Environmental or ecological flow as a share of total flow—Hydropower
Measurement answer
What this metric measures
Percentage of total flow represented by environmental or ecological flow in covered hydropower systems, with disclosed treatment of climatic variability.
Specification
Metric specification
- Result format
- Single value
- Unit
- percent (%) — source-defined reporting unit
- Reporting basis
- Reporting period specified by the reporting organization
- Aggregation
- Percentage calculated for the disclosed hydropower-system reporting boundary; disclose any aggregation across assets, locations or time periods.
- Pillar
- Environmental
- Topic
- Water management and freshwater ecosystems
- Controlled domain
- Water and marine resources
- Entity type
- Metric
Reporting boundary
Hydropower systems within the reporting organization’s disclosed operational and geographic boundary for which environmental or ecological flow and total flow are assessed.
Verified source occurrences
Framework coverage
This is one canonical metric. The bindings below show every verified framework occurrence without creating duplicate metric pages. Edition, disclosure, role, and relationship remain source-specific.
- Adopting DisclosureSource evidence
TNFD sector guidance
- Publisher
- Taskforce on Nature-related Financial Disclosures
- Edition
- Final English sector guidance collection through August 2026 (17 documents)
- Requirement
- Not Specified
- Relationship
- Defines Disclosure
- Mapping outcome
- Direct Evidence
- Source locator
- p.68, Section 3.2, Table 13, EP.C1.1
- Adopting DisclosureEP.C1.1
TNFD sector guidance
- Publisher
- Taskforce on Nature-related Financial Disclosures
- Edition
- Version 1.0, June 2024
- Requirement
- Conditional
- Relationship
- Maps Source Identity
- Mapping outcome
- Published
- Source locator
- p.68, Section 3.2, Table 13, EP.C1.1
Value structure
Dimensions and units
- Unit
- percent (%) — source-defined reporting unit
- Reporting basis
- Reporting period specified by the reporting organization
Unit meaning: Values use percent (%) under the disclosed TNFD sector-guidance method, reporting period and boundary.
Published dimensions
- hydropower system or asset
- geographic location or watershed
- environmental or ecological flow basis
- total-flow basis
- time basis for flow measurement
- climatic-variability treatment
Calculation method
Formula information
- Status
- Specified
- Formula type
- Percentage
Formula
(Environmental or ecological flow / Total flow) × 100Apply the source-defined TNFD sector-guidance method within the stated reporting boundary. The source identifies a directly reportable percentage outcome with an explicit numerator concept, denominator concept and percentage unit. It is distinct from environmental provisions, pollutant removal, supplier assessments and certification metrics in the shortlist. Because climatic variability and aggregation choices affect comparability, they are retained as required method disclosures rather than converted into separate metrics.
Variables
| Symbol | Variable | Definition | Unit |
|---|---|---|---|
EF | Environmental or ecological flow | Flow maintained or designated as environmental or ecological flow for the covered hydropower system under the disclosed basis. | same flow unit and time basis as TF |
TF | Total flow | Total flow for the covered hydropower system over the same disclosed measurement basis as EF. | same flow unit and time basis as EF |
Verified sources
Evidence and status sources
Sustopedia checked each record-specific claim directly against primary publisher material. Labels distinguish current measurement authority from future compatibility and corroborative, legal, edition, or method status context. Corroborative evidence can support a stated limitation but cannot establish the core measurement by itself.
Measurement evidence
- Measurement evidenceChecked 30 August 2026
TNFD additional sector guidance collection
- Publisher
- Taskforce on Nature-related Financial Disclosures
- Edition
- Final English sector guidance collection through August 2026 (17 documents)
- Locator
- p.68, Section 3.2, Table 13, EP.C1.1
Supports: The official TNFD sector guidance supports the identity, boundary and method basis of “Environmental or ecological flow as a share of total flow—Hydropower”.
Open official source
Use with context
Interpretation boundaries
Method disclosures required
Source-edition basis: TNFD sector guidance, Final English sector guidance collection through August 2026 (17 documents).
- Define environmental or ecological flow and identify the ecological, regulatory or permit basis used.
- State the total-flow denominator and the measurement time basis used for both numerator and denominator.
- Identify covered hydropower systems, locations or watersheds and the organizational and operational boundary.
- Describe how climatic variability was considered, including El Niño–Southern Oscillation where relevant.
- Disclose the approach used to aggregate results across hydropower assets, locations or reporting periods.
Record-specific limitations
- The source excerpt does not prescribe a common hydropower-asset aggregation method.
- Environmental or ecological flow definitions and measurement methods may differ by watershed, permit regime and ecological assessment approach.
- Comparability depends on disclosure of the time basis and treatment of climatic variability, including El Niño–Southern Oscillation where relevant.
Interpret this metric with the stated reporting boundary, period convention, value shape, and unit. Results prepared with different boundaries or conventions may not be directly comparable.
Measurement evidence supports the core record-specific claims described above. Corroborative evidence can support limitations, while compatibility and status sources provide their separately labelled context. None of these cards by itself determines an organisation's legal applicability, filing readiness, assurance status, or compliance conclusion.