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