Drainage Operations Natural Resources South East The Bool: - - PowerPoint PPT Presentation

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Drainage Operations Natural Resources South East The Bool: - - PowerPoint PPT Presentation

Jan 18, 2024 102 likes •349 views

Drainage Operations Natural Resources South East The Bool: balancing flows for both ecological and flood mitigation In a RAMSAR listed wetland Goal 1: Manage the Drainage Network and infrastructure to retain water and flows to benefit primary

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Drainage Operations Natural Resources South East

The Bool: balancing flows for both ecological and flood mitigation In a RAMSAR listed wetland

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Goal 1: Manage the Drainage Network and infrastructure to retain water and flows to benefit primary production, connected groundwater systems & wetlands

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Management of Bool Lagoon

Balancing flows for both ecological and flood mitigation in a RAMSAR listed wetland

Photograph by: James Davey & Ben Lively

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Agreed Target Operating Levels

Big Hill Gauge Reading at Bool Lagoon Bool Lagoon Outflow (Regulator) – NB: indicative gauge

readings at Regulator gauge board subject to draw down when regulator is in use

Management Action at Bool Lagoon Regulator Acceptable Levels

< EL 48.55 AHD

Up to EL48.5 (flow up to 19.8 cumecs)

Levels are based on the average at the Bool Lagoon Regulator, the Yards, at Big Hill, the NPWS Office and at Hacks Lagoon. However, the Big Hill gauge is an indicative average. Optional level for discharge when saturated (winter) and heavy Rainfall pending

EL 48.55 AHD *

EL 48.60 m

At least daily gauge readings, and recorded . *This level allows for up to 1.4 GL of storage prior to reaching EL 48.61 AHD. Based on the 2016 this is approximately equivalent to a single 25mm rainfall event in a saturated Mosquito Creek catchment Target discharge Level during ongoing saturated conditions

EL 48.61 AHD

EL 48.7m to allow for balancing of flow where

Optimal target level, with discharge equalling the rate of inflow from Mosquito Creek. (See diagram below) Landholders advised 48 hours in advance, see landholder list below in Item 7. Maximum height Very High Level (mid winter)

EL 49.50 AHD

EL49.52 (= Flow over the top is 5.2 cumecs)

EL49.52 (remove logs if Bool Lagoon exceeds EL 49.52) Or Very High Level (early spring)

EL 48.58 AHD

EL49.52 (leave the stop logs)

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Aerial View 23/09/2016

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Statutory Plan of SEWCD Board

  • South Eastern Water Conservation and Drainage Act 1992
  • SEWCD Board Management Plan to 2018/19
  • Goal 1: Manage the Drainage Network and

infrastructure to retain water and flows to benefit primary production, connected groundwater systems & wetlands

  • Bool Lagoon Game Reserve and Hacks Lagoon Conservation Park, Park

Management and Ramsar Plan (Park Management Plan, 2006).

  • Guidelines for the Operation of Bool Lagoon and Drain M Regulators for

Flood Mitigation Purposes (J.E. Nitschke, 1984)

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Operating Challenges

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Groundwater

  • Hacks and Bool Lagoon very complex site
  • Known as a Boinka – wetland generated

through the occurrence of a major groundwater discharge zone over a long period

  • Studies have shown that there are periods

where groundwater will discharge into Bool Lagoon and other periods where surface water is recharging to groundwater.

  • Landholders concerned of the effect surface

water levels within Bool Lagoon is having on the water table in surrounding agricultural land during wet years

Oct 2016 RSWL (mAHD)

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Groundwater- surface water dynamics

  • Water balance for 2016 wet season

Precipitation (GL) = Evaporation (GL) = Evapotranspiration (GL) = 17.15 11.16 3.49 Bool Lagoon Water Balance Inflow (GL) = 73.62 Outflow (GL) = 53.52 Recharge (GL) = 6.13

NET (GL) = 19.11

Gauge Reading Volume-Depth Relationship Gauge Height (m AHD) = 48.52 48.51

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Groundwater – Surface Water Relationship

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Southern Transect Middle Transect Northern Transect

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46 48 50 52 54 56 58 60 62 64 1500 3000 4500 6000 7500 9000 10500 12000 13500 15000

Elevation (mAHD) Distance (m)

Morphometry - LiDAR GW Levels (Oct) GW Levels (Mar)

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43 45 47 49 51 53 55 57 59 61 44 46 48 50 52 54 56 58 60 62 1500 3000 4500 6000 7500

Elevation (mAHD) Distance (m)

Morphometry - LiDAR GW Levels (Mar) GW Levels (Oct)

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Localised issues:

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50 100 150 200 250 300 1000 2000 3000 4000 5000 6000 1/06/2016 1/07/2016 1/08/2016 1/09/2016 1/10/2016 1/11/2016 Discharge Volume (Ml) Lammermoor Rainfall Edenhope BoM rainfall last 60 days - Edenhope

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Proposed Next Steps:

  • Installation of more piezometers to evaluate extent of groundwater mound and relationship

with surface water levels in Bool Lagoon

  • Installation of monitoring stations at proposed sites within Mosquito Creek catchment
  • Review of “Guidelines for the Operation of Bool Lagoon and Drain M Regulators for Flood

Mitigation Purposes” developed in 1984 to check still relevant with current catchment and new information

  • Produce new operation guidelines for Bool Lagoon
  • Publish 2017 Bool Lagoon Technical Report
  • Development of water balance model for predictive/scenario tool
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