RESTORING RIPARIAN VEGETATION – A PROMISING MEANS TO ENSURE CLEAN WATER

Kamal Melvani, Neo Synthesis Research Centre, Sri Lanka,

email: neosynth@sltnet.lk

SURFACE WATER

Riparian zones can be broadly defined as the land that adjoins or directly influences a body of water (Price & Lovett 2002)

Paradeke Oya, Gampola

Structure and characteristics of riparian lands

Riparian ecosystems:• Shade and lower stream temperatures• Filter and sorb pollutants• Provide areas for sediment deposition • Promote microbial decomposition of organic

matter and nutrients• Minimize stream bank erosion • Provide habitat for biodiversity • Open wildlife corridors • Enhance infiltration replenishing groundwater• Increase reservoir life (Chin 2012)

Major components of riparian vegetation that affect stream water chemistry

(Dosskey et al. 2010)

Soil Organic Matter is a biomembrane that filters pollutants, reduces sediment load in rivers, degrades contaminants, and is a major sink for atmospheric CO2 and CH4 (Lal, 2004)

Processes through which major components of vegetation in riparian ecosystems affect stream water chemistry

(Dosskey et al. 2010)

• Deep rooted trees in biologically active zones remove Nitrates in shallow ground water. Hydraulic residence time critical (Melvani, 2011).

• Nitrate removal minimal when water moves to regional groundwater and emerges as base flow(Dosskey et al. 2010).

• For sediment borne P retention, fine sediment control coupled with use of vegetation, can increase P uptake into plant tissue (Dosskey et al. 2010)

• However, riparian forests have low net dissolved P retention (Dosskey et al. 2010).

• Non nutrient chemicals absorbed from soil by plant roots. Heavy metals (e.g., Cd, Cr, Hg, Ni, Pb), metalloids (e.g., As, Se), and other elements (e.g.: B, Cs, Sr) (Dosskey et al. 2010).

• Riparian buffers could reduce electrical conductivity (Melvani, 2011).

Riparian zone destructionIllicit felling, dumping ground for garbage and erosion

Lemastota Oya, Haputale

• reduce Non Point Source pollution after it leaves source area but before it reaches the stream

• important on 1st and 2nd order streams where intense interaction between terrestrial and aquatic ecosystems occurs

• slope of the RFBS main factor limiting the effectiveness of sediment removal

• use of native vegetation a key factor (Lowrance & Vellidis 2004).

Restoration Riparian forest buffer systems (RFBS)

Vegetated riparian zones canstrongly influence the chemical contents of adjacent

streams, particularly through the removal of nutrientsin runoff from agricultural uplands

Maragala Oya, Maragalakanda, Moneragala

RESTORATION WITH COMMUNITY

Riparian forest buffers for gullies in forest gardens on Maragalakanda, Moneragala

Arumugam’s forest garden

Jane Nona’s garden

Arumugam’s gully restored

Before

After

Podisingho’s garden with Spathyphyllum patini planted on stream bank

Maha Oya, sub catchment in Great Valley, Deltota

Planting in year 1

RESTORATION WITH PRIVATE COMPANY

Contour

Restoration of the riparian zone of Lake Richmond through Landcare

CLEARING GULLY PLANTING GULLY

PLANTED GULLIES

o Planting in micro watershed 4,724 trees and plants in 39+ native and indigenous species were planted in the micro watershed of Lake Richmond.

Ground Water

Bioremediation

Kalpitiya

Kalmunai

Dense planting round the well with deep rooted, native trees forming a ‘root mat ’ below the surface to uptake the contaminants.

2003

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Concentration of N-No3 over time

Lower Well

Upper Well

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-N03

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Concentration of Nitrate Nitrogen over time

Electrical Conductivity at 250C over time

ReferencesChin, DA 2012, Water-Quality Engineering in Natural Systems : Fate and Transport Processes in the Water Environment, 2 edn, Wiley, New York.

Dosskey, MG, Vidon, P, Gurwick, NP, Allan, CJ, Duval, TP & Lowrance, R 2010, 'The Role of Riparian Vegetation in Protecting and Improving Chemical Water Quality in Streams1', JAWRA Journal of the American Water Resources Association, vol. 46, no. 2, pp. 261-77.

Lal, R 2004, 'Soil Carbon Sequestration Impacts on Global Climate Change and Food Security', Science, vol. 304 no. 5677 pp. 1623-7.

, R & Vellidis, G 2004, 'Riparian forest buffers: hype? Or the silver bullet for NPS pollution control?', Resource: Engineering & Technology for a Sustainable World, vol. 11, no. 10, p. 7+.

Melvani, K 2011, 'Bioremediation of Nitrates in Ground Water', M.Sc. thesis, University of Peradeniya

Price, P. and Lovett, S. 2002, ‘Managing riparian land’, Fact Sheet 1, Land & Water Australia, Canberra

Thank you!