Research Library Resource management technical reports Natural resources research 1-12-2001 Lort and Young Rivers Catchment : catchment appraisal 2001 Jamie Bowyer Esperance Catchment Support Team (WA) Follow this and additional works at: https://researchlibrary.agric.wa.gov.au/rmtr Part of the Agriculture Commons, Hydrology Commons, Natural Resources Management and Policy Commons, Soil Science Commons, and the Water Resource Management Commons Recommended Citation Bowyer, J, and Esperance Catchment Support Team (WA). (2001), Lort and Young Rivers Catchment : catchment appraisal 2001. Department of Primary Industries and Regional Development, Western Australia, Perth. Report 231. This report is brought to you for free and open access by the Natural resources research at Research Library. It has been accepted for inclusion in Resource management technical reports by an authorized administrator of Research Library. For more information, please contact [email protected]. ISSN 1039-7205 December 2001 Lort and Young Rivers Catchment Catchment Appraisal 2001 Compiled by Jamie Bowyer for the Esperance Catchment Support Team Resource Management Technical Report 231 LORT AND YOUNG RIVERS CATCHMENT APPRAISAL Disclaimer While all reasonable care has been taken in the preparation of the material in this document, the Western Australian Government and its officers accept no responsibility for any errors or omissions it may contain, whether caused by negligence, or otherwise or for any loss, however caused, sustained by any person who relies on it. © Chief Executive Officer, The Department of Agriculture 2001 ii LORT AND YOUNG RIVERS CATCHMENT APPRAISAL Contents Summary....................................................................................................................3 1.0 Introduction .........................................................................................................4 2.0 Catchment resource base ..................................................................................7 2.1 Geological history ..................................................................................................................7 2.2 Climate ...................................................................................................................................8 2.3 Soil-landscape summary......................................................................................................12 2.4 Hydrogeology .......................................................................................................................17 2.5 Native vegetation..................................................................................................................18 2.6 Waterways and wetlands .....................................................................................................21 2.7 Agricultural production..........................................................................................................23 2.8 Land use ........................................................................................................26 3.0 Catchment condition and future risk...............................................................28 3.1 Salinity and groundwater......................................................................................................28 3.2 Impact of agriculture and salinity on native vegetation ........................................................39 3.3 Impact of agriculture and salinity on waterways & wetlands................................................40 4.0 Salinity management ........................................................................................44 4.1 Recharge management .......................................................................................................44 4.2 Groundwater discharge management..................................................................................51 4.3 Other uses for saline land...................................................................................53 5.0 Further information and contacts....................................................................54 6.0 References.........................................................................................................57 Appendices 1. Vegetation types and present cover in the Lort and Young Rivers Catchment ....58 2. Declared rare and priority flora in the Lort and Young Rivers Catchment ............59 3. Conservation codes for declared rare and priority flora .......................................60 4. Revegetation species for the Esperance district ..................................................61 iii LORT AND YOUNG RIVERS CATCHMENT APPRAISAL SUMMARY • The Lort and Young Rivers Catchment (the catchment) is 75 km west of Esperance on the South Coast of Western Australia. It covers two broad areas known as the Esperance Sandplain and the Esperance Mallee totalling 503,273 hectares. The climate is typically Mediterranean with cool wet winters and dry warm summers. • The two major river systems, the Lort and Young Rivers, drain into Stokes Inlet on the coast. Stokes Inlet is the largest estuary in the Esperance Shire and one of the deepest in the South Coast region. There are regionally significant wetlands in the Lort River Catchment. Although these rivers are naturally saline, salinity levels and flow rates have increased since clearing. The overall condition of these rivers is good to excellent. • The dominant soil types in the catchment are alkaline grey shallow sandy duplex, grey shallow sandy duplex and grey deep sandy duplex. These and other soil types combine to form the 20 soil-landscapes. • Groundwater salinity increases away from the coast. Groundwater on the Esperance Sandplain ranges from 50 to 4000 milliSiemens per metre (mS/m) while groundwater salinity in the Esperance Mallee can be as high as 6,500 mS/m (seawater is 5,300 mS/m). • The annual value of agricultural production in the catchment is about $52 million. Crops include wheat, barley, canola, lupins, oats and other pulses. Beef cattle along with sheep meat and wool are the livestock enterprises. • Depth to watertable varies greatly and the rate of groundwater rise is 0.05 to 0.30 m/year. The Land Monitor Project mapped 1.4 per cent of the agricultural area as salt-affected and 21 per cent of the catchment as having low-lying areas with the potential for shallow watertables. Twenty per cent or 120 km of the roads lie within low-lying areas with the potential for shallow watertables. • Approximately 49 per cent of the original vegetation cover remains in the catchment. This vegetation contains 51 species of priority flora and four species of rare flora. Twenty per cent of the remnant vegetation in the agricultural area is found in low-lying areas with the potential for shallow watertables. Consequently, two species of rare flora and 10 species of priority flora will be threatened. • Salinity can be managed by reducing recharge to groundwater, increasing groundwater discharge, and productive use of salt-affected land. Factors such as soil type, annual rainfall, enterprise mix and financial structure will determine what is the most suitable approach for a farm business. iv LORT AND YOUNG RIVERS CATCHMENT APPRAISAL v LORT AND YOUNG RIVERS CATCHMENT APPRAISAL 1.0 Introduction Dryland salinity is one of the more urgent environmental problems facing communities in Australia. It is having a detrimental effect on biodiversity, infrastructure and the health of waterways and wetlands in affected regions. Dryland salinity is also impacting negatively on agricultural production. The Western Australian Government released its State Salinity Strategy in 2000. The aim is to ‘reduce the impact’ of salinity. Rapid Catchment Appraisal (RCA) is one of the processes included in the strategy to tackle salinity and its management. The objective of RCA is to provide all landholders by 2005 with access to the most up-to-date information for salinity management. The RCA process provides a ‘snap shot’ of information on the risk and impact to agricultural production and natural resources within regional geographic catchments. The process also attempts to identify the best or most suitable options to manage the risk. As part of the process, landholders are given direction on where to access further information and support if necessary. This report has been prepared by the Esperance Catchment Support Team, which contains representatives from relevant government departments. The report summarises current information for the Lort and Young Rivers Catchment. Land managers are urged to use it as a starting point and to gather further information from the sources listed. LORT AND YOUNG RIVERS CATCHMENT APPRAISAL Figure 1: Esperance Regional Catchments showing the Lort and Young Rivers Catchment 2 LORT AND YOUNG RIVERS CATCHMENT APPRAISAL Figure 2: Drainage in the Lort and Young Rivers Catchment 3 LORT AND YOUNG RIVERS CATCHMENT APPRAISAL 2.0 Catchment resource base The Lort and Young Rivers Catchment is approximately 75 kilometres west of Esperance on the South Coast of Western Australia. The catchment covers approximately 503,273 hectares which includes uncleared land north of that allocated for agriculture and agricultural land. For the purposes of this report, spatial data has been analysed using that portion of the catchment within the allocated agricultural land and covers 328,863 hectares. The Catchment covers two broad areas known as the Esperance Sandplain and the Esperance