Satellite data provides new information on the amount of water in the Nile basin


Crossing 11 African countries, the the Nile plays an important role in the lives of over 24% of the African population. Both upstream and downstream countries, the waters of the Nile are crucial in development planning, food and energy production.

As countries compete for these resources, there has been immense tension. Specifically, Egypt and Sudan challenged Ethiopia’s decision to build and complete the Great Ethiopian Renaissance Dam. This is a large project on one of the main tributaries of the Nile, the Blue Nile, which provides over 80% of the water reaching Egypt.

Read more: Colonial-era treaties are to blame for the unresolved dispute over the Ethiopian dam

Treaties are needed to govern the distribution of water resources in the region. For this to happen, it is essential to have accurate data on how much water there is. But global data on water scarcity is based on insufficient ground observations. They are grossly out of date and do not cover the major ones enough transboundary river basins. This is due to funding, maintenance costs, terrain and topography. In the Nile basin, hydrological monitoring stations have considerably decreased in number over the past 30 years.

But that is about to change. Recent advances in hydrological satellite observations allow the frequent collection of much more reliable information. This opened the door to new research efforts to update the global availability of water.

Hydrological satellite observations when to arrive a satellite – hundreds of kilometers from the Earth’s surface – observes and makes recurring visits to the same site several times a month. One of them – which allows a better assessment of total changes in water volume – is the joint NASA satellite mission Gravity recovery and climate experience.

Our Research Team is among the first to use the data from this satellite mission for an assessment of water scarcity in Africa. We used the data in many studies of the Nile Basin. This includes assessments of how water levels in the Nile Basin are affected by climate and people.

The data allowed us to make precise calculations that were not possible before. For example, we were able to assess the amount of surface water, soil moisture, and groundwater levels. Previous studies have mainly focused on one or more of these variables, such as the water of the river flow.

Our study shows that there is a looming water crisis in the Nile basin. This requires an urgent regional basin initiative on the sustainable management of water resources.

Monitoring from space

Launched in 2002, the Gravity Recovery and Climate Experiment satellite monitor changes in the world’s water resources in all their forms. Data is available on a monthly basis.

We used these observations to determine the total water storage available in the Nile basin between 2002 and 2020. Overall, the data revealed that the total water storage available in the basin from all sources could reach an average of 180 billion cubic meters per year. This estimate is approximately double the current estimated storage of 88 billion cubic meters per year. Having such data would provide information on the amount of water allocated in the basin water sharing agreements.

We also used satellite data to estimate the total water storage available for two main water tower regions (the source of the river) – Lake Victoria and the Blue Nile basin – and two major water regions. well regions (where low flow water is lost through evaporation) – Sudd wetlands in South Sudan and the Main Nile region across Egypt.

Of what was Previously reported, recent Gravity Recovery and Climate Experiment satellite observations have shown that the Lake Victoria water tower receives approximately twice the volume of water that the Blue Nile basin receives during the rainy season. And the Sudd Basin (the southern water well) loses about twice as much water as the northern Main Nile region.

These updated figures call for a progressive planning of water resources in order to save additional water resources for the future development of the region.

Satellite observations also confirmed that between 2002 and 2020, the Nile basin experienced more humid conditions. In 2020, the Nile basin had about eight times more water storage than in 2002. These wetter conditions require further planning for more water volumes during flood seasons.

Despite this, our conclusion confirms previous assessments that the basin is under water stress.

Water stress

A region is said to experience water stress if the water available to use per person per year – for domestic, agricultural and industrial needs – is less than 1000 cubic meters per year, approximately 1,000,000 liters per person per year.

For basic daily needs, a person uses about 150 liters per day. In Egypt (a large receiver of water from the Nile), a person uses about 200 liters on average for domestic water needs per day. However, the needs of agriculture – such as food production – need between 2,000 and 5,000 liters of water per day.

If the water available for use becomes less than 500 cubic meters per year – about 500,000 liters of water per person per year – to meet all water demands, a region is in conditions of water scarcity. absolute.

Due to the current and growing population projections – the population of the basin should reach 800 million by 2050 – the basin is subject to severe water stress.

To estimate the water available annually per capita, we need to divide the total water available in the region – which we found to be 180 billion cubic meters per year – by total population. We have therefore estimated that the available water for use per capita is approximately 450 cubic meters per year, or approximately 1,230 liters per person per day. But there is an important caveat; the total amount of water available cannot be fully extracted and used due to technological and economic constraints. Therefore, the actual amount of usable water is probably considerably less than 1230 liters per person per day.

More than ever, riparian nations need to strengthen agreements on future water planning and new water sharing policies.

Data to the rescue

It will not be easy to get the 11 countries of the basin to agree on a water sharing plan to avoid chronic water shortages in the future. But the key to ensuring cooperation is good information sharing and technical cooperation among riparian states.

Having accurate information on available water will improve understanding of shared water resources and build trust among basin states.

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