Effects of Teak Plantations Effects of Teak Plantations on Water Supply at KVTCon Water Supply at KVTC

HJ van Hensbergen HJ van Hensbergen

forfor

Dave ScottDave Scott

Trees and Water UseTrees and Water Use

Trees use water to cool.Trees use water to cool. Trees use water for transport of nutrients.Trees use water for transport of nutrients. Trees use water to grow.Trees use water to grow. Big trees use more water.Big trees use more water. Trees with big leaves use more water.Trees with big leaves use more water.

This does not necessarily mean that teak This does not necessarily mean that teak at Kilombero will reduce streamflow.at Kilombero will reduce streamflow.

Hydrology of KilomberoHydrology of Kilombero Rainfall is approximately 1550mmRainfall is approximately 1550mm

Ranging from less than 1000 C20yr low to more than 2100 Ranging from less than 1000 C20yr low to more than 2100 C20yr highC20yr high

High temperatures lead to high evaporation.High temperatures lead to high evaporation. Some water is lost during storms as overland flow.Some water is lost during storms as overland flow. Rest is effective rainfall.Rest is effective rainfall.

Interception lossInterception loss Net RainfallNet Rainfall

Available to vegetationAvailable to vegetation Tree growth at KVTC reflects water availability.Tree growth at KVTC reflects water availability.

Trees use most or all of the water where they grow.Trees use most or all of the water where they grow. Models developed for South Africa can be used to model this Models developed for South Africa can be used to model this

situation.situation.

Teak and Streamflow.Teak and Streamflow.

If teak was planted over entire catchments If teak was planted over entire catchments it could have a serious effect on it could have a serious effect on streamflow.streamflow.

The situation at KVTC is different there is The situation at KVTC is different there is likely to be little effect on streamflow.likely to be little effect on streamflow.

Area PlantedArea Planted

15000ha of which 3636 could be planted 24%

Position in CatchmentPosition in Catchment

Upper Catchment

High Rainfall

Lower Catchment

Low Rainfall

Teak

Spread across many CatchmentsSpread across many Catchments

Effect on any one catchment small.

Effects on StreamflowEffects on Streamflow

BaseflowBaseflow Little effect because there is only a very small Little effect because there is only a very small

surplus over evaporation at teak sites in any surplus over evaporation at teak sites in any case.case.

StormflowStormflow Little effect because most of this is from Little effect because most of this is from

overland flow.overland flow. Any teak effect would be positive by slowing Any teak effect would be positive by slowing

release and improving interception.release and improving interception.

Recommendations of ReportRecommendations of Report

Monitoring of RainfallMonitoring of Rainfall Monitoring of StreamflowMonitoring of Streamflow Road design construction and Road design construction and

maintenance to reduce possible impact on maintenance to reduce possible impact on water qualitywater quality