3.27 AVERAGE RATES OF EVAPORATION PER YEAR AND MONTH

Data ID

Description:

Average rates of evaporation per year and month

Chapter:

3 Climate

File name:

Average rates of evaporation per year and month

File type:

ArcView shapefile

Geographical area:

Namibia

Keywords:

evaporation

water

Notes on data, analysis and

This is based on measurements of water loss from standard-sized evaporation ponds, but rates of water loss from open

compilation:

dams, pans and rivers are generally about 30% lower than those from small evaporation ponds. This is because rates of

evaporation decrease as the air moving across large expanses of open water picks up moisture. Values used are therefore

30% lower than those recorded at weather stations.

The polygons making up the shapefile were created from hand drawn contours on a hard copy map. This manual

interpolation approach was done by Peter Hutchinson using the point data from all available stations. Because the

number of stations was small (24) an automatic interpolation produced nonsense results.

Data quality and organisation

Positional Accuracy:

Low

Vector/Raster:

Vector

Spatial reference

Projection:

Geographic

Fields

Field name

Field description

EVAP	Evaporation in mm per year

EVAP-30

Evaporation less 30 % in mm per year

Source/Distribution

Data Source:

Evaporation Map for Namibia Report No. 11/1/8/1/H1 (1998), Dept of Water Affairs, Ministry of Agriculture, Water

and Rural Development, Windhoek

Contact:

Online/Offline Address:

Ministry of Agriculture, Water and Rural Development

Private Bag 13184

Windhoek

Distribution notes:

Unrestricted