Effects of Teak Plantations on Water Supply at KVTC

1
Effects of Teak Plantations on Water Supply at
KVTC

• HJ van Hensbergen
• for
• Dave Scott

2
Trees and Water Use

• Trees use water to cool.
• Trees use water for transport of nutrients.
• Trees use water to grow.
• Big trees use more water.
• Trees with big leaves use more water.
• This does not necessarily mean that teak at
  Kilombero will reduce streamflow.

3
Hydrology of Kilombero

• Rainfall is approximately 1550mm
• Ranging from less than 1000 C20yr low to more
  than 2100 C20yr high
• High temperatures lead to high evaporation.
• Some water is lost during storms as overland
  flow.
• Rest is effective rainfall.
• Interception loss
• Net Rainfall
• Available to vegetation
• Tree growth at KVTC reflects water availability.
• Trees use most or all of the water where they
  grow.
• Models developed for South Africa can be used to
  model this situation.

4
Teak and Streamflow.

• If teak was planted over entire catchments it
  could have a serious effect on streamflow.
• The situation at KVTC is different there is
  likely to be little effect on streamflow.

5
Area Planted
15000ha of which 3636 could be planted 24
6
Position in Catchment
Upper Catchment High Rainfall
Teak
Lower Catchment Low Rainfall
7
Spread across many Catchments
Effect on any one catchment small.
8
Effects on Streamflow

• Baseflow
• Little effect because there is only a very small
  surplus over evaporation at teak sites in any
  case.
• Stormflow
• Little effect because most of this is from
  overland flow.
• Any teak effect would be positive by slowing
  release and improving interception.

9
Recommendations of Report

• Monitoring of Rainfall
• Monitoring of Streamflow
• Road design construction and maintenance to
  reduce possible impact on water quality