Presentation is loading. Please wait.

Presentation is loading. Please wait.

Water resources in karst and quarrying impacts Prof. David Gillieson Earth & Environmental Sciences James Cook University Cairns, Australia.

Similar presentations


Presentation on theme: "Water resources in karst and quarrying impacts Prof. David Gillieson Earth & Environmental Sciences James Cook University Cairns, Australia."— Presentation transcript:

1 Water resources in karst and quarrying impacts Prof. David Gillieson Earth & Environmental Sciences James Cook University Cairns, Australia

2 Outline of talk Karst hydrological zones and the epikarst Limestone mining for cement Quarrying impacts and rehabilitation Expect the unexpected!

3 Zonation of karst aquifers Diagram by Ken Grimes, Regolith Mapping P/L

4 Porosity types and karst aquifer properties Primary porosity Secondary porosity Conduit porosity ComponentsPore spaces Vughs Linked joints and fractures Open channels and pipes Flow regimeLaminarLaminar to just turbulent Turbulent Governing lawDarcyHagen- Poseuille Darcy- Weisbach Response to input water Slow <1mm/day Moderate 1-10 metres/day Rapid 100s of metres/day Gillieson D 1996 Caves: Processes, Development, Management, Blackwells

5 Clearwater Cave, Sarawak – 135km long Karst is a triple porosity aquifer! conduits 100s of metres/day fissures 10s of metres/daypore spaces mm/day

6 Epikarst- the karst engine house Close relations between vegetation soils microbiota epikarst fissures solution processes and drainage Gillieson D 1996 Caves: Processes, Development, Management, Blackwells

7 Epikarst depth & zonation

8 Epikarst storage and transmission The epikarst or subcutaneous zone is located at the top of the aerated or vadose zone From the epikarst, water percolates downwards and delivers slow recharge to the phreatic zone Epikarst storage can buffer the effects of rainfall events on water percolation

9 Karst groundwater fragility of karst environments evidenced by karst groundwater systems extremely important water supplies - about 25% of the global population is supplied largely or entirely by karst waters but whose quality is VERY susceptible to degradation

10 What goes down, must come up... rapid transport of pollutants in cave conduits main problems are turbidity and sewage also herbicides (Atrazine) and pesticides (Metamidophos)

11 Mining and quarrying Limestone widely used for building stone, cement manufacture, agricultural lime, industrial flux and toothpaste Caves may be totally quarried away Local pollution of groundwater Rehabilitation costly and slow

12 Mining for cement Top graph is % change in use Lower graph is volume of limestone quarried for cement

13 Limestone quarry rehabilitation Benders Quarry, Lune River, Tasmania Quarry operating in World Heritage Area for 40 years Operations affecting WH values, especially in large cave underlying quarry Commonwealth closed quarry and funded rehabilitation and monitoring Joint project with Tasmanian Parks & Wildlife Service

14 Exit Cave Tasmanian WHA Cave is 25km long with extensive glowworm colonies and other rare invertebrates Extensive dye tracing using Rhodamine WT Proved connection between quarry drainage and Eastern Passage of Exit Cave Monitoring sites established with water quality probes and dataloggers

15 Quarrying impacts at Lune River, Tasmanian World Heritage Area Removal of cave passages and destruction of palaeokarst fills by quarrying Increased sedimentation of fine clays in caves underlying the quarry Recurrent turbidity in Eastern Passage and Exit Cave Creek Changes in pH, conductivity and sulphate ion concentrations in passages draining the quarry Re-solution of stalactites by acidified drainage waters Reduced densities of indicator species of hydrobiid snails (Fluvidona spec. nov.) in passages draining the quarry Gillieson & Houshold, In Drew & Hotzl eds. Karst Hydrogeology & Human Activities, Balkema

16 Dissolved sulphate (ppm) at Benders Quarry, Lune River, Tasmania

17 Rehabilitation strategy Restore the hydrology of the site by simulating the drainage characteristics of the unimpacted karst Reduce peak runoff by the creation of small internal drainage basins which simulate dolines Control sediment movement at source by the use of control structures and filters Establish a stable vegetation cover, preferably of perennial plants Reactivate the soil biology Monitor progress above and below ground

18 Quarry rehabilitation strategy

19 Detail of drainage control

20 Expect the unexpected in karst! "Nature to be commanded must be obeyed", Francis Bacon, Lord Chancellor of England, ('Essays' 1620) Karst surface and subsurface systems are integrated and this renders karst especially susceptible to human impacts Epikarst is of fundamental importance in the control of recharge. It stores and mixes water and redistributes recharge - and any pollution Conventional groundwater models should not be applied to karst for management purposes, because karst aquifers have triple porosity characteristics Best place to monitor the condition of karst is at the outflow spring, because spring outflows integrate the effects of all upstream activities


Download ppt "Water resources in karst and quarrying impacts Prof. David Gillieson Earth & Environmental Sciences James Cook University Cairns, Australia."

Similar presentations


Ads by Google