Terms of Reference for Ground Water Resource Mapping in Turkana East Sub County, Practical Action

Enhancing Water Access and Systems Strengthening for Arid and Semi-Arid Lands Project
(EWASSA II)

Introduction
Practical Action is an Innovative International Development Organization putting ingenious ideas to work so people in poverty can change their world. Practical Action has over 50 years of expertise in Africa, Asia and Latin America, with the East Africa Headquarters’ office based in Nairobi- Kenya. We have a strong heritage and track record of bringing communities and experts together to find practical, sustainable solutions which work for both people and the planet; solutions that enable people to meet their needs and lead dignified lives.

Technology features in everything we do. We partner with people whose lives are transformed by these efforts and ensure local ownership and solutions that work in the longer term, without us.

Purpose of the Project

The main objective of the ground water mapping exercise is to determine the existence of both shallow (up to <100m) and deep (greater than 100 m depth) groundwater resources underlying the Turkana East, Turkana County. Secondly, the consultancy will guide on water quality with strong emphasis on zones that have potable (fresh) water and those that are heavily saline. The study shall be conducted using multi-approach methods outlined in the scope of work.

1.2 Specific Objectives

• Identify all the water-bearing lithological formations (aquifers) in Turkana East
• Ascertain the relationship between the degree of faulting in a particular lithology and respective borehole capacities
• Determine hydraulic characteristics of the aquifers
• Estimate the quantity of groundwater water in the aquifers
• Determine the quality of groundwater in the aquifers and produce a water quality index map for area
• Estimate the amount rate of groundwater recharge, flow and storage based on available/acquired datasets
• Provide recommendations on alternative and sustainable solutions for water access in highly saline zones where boreholes and shallow wells are not appropriate
• Assess the potential impacts of human activities and climate variability on ground water potential
• Map hotspots where extreme pressure to ground water are likely to be experienced

Scope of the Consultancy
The study will take place in two wards in Turkana east; Lokori Kachodin and Katilia. The resultant groundwater resource map and water quality index map will form the primary knowledge products resulting from the Consultancy.
It will take the form of a Project GIS (QGIS and Google Earth. kml File formats) with as many relevant information layers as feasible.

• Drainage (SRTM Digital Elevation Model)
• Monthly Rainfall Averages (MODIS Model)
• Geology
• Springs
• Existing boreholes & hand pumps

The information layers in the GIS, combined with the results of secondary literature review, and new ground-truthing verification fieldwork, will form the basis for the analysis leading to the ‘subjective’ interpretation of the regional scale groundwater architecture and its major geological and landscape controls.

• Groundwater Piezometric Map/Flow Paths
• Groundwater Boundaries / Recharge Zone Map
• Groundwater Quality Index Map
• Groundwater Borehole Yield/Depth/Transmissivity Map(s)

The Consultancy aims to improve the understanding of the groundwater resources in Turkana East and drilling sites for Practical Action/ other actors/ county government for community water supply boreholes. Priority will be given to areas with high potential for new freshwater sources.

2.1 Expected Outputs
The Consultant should complete the following key activities:

2.1.1 Phase 1: Desk Study
The work should start from data collection and review of all available information (available maps, documents, reports, hydro meteorological data, well data, water quality data, geological settings, demographic data, etc.). Background information should be gathered and collated by the Consultant and should include;

• Review of existing hydrogeological datasets in the project area, including the borehole completion records
• Preparations of field survey and GIS base maps for the project area
• Drafting inception report detailing existing hydrogeological datasets, the proposed methodology for detailed mapping
• Submission of the draft inception report to the Practical action (client)

2.1.2 Phase 2: GIS-Based Groundwater Potential
The consultant shall initially utilize GIS and remote sensing approaches to evaluate the groundwater resource potential in the project area. This approach helps to delineate target areas for hydrogeological and water quality assessment details. The outputs of this phase shall include a comprehensive report t including:
1) Drainage map of the project area
2) STRM/Digital terrain model
3) Vegetation classification
4) Groundwater point distribution
5) Statistical analysis of the soil types
2.1.3 Phase 3: Hydrogeology and Water Quality Study

The consultant shall investigate the hydrogeology of the aquifers and determine their characteristics in the project area. These characteristics shall include yields, depth to the aquifer, transmissivities, hydraulic properties, recharge, discharge, etc. The water quality study shall entail water sampling and the determination of physicochemical parameters. The primary outputs expected in this phase include:
1) Groundwater potential map, and;
2) Water quality index map
3) Aquifer delineation and recharge zones
4) Groundwater Borehole Yield/Depth/Transmissivity Map(s)

Apart from the above outputs, the consultant shall submit to the Practical Action the datasets acquired during this phase.

• Inventory of wells and all boreholes and recording their GPS coordinates and codes
• Identifications of possible target areas for geophysical investigation work to supplement the hydrogeological analysis.
• Interpretation of groundwater flow directions.

2.2 Methodology
The Consultant will be required to present a detailed proposed methodology as part of their technical bid. This methodology should be informed by the previous successful experience in other similar environments. The Consultant should elaborate on the approaches, tools, and outputs for each phase.

2.3 Deliverables and Timelines
The following are expected deliverables from the Consultant.

Background and Experience of the Consultant

• Advanced University degree in Hydrogeology/geophysics or relevant field
• Minimum 5 years’ experience managing and implementing groundwater mapping projects in Sub-Saharan Africa.
• Minimum 5 years’ experience in providing technical quality assurance on GIS, hydrological, geological, and geographical studies. Experience working in Turkana County would be an added advantage.
• Have the capacity to put together a professional team to carry out feasibility studies with similar complexity.
• The consultant should have excellent English writing/communication skills.
• Ability to mobilize all the required equipment/instruments at the required time and place.

Guidelines for Submission of Expression of Interest

Qualified and interested consultants should submit the following: