Surface water management

Page last updated: Tuesday, 19 May 2020 - 8:25am

Surface water management is needed wherever water erosion is a risk and where water movement control or water harvesting is required, and as part of a salinity management program.

This page lists suitable earthwork structures, and links to detailed pages on those structures.

The Department of Primary Industries and Regional Development recommends that any dryland salinity management is part of a whole farm, and preferably a whole catchment, water management plan.

Surface water management options used in Western Australia

The information in this table is only a guide – seek expert advice before planning, and use expert contractors for construction where necessary. Each landholder has a duty of care to make sure that flows are not discharged indiscriminately on a neighbour and that stream flows are not significantly diminished.

Advantages of surface water management compared to subsurface drainage

  • treats the cause of groundwater problems, rather then the problem
  • cost of construction is relatively lower
  • surface run-off water is usually of good quality and can be stored in farm dams or directed into natural watercourses
  • water erosion and groundwater recharge are reduced
  • peak stream flow in creeks is reduced, reducing flooding, channel erosion and sedimentation
  • maintenance needs are low
  • notification of surface water earthworks is not required under the Soil and Land Conservation Act (but subsurface drainage may be).

Environmental considerations

Waterways and wetlands in catchments are important for nature conservation and local ecology as well as local drainage and floodwater discharge. Avoid disturbing the normal patterns of flow and the natural water balance of the existing ecosystems.

Integration in whole-farm plans

We recommend whole-farm water management as part of a farm plan. That is, land use, management systems and infrastructure need to meet the business goals and comply with legislation.  In most cases, you will need a combination of surface and subsurface water management options to achieve a sustainable system with minimal degradation.

Before constructing any earthworks, seek expert advice to avoid technical, environmental and safety risks associated with water management.

Table 1 Surface water management options
Earthwork Land slope

(%)

Soil type Grade

(%)

Landscape position Purpose
Absorption banks and level banks up to 10 clay, clay loam, rocky   upper slope, below areas producing a lot of run-off controlling run-off water where a grassed waterway cannot be safely maintained
Grade bank up to 10 shallow duplex, loam 0.2 to 0.5 upper and mid-slope controlling surface water erosion; harvesting water from slopes
Dams (excavated earth tanks) up to 10 clay, shallow duplex, deep duplex, loam up to 10 not in valley watercourse storing and providing access to water for agricultural or household use
Roaded catchments up to 6 clay, shallow duplex up to 6 good clay required close to surface improving water run-off from reduced catchment areas into dams
Grassed waterways up to 10 most soils up to 10 running downhill on a natural water accumulation line providing safe disposal of overflow from dams or discharge from the end of grade banks
Seepage interceptor bank up to 10 shallow duplex, deep duplex, sand   lower and mid-slope controlling shallow seepage and waterlogging
Broad-based banks 2 to 6 shallow duplex, loam 0.15-0.3 upper, middle and lower slope controlling surface water erosion; allowing easy vehicle traffic across banks
Shallow relief drains (W-drain, V-drain, spoon and spinner drains) up to 0.2 clay, shallow duplex up to 0.2 valley floor removing surface water from flooded areas
Levee waterways up to 10 clay, sand, deep duplex, shallow duplex up to 10 valley floors and hill slopes guiding and controlling the spread of water in drainage lines
Raised beds 0.1 to 2   0.1 to 2 valley floors and fairly level waterlogged areas raising seed beds above the saturated soil of waterlogged areas
Evaporation basins site specific       holding saline discharge and preventing salt discharge to environmentally sensitive areas

 

Layout of surface water earthworks

Landscape cross section showing where surface water earthwork options should be placed
Placement of surface water earthworks in the landscape

Contact information

Tilwin Westrup
+61 (0)8 9780 6165
John Simons
+61 (0)8 9083 1128