Dealing with salinity in Wheatbelt Valleys - Department of Water

More documents

Recommendations

Info

EFFECT OF ARTERIAL DRAINS The increasing extent of salinisation predicted for the Avon catchment mean that there is increased likelihood of waterlogged valley floors. Therefore without any further intervention there will be significant increases in flooding along these valley floors. Mechanisms to alleviate land salinisation and waterlogging include surface water management and arterial drainage. The impact of the approaches on the downstream infrastructure and environment will depend on aspects such as the location, design and management of these drains. In some cases the impacts of arterial drainage will be limited to the immediate catchment. There are some lake systems which are terminal, which mean that the impacts of arterial drains will be limited to the receiving lake system. However other lake systems are inter-connected and can impact on significant areas downstream. Arterial drainage can provide a number of benefits including reducing waterlogging and salinisation, reduction in water table levels, enhanced evacuation of floodwaters, and reduced road maintenance and construction costs. However arterial drainage can result in adverse impacts such increased severity and duration of downstream flooding, increased export of sediments, salt and nutrients into downstream receiving waters and damage to wetlands and fringing vegetation. It is important that any arterial drainage scheme ensures that the adversed impacts are avoided. Drainage projects can have both on-site and off-site impacts, and may also have a cumulative effect. By this we mean that, while one drainage project draining into a large river basin may not significantly affect water quality or flood risk, the effects could increase as more projects were implemented and larger areas drained into the same river basin.
APPENDIX 2 WATER MANAGEMENT OPTIONS Bus Tour Notes - Doodlakine to Merredin. This conference tour will cover aspects of Wheatbelt valley water management, in particular, engineering options for lowering watertables and reducing inundation and waterlogging of valley soils. The bus trip travels east from Doodlakine then turns south at Hines Hill through extensively saline soils of the ‘Baandee’ soil association. These areas contained large areas of primary salinity that were once covered by ‘boree’ (Melaleuca) and other salt tolerant trees and shrubs, prior to clearing. Prior to clearing, there was little or no salinity south of Hines hills at settlement (c1910). The distribution of salinity and valley form should be noted. Turning east, the bus crosses the lower Belka Valley (catchment area ~170,000 ha) at a site where surface water management, such as pumping impounded waters and other forms of drainage were undertaken in the late 1970s and early 1980s. To the southeast, WISALTS banks were monitored over several years (1980s) and their impacts documented. The Belka valley was the first studied in the Wheatbelt (Bettenay et al, 1964). Research on the hydrologic processes concluded that valley morphology was a good indicator of risk, with ‘Baandee’ at highest risk, ‘Belka’ type valleys at high risk and ‘Merredin’ type valleys at lower risk. The later had higher mainstream slopes. Bettenay also drilled shallow wells and indicated that salinity was mainly associated with ‘…a more spatially extensive wet zone…’ than watertable rise. There was no documented evidence of the later. They also associated recharge with granite runoff and valley recharge in extreme events. Recent monitoring has shown that watertables remain close (< 2-3m) throughout much of the Belka, and salinity is expanding in most areas, especially in tributary valleys and to the east. Watertable monitoring in these valleys (cleared 1910 to 1950) and on slopes, mainly cleared in the 1950’s and 1960’s show 0.2-0.3 m/yr. rates of rise. Sandplain seeps are common. Current drainage works in the valleys are restricted by infrastructure such as roads and railways. The bus will stop and discuss the impacts of restricted drainage on upstream managers. Groundwater pumping is an alternative for salinity management in valleys, although little experience exists to determine its practicability in valleys such as the Belka. Several aquifers systems exist although most are relatively low yielding and the radial impact of wells uncertain. The location of palaeochannel and related sediments has not been determined although airborne geophysics (AEM) maybe a means of locating such features. Aspects of pumping will be discussed and compared to other forms of drainage. Management of discharged water within and from drains represents a significant issue for land managers. Groundwater seepage may either be lost to larger lakes, evaporate or infiltrate as transmission losses through sediments can be high, especially where drains and watertables are shallow. The bus will pass an extensively altered remnant (Belka Rail reserve), typically saline ‘Salmon Gum’ dominant valley soils, giving visitors a view of damage due to shallow watertables and salinity. Remnants in valley locations are at significant risk of salinity, with many reserves in valley locations. Surface and groundwater drainage examples, upstream and downstream, can be seen. Turning north towards Merredin on the Bruce Rock Rd, the bus will stop to discuss large surface water management systems. Large floodways were constructed to the Belka to reduce the impacts of severe flooding experienced in the 1960s and again in the 1970’s. Recently, deep drains have been constructed near these banks. Jones’ drains are an example of salinity management at the foot of a sandplain slope. Drainage systems into well-structured clays will be shown and the landowner and contractor will discuss their effectiveness, problems and constraints. Leaving this site, the bus will travel to Merredin, passing upland remnants as we head onto the Merredin
Page 1 and 2:
Foreword Dealing with Salinity in W
Page 3 and 4:
1Day one: Monday 30th July. Field t
Page 5 and 6:
Papers Dealing with Salinity in Whe
Page 7 and 8:
Ali and Coles biggest challenges fa
Page 9 and 10:
Ali and Coles erosion, maintenance
Page 11 and 12:
Ali and Coles expected under these
Page 13 and 14:
Ali and Coles Coles, N.A. & Ali, M.
Page 15 and 16:
Commander, Schoknecht, Verboom and
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
APPRECIATING AND CREATING OUR HISTO
Page 43 and 44:
services. The Government responded
Page 45 and 46:
WHEATBELT VALLEYS IN DIFFICULTIES T
Page 47 and 48:
argue that they were really abnorma
Page 49 and 50:
1990s, the wheatbelt valleys in par
Page 51 and 52:
REFERENCES Agstats (1997). Agricult
Page 53 and 54:
George and Coleman two to four fold
Page 55 and 56:
George and Coleman surface, the vas
Page 57 and 58:
George and Coleman for example in t
Page 59 and 60:
George and Coleman current trends c
Page 61 and 62:
George and Coleman While not as div
Page 63 and 64:
George and Coleman SPECIES Table 5:
Page 65 and 66:
George and Coleman advantages of so
Page 67 and 68:
George and Coleman this volume). In
Page 69 and 70:
George and Coleman Venture Economy
Page 71 and 72:
George and Coleman Lawrence, C. (19
Page 73 and 74:
Hatton and Ruprecht WATCHING THE RI
Page 75 and 76:
Since the mid 1970s annual rainfall
Page 77 and 78:
Effect of clearing on runoff The ot
Page 79 and 80:
Salinity Monthly streamflow (ML) 10
Page 81 and 82:
The ratio of the salt outputs to in
Page 83 and 84:
- 11 - Hatton and Ruprecht Table 4:
Page 85 and 86:
THE FUTURE In looking at the future
Page 87 and 88:
McFarlane, D.J., George, R.J. & Far
Page 89 and 90:
Keighery, Halse and McKenzie Terres
Page 91 and 92:
Keighery, Halse and McKenzie Wetlan
Page 93 and 94:
Keighery, Halse and McKenzie specie
Page 95 and 96:
Keighery, Halse and McKenzie enviro
Page 97 and 98:
Lloyd number of legal cases pending
Page 99 and 100:
Lloyd 0 -500 -1000 -1500 -2000 -250
Page 101 and 102:
Lloyd Table 3. Sheep grazing days i
Page 103 and 104:
Lloyd Hectares project to provide w
Page 105 and 106:
INTRODUCTION The Lake Chinocup Catc
Page 107 and 108:
agriculture) in various stages, the
Page 109 and 110:
- 3,477 ha of remnant vegetation or
Page 111 and 112:
Scientists talk of up to 30% of the
Page 113 and 114:
6320000 6300000 6280000 6260000 624
Page 115 and 116:
Although the waterlogged area under
Page 117 and 118:
eliminates drainage through the nex
Page 119 and 120:
REFERENCES Dawes, W.R., Stauffacher
Page 121 and 122:
Pannell ECONOMICS, SOCIETY AND ENVI
Page 123 and 124:
Pannell • the area of land protec
Page 125 and 126:
Pannell Proposals to construct majo
Page 127 and 128:
Pannell been conducted for the Cent
Page 129 and 130:
Pannell investments in long-term la
Page 131 and 132:
Pannell Pannell, D.J. (2001). Dryla
Page 133 and 134:
Porter, Bartle and Cooper Table 1:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Porter, Bartle and Cooper operation
Page 141 and 142:
Porter, Bartle and Cooper Increase
Page 143 and 144:
Page 145 and 146:
Porter, Bartle and Cooper support i
Page 147 and 148:
Porter, Bartle and Cooper that is a
Page 149 and 150:
CASE STUDY - TOOLIBIN LAKE AND CATC
Page 151 and 152:
• The distribution, storage and m
Page 153 and 154: Secondly, there is a set of practic
Page 155 and 156: within three categories: relationsh
Page 157 and 158: CONCLUSIONS Actions to protect and
Page 159 and 160: FIELD TOUR LOCATIONS FIELD TOUR NOT
Page 161 and 162: COLES FARM “Avon River Basin Over
Page 163 and 164: Conference Outcomes Dealing with Sa
Page 165 and 166: with Salinity in Wheatbelt Valleys:
Page 167 and 168: with Salinity in Wheatbelt Valleys
Page 197 and 198: Photo Gallery 2 Dealing with Salini
Page 199 and 200: APPENDIX 1 BACKGROUND HYDROLOGY AND
Page 201 and 202: WHEATBELT HYDROLOGY Flow in the Yil
Page 203: Flow (ML) STREAM SALINITY Salt Rive
Page 207 and 208: APPENDIX 3 MANAGING WATER AND SALIN
Page 209 and 210: SUMMARY- TIMELINE OF RECENT SIGNIFI
Page 211 and 212: RECENT HISTORY OF WATER AND SALINIT
Page 213 and 214: Figure 1. Hydrological cross-sectio
Page 215: Depth (m) 316 315 314 313 312 311 M
Page 218 and 219: FURTHER INVESTIGATIONS AND MANAGEME
show all

Dealing with salinity in Wheatbelt Valleys - Department of Water

Create successful ePaper yourself

Delete template?

Save as template?