Untitled Page
DWA Home Page  
 
Untitled Page

BERG RIVER MONITORING PROGRAMME

Untitled Page

Announcements

Surveys


Groundwater


Hydrocensus and data review
Additional boreholes and monitoring

Hydrocensus and data review
After initial data collation and synthesis, including compilation of a project database, a hydrocensus will be designed and conducted throughout the Berg River Catchment, with particular focus in the 50 km downstream of the proposed Skuifraam Dam. This will entail visiting farms, collecting basic groundwater information (borehole position, depth, yield, abstraction etc.) and measuring water levels and electrical conductivity. Other organisations such as state departments, regional and local authorities, farmers unions, drillers and pump contractors will be contacted to ensure as many of the existing boreholes in the area are identified. Potential for inclusion into a regional monitoring network will also be assessed. All data will then be captured onto the project database. Data thus collated and collected will be analysed and a conceptual geohydrological model of the catchment developed (Initialisation report). This will include the construction of groundwater flow direction maps and water quality maps. Using both surface and groundwater data, an attempt will be made to assess the surface - groundwater interaction and groundwater-ecosystem dependence and groundwater contribution to baseflow, and to identify stretches along the river that may be losing water to the groundwater system. This report will form the basis for the design of the groundwater monitoring programme.

Additional boreholes and monitoring
Based on the outcome of the first two tasks, a groundwater monitoring network in the Berg River Catchment will be designed. This network is to link with that established in the Langebaan Road Aquifer.

As soon as practically possible, water level and water chemistry monitoring of existing boreholes will be initiated. It is expected quarterly monitoring on existing boreholes will commence on completion of the hydrocensus, in order to collect as much information as possible during the project.

Data collection:
· Monitoring will include the measurement of groundwater levels and EC, pH and temperature in the field and collection of groundwater samples for analysis by the IWQS in Pretoria. Sampling and the storage and transportation of samples will be in accordance with recommended sampling procedures (Weaver, 1993).

Monitoring frequency:
· Selected existing boreholes will be monitored on a monthly basis for the duration of a year. Thereafter, quarterly monitoring will continue until the completion of the project. On completion of the project this function is to become the responsibility of the DWAF Regional Office.

In places where existing boreholes cannot be used, dedicated monitoring boreholes will have to be drilled. Dedicated monitoring boreholes may also be required to investigate specific issues such as surface - groundwater interaction or suspected contamination. Proposed drilling sites will be selected in consultation with DWAF's regional geohydrological staff. It is specifically required that lithological characteristics be considered in the site selection process. The consultants will manage the drilling and logging of the estimated 10 boreholes.

It has been requested by the DWAF Regional Office that the 10 additional boreholes be fitted with continuous data loggers to monitor groundwater levels and electrical conductivity. This equipment is relatively costly (water levels only = R 11 700; water level and electrical conductivity = R 35 000), but could provide very meaningful data regarding surface - groundwater interaction. It is therefore proposed that 8 water level loggers be installed together with 2 water level and electrical conductivity loggers. Data will be downloaded from the loggers every three months to coincide with the baseline monitoring run of existing boreholes. At the same time, data from continuous rain gauges (to be supplied and installed by DWAF) will also be downloaded.

Deliverables:
All data collected during the project will be used to compile the Baseline Report. This report will present:
· a conceptual understanding of groundwater conditions in the catchment,
· an assessment of surface groundwater interaction
· an initial assessment of potential impacts resulting from the construction of the proposed dam
· the results of monitoring, and
· recommendations for further monitoring.

It is proposed the report will contain sufficient data on which to base an intermediate-level Reserve determination. Collected data will be submitted to DWAF electronically for capture onto the NGDB.