Challenges of Modeling the Congo (SSAWRN)

Alan Anderson

Raphael Tshimanga is the first RISE student in the SSAWRN network to have completed his PhD, and he is impatient to put it to good use. He will do so by returning to his home institution, the University of Kinshasa, in the Democratic Republic of Congo (DRC), where he has been appointed Deputy Head of the Department of Natural Resources Management. While the department has few resources to support either his teaching or his research on the hydrology of the Congo River basin, his task is clear to him and his work is already begun. It is nothing less than to quantify the water use of human populations in the Congo and to calculate the amount that can safely be used in the future without jeopardizing the health of the river basin itself.

While the task of formulating sound policies is inherently difficult in a land with few scientific resources, the difficulty is compounded by the country’s political instability and the many demands on a vast but finite water resource. At first glance, the Congo might seem large enough to slake the thirst of all Africa; it is, after all, the world’s deepest river (in places more than 700 feet), and the third largest in volume of flow, behind only the Amazon and the Ganges-Brahmaputra. Its flow is also unusually constant, because the Congo River basin straddles the Equator. The rainy season north of the Equator peaks in August, while the rainy season south of the Equator peaks in March, bringing heavy rains to the basin almost constantly. The region itself, within the Intertropical Convergence zone, is also the wettest part of the continent.

However, the present and especially the future demands on the Congo are enormous. Not only do the DRC’s 10 neighboring countries expect a large share, but so do other drought-plagued regions from Cairo to Johannesburg. Complex inter-basin treaties have developed over the years, as have the DRC’s own needs.

Amid these complex demands, Raphael will attempt to focus on the science. In particular, he will attempt to quantify the future impacts of land use and climate change on the amount of water that may be available for use.

His interest in helping the DRC is deep and life-long. He was born in Kinshasa, and earned his bachelor’s at the University of Kinshasa. He majored in agricultural engineering, specializing in soil and water science, and went on for post-graduate studies in Cairo. There he learned much about hydraulic engineering and river basin development in a country that has managed its own great river for many centuries. He also shares a connection with Egyptian water managers in that both the Nile and the Congo are fed by the same wet highlands that rise along the western edge of Lake Victoria.

After earning a master’s degree in hydrology at the University of Dar es Salaam, in Tanzania (another country bordering Lake Victoria), he worked as a research fellow at the University of Bergen, Norway, in water resources management. There he heard about RISE, through his connections with WaterNet, a southern African network of water researchers and students. After receiving information about SSAWRN from academic director Denis Hughes, he wrote a proposal for the work he had long hoped to do on the Congo. His title – “Hydrological Uncertainty Analysis and Scenario-based Stream-Flow Modeling of the Congo River Basin” – described his ambitious goals of quantifying and predicting the water resources of the basin.

Once accepted to RISE, his first challenge was to assemble enough accurate data from a region with little instrumentation or meteorological expertise. He needed as much data as possible about rainfall, evaporation, stream flow, and other features. Because monitoring instruments were few across the vast countryside, he had to depend heavily on data from satellites and from other institutions, especially the University of East Anglia, the Food and Agriculture Organization of the United Nations, and the Global Runoff Data Centre in Germany. Along with meteorological data, he also learned as much as he could about the physical properties of the basin, including land cover, soil type, geology, and geomorphology.

Because of these data shortcomings, building a model capable of simulating the climate of the entire Congo basin – second in drainage area to only the Amazon – was an enormous challenge. Raphael calls the result a “conceptual hydrological model,” or an “aggregation of processes.” Nonetheless, after much work in testing and validating his model, he concludes that it is sufficiently useful for the task of calculating future runoff. “We concluded that our model is good,” he said, “by using international standards that have been established to evaluate models such as these. It works well to estimate and predict water resources, and the future impact of various land uses and climate changes.”

The early estimates based on the model have already been useful, for example, in predicting near-term responses to climate. Should climate change proceed as predicted, he said, it would decrease rainfall in the northern Congo, and increase evapotranspiration. The combined result, he calculates, is likely to be a decrease in the mighty Congo’s stream flow of about 10 percent.

But such early results, he said, while encouraging, are not good enough. When assembling the model, he had sufficient ground data only to make rough predictions for the northern part of the basin – the portion above the equator that borders Uganda, Sudan, Central African Republic, the Republic of the Congo, and others. “More local data are needed to validate the satellite data, including at least 30 reliable ground stations,” said Raphael. “There should be more than 30, but that would help.”

And Raphael is even more concerned about having insufficient data for the large portion of the DRC that borders Tanzania, Zambia, Angola, and other countries south of the Equator. This region supports about 150 weather stations, but their maintenance is not efficient or consistent.

And he anticipates many requests for stream flow data in next decade. These are not yet quantified, but he needs to be prepared with responses when they do arrive. “We will need many studies to bring deep understanding of hydrological behavior of the basin and how it will respond to water withdrawals,” he said.

The needs for Congo water will be both internal and external. The DRC itself will use more water for electricity, irrigation, industry and drinking water. The country will also face pressures from other water-poor countries, and Raphael will help devise the most efficient ways to comply. One technique is “virtual water transfer,” such as growing corn in the Congo and sending it to Botswana or elsewhere as food instead of by constructing pipelines, which is very expensive. He will also be asked to explore the feasibility of hydropower network development, such as joint projects of the Congo and Nile basins. The water of the Nile is being used mainly by downstream countries such as Egypt on the basis of long-standing colonial agreements. Upstream countries are eager to find their own water to promote development – water they would like to receive from the Congo.

Political pressure is already coming from the many countries that depend on the dwindling waters of Lake Chad, located along the borders of Chad and Nigeria. About 5,000 years ago, this enormous expanse of water and wetlands was a vast inland sea, thought to have covered about 150,000 square miles. Its size has fluctuated dramatically since then, shrinking to less than 10,000 square miles in 1983 and only 580 square miles in 2000. While it has recovered somewhat since then, it has always been extremely shallow and vulnerable to evaporation. Comparable in area to Lake Tanganyika, its maximum depth is only about 34 feet, compared with a maximum depth of nearly a mile (4820 feet) for Lake Tanganyika.

Lake Chad, dependent on the unreliable inflow of the Chad River, faces heavy demands from farmers and ranchers. The Lake Chad Basin Commission (LCBC), including many countries with legal claims on the lake’s waters, has discussed ways to replenish the lake. In 2008, a summit meeting of the LCBC announced plans for an interbasin diversion project featuring water from the Congo. Part of Raphael’s challenge will be to calculate the consequences of diverting various quantities of water from the Congo basin without jeopardizing the DRC’s own water security. “There will be a lot of pressure on us,” predicted Raphael. “There will be more competition for development, and when they say development, they mean water.”

He added that he also must educate leaders in his own country about the need for better data before making political decisions. For example, there is almost no data on the present uses of Lake Chad water, which must be known before an agreement can be valid.

“The future of the Congo basin is now unknown,” said Raphael. “People don’t want to wait for the science, they just want to go ahead with the planning. But what is planning without science, without information? How can we do good planning without knowledge?” The DRC government today has a better understanding of water resource issues than it did 10 years ago, he said, but its policy options are limited by shortages of money, skills, and public will.

Meanwhile, he is anxious about having sufficient time and resources for both teaching and research, but is determined to do his best. He has already organized three orientation courses at the university, on soil and water, flora and fauna management, and forestry, and he expects to plan more courses to educate students about water resources. He has published five papers about his work, and submitted three more to journals, but raising funds for continuing research is a challenge. He has early indications of interest from the IDRC of Canada and Laval University in Quebec City, but he will have to work hard to build a program of the quality he envisions.

“I am going back because I have done this work, and it is appreciated, and I would like to try to implement these ideas in the Congo,” he concluded. “I hope to help bridge institutional barriers, and bring researchers together with decision makers. When it comes to political activity, good decision making requires information and skills. If we are able to provide those, we can help good decision making.”