ACEDP Project: Environmental Flows in The Lower Yellow River Jiang Xiaohui YRCC Workshop, Beijing 2012 Feb 23
Jul 12, 2015
ACEDP Project: Environmental Flows in The Lower Yellow RiverJiang XiaohuiYRCC
Workshop, Beijing
2012 Feb 23
Contents
Background
General environmental flow assessment methodology
Brief description of work
Experience and recommendations
Sanmenxia
Xiaolangdi
Dam
N
Lake
City
Hydrological station
River
Lijin
Luokou
Aishan
Sunkou
Gaocun
Huayuankou
Dongping Lake
,
Kaifeng
Lijin
Zibo
Tai an
Dongping
Liaocheng
Qinyang
LuoyangSanmenxia Zhengzhou
Jinan
Survey
Site three
Study AreaBackground
Lower Yellow River Flow Issues• “Mother River”
– High water demand– High degree of regulation
• Climate change and human activities– Flows reducing over past 50 years, cease to flow sometimes
from 1970s to 1990s• Sediemnt
– A very high sediment load to the lower river,flood• Yellow River Delta – a dynamic estuarine Ramsar wetland
– Depends on sediment supply for growth• Riverine wetlands
– Mostly disconnected due to flood dyke construction• Aquatic ecosystem
– lost diversity
In China there is a strong awareness of the need and importance of
environmental flows. Environmental flow assessments have been undertaken in
a number of rivers,
Environmental flow methods used in China:• Hydrological--Tennant• Hydraulic rating-Wetted perimeter method,
R2CROSS(Focus on one or a few key species)• Habitat simulation-IFIM (focus on one or a few key species)• Holistic• --Consider the entire ecosystem• --Not constrained by the analytical tools• --Consider other water user• --expensive
General environmental flow assessment methodology
General environmental flow assessment
Brief description of work
Select sites and reaches
Field trip、 sample 、 workshop and literature search
Mengjinwetlands
Zhengzhouwetlands Kaifeng
wetlands
DongpingLake
Deltawetlands
River channelReaches
1
2
3
4
Identify ecological assets
• A river asset is any attribute of the natural ecosystem of value to society. The value could be ecological, social and/or economic.
• River assets include species, biological communities, habitats and ecosystems of conservation importance (collectively referred to as “conservation assets”).
River asset
Assets in the low Yellow River
• Fish species, e.g. Yellow River Carp• Wetland vegetation• Birds
• Spawning process• Sediment transport• Water quality
• Geomorphology
Develop conceptual models linking asset health and flow componentsGeomorphology, plants, fish, macroinvertebrates, water quality, birds…
Flow regime
Low flows Flow pulses High flows
Maintain depth of water in
refuge pools
Maintain adult fish population
Maintain larval andjuvenile habitat in river channel
Sediments from upstream and catchments increase. and DO decreases
Maintain backwater refuges and food resources for fish. Fish mortality increases.
Floods
Stimulate spawning
Food resources
Figure. The links between individual flow components and flow requirements for carp
July-OctoberAverage D > 0.8 m; V: 0.5 ms-1-1.2ms-1
FloodProvide new habitat and feeding opportunities for fish, but increased sediment and low DO may increase mortality
July-OctoberAverage D > 0.7 m; V: 0.3 ms-1-1ms-1
High flowProvide new habitat and feeding opportunities for fish
April - JuneD: 1-2 m at peak of flow pulse.Inundated beach area, and increase back water V<0.3 ms-1
Flow pulseStimulate spawning
Nov-Mar,April-June
Max D > 1.5 mV: 0.1-0.8 ms-1
Low flowMaintain sufficient water depth in pools for large bodied fish
TimingHydraulic criteriaFlow component
Objective
Table. Flow components and hydraulic criteria relevant to Yellow River Carp requirements. D = depth, V = velocity
Fish
No. Flow component Hydraulic/hydrologic criteriaF1 Cease-to-flow; Low flow Q ≥ YRCC warning standards of low flow emergency; maintain area‡
≥ critical depth* at pool crossings (specified each month)
F2 Low flow Maintain area‡ ≥ critical depth* with V ≤ 2.0 m/s1,2
F3 High flow, high flow recession Maintain longitudinal connectivity and area‡ ≥ critical depth* over barriers (shallow areas)
F4 Low flow Maintain area‡ with depth ≥ critical depth* in pools
F5 High flow pulse Achieve area‡ with depth ≥ critical depth* over barriers (shallow areas)
F6 High flow Maintain area‡ with D = 0.5 – 1.0 m1,2 and V ≤ 1.4 m/s1,2
F7 High flow Maintain area‡ with velocity 1.0 – 2.0 m/s1
F8 High flow pulse Maintenance of appropriate† salinity gradient in estuary
F9 Low flow and high flow Maintain area‡ of D ≥ 1.5 m1,2 and V ≤ 1.0 m/s1,2
F10 Low and high flow pulses Achieve sufficient depth* to replenish/maintain water in river associated wetlands and backwaters
F11 Low flow and high flows Maintain adequate cross-sectional area/discharge* to transport nutrients required to sustain primary productivity
F12 Bankfull 2,600 - 4,000 m3/s - see Geomorphologic objective G1
F13 Bankfull 2,600 - 4,000 m3/s - see Geomorphologic objective G2
F14 High flow See Vegetation objective V1F15 High flow and low flow See Vegetation objective V7F16 Low flow Maintain mean pool velocity ≥ 0.01 m/s
F17 High flow and low flow Sufficient discharge* to maintain morphology in and around the estuary mouth
F18 Bankfull 2,600 - 4,000 m3/s - see Geomorphologic objectives G3 and G4
PlantsNo. Objective Flow component Hydraulic/hydrologic criteria
V1 Maintain submerged aquatic vegetation (e.g. Vallisneria, Potomageton and Myriophyllum spp.)
High flow Inundation to ≤ 1 m
V2 Maintain meadow vegetation High flow Inundation to ≤ 0.3 m
V3 Maintain Tamarix/Salix shrubland High flow, low flow and low flow pulse
100% of time shallow groundwater; Jul – Sep waterlogging; inundation by summer flow pulse events ≤ 30 days; soil salinity 10 – 30 psu
V4 Maintain Tamarix/Salix woodland High flow, low flow and low flow pulse
100% of time shallow groundwater (at 1.5 – 3.0 m); inundation by summer flow pulse events ≤ 30 days; soil salinity 10 – 30 psu
V5 Maintain sand flats High flow and low flow 100% of time shallow groundwater (at ≤ 1.8 m); soil salinity ≥ 30 psu
V6 Maintain Suaeda salsa High flow pulse Inundate once per year for ≤ 30 days or 30 to 180 days of varying depth from -0.1 to +0.1 m; 100% of time shallow groundwater (at 1.8 m); soil salinity 5 – 30 psu
V7 Maintain Phragmites australis grassland
High flow and low flow 100% of time waterlogging; varying inundation 0 – 0.5 m deep (1.5 m max.; 0.3 m mean) in summer
Birds
No. Objective Flow component Hydrologic/hydraulic criteria
B1 Foraging Low flows Expose CarexB2 Foraging Low flows Shallow water (<0.3 m)
over submerged or emergent aquatic plant community with mud or sand base
B3 Foraging Low flows Expose mudflatsB4 Wintering area Low flows Maintain ice free water
bodies*B5 Food supply and breeding High flows Inundate areas of
submerged macrophytes (Vallisneria, Phragmites, Typha, Carex, Tamarisk)
B6 Foraging High flow recession Gradually receding water levels from Bankfull peak
B7 Mudflat foraging habitat creation
Bankfull An annual event that supplies enough sediment load to at least maintain delta area
B8 Summer-autumn habitat area
Bankfull An annual event to inundate backwaters and wetlands
Geomorphology
Geomorphologic-based objectives and flow requirements.
No. Objective Flow component
Hydrologic criteria Mean annual frequency/duration
Inter-annual frequency
Timing Reach Reference
G1 Scour and deposition processes to maintain dynamic and diverse habitats in the channel and connected floodplains
Bankfull 2,600 - 4,000 m3/s ≥ 1 per year / ≥ 1 day* duration
≥4 in 5 years Jun – Sep
Reach 1 Richards et al. (2002)
G2 Maintain channel capacity at 4,000 m3/s
Bankfull 2,600 - 4,000 m3/s ≥ 1 per year / ~10 – 30 days duration; rates of rise and fall within natural range
≥4 in 5 years Jun – Sep
All reaches
Liu et al. (2006)
G3 Seaward progradation of the delta
Bankfull Sediment load >3.45 × 108 tonnes at Lijin; event mean sediment concentration ≥ 35 kg/m3
≥ 1 per year ≥4 in 5 years Jun – Sep
Reach 4 Wang K et al. (2007); Wang et al. (2010)
G4 Flow into delta wetland channels to maintain channel form (and also provide freshwater and nutrients to the delta wetlands)
Bankfull >3,000 m3/s to allow gravity flow
≥ 1 per year / ≥ 10 days* days duration (or as required)
≥4 in 5 years Jun – Sep
Reach 4 Jiang Xiaohui (YRCC, pers. comm., November 2010)
* Based on expert opinion; refinement of this criterion will require investigation.
Set objectives for each asset and important process•Ecological management objectives (what level of river health is desired?
taking account of constraints, and other uses of the river)•Hydraulic/hydrologic objectives to achieve the ecological objectives
Set objectives
• 18 Fish objectives• 6 Water quality objective• 8 Bird objective• 8 Macroinvertebrate objectives• 4 Geomomorphic objectives
• These can be rationalised to a smaller group for evaluation– 13 objectives
Key obj.
Obj. met Objectives description Flow component
A F1; M1 Prevent habitat loss through drying of shallow areas Cease to flow
B B1; B2; B3 Expose Carex and mudflats; shallow water over submerged aquatics Low flow
C F2 Maintain shallow habitats with moderate-high velocity for shallow water dwelling species and spawners during low flow periods
Low flow
D WQ1, WQ2, WQ3, WQ4
Dilute contaminants to Grade III standard Low flow and high flow
E V3; V4 Maintain Tamarix/Salix shrubland and woodland Low flow and high flowF M2; M5; F3; F4; F11;
F16Maintain reasonable area of habitat for most of the time for longitudinal connectivity, survival of large-bodied fish, maintenance of primary productivity in the estuary; and maintenance of DO levels in deep pools
Low flow and high flow
G F6; F7; F9 Provide suitable habitats for spawning, allow access of large bodied fish to backwater and wetland habitats; maintain downstream transport of semi-buoyant eggs within the water column; and sufficient depth in pools for large-bodied fish
High flow
H V1; B5; M3; M4; F14 Maintain submerged aquatic vegetation High flowI V2 Maintain meadow vegetation High flowJ M6; F8 Maintain favourable salinity at estuary and mouth for rearing of Chinese shrimp; and
maintain salinity gradient for anadromous fish spawning migrationHigh flow
K V3; V4; F10 Maintain Tamarix/Salix shrubland and woodland; and replenish/maintain water in river associated wetlands and backwaters
Low flow pulse
L F5; F10 Stimulate spawning, migration (anadromy and potadromy) and maintain habitat continuity between near-shore/estuarine and freshwater habitats to allow free upstream passage; and replenish/maintain water in river associated wetlands and backwaters
High flow pulse
M G1, G2, G3, G4, WQ6; B6; B7; B8; M7; M8; F12; F13;
Scour and deposition processes to maintain dynamic and diverse habitats in the channel and connected floodplains; maintain channel capacity at 4,000 m3/s; seaward progradation of the delta; allow flow into delta wetland channels for habitat provision and physical maintenance; provide low velocity littoral habitats for small bodied species; and maintain shallow pool crossings with moderate-high velocities
Bankfull
Hydrological and hydraulic modellingDetermine the characteristics of the flows (magnitude, duration,
frequency and timing) required to meet the objectives
Hydraulic model
• 1-dimension– Inexpensive– Cover a long reach– Cross-section average
• 2-dimension– Expensive
– Cover a short reach– Depth-averaged
Mean velocity V Depth D
Mean velocity VDepth D
Convert Hydraulic index to flow index
1-D HEC-RAS model output
2-D River2D model output
Velocity Flow direction
Mesh Depth
Lower Yellow River data
• 370 cross-sections– Surveyed every year
• Use for 1-D model of whole river
• 3 sites surveyed in detail– Lijin
– Huayuankou– Yiluo junction
• Use for 2-D model
Establish flow rulesIntegrate the information through collaboration:
•Produce a set of practical flow rules that stakeholders agree on•Create options with different levels of risk to the health of the assets
Huayuankou recommendation – low riskObjectives met Flow component Hydrologic criteria Mean annual
frequency/durationInter-annual frequency
Timing
F1; M1 Cease to flow No cease to flow Continuous 100% of the time All yearB1; B2; B3, F2; WQ1, WQ2, WQ3, WQ4; V3; M2; M5; F3; F4; F11; F16
Low flow Dec ≥ 307
Jan ≥ 280
Feb ≥ 321
Mar ≥ 377
Apr ≥ 463
May ≥ 430
Continuous ≥ 75% of the time Dec - May
F6; F7; F9; V1; B5; M3; M4; F14
High flow Jun ≥ 434
Jul ≥ 783
Aug ≥ 1,137
Sep ≥ 1,124
Oct ≥ 866
Nov ≥ 543
Continuous ≥ 75% of the time Jun - Nov
V3; V4; F10 Low flow pulse ≥ 2,000 ≥ 1 per year /1 – 30 days; rates of rise and fall within natural range
≥4 in 5 years Nov - May
G1, G2, G3, G4, WQ6; B6; B7; B8; F12; F13; F5; F10
Bankfull 3,000 – 4,000 ≥ 1 per year / ~10 – 30 days duration;rates of rise and fall within natural range
≥4 in 5 years Jun – Sep
Not provided
V3; V4; F10
Jun – Sep≥4 in 5 years≥ 1 per year / ~10 – 30 days duration;rates of rise and fall within natural range
3,000 – 4,000BankfullG1, G2, G3, G4, WQ6; B6; B7; B8; F12; F13; F5; F10
Jun - Nov≥ 75% of the time
ContinuousJun ≥ 265Jul ≥ 466Aug ≥ 754Sep ≥ 744Oct ≥ 534Nov ≥ 335
High flowF6; F7; F9; V1; B5; M3; M4; F14
Dec - May≥ 75% of the time
ContinuousDec ≥ 185Jan ≥ 174Feb ≥ 191Mar ≥ 229Apr ≥ 284May ≥ 263
Low flowB1; B2; B3, F2; WQ1, WQ2, WQ3, WQ4; V3; M2; M5; F3; F4; F11; F16
All year100% of the time
ContinuousNo cease to flowCease to flow
F1; M1
TimingInter-annual frequency
Mean annual frequency/duration
Hydrologic criteria
Flow component
Objectives partly met
Huayuankou recommendation – medium risk
Model water resources availabilityWhat are the impacts on river users from the flow options?
Experience and recommendations
Experience
--- Get new think, method from Australian expert
---The result close to the think of river manager, and can be implement
Recommendation
---The e-flow assessment can be applied in other river in China
THANK YOU FOR YOUR ATTENTION