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WEEK SIX: HOW DO WE MANAGE WATER SYSTEMS? | ESSAY ONE

River of Life: A Case Study of the Zambezi River

by Ashton Applewhite, Christine Kirchhoff, and Jonathan Bulkley

Victoria Falls

The Zambezi River is more than 2 kilometers (1.2 miles) wide when it reaches Victoria Falls (or Mosi-oa-Tunya, literally “the smoke that

thunders”). The river drops a dazzling 108 meters (354 feet) into basalt gorges, raising an iridescent mist that can be seen 20 kilometers (12

miles) away. ©UNESCO

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As we saw with the Mekong River and its fertile delta, when rivers cross national borders, water management challenges grow. Transboundary

pressures can lead to potential conflicts and complicate the sustainable use of a resource upon which diverse nations place multiple demands.

Eight countries and some 40 million people rely on the Zambezi River Basin, the largest in Southern Africa. The water is used for drinking,

fisheries, irrigation, hydropower production, mining and industry, ecosystem maintenance, and other purposes. The Zambezi also attracts

tourists from around the world to Victoria Falls and to the wildlife along its banks. Tourism supports local economies and brings much-needed

foreign currency into the basin countries.

Known as the “River of Life,” the Zambezi drains the entire south-central region of the African continent. It rises out of a marshy bog in

Zambia about 1,460 meters (4,800 feet) above sea level, and flows 3,540 kilometers (2,200 miles) to the Indian Ocean to end in a wide, marshy

delta. Over its course, the river changes dramatically, from a placid flow across sandy plains to a tumbling river of falls and rapids. At Victoria

Falls (where author Eleanor Sterling was married), dramatic cataracts twice the height of Niagara Falls are considered the dividing line between

the Upper and Lower Zambezi.

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The River of Life

The Zambezi River Basin covers some 1.37 million square kilometers (529,000 square miles) across eight countries. Six of these countries have

ample water supplies for their people, including Angola, Botswana, Mozambique, Namibia, Tanzania, and Zambia; but Malawi and Zimbabwe

are water-stressed. A warning symbol indicates a country that is water stressed; a water droplet indicates a country that has adequate water

supplies. ©AMNH

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Management ChallengesNowhere in Southern Africa has transboundary water management faced more obstacles than in the Zambezi River Basin, where water must beshared by multiple countries with many competing interests, all of which demand time, attention, and money. Basin-level institutionalstructures are only now emerging. Each country faces legal, economic, and technological constraints, and each has a pressing need for moretrained water resource professionals.

The eight basin countries share the watershed, but their location, rainfall, and level of economic development all shape differing priorities.[Table 1 summarizes each country’s water resources.] The lion’s share of the watershed lies within Zambia and Zimbabwe, which are the onlycountries that currently participate in bilateral management of the river because they share Victoria Falls, Lake Kariba, and the Kariba Dam.Relatively water-rich countries like Angola, Mozambique, and Zambia are less reliant on surface water for irrigation. Namibia receives scantrainfall and is reliant on groundwater for irrigation, which is likely to be an unsustainable practice given Namibia’s relatively low rainfall andrate of groundwater recharge.

Two major dams, the Kariba Dam (completed in 1959, and which has two hydropower stations, one in Zambia and one in Zimbabwe), and theCahora Bassa Dam (completed in 1973) are important sources of hydroelectric power. They have profoundly affected the ecology of the LowerZambezi Basin, stressing wetland ecosystems and mangrove swamps, and contributing to a dramatic reduction in the size of the delta. Seasonalrainfall variation is also an issue for Mozambique and other downstream countries. The Zambezi has an average yearly flow of 3,600 cubicmeters per second (127,000 cubic feet per second), but in the wet season, flows increase substantially, sometimes causing damaging floods.These floods were once cyclical, with people living along the river migrating toward and away from the shoreline to follow the natural seasonalpattern. However, dams have completely changed that pattern. Midlevel floods are smaller and less frequent, but massive floods still occurwhen upstream runoff combines with heavy rain in the lower basin. For example, on occasion large volumes of water have had to be released toavoid overtopping the dams. Tensions between upstream and downstream nations result because communications are poor, and people caughtunaware lose lives and property from these now-unpredictable floods. In water-scarce countries, drought is an ever-present concern. Malawiand Zimbabwe are already under water stress, which will likely worsen along with the predicted changes in precipitation and temperatureassociated with climate change.

Even in regions of Southern Africa where water is plentiful, access to clean drinking water and sanitation remains a persistent and significantchallenge. [Table 2 summarizes the percentage of rural and urban populations in the eight basin countries with access to clean drinkingwater and sanitation.] This critically important issue is only one of the many that compete for time, attention, and money in the region.

Rain-Soaked

In March 2009, flooding along the Zambezi in Namibia rose to the highest levels in 40 years, affecting more than 350,000 people. Thesesatellite images (acquired in March 2009 and during a typical dry season in October 2002) show the incredible amount of flooding thatoccurred beyond the normal rainy season. ©NASA Earth Observatory

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Additional ChallengesIn addition to governance and economic deficits at the national level, Southern Africa must grapple with political and ecological issues thatrespect no borders and threaten the region as a whole.

Population growthThe population in the Zambezi River Basin is increasing at the rate of 2.9 percent per year, and is expected to grow until at least 2015.

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Partly as a consequence of adult deaths related to HIV-AIDS, more than 40 percent of the current population is under 14 years of age.The demand for water, for irrigation in particular, is increasing along with the population. Rainfall is the basin’s primary source ofrenewable freshwater.Climate change

Climate change is already manifesting in much of Southern Africa, including the Zambezi River Basin. Air temperatures are increasing,as are evaporation rates; the storm cycle is changing, bringing unusually severe rainfall at atypical times. Overall, however, the totalamount of rainfall appears to be declining and droughts are more frequent.Pollution

The surface waters of the Zambezi Basin are polluted by mining, industry, and agriculture, as well by human wastes discharged withoutadequate treatment. In-stream manifestations include eutrophication (excessive nutrients causing algal blooms), increased dissolved andsuspended solids, and increased nitrates and toxic contaminants from mining operations.Invasive species

Native to South America and first observed in the Zambezi in 1994, the water hyacinth’s (Eichhornia crassipes) thick, floating mats cancause oxygen deprivation and fish kills. The Kafue River (a Zambezi tributary) transports nutrients from agricultural areas in Zambia,providing a major nutrient source for the plants. Water hyacinth also grows at an alarming rate in bays polluted with human sewage.Overfishing

Fish are a vital resource for communities living along the Zambezi, which depend on them for income, trading, and protein. One non-native species, the Lake Tanganyika sardine (Liomnothrissa miodon), has been introduced to Lake Kariba with positive results. Knownas the kapenta, this fish has become a major source of protein for people in the basin. The overall fish catch, including that of the kapenta,has been declining year after year because of overfishing and pollution.Siltation

Nearly 74 percent of the Zambezi River Basin’s energy use by people comes from burning biomass or wood. This consumption of woodfor fuel and lighting has caused widespread deforestation and erosion, with rain carrying soil into regional rivers. Silt builds up behinddams, and when the volume of water in the reservoir declines, so does the amount of hydropower the dam can generate. Twelve of the 20dams built on the Zambezi’s tributaries have already lost 50 percent of their reservoir capacity.Poverty

As evidenced by Zimbabwe’s devastating cholera epidemic of 2008–2009, the country lacks the resources to build or maintain watertreatment plants. While water at the center of large lakes may be clean, inshore and along the riverbanks it can be contaminated byagricultural runoff and human waste that carries waterborne disease. The urban poor are also at risk. While 88 percent of Zambia’s city-dwellers have access to clean drinking water [see Table 2], cholera outbreaks occur in poor urban settlements when water iscontaminated in the process of being collected from a central pipe.

Table 1: Water Resources

This data shows the supply and demand of water available for the eight countries in the Zambezi River Basin. A warning symbol indicateswater stress on the table. (data from Scholes and Biggs, 2004)

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Table 2: Clean Water and Sanitation Access

This data shows the urban and rural access to clean drinking water and modern sanitation solutions for the eight countries in the Zambezi RiverBasin. A warning symbol indicates low levels of access on the table. (data from Kirchhoff and Bulkley, 2008)

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Potential Infrastructure

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A severe drought during the 1991/1992 rainy season brought home the vulnerability of the Zambezi River Basin’s water resources and all those

who depend upon them. Several projects that have since been proposed—dams, a within-basin diversion, and an out-of-basin diversion—

exemplify different approaches to meet growing demands:

A hydroelectric facility—including a dam, a powerhouse, and a reservoir—in the gorge region below Victoria Falls.Under discussion are a dam at Batoka Gorge that would generate 1,600 megawatts and one at Devil’s Gorge that would generate 1,240

megawatts. (Eight more dam sites along the Zambezi’s main stem have been identified, plus four in Malawi to the north, but these two

are the largest in terms of power production—though small compared to the world’s largest dams.) Construction would involve raising

significant capital and also submerging 100 kilometers (62 miles) of world-class whitewater rapids, which has generated real dispute.

A diversion from the Zambezi River below Victoria Falls, to provide municipal and irrigation water to a region chronically short ofwater. Bulawayo, Zimbabwe’s second major city, sits at the far end of the drainage basin and is 1,000 meters (3,000 feet) higher than the river.

The first phase of the diversion plan is the Gwayi-Shangani Dam, which is being built by a Chinese company at the confluence of two

tributaries. The government of Zimbabwe has committed $500 million to the project. A pipeline will connect Bulawayo to the dam, and

another to the Zambezi has been proposed. The diverted water would need to be pumped uphill about 450 kilometers (225 miles). Also

on the drawing board is a plan to irrigate the same region, but the demand would be far greater (50 times the municipal supply), and

meeting the city’s needs is the first priority.

A water diversion project that would transfer 95 cubic meters per second (3,300 cubic feet per second) from the Zambezi River whereit meets the Chobe River into South Africa’s Vaal River system. This represents about 7 percent of the historic mean annual flow of the Zambezi River at this location. Both the scale and the energy

requirements of the project are daunting:It would require building a pipeline about 800 kilometers (500 miles) long and a generator

capable of producing 1,300 megawatts to pump the water that distance. In addition, because South Africa is not part of the Zambezi

Basin, construction would necessarily involve negotiations with basin countries. South Africa does have other power-generating facilities

and has significantly replumbed its own rivers, but the country faces ongoing chronic water scarcity, so a project of this magnitude is

plausible.

Whether or not they have direct access to the Zambezi, water-scarce countries in the region all have their eyes on the river. Drought is an ever-

present concern, and Malawi and Zimbabwe are already under water stress. Dams are the projects most likely to be completed if external

funding is in place, because of the need for electricity. Resistance to building additional large dams is growing because of the environmental

costs and, more recently, because of concerns regarding water loss from reservoirs through evaporation. In-country diversions are limited by

the costs involved, but the fact that they involve a single government makes them relatively feasible. Out-of-basin diversions are the least likely

of all, because of the costs and the political complexities involved. Each of these projects has different impacts upon the environment and upon

the ways the river is presently being used, all of which would have to be worked out among the basin stakeholders.

One initiative making headway in the Zambezi River Basin, promoted largely by nongovernmental organizations such as the Nature

Conservancy and the World Wildlife Fund, is environmental flows (e-flows): releasing water from dams in an attempt to mimic natural flood

regimes. Coordinating releases upstream and down, and taking storm events that occur throughout the basin into account would require very

sophisticated communication and control. These e-flows would also have to be carried out without compromising hydropower output from the

dams, since electricity for cities and industries is in high demand. But balancing these multiple and complex demands as well as coordinating e-

flows down the length of the Zambezi River is increasingly feasible—and important.

Southern Africa’s Water Resources

This map shows the percentage of seasonal rainfall during the 2003-2004 rainy season. ©USDA

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A New Approach to Dams?

Dams in Zambia and Zimbabwe, such as the Kariba (shown here), have come into question for their degradation of the surroundingenvironment. However, the promise of environmental flow practices in the United States and China is being considered for application on theZambezi. ©The Nature Conservancy

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Progress on Management and GovernanceNational sovereignty, competing water demands, human and financial resources, lack of knowledge, and political power differentials havemade it difficult to institute sustainable water resource planning and management. Governance remains a key constraint. Sustainable waterresource management is also impeded by limited data collection, management, and dissemination systems, inadequate training, and weakstakeholder participation. But the tide may be turning.

The Southern African Development Community (SADC), which encompasses Southern Africa from the Democratic Republic of the Congo toSouth Africa and Madagascar, is a supra-regional body established to foster integration, harmony, and sustainable development within theregion. SADC’s Water Division has been instrumental in assisting member countries in developing institutions to manage Southern Africa’s 15rivers more sustainably. The Zambezi is just one of those river basins, but a significant one because it involves so many countries.

An institutional framework, the Zambezi Watercourse Commission (ZAMCOM) was established in 2004 between the eight river basincountries. Only Zambia has yet to sign. ZAMCOM’s objective is to promote the equitable and reasonable use of the Zambezi River Basin’swater resources. The next step is to finalize a draft “integrated water resources management” (IWRM) strategy for the basin. Member states arerecognizing the critical importance of educating and training water professionals. Cooperation with the other countries (in Europe in particular)that are providing assistance with IRWM is increasing. Decades of planning for sustainability are finally coming to fruition, but there’s a longway to go.

Christine Kirchhoff is a PhD candidate in resource policy and behavior at the University of Michigan's School of Natural Resources andEnvironment. Jonathan Bulkley is a professor of engineering sustainable systems at the University of Michigan and holds a PhD in politicalscience from MIT.

Related Links

Zambezi River Authority »

The government agency that manages the water resources and dams of the river basin.

Nature Conservancy: Great Rivers Partnership »

An environmental policy partnership between conservation groups working in the Mississippi, Paraguay-Paraná, Yangtze, and Zambezi RiverBasins.

Southern African Development Community »

Learn about the agriculture, social, and infrastructure programs of this 15-country project.