Water, Salinity and Irrigation in Australia s Murray-Darling Basin & Hetao Irrigation District Ian White Australian National University
Ian White FTSE Research Major research area is water resources with emphasis on: sustainable and safe water use and management, surface-groundwater interactions and water quality, mitigation of and adaptation to climate change and land use impacts on water security and quality water policy & planning Very proud to be a colleague of Professor Yang Jinzhong from Wuhan University
Previous Work in China 2009-12 Miyun Watershed With MWR & MEP Dongjiang Watershed NDRC Visit 22 Feb 2012
Outline 1. Comparison of Challenges 2. Brief overview Australian climate 3. Characteristics of the Murray-Darling Basin 4. Salinity and irrigation problems in the Basin 5. Water reforms & the Basin Salinity Management Strategy 6. Some observations from Hetao Irrigation District
Comparison of Problems Faced in Water Issue China Australia Water scarcity Yes Yes Floods Yes Sometimes Droughts Yes Yes Point source pollution Yes No Diffuse Source Pollution Nutrients, Sediment, Salinity Salinity, nutrients, sediments Priorities People, Crops, Industry, Environment People, Environment, Crops, Industry
Comparison of Climates Peel, M. C.; B. L. Finlayson; T. A. McMahon (2007). Updated world map of the Köppen-Geiger climate classification". Hydrology and Earth System Sciences. 11: 1633 1644. doi:10.5194/hess-11-1633-2007 Differences between cold and warm arid and semi-semi-arid regions
Distribution of Mean Annual Rainfall in Australia Most of Australia has less than 400mm/year 1/3 continent has zero runoff The driest inhabited continent
Rainfall Variability, the Critical Issue Var = 90 p 10 p 50 p Large Variability Frequent Severe Droughts For Hetao Irrigation District Index of Variability 0.89
Average Annual Pan Evaporation Range 1000<Epan<4000
Main Irrigation Area in Australia \
Murray-Darling Basin A transboundary basin River shared between 4 States (owners of water) & 1 Territory
Physical Characteristics of the Murray-Darling Basin http://www.abs.gov.au/ausstats/abs@.nsf/mf/4610.0.55.00 Basin Area 1,059,000 km 2-14% of Australia's land area. Owned & managed by 4 States, 1 Territory, Qld, NSW, ACT, Vic, SA Has Australia's three longest rivers, Darling 2,740 km long Murray 2,530 km long Murrumbidgee 1,690 km long. 67% of the MDB is used for growing crops and pasture Irrigated Area = 19,000 km 2 (75% total Australian irrigation) = 1,900,000 ha = 0.285x10 8 mu
Irrigation Areas in the Basin 19,000 km 2 of irrigated area =3.3x area of Hetao Irrigation District
Annual Water Balance of the Basin Average Rainfall 501 mm Average Evapotranspiration 471 mm (94%) Average Groundwater Recharge 10 mm (2%) Average Runoff 22.5 mm (4%) Average Discharge 12.9 km 3 Specific Yield 12.2 mm Total Storage Capacity 22.2 km 3 http://www2.mdbc.gov.au/subs/eresource_book/index.htm
Water Use in the Basin Developed Yield 11.72 km 3 Diversion - 12.05 km 3 Water Use - 11.15 km 3 Water Use > Sus. Yield Sustainable Yield - 9.13 km 3 Cotton - 20% of water used for agriculture Dairy farming - 17% Pasture - 17% Rice - 16% 66% of Australia s agricultural water use
People in the Basin-2006 Census Population - 2,004,560-10% of Australia's population. 10% of people employed in Agriculture (3% Australia) 38% of Australia's farmers live in the MDB. 39% of people employed aged 65 years or over in the MDB were farmers 61,033 farms accounting for 39% of all farms in Australia
Food Production in the Basin Proportion of Australia's food production in 2005-06: 100% of rice; 95% of oranges; 62% of pigs; 54% of apples; and 48% of wheat.
Murray Darling Basin Concerns By 1980 s increase in diversions/irrigation a problem for: water quality- salinity downstream water supply the riverine environment rising water tables Some rivers were over allocated by 600% (the perils of ignoring the water balance equation)
Impacts of Regulation and Irrigation Reduced flooding of wetlands Decrease in wetlands and wetland health Algal blooms Sedimentation in dams Rising water tables Salinisation Tail water pollution (pesticides/ fertilizers)
Water Reforms in Australia over last 2 decades Cap on surface water abstraction from Murray-Darling 1995 Australian Bureau of Statics Water Accounts 1996 National Land & Water Audit 1999 & Salinity Audit 1999 Basin Salinity Management Strategy 2001-2015, 2015-2030 MDB Council Integrated Catchment Management Policy-2001 National Water Initiative -2004 Commonwealth Water Act 2007 (Amended 2008) Murray-Darling Basin Management Strategy 2015
1995 Cap on Surface Water Abstraction in MDB http://www2.mdbc.gov.au/ data/page/86/cap_brochure.pdf Restricted SW abstraction to 1993/4 levels but neglected groundwater
Salinity in the Murray-Darling Basin Three sources of increased salinity discharge: 1. Natural groundwater discharge 2. Irrigation drainage and increased saline groundwater discharge due to rising water tables 3. Dryland salinity (minor)
Geology of Murray Darling Basin
http://www2.mdbc.gov.au/ data/page/303/final_salt_audit2.pdf Groundwater Zones of the Murray Darling Basin Murray Basin
Irrigation Areas in the Basin Major irrigation areas in regions with saline groundwater
http://www2.mdbc.gov.au/ data/page/303/final_salt_audit2.pdf Depth to Water Table in Irrigation Areas Irrigation, a key contributor to rising water tables & salinity discharge
Transect of River Murray Salinity as Electrical Conductivity (EC) Salinity EC =μs/cm TDS (mg/l) 0.64xEC
The Indicator Site for Salinity in the Murray- Darling Basin Morgan South Australia Basin managed to keep salinity EC < 800 µ S/cm TDS < 0.5 gm/l
EC25 (ms/cm) 1400 1200 1000 800 600 400 200 0 River Murray Salinity vs Flow Salinity Target Flow Limit 0 5 10 15 20 25 30 Annual Flow (km 3 /y) Impact of River Flow on Salinity: River Murray in South Australia
The Basin Salinity Management Strategy 2001-2015 Introduced in 2001 by the Murray-Darling Ministerial Council (MDBC, 2001a). The Strategy is intended to guide communities and Governments in working together to control salinity and protect key natural resource values within their catchments, consistent with the principles of the Integrated Catchment Management.
The Basin Salinity Management Strategy 2001-2015 The objectives of the Strategy are to: Maintain river salinity in South Australia, < 800 EC for 95 per cent of the time; Maintain the water quality of the shared water resources of the Murray and Darling Rivers for all uses. Control the rise in salt loads in all tributary rivers of the Murray-Darling Basin, Control land degradation and protect important terrestrial ecosystems, Maximise net benefits from salinity control across the Basin.
Main Thrust of Water Reforms 1. Increase the share of water for the environment 2. Decrease groundwater recharge beneath irrigation areas 3. Move irrigation water from low value to high value crops 4. Improve irrigation efficiency A$15B 5. Control the discharge of saline groundwater A$15B Uses water entitlements and economic incentives to achieve 1 to 4
Features of the Basin Salinity Management Strategy Audited independently every year Reviewed 2007, 2015 Cost benefit analysis performed on activities Paid for by Commonwealth Legacy of History Aus $15 billion Paid for by State Governments Development Offsets Paid for by catchment management agencies (State & federally funded programs
Control Saline Groundwater Discharges in Irrigation Areas Saline Groundwater pumped to saline evaporation basins Pumping lowers water table in irrigation areas
Saline Groundwater Disposal Basins Wakool Tullakool NSW
Disposal of Intercepted Salinity in Salt Lakes WRR (1995) 31, 1343-53 Proposed Salt Lake Disposal Engineered Disposal Basin Will there be environmental consequences?
Nulla Spring Lake Natural Groundwater Discharge Zone Salinity 10xSeawater Stratigraphically complex WRR (1995) 31, 1343-53
Salt Lake Model Brine Pool 10xSW Do Groundwater Discharges Confine Brine Pools? WRR (1997) 33, 1199-1217
Groundwater Composition versus Modelled Evaporation Re-solution Yamba Clay Yamba Clay Parilla Sand Re- solution WRR (1995) 31, 1343-53
Hele-Shaw & Numerical Models of Plume Development WRR (1997) 33, 1219-1228 WRR (1997) 33, 1219-1228
Conclusions from GW Geochemistry, H-S & Numerical Models of Evolution of Salt Plumes beneath Salt Lakes Salt lakes capped with significant thicknesses of clay - suitable for use as disposal basins - evaporating boundary layer is stabilised by the groundwater evaporative discharge WRR (1995) 31, 1343-53; WRR (1997) 33, 1199-1217, WRR (1997); 33, 1219-1228
Some Observations from Hetao Irrigation District
Irrigation Inputs & Outputs Hetao Irrigation District Input from Yellow River Water Supply Bureau, Dengkou Output to Yellow River
Other Inputs Salinity of Shallow Aquitard (Top Layer) Seepage from: Yellow River Mountains Infiltration from precipitation
Where does the water and salt imported into Hetao Irrigation District go?
Input/Output Flow Data 1967-2006 Water Input from & output into Yellow River (10 8 m 3 ) Very small drainage outflow until 1977 Input from Yellow River Outflow on average about 1/10 of irrigation inflow Year Output into Yellow River Leakage of drainage to groundwater?
(mm/y) Estimation of Annual Specific Irrigation Losses 1000 900 Hetao Irrigation District Annual Irrigation Water Losses Mean specific irrigation water losses 1967-2006 = 749 ± 77 mm/y 800 700 600 500 y = 2.3338x - 3887.5 R² = 0.1254 400 1960 1970 1980 1990 2000 2010 Year Increasing trend caused by small drainage outflow before 1977 This is the minimum water lost from Hetao Basin since does not include YR seepage & rainfall
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Annual Precipitation (mm/y) How Does Precipitation Affect Irrigation Losses? 300 250 200 150 100 50 0 Mean Annual Precipitation Hetao Basin, 1990-2013 y = 1.2734x + 139.65 R² = 0.0304 Year Have estimated additional P data from 1990 to 2000, better data 2000-2013 Appears to be a single station? Mean Annual P from 1990 to 2013, = 156 ± 52 mm/y (CV =0.332) Need spatially interpolated rainfall data
(mm/y) 900 850 800 750 700 How Does Precipitation Affect Irrigation Losses? Hetao I D Annual Water Losses vs Annual Precip 2000-6 Estimated from P data from 1990 to 2006 Is a non-linear response, as expected. 650 600 550 500 50 100 150 200 250 Annual Precipitation (mm) Clearly depends on monthly distribution of rainfall Low rainfalls minimum impact on irrigation water losses. Higher rainfalls decrease irrigated water losses due to decreased supply from lower demand and increased drainage!
The irrigation input water carries salt with it. What happens to the input salt in Yellow River water (0.5 g/l)?
(kg/mu/y) Is Salt from Irrigation being Stored or Exported from Basin? 300 Hetao I D Annual Salt Stored from Irrigation in Basin Assume a closed Basin 250 200 150 100 Drainage 2 gm/l Estimated salt storage based on estimated drainage salinity 2 g/l Mean annual storage = 174 kg/mu/y 50 0 1960 1970 1980 Year 1990 2000 2010
Cumulative Salt Store (10 4 tonne) Total Increased Salt Storage in HID due to Irrigation since 1967 7000 6000 5000 4000 3000 2000 1000 Hetao I D Cumualtive Salt Stored in Basin Drainage 2 gm/l y = 144x - 282821 Between 1967 & 2006 about 0.6x10 8 tonnes of salt added to the Basin by irrigation water from Yellow River. Increasing at a rate of about 144x10 4 tonnes/year 0 1960 1970 1980 1990 2000 2010 Year
Where does irrigation-added salinity go? Evaporation causes denser salt water to accumulate at groundwater surface above fresher groundwater This can be convectively unstable and saline groundwater could fall to the bottom aquifer if connected
Where does irrigation added salinity go? We have studied this groundwater convection problem experimentally and numerically in evaporating salt lakes in Australia Wooding, R.A.,.Tyler, S.W. and I.White I. (1997). Convection in Groundwater below an evaporating salt lake: 1. Onset of instability. Water Resour. Res.,33, 1199-1217. Convection occurs when K crit > 0.01 m/d Wooding, R.A., S.W.Tyler, I.White and P.A. Anderson (1997). Convection in Groundwater below an evaporating salt lake: 2. Evolution of fingers or plumes. Water Resour. Res., 33, 1219-1228.
Where does irrigation added salinity go? Salinity of Shallow Aquitard (Top Layer)
Where does irrigation added salinity go? Salinity of First Aquifer
Where does irrigation added salinity go? Salinity of Second Aquifer Predicts accumulation of salt in second aquifer if aquifers leaky and closed Basin
Is the Basin closed??? Salinity of Second Aquifer Possibility of density-driven flow under and down Yellow River?
Bredehoeft (1997) Hierarchy of Factors Contributing to Decisions about Water LAW POLITICAL ECONOMIC TECHNICAL Reflections on Hydrology: Science and Practice. N. Burras (ed.) AGU 1997, pp 36-61. IAH London 20 Oct 2011
Concluding Comments Australia and China share concerns in water, irrigation & salinity In the Murray-Darling Basin Australia has experimented with a range of reform options to control water use and salinity A critical issue is the availability of good quality spatial & temporal data The disposal of saline drainage waters in MDB is an on-going issue A very rough analysis of Hetao Irrigation District suggests storage of salt there may be a problem The analysis in the MDB of salinity-driven groundwater convection appears directly applicable to Hetao The rough analysis gives a number of predictions which can be tested It also suggests solutions to apparent build up of salt
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