Droughts in the Anthropocene

Zambia – Managing multiple objectives in a changing environment

In the centre of southern Africa lies the landlocked country of Zambia. In its capital, Lusaka, an estimated 60–70 per cent of the 2.5 million inhabitants live in informal settlements or peri-urban areas [1] [2]. During the dry season, Zambia is prone to drought and has struggled with insufficient water resources. Climate change is projected to lead to lower rainfall and higher temperatures in the region, which in turn would lead to lower water levels and higher levels of evaporation. The Iolanda water treatment plant provides about 40 per cent of the water supply for the utility that serves Lusaka, with boreholes providing the rest [3]. This treatment plant depends on hydropower to operate and often experiences power shortages. The water supply for Iolanda comes from the Kafue River, and the hydropower supply comes from the Kafue Gorge dam. This means that the water level in the Kafue Gorge reservoir affects both water availability and power availability, making Lusaka especially vulnerable to climate- related risks, since lower levels of water cause power shortages, which in turn affect the town’s service water supply [3]. Climate Risk Informed Decision Analysis (CRIDA) is a bottom-up approach to decision-making specifically designed to address water-related issues in vulnerable areas. It targets practitioners and stakeholders in developing countries facing drought and other factors that are difficult to predict, such as climate change. Its core approach is based on involving all relevant stakeholders and collaboratively defining the objectives of specific decisions to be made. The Millennium Challenge Corporation (MCC) piloted this approach as it considered how to address the problems facing the Iolanda water treatment plant. MCC

had previously committed to rehabilitate the Iolanda plant as a part of the Lusaka Water Supply, Sanitation and Drainage (LWSSD) project [4]. IHP has worked within the CRIDA framework to engage various stakeholders in different regions to design a robust climate stress test in order to identify the uncertainty of climate projections for water resources management in cooperation and collaboration with Category 2 centres and centres of excellence. In collaboration with the Alliance for Global Water Adaptation (AGWA), the U.S. Army Corps of Engineers (USACE), Deltares and the Dutch Ministry of Water and Infrastructure, UNESCO and the International Center for Integrated Water Resources Management (ICIWaRM) have recently published Climate Risk Informed Decision Analysis (CRIDA): Collaborative Water Resources Planning for an Uncertain Future [5]. The CRIDA approach analyses risk through a process called decision scaling, which means first identifying the status of current operations in the water supply system before taking different risks into the analysis. In the Iolanda case, the treatment facility required investment regardless of future climate risks, due to frequent power shortages. The subsequent vulnerability analysis identified the main problem as the lack of power, since a power shortage would occur before the water level fell below the treatment plant intake valves. A lack of treated water from the plant could lead to increases in waterborne diseases, stunting, increased mortality and lower economic productivity. Since the risk was deemed to be high, robust and flexible mitigation strategies were needed [3]. Three strategies were identified: buying and installing back-up generators, creating a power

agreement that would favour the plant during power shortages and building large transfer tanks to store water for the city. These alternatives were then evaluated for effectiveness, feasibility and cost. The final strategy selected via incremental cost analysis and considering political will, recommended the option of generators. While it was not deemed necessary to implement the solution at the time, ongoing rehabilitation work could ensure infrastructure is in place for when the generators are needed [3]. Infrastructure development that considers current and future risks enables more robust services, increasing the chance of long-term sustainability of water and power supplies. The improvement of the Iolanda water treatment facility cannot be solely attributed to the CRIDA approach, since the MCC-funded work at Iolanda was inscribed in a larger development project aimed at improving water, sanitation and sewage in Zambia. However, this example is one of several projects initiating a new global community of practice, which can inspire others to use similar methods to make informed and sustainable decisions related to water resource management.

AFRICA

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