Table 2.6: Methods used in the assessment of ecological flow requirements and the types of hydrological alteration for which they could be used
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| Rivers and streams |
Situation where model could be used |
Tool |
|---|---|---|
Historical flow methods Regional methods Expert panel |
Abstraction of water |
|
Flow variability analysis |
Assessment of the degree of hydrological alteration and identification of elements of flow regime that are changed |
RVA (Range of Variability), Indices of Hydrological Alteration (IHA), Ecological Limits of Hydrological Alteration (ELOHA) |
Generalised habitat models |
Abstraction of water |
WAIORA (Water Allocation Impacts on River Attributes) |
Periphyton biomass model |
Impoundments or diversions where the frequency of floods and freshes is altered |
Look-up Table in Periphyton Guidelines |
1D hydraulic model and habitat evaluation |
Abstractions, diversions, or impoundments |
RHYHABSIM (river hydraulic habitat simulation), PHABSIM (physical habitat simulation), RHABSIM (river habitat simulation) |
2D hydraulic model and habitat evaluation |
Abstractions, diversions, or impoundments affecting hydraulically complex rivers (eg, braided rivers) |
River2D, Hydro2de (Hydro2de habitat analysis is done by post-processing of results) |
Connectivity/fish passage assessment |
Abstractions, diversions, or impoundments, where passage is thought to be an issue |
1D models (2D models do not have passage analysis capability and analysis is done by post-processing of results either visually or numerically) |
Entrainment model Sediment transport |
Impoundments or diversions where the frequency of floods and freshes is altered |
RHYHABSIM (1D model) and post-processing of 2D model results |
Bank stability |
Impoundments or diversions where the frequency of floods and freshes is altered |
Post-processing of 1D and 2D model results |
| Suspended sediment | Significant abstractions, diversions, or impoundments, where suspended sediment or water clarity is an issue | RHYHABSIM (1D model) |
| Seston flux | Significant abstractions, diversions at or near below lake outlets | |
Inundation model |
Impoundments or diversions where the frequency of floods and freshes is altered |
2D models |
Flow variation analysis |
Impoundments or diversions where the frequency of flow fluctuations is altered |
1D models (RHYHABSIM or HABEF HABTAM in PHABSIM) |
Fish bioenergetics model |
Significant abstractions, diversions, or impoundments involving important trout fisheries |
Kelly et al (2005) (ie, Cawthron model), Addley (2006), Booker et al (2004) |
Water quality models |
Abstractions, diversions, or impoundments in low-gradient macrophyte-dominated streams |
WAIORA, RHYHABSIM |
Groundwater models |
Significant groundwater abstractions in alluvial river valleys |
