricultural lands was estimated with respect to nitrogen.
Assessment: Water Pollution Level (WPL) = Total Grey WF (point source_surface + non-point source_surface) / Actual Runoff
Here Actual Runoff = Gauged flow + Return flow (i.e. the lost return flow coming from other APs).
Some of the APs have high WPL (e.g. those in the upstream catchment), due to high grey WF from non-point source (agri.) leaching, in combination of relatively low actual runoff.
Assessment:
1 = blue footprint is equal to safely available water for environment
3 = blue footprint is three times the safely availabe water.
It changes over the year because of changes in effective rainfall recharge
Blue Water Scarcity = Total Blue WF / (10% of natural effective rainfall)
Total Blue WF (&ground water) = Blue WF_indus + Blue WF_domes + Blue WF_agri, only groundwater.
This analysis gives a first indicative result based on generally applied sustainability criterion of 10% effective rainfall availabe for abstractions.
Water Footprint and EA remit / roles
Following this approach, we present a new systematic licensing scheme, as shown here. As elaborated in the last slide, a license can be granted with conditions based on both water scarcity and water pollution level of the catchment. It can be based on only water scarcity situation if grey WF does not exceed the sustainable level or only on the water pollution level if the blue Wf does not exceed the sustainable limit. And so on.
To conclude, we share here some key learnings from this study.
This WFA study explored the effect of return flows through sewage treatment works on both blue water scarcity and water pollution levels at the sub-catchment level. This exploration may suggest a possible strategy to cope with climate change and future water demand increases.
The WFA results make the spatial and temporal nature of water consumption and pollution explicit.
The information from this WFA results can function as an instrument for discussion and dialogue between regulators, water utilities and water users for a better informed water management.
