Volta River basin, Ghana

Site Summary

The Nodwua, Ejura and Novrongo experimental catchments were established in April 2001 as part of the GLOWA Volta Project (www.glowa-volta.de). They were chosen because they represent three different agro-ecological zones in the Ghanaian portion of the Volta River basin. The basins are located in a north to south transect, with the northern most being Novrongo (10.92° N, 1.03° W), then Nodwua (9.48° N, 0.92° E), and the most southern being Ejura (7.33° N, 1.27° W). The respective sizes of the experimental catchments are approximately 10, 20 and 15 km2.

The climate is tropical savannah with a natural landcover of grassland and scrub forest. Precipitation in the region is characterized by summer convective storms, resulting in large variability, as expressed in periodic droughts. The precipitation in the region is heavily influenced by the location of the ITCZ. Interannual variability in river discharge is also high, with periods above and below the long term mean lasting many years to a decade.

The Glowa-Volta project is an integrated project designed to better understand the complex relationships between the water cycle, climate, landcover change and economic development. The project utilizes observations across a range of spatial scales, and includes measurement of surface meteorology, turbulent heat fluxes, runoff at experimental catchments, and land cover. Remote sensing is used to obtain information at the larger Volta basin scale. It is expected that four additional experimental areas (numbered 4 through 7 in figure 1) will be added during 2003 and 2004.

Data Summary

Drainage area to outlet:

Novrongo ~10 km^2

Nodwua ~20 km^2

Ejura ~15 km^2.

Basin outlet latitude-longitude:

Novrongo: 10.92°N, 1.03°W;

Nodwua: 9.48°N,0.92°E

Ejura: 7.33deg;N, 1.27°W

Stream gauge/water level recorder period of record: April 2001 to present (with gaps)
Precipitation gauges:There are raingauges at all seven sites located in Figure 1.
Water level gages:
Micrometeorological data:

Novrongo: Turbulent flux measurement takes place with Scintillometers, sensible heat only (2001-present with some gaps). Instrumentation will be moved to another site in 2004;

Nodwua: Turbulent flux measurement takes place with Scintillometers, sensible heat only (2001-present with some gaps). Eddy correlation during some campaigns;

Ejura: Turbulent flux measurement takes place with Scintillometers, sensible heat only (2001-present with some gaps).

Turbulent flux measurements:

Novrongo: Turbulent flux measurement takes place with Scintillometers, sensible heat only (2001-present with some gaps). Instrumentation will be moved to another site in 2004.

Nodwua: Turbulent flux measurement takes place with Scintillometers, sensible heat only (2001-present with some gaps). Eddy correlation during some campaigns.

Ejura: Turbulent flux measurement takes place with Scintillometers, sensible heat only (2001-present with some gaps).

Soil moisture:

Novrongo: Soil moisture with Delta-T Probe(10, 20,30,40,60,100 cm) at weekly time intervals;

Nodwua: Soil moisture with Delta-T Probe(10, 20,30,40,60,100 cm);

Ejura: Soil moisture has been measured, but no details available.

Other measurements:

Novrongo: Surface radiometric temperature (field campaign observations, but permanent instrument to be installed in 2003, detailed landcover classification;

Nodwua: Ground heat flux using Hukseflux plate (2001-present with some gaps), tree density CO2 measurements (campaigns), PAR, landcover classifications, species characterization, soils (particle size distribution, hydraulic conductivity, organic matter, pH;

Ejura: Albedo, ground heat flux using Hukseflux plate (2001-Present with some gaps), tree density event based runoff measurements and infiltration measurements have been taken in field plots various soil parameters such as particle size distribution, hydraulic conductivity, organic matter.

Reference

Contact Information

Dr. Nick van de Giesen (nick@uni-bonn.de)