Mapping Water Potential:To Support UNHCR Refugee Camp Operations in Eastern Chad

Mapping Water Potential:To Support UNHCR Refugee Camp Operations in Eastern Chad


Firoz Verjee
SEAS Doctoral Fellow & Research Associate,
Institute for Crisis, Disaster & Risk Management,
The George Washington University
[email protected]

Alain Gachet
Managing Director,
Radar Technologies France (RTF)
[email protected]

In 2004 the UNHCR commissioned the use of remote sensing to map the potential of buried water reservoirs in the massive Ouaddaï region in eastern Chad. The UN needed to discover renewable water sources urgently and efficiently, as the challenge of providing water to Sudanese refugees and their local host communities was overwhelming. Using a proprietary process called WATEX, French exploration firm RTF analyzed a variety of remotely sensed data to identify areas suitable for refugee camps along the Chadian border near Darfur. Early results are impressive – after drilling test wells at Wadi Dalal, one of RTF’s recommended sites, the UNHCR established a major camp in early 2005, announcing that the camp has enough water to support up to 30,000 refugees. This paper provides an overview of the data and methods employed in eastern Chad. It also provides a promising example of how geospatial technologies can support humanitarian operations in arid and semi-arid regions.

In its March 2004 appeal to the General Assembly of the United Nations, the UN Office for the Coordination of Humanitarian Affairs (UNOCHA) noted the severe challenge of providing assistance to host communities and refugees from Darfur due to water scarcity in eastern Chad (United Nations 2004). Facing an estimated 110,000 refugees at the time, the UNHCR and UNICEF began costly water trucking operations while simultaneously rehabilitating existing water points and undertaking extensive water sanitation training programs. Through its affiliates UNOPS and UNOSAT, the UNHCR also retained the services of Radar Technologies France (RTF) to develop water potential maps to support existing and future refugee camps throughout the region.

After a rapid assessment of available geological, hydrological, topographical, and geospatial data, RTF employed state-of-the-art remote sensing to map the water potential of a region nearly 100,000 square kilometers in size. The humanitarian dimension of the project demanded timely and efficient identification of belowground reservoirs capable of producing sufficient volumes of clean water to support existing and future refugee operations. According to the Sphere Humanitarian Charter minimum standards, this entailed finding reserves capable of providing 15 liters per person per day, without burdensome walking distances or container refilling times (The Sphere Project 2004). For a typical camp population of 20,000 refugees, this meant finding reservoirs of at least 90,000 annual cubic meters of water in volume.

This paper describes how geospatial analysis was utilized to remotely assess the water potential of the Ouaddaï region in eastern Chad, rapidly and without extensive field survey. Trial and operational phases of the project were completed over a total of four months between March 2004 and February 2005; as demonstrated in the case study of Wadi Dalal, the project enabled the UNHCR to identify new campsites capable of supporting tens of thousands of Sudanese refugees.

Challenge & Opportunity
The reader is no doubt aware that there were a number of significant challenges presented by the Darfur humanitarian crisis as it began to unfold in 2003 (Bouchardy 2005). Response agencies needed to maintain operations over a border region approximately 650 km long and 84,000 square kilometers in size – a region the size of Portugal. Not only was this region undeveloped and largely inaccessible, it was within a zone of conflict that affected the security of both refugees and humanitarian relief workers. Facing a refugee population that quickly approached 200,000, authorities needed to discover massive water reserves able to sustain refugee camps for several years, without compromising the interests of local host communities in Chad (Bouchardy 2005).

This challenge was made even more complicated by the extreme urgency imposed by the escalation of the refugee crisis, the limited resources with which to assess hydrological potential of eastern Chad, and a poor understanding of regional geological phenomena. Basic analysis confirmed that the region’s Proterozoic granite basement renders land surfaces generally impermeable, reducing groundwater collection except in alluvial sediments, which are prone to rapid evapotranspiration. Long-term programs to deliver water by tankers to the refugee camps were not sustainable because of long distances and unreliable tracks and deficient bridge infrastructure. An alternative solution was needed to prevent dehydration, water-washed and waterborne disease amongst vulnerable populations.

Recognizing the severity of these challenges, and the inadequacy of traditional water exploration methods, the UNHCR decided to employ a remote sensing process, WATEX, in order to guide water-drilling operations and optimize the location of refugee camps. Developed to support water exploration in arid and semi-arid areas, WATEX exploits the evolution of civilian geospatial technology to analyze large, heterogeneous climatic and geologic regions for groundwater potential. Several recent trends have made the use of such technology possible:

  1. The availability of Synthetic Aperture Radar (SAR) earth observation satellite imagery, which provides highly-sensitive geological and hydrological intelligence not discernable through optical imagery;
  2. The 2003 release of the Shuttle Radar Topographic Mission (SRTM) global terrain model, which provides slope and elevation data of unprecedented quality compared to other topographic information of the region;
  3. The removal of “selective availability” from Global Positioning System (GPS) signals, enabling civilian access to precise location information almost anywhere on the surface of the Earth;
  4. The widely appreciated “digital revolution”, which now gives even small firms access to high-power computing, user-friendly analysis software, and rich data archives accessible via the Internet. (Verjee 2005)