satellite data provides fresh insights into the amount of water in the Nile Basin

Flows through 11 African countries, the Nile River plays an important role in the lives of more than 24% of Africa’s population. For both upstream and downstream countries, the Nile waters are of cardinal importance in development planning, food and energy production.

As countries compete for these resources, there has been tremendous tension. Most importantly, Egypt and Sudan dispute Ethiopia’s decision to complete construction Great Ethiopian Renaissance Dam. This is a major project on one of the most important tributaries of the Nile, the Blue Nile, which supplies more than 80% of the water that reaches Egypt.

Treaties are needed to determine the allocation of water resources in the region. To make this happen, it is critical to have accurate data on how much water there is. But global water scarcity data is based on insufficient ground observations. They are very outdated and do not cover enough of the major adjoining river basins. This is due to funding, maintenance costs, terrain and topography. In the Nylkom, hydrological monitoring stations have significantly decreased in number over the past 30 years.

But that is changing. Recent progress in hydrological satellite observations it is possible to regularly collect more reliable information. This has opened the door to new research efforts to update the global availability of water.

Hydrological satellite observations happens when a satellite – hundreds of kilometers away from the earth’s surface – observes repeated visits to the same site several times a month. One of these – which can better assess the total changes in water volume – is NASA’s joint satellite mission Gravity recovery and climate experiment.

We research team is one of the first to use data from this satellite mission for a water scarcity assessment in Africa. We have the data in use various studies of the Nylkom. This includes assessments of how the water levels in the Nile Basin are affected the climate and people.

The data enabled us to make accurate calculations that were not possible before. For example, we were able to determine how much surface water there is and what the soil moisture is and the level of groundwater. Previous studies have mainly focused on one or some of the variables, such as the water from the river flow.

Our study shows that there is an imminent water crisis in the Nile Basin. This calls for an urgent regional initiative on sustainable management of water resources.

Monitoring from space

Founded in 2002, monitor Gravity Recovery and Climate Experiment satellites changes in global water resources in all forms. The data is available monthly.

We used these observations to determine the total available water storage in the Nile Basin between 2002 and 2020. Overall, the data revealed that the total available water storage in the sink, from all resorts, can reach an average of 180 billion cubic meters per year. This estimate is approximately twice the current estimated storage of 88 billion cubic meters per year. If you have such data, it will inform how much water there is in the basin’s water sharing agreements.

We also used the satellite data to calculate the total available water storage for two main water tower areas (the source of the river) – Lake Victoria and the Blue Nile basin – and two large bodies of water. zinc regions (where slowly flowing water is lost due to evaporation) – the 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 show that Victoria Water Tower receive approx. twice the water volume that the Blue Nile basin receives during the wet season. And the Sudd basin (the southern basin) loses about twice the water compared to the northern Main Nile region.

These updated figures require that progressive water resources be planned to save additional water resources for future development in the region.

The satellite observations also confirmed that the stream area of ​​the Nile was experienced between 2002 and 2020 wetter conditions. The Nile River basin had approximately eight times more water storage in 2020 than in 2002. These wetter conditions require further planning for more water volumes during flood seasons.

Despite this, our conclusion confirms previous reviews that the sink is under water.

Water stressed

It is said that a region experiences water stress if the available water per person per year – for domestic, agricultural and industrial needs – is less than 1000 cubic meters per year, about 1,000,000 liters per person per year.

For daily basic needs a person uses approx. 150 liters per day. In Egypt (an important recipient of the Nile), someone uses approx. 200 liters average for domestic water needs per day. However, agriculture needs – like food production – needed between 2,000 and 5,000 liters of water per day.

If the available water becomes less than 500 cubic meters per year – about 500 000 liters of water per person per year – to meet all water needs, an area is under absolute water scarcity conditions.

Due to the current and thriving population projections – the population of the basin is expected to reach 800 million by 2050 – the basin is under severe water stress conditions.

To estimate the annual available water per capita, we need to divide the total available water in the region, which we estimate is 180 billion cubic meters per year, by total population. We therefore estimated that the available water per capita could be used 450 cubic meters per year, or about 1230 liters per person per day. But there is an important caveat; the total amount of available water cannot all be extracted and used due to technological and economic constraints. Therefore, the actual amount of usable water is probably less than 1230 liters per person per day.

Shoreline countries must, more than ever before, strengthen agreements on future water planning and new water-sharing policies.

Data for rescue

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

Having accurate information about the available water will improve the understanding of common water resources and promote trust between the washing states.

Emad Hasan, Postdoctoral researcher in hydrological remote sensing, Binghamton University, New York State University and Aondover Tarhule, Professor, Vice President of Academic Affairs and Pastor, at Illinois State University, Illinois State University


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