HYDROLOGY AND ECOLOGY
Dec 29, 2015
HYDROLOGY AND ECOLOGY
HYDROLOGY
WATER QUALITY
HYDRAULICS
GEOMORPHOLOGY
ECOLOGY
SOCIO/ECONOMICS
RESEARCH TEACHING POLICYCONSULTANCY
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ICA
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EG
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HORIZONTAL INTEGRATION
CATCHMENT PROCESSES: rainfall, evaporation, runoff infiltration, erosion Hydrology production, decomposition etc. Water quality Geomorphology Hydraulics Instream habitats Instream biota
The process used for assessing the water quantity aspects of the ecological Reserve for rivers
Relating Biota to Hydrology
THE FLOW STRESSOR RESPONSE METHOD
A Generic Stress Index
• An index of 0 to 10 where 0 indicates no stress, and 10 the highest level of stress
• Stressors: Flow-related hydraulics and habitat• Biological responses: Reduced abundance (1 to 3),
increasing risk to critical life stages (4 to 6), and disappearance of populations (7 to 10)
• Flow-related hydraulics: Velocity, depth and wetted perimeter
• Habitat: Quantity and quality (the diversity and connectivity of habitat types)
Stress
% Duration
Natural (A)
Inc. Flow (C)
Decreased Flow (C)
Assessing increased and decreased stress
The process for applying the FS/R method
• Select a site, survey and model hydraulic characteristics
• Specialists apply the stress index to the site, in relation to selected species/groups, to develop stress curves
• The hydrologist converts the resulting critical stress curve to stress time series for flow scenarios
• Analyse the stress profile of each scenario in terms of the magnitude, frequency and duration of different stresses
• Assess the severity of each stress profile in relation to the natural stress profile
AN EXAMPLE OF A SITE SPECIFIC STRESS INDEX FOR INVERTEBRATES
Flowrate
(m33/s)
Stress Response
4 0 Average velocities > 0.6 m/s, and average depth > 0.4m provides abundant fastdeep and fast shallow habitat for rheophilic species (such as simuliids andhydropsydhids.
3.8 1 Average velocity 0.61 m/s, average depth still > 0.4m. Abundance of criticalhabitats is slightly reduced, but all species are still abundant.
0.3 3 Average velocity 0.2 m/s (therefore maximum velocity approximately 0.4 to 0.5m/s). Average depth 0.17m, maximum 0.4m. Still some critical habitat, butrheophilic species abundance much reduced.
0.13 5 Average velocity 0.12 m/s (therefore maximum velocity 0.2 to 0.3 m/s). Averagedepth 0.14m, maximum 0.34m. Wetted perimeter 9m - marginal vegetationhabitats only just in the water. Rheophilic species confined to very small areas,egg and early larval stage probably non-viable.
0.03 7 Average velocity 0.05 m/s (maximum approximately 0.1 m/s). Average depth0.12m, maximum depth 0.28m. Wetted perimeter 6.4m, no longer in marginalhabitats. Loss of all critical flowing habitat, only remnant areas for short-termsurvival of hardy rheophilic species.
0.01 8 Average velocity 0.01 m/s, only slow trickles and standing water habitats remain.All rheophilic species will disappear if this flow condition persists.
0 9 Standing water only
Note: Stresses of 2, 4 and 6 have not been specifically motivated, and are simply extrapolations of theadjacent stress motivations.
0.001
0.01
0.1
1
10
100
0 2 4 6 8 10 S tress
Barbus Cpre Inv Rip Veg Total
B lyde R iver
Black = Natural, Red = Recommended, Blue = Present day
Blyde River spell analysis (Stress = 1.5)White = natural, Red = recommended, Blue = Present day
EXAMPLE OBJECTIVES(e.g. to maintain Category B)
• Maintain perennial flow • Summer flows > winter flows• Av. velocity > 0.1 m/s at all times for target fish (stress never > 6)• Sufficient depth (30 cm) to allow target fish to feed and breed 85%
of time in summer (stress < 1 for 42.5% of time)• Av. velocity > 0.3 m/sec for 80% of time, to ensure Trichoptera
habitat (stress < 3 for 80% of time)• Wetted perimeter in reeds for 60% of summer to provide marginal
habitats (stress < 0.8 for 30% of time)
10
8
6
4
2
0
Stress
% Time Exceeded
0 10 20 30 40 50 60 70 80 90 100
Inverts:Stress <380% time
Fish:Stress <1
42.5 % time Riparian veg:Stress <0.830% time
Fish:Stress never >6
Application of objectives to define ecological category B
10
8
6
4
2
0
Stress
% Time Exceeded
0 10 20 30 40 50 60 70 80 90 100
B
Inverts:Stress <380% time
Fish:Stress <1
42.5 % time Riparian veg:Stress <0.830% time
Fish:Stress never >6
Application of objectives to define ecological category B
10
8
6
4
2
0
Stress
% Time Exceeded
0 10 20 30 40 50 60 70 80 90 100
D
CB
Inverts:Stress <380% time
Fish:Stress <1
42.5 % time Riparian veg:Stress <0.830% time
Fish:Stress never >6
Application of objectives to define ecological category B
Thukela IFR4 Based on dry season flows
B B/C
Ecological Reserve procedures
PHABSIM
DRIFTDatabase
DRIFT
Flow StressorResponse
Classification and objectives
Referenceconditions
PresentEcological
State
EcologicalImportance
andSensitivity