Water Resources Assessments

Aquaquest undertakes a broad scale of water resources assessments, from the collection of baseline data to the development of comprehensive, long-term water resources management programmes. Assessments provide the foundation to make informed decisions in water resources development, ranging from large scale water supply for human settlements, irrigation for commercial farming, industrial use, to dewatering operations.

Borehole Site Surveys

Aquaquest conducts hydrogeological studies and geophysical surveys to determine the most optimal locations for groundwater exploration. The company has modern equipment for electrical resistivity and magnetic surveys. Detailed data reviews are part of all groundwater investigations by Aquaquest. This includes the analysis of satellite imagery, GIS, aerial photography and database / statistical techniques.

Borehole Drilling & Test Pumping Supervision

We provide professional and independent advice during the drilling, installation, and test pumping of boreholes. Our quality assurance and control protocols result in costs savings for our clients, among others, through improved pumping efficiency and extended operational lifetime of each borehole. Aquaquest works with drilling and test pumping contractors to incorporate best practices and suitable construction materials during borehole developments.

Groundwater Monitoring & Modelling

Long term monitoring of groundwater and surface water is of utmost importance if large amounts of water are pumped from boreholes, dams, or rivers. Aquaquest is equipped to develop modern water and climate monitoring stations and automated networks that provide an early warning against possible negative impacts on established water supply systems. Climatic changes or excessive pumping can lower water levels, which may result in decreased yields or even depleted boreholes. An early adjustment of the pumping regime can reduce the long-term impact and save the local aquifer or surface water body (and with that, your business) from irreparable deterioration.

Irrigation & Water Supply

Aquaquest is able to assist you with various activities required for agricultural development ranging from topographic surveys, soil surveys, agro economic analyses, irrigation requirements, irrigation system design and implementation. We have experience developing ground- or surface water based water supply for irrigation and (gravitation based) irrigation schemes. We can help you identify the most ideal source of water supply, either surface or groundwater. Aquaquest is highly experienced in conducting catchment yield analyses for surface water supply, topographic surveys for design purposes and geophysical field surveys (both 1D profiling, 2D ERT and VES) to identify ground water sources.

Hydrometric & Meteorological Instrumentation

Aquaquest has extensive experience with the installation of various hydrometric and meteorological instruments. Projects include the installation of automated water level, water quality and climate monitoring systems for the mining, meteorological, agricultural and water management sectors. Aquaquest is also the main supplier of Van Essen equipment in Zambia.

WASH (Water, Sanitation & Hygiene)

Baseline, mid-term and endline evaluations for WASH projects and other socio-economic studies are part of the services provided by Aquaquest. Household surveys, field observations, key informant interviews, sample selection statistics, and mapping activities play an important role in these studies. Collection and analysis of available data, interviews and questionnaires, and stakeholder analysis are key elements for socio-economic studies.

Water Quality Sampling and Analysis

Aquaquest can assist with the sampling, delivery and analysis of water samples. Samples are tested by licensed, professional laboratories within Zambia. With a strong background in geo- and hydro-chemistry, Aquaquest is well suited to analyse results and provide appropriate recommendations for treatment options.

Borehole Camera Surveys

Our borehole camera inspections allow detailed internal examination of boreholes, helping diagnose structural issues, confirm construction quality, and guide rehabilitation or maintenance work.

Borehole Site Surveys - Methodology

Hydrogeological Assessment

Aquaquest undertakes a desk-based review of readily available data to develop an understanding of the hydrogeological setting. Typical data for review may include, but are not limited to:

Topographic, geological and hydrogeological data, maps, studies, and other relevant reports covering the area.
Available satellite images and photographs.
Information on existing boreholes, local wells, and other water sources in the immediate surrounding area of the target location.
Available historical water data reports (boreholes, springs, dams, river flows, etc.).
General information on surface water sources, including drainage direction, seasonal or perennial flow, source areas, and water quality.
Borehole drilling and siting reports, if available.
Information on land use systems and potential sources of pollution (e.g., agricultural areas with intensive fertilizer/pesticide use, petrol stations, industrial facilities, landfill areas, accumulated waste).
Other relevant technical information related to the site or region.

This review provides insight into the local geomorphology, underlying geology, and the presence of lineaments, which may be linked to subsurface features or structural weaknesses such as faults and fractures. The analysis also helps identify surface water features (springs, perennial streams, dry stream channels, wetlands/dambos), which assist in selecting suitable borehole drilling locations. Flood-prone areas—generally unsuitable for handpump sites—can also be identified.

The desk-based review incorporates remote sensing techniques to identify geological lineaments and assess the general groundwater potential of the site. An analysis of lineaments and other hydrogeological indicators is carried out to determine the most promising target areas for the geophysical survey.

Survey Methodology

The geophysical survey verifies assumptions from the hydrogeological assessment and supports the identification of locations with the highest groundwater development potential. The survey uses electrical resistivity profiling and Vertical Electrical Soundings (VES) at selected locations, using an ABEM SAS 4000 Terrameter (Figure 1).

Resistivity Methods

Resistivity measures how strongly a material opposes electrical current flow. Different geological units can be distinguished by their resistivity range—compact formations like granite show high resistivity, while clay, weathered material, fractures, and water-bearing zones show lower resistivity.

Resistivity (ρ) is defined by the equation:

R = U / I = ρ · (l / A)

Where:
R = resistance (Ω)
U = voltage (V)
I = current (A)
ρ = resistivity (Ωm)
l = length (m)
A = cross-sectional area (m²)

Because contact resistance affects direct measurements, voltage is measured using separate electrodes connected to a high-impedance voltmeter. This produces an apparent resistivity (ρ_a), which represents a simplified constant value if the subsurface is homogeneous.

The Schlumberger array is used for measurements. The apparent resistivity for the array can be approximated as:

ρ ≈ πL² / (2l) · (V / I)

Schlumberger Array Diagram — Figure 2. Schlumberger Array

Resistivity methods rely on several assumptions, and the topsoil is rarely homogeneous. For this reason, measurements are interpreted alongside other data sources such as geological maps, satellite imagery, and field observations.

Resistivity Profiling

Resistivity profiling identifies lateral variations at a constant depth. Target areas with high groundwater potential are selected based on:

Desk study findings, including remote sensing and geological analyses
Field reconnaissance and ground-truthing observations

Profile lines are oriented perpendicular to geological lineaments, topographic trends, or suspected faults. The most favorable locations for VES and potential borehole drilling are identified by resistivity anomalies, which indicate:

Fractures and fault zones
Geological boundaries
Weathered zones
Potential water-bearing pockets

The profiling setup uses the Schlumberger configuration with a total electrode spread of 120–200 m, depending on target depth and known aquifer characteristics. Readings are typically taken every 10 m.

Vertical Electrical Soundings (VES)

VES identifies vertical variations in subsurface conditions and is particularly useful for determining depth to bedrock. Where drilling data exists, VES results can interpolate conditions between known points.

VES surveys typically use a 400–480 m spread, allowing for an investigation depth of approximately 100–120 m below ground level.

Borehole Drilling & Test Pumping Supervision - Methodology

Drilling Supervision

Following the results of the geophysical survey, an exploratory drilling programme is generally recommended to confirm water availability and determine the sites with the highest sustainable yields. The highest-yielding pilot holes are then developed into production wells to match the anticipated water demand.

Aquaquest provides independent supervision of drilling contractors during the drilling, installation, development and test pumping of exploratory and production boreholes. This ensures both quality and quantity assurance for the client, while guaranteeing that relevant data is properly collected and recorded, and that boreholes are installed to appropriate technical standards to achieve a sustainable maximum yield.

Aquaquest staff are onsite throughout drilling operations to collect and interpret key information on geology, water strikes and estimated aquifer yields. These parameters and observations are used to design and construct the most efficient and cost-effective production well.

Exploratory drilling is typically executed using a 6-inch diameter hammer to identify the most economically viable sites. Once the best sites are confirmed, production boreholes are reamed, installed, developed and tested. A pilot hole is usually completed within half a day, while reaming, installation and development into a production borehole generally takes two or more days. Actual completion time varies with depth, drilling speed, rig type, contractor experience and ground conditions.

Drilling and construction are carried out by an independent drilling contractor, who provides all necessary equipment and materials. Aquaquest prepares a detailed drilling record for each borehole, and the full results of the drilling programme are presented and analysed in a borehole completion report.

Test Pumping to Assess Long-Term Sustainable Abstraction Rates

After drilling, installation, development and completion, all boreholes are test pumped to determine their sustainable yield. Aquaquest supervises and analyses controlled test pumping of each completed production well to gather information on well performance, aquifer behaviour, long-term abstraction potential and interactions with neighbouring boreholes.

The recommended test-pumping programme typically includes:

A step-drawdown test (four steps of 1–1.5 hours each)
A 24-hour constant discharge test
Recovery measurements

Aquaquest provides full data analysis, graphical presentation, interpretation and recommendations on long-term sustainable abstraction rates, as well as the most suitable pump types and installation depths.

The required submersible pumps, piping and power supply are typically provided by the client or the drilling contractor (directly or via a selected test-pumping contractor). Aquaquest ensures that all work is carried out in accordance with professional standards and the predetermined testing regime. All collected data is analysed to determine sustainable pumping rates, optimum pump settings and related operational recommendations.

Our Services