river corridor management of gravel-bed rivers in … · 2018-10-31 · channel form meander widths...
TRANSCRIPT
DESIGN by NATURAL CHARACTER
RIVER CORRIDOR MANAGEMENT of
GRAVEL-BED RIVERS in AOTEAROA/NEW ZEALAND
GARY WILLIAMSWATERSCAPE
www.waterscape.co.nz
HOW DO WE MANAGE THIS REACH?
SITE DESIGN — WHOLE SYSTEM
RIVER
Wave pattern W = function of (Coast shape C)
Sediment movement S = function of (Wave pattern W)
Coast shape C = function of (Sediment movement S) COAST
RIVER PROCESSESINTER-CONNECTED
WHOLE SYSTEM DYNAMICS
Channel shape C = function of (Sediment movement S)
Sediment movement S = function of (Flow pattern Q)
Flow pattern Q = function of (Channel shape C)
CHANNEL SHAPE
WATERWAYS
SEDIMENT MOVEMENTInterwoven spirals
Meander migration
Erosion & Deposition
RIVER SYSTEMS
CATCHMENT
FLOW PATTERN
Oscillating formChannel/Floodplain exchanges
Seepage/Runoff
Changes in Climate & Geological landform
RIVER TYPE
Floods
RE-CYCLING SYSTEMS
Pulse movement
Landscapeshaping
Transport
Imposed form
DrainageNetwork
Integrated systems, with feedback loops, where the river type depends on the catchment and climatic context and local conditions.
INTEGRATED RIVER SYSTEMSCATCHMENT CONTEXT & LOCAL CONDITIONS
Sediment supply/Transport
LIVING ECOSYSTEMS BIO-PHYSICAL SYSTEMS⟺
OCEANIC
AOTEAROA / NEW ZEALAND
PLACE BASED
LOCATION ENVIRONMENT
CLIMATE
LANDSCAPE TECTONIC
Large Islands on the “Ring of Fire”
Steep landscape
Rapidly uplifted & shattered base rock
High intensity rainfall
Highly mobile gravel bed rivers
AOTEAROA
NEW ZEALAND
LOCATION ENVIRONMENT
PLACE BASED
NATURAL CHARACTER RIVER MANAGEMENT
LOCATION of REACHES
APPLICATIONS
VOLCANIC
MOUNTAINS
REACHES APPROACH APPLIED
REGIONLOWER
NORTH ISLAND
METHODOLOGY
CONTEXT
DIFFERENTIATEBASED ON DRIVERS
TA
UH
ER
EN
IKA
U
WA
IOH
INE
WA
ING
AW
A
WAIKANAE
OTAKI
HUTT
CATCHMENT CHARACTERWAIRARAPA — TARARUA RANGE CATCHMENTS
TAUHERENIKAU
WAIOHINEWAINGAWA
RUAMAHANGA
CATCHMENT
FAULT
FAULT
FAULT
FAULT
FAULT
FAULT
FAULT
FAULT
GEOMORPHOLOGY
TAUHERENIKAU
WAIOHINEWAINGAWA
RUAMAHANGA
REACH CHARACTER—WAIOHINE RIVER
WAIOHINE
RUAMAHANGA
PLAINS REACH
TERRACED
Confined SEMI-BRAIDED
VALLEY PLAIN
WANDERING
VALLEY FAN
SEMI-BRAIDED
GEOMORPHOLOGY
PLAINS REACH
WAINGAWA
RUAMAHANGA
PERCHED
WANDERING
TERRACED
SEMI-BRAIDED
CROSS-VALLEY
SEMI-BRAIDED
VALLEY PLAIN
SEMI-BRAIDED
FAULT
FAULT
FAULT
GEOMORPHOLOGY
REACH CHARACTER—WAINGAWA RIVER
CHANNEL CHANGES OVER TIME —WAINGAWA RIVER
CHANNEL FORM
SPACE VARIATIONS
DISCHARGE (Q2)
BED MATERIAL SIZE (d50)
SLOPE (s)
DISCHARGE (Q2)
BED MATERIAL SIZE (d50)
SLOPE (s)
DISCHARGE
GRADE
BED MATERIAL
CHANNEL FORMINFLUENCING FACTORS
WAIRARAPA
GRAVEL - BED RIVERS
CHANNEL FORM DRIVERS
CHANNEL FORMMEANDER WIDTHS
EMPIRICAL FORMULAE RESULTS
RIVER REACH
FLOW MATERIAL SLOPETHRESHOLD OF MOTION WIDTH
FLOW DOMINANT WIDTH
DESIGN FAIRWAY WIDTH
XS Q2d50 s at REGIME at SLOPE LACEY RUSSIAN NARROW WIDE
(m3/s) (m) H Chang II
ESK 7 215 0.02 0.0025 26 45 71 75 73 122
Waipumga 215 0.025 0.0025 25 43 71 75 73 122
NGARURORO 20 875 0.02 0.0015 50 90 143 145 145 242
33 875 0.03 0.002 47 86 143 137 145 242
42 825 0.04 0.0025 43 81 139 128 135 225
50 800 0.045 0.004 42 86 137 115 135 225
63 625 0.06 0.0035 36 68 121 107 120 200
TUKITUKI Lower 4 1050 0.045 0.0015 48 83 157 156 155 259
Middle 2 885 0.065 0.002 42 76 144 137 140 234
T15 330 0.06 0.002 27 47 88 93 90 150
T30 330 0.055 0.0025 27 48 88 89 90 150
T47 135 0.035 0.0045 19 34 56 55 55 92
T73 120 0.075 0.008 16 31 53 47 50 84
WAIPAWA W12 370 0.05 0.003 29 52 93 89 90 150
W33 260 0.065 0.0065 24 46 78 67 75 125
W64 280 0.12 0.0065 22 44 81 69 80 134
MANGAONUKU MU2 160 0.055 0.0035 19 34 61 62 62 104
MAKARETU MK9 65 0.035 0.004 14 23 39 42 40 67
MK18 65 0.1 0.006 12 22 39 39 40 67
TUKIPO TP36 120 0.09 0.0065 16 29 53 49 50 84
WAITARA Lower 950 0.11 0.0015 40 83 149 150 150 251
Recorder 950 0.115 0.0025 40 78 149 135 145 242
WHANGANUI Lower - City 2330 0.005 0.0004 96 176 234 279 250 418
Lower - City up 2330 0.01 0.0005 86 147 234 267 250 418
Upper - d/s Br 500 0.15 0.0025 28 62 108 105 105 175
Upper - u/s Br 500 0.15 0.0035 28 59 108 98 100 167
MANAWATU d/s Floodway 1350 0.01 0.0002 67 92 178 273 180 301
d/s Oroua 1500 0.03 0.0003 60 104 188 257 190 317
d/s PN 1510 0.04 0.0015 57 102 188 180 185 309
u/s PN 1510 0.07 0.001 53 99 188 196 190 317
OROUA u/s Kiwitea 167 0.11 0.004 18 35 63 61 63 105
KIWITEA Lower 60 0.04 0.0075 13 24 38 36 37 62
POHANGINA Lower 490 0.08 0.004 31 58 107 94 100 167
TAMAKI Hartridge 45 0.1 0.0065 10 19 33 33 33 54
MANGATAINOKA Lower 385 0.06 0.003 29 52 95 91 95 159
Pukewhai Br 240 0.09 0.003 22 41 75 75 75 125
Rail Bridge 230 0.12 0.0037 20 41 74 71 73 122
OHAU Lower 225 0.075 0.004 22 40 73 69 70 117
Inter-decadal Pacific OscillationChange over
Inter-decadal Pacific OscillationChange over
TIME DYNAMICSCLIMATIC CYCLES
WAIRARAPA RIVERS1955 - 2015
TIME VARIATIONS
WA
ING
AW
A
WA
IOH
INE
EXISTINGHEAVY CONTROL
Design ChannelHeavy strengthening
Vegetation buffer
RETREATFenced off
Wide vegetation bufferSome channel clearing
INTERMEDIATEDesign Fairway
Partial strengtheningWider vegetation buffer
High cost of river works.Degraded river environment.
“STABLE”
High cost from loss of land.Longer term management difficulties.
“CHAOTIC”
Cost effective.Managed river environment.
MANAGEMENTALTERNATIVES
GENERAL CONCEPTS
INTERMEDIATE ALTERNATIVE
MANAGEMENT FACTORS — WAIOHINE RIVER
MANAGEMENT REACHES
TERRACE
TERRACE
TERRACE
GRADE CHANGE
FLOODING
GRADE CHANGE
FLOODING
POTENTIAL
CHANNEL
CHANGE
POTENTIAL
CHANNEL
CHANGE
TERRACE
TERRACE
TERRACE
GRADE CHANGE
GRADE CHANGE
FLOODING
FLOODPLAIN
FAULT
FAULT
MANAGEMENT FACTORS — WAINGAWA
RIVER
MANAGEMENT REACHES
POTENTIAL
CHANNEL
CHANGE
MANAGEMENTEXAMPLE DESIGN
WAINGAWA RIVER
AERIAL PHOTOGRAPHY COMPARISON
DESIGN FAIRWAY
RIVER CORRIDOR
MANAGEMENT CORRIDOR
FAIRWAY Clear channel
Continuous Buffers
EDGE CONTROLClear channel
Edge rock & Buffers
FAIRWAY Clear channel
Consistent Buffers & some Rock
RETREAT No scheme
Breakouts repaired
MANAGEMENT OPTIONS MANAGEMENT OPTIONS
DESIGN FAIRWAYMANAGEMENT
ZONE
STANDARD
APPROACH
HIGH
LOW
Channel re-direction &
Structural edge protection
Bar clearance &
Vegetation buffers
SCHEME OPTIONS
UPGRADED
ORIGINAL
FAIRWAY(CHANNEL & ROCK)
FAIRWAY(BEACH & VEGETATION)
EXISTINGMINIMAL
RETREAT
RETIREMENT
MANAGEMENTOPTION EVALUATION
OPTION EVALUATION
CHRYSTALLS BEND
RAHUI WIDENING
MANAGEMENTEXAMPLE DESIGN
OTAKI RIVER
DESIGN FAIRWAY
MANAGEMENT ZONE
EXAMPLE —WANDERING/SEMI-BRAIDED
JIM COOKE PARK
MAPLELANE
WAIKANAE RIVER
DESIGN CHANNEL
MANAGEMENT ZONE
EXAMPLE —SINGLE CHANNEL/ALTERNATING BAR
MANAGEMENTEXAMPLE DESIGN
MANAGEMENTEXAMPLE DESIGN
WAIMAKARIRI
RIVER
EXAMPLE —WIDE, SHALLOW/FULLY BRAIDED
1 km
DESIGN by NATURAL CHARACTER
•WHOLE SYSTEMS DYNAMICS — CONTEXT & CONNECTION
•PLACE BASED — CLIMATE & LANDSCAPE
•GEOMORPHOLOGY — INTER-DEPENDENT INFLUENCES
•REACH CHARACTER — MANAGEMENT ZONES
•SPACE / TIME VARIATIONS — RIVER CORRIDORS
GARY WILLIAMSWATERSCAPE
www.waterscape.co.nz