After Nile Waters Recede in Sudan, What Do Satellite Images Reveal?

At the height of the season when Nile waters are expected to begin rising, children on Narnarti Island in northern Sudan were forced to push their boat through a shallow riverbed to reach their school, while pumps at the Salha water station south of Omdurman stopped operating after water levels receded.

From the Northern State to Khartoum, another video showed widened riverbanks and exposed sandbars, while satellite images revealed a reduction in surface-water coverage at several locations compared with previous years.

Despite the clear decline, its causes remain disputed. While rainfall data indicate a severe deficit over parts of the Blue Nile Basin, Sudan, Ethiopia, and Egypt have presented conflicting accounts of the role of the Grand Ethiopian Renaissance Dam (GERD) and its operating procedures.

This Misbar investigation tracks the extent and timing of the decline and examines whether it resulted from a weak rainy season, changes in dam releases, or a combination of both.

From Narnarti to Tuti, Water Levels Decline at Several Locations

A comparison of satellite images captured over the Nile River near Narnarti Island during the second half of July 2026 with images of the same area during the corresponding periods in 2023, 2024, and 2025 shows a noticeable decline in river water levels, particularly in the channel between the island and the opposite western bank.

The sharp decline in water levels in that channel continued through the first week of August 2026 compared with the same period in 2025, the year the GERD began operations.

On Tuti Island, opposite the capital Khartoum, satellite imagery shows that the recession exposed an area of up to two square kilometers at the southern tip of the island, roughly coinciding with an announcement by the Khartoum State government that the Salha water station had temporarily gone out of service because of low water levels.

The Salha station is located south of Omdurman in Khartoum State, about five kilometers south of Tuti Island. On July 13, Sudanese authorities said a significant decline in Nile water levels had caused the intake pumps at the Salha station to stop operating.

Although satellite imagery shows a significant decline in Nile waters near the station in July 2026 compared with June, it also indicates that the decline appears to be seasonal, recurring around the same time each year, according to a sequence of satellite images from 2022 through 2026, with the decline becoming more pronounced since 2024.

The Salha station relies on water from the White Nile. The White Nile originates from Lake Victoria in the Great Lakes region at the Uganda-Kenya-Tanzania border. Although the Sobat River, one of the White Nile's major tributaries, is partly fed by the Baro River originating in the Ethiopian Highlands, it is not directly affected by the GERD, which is located on the Blue Nile.

Further south of Khartoum, in Ketranj village between Gezira and Khartoum states, exposed areas of dry land can be seen following the recession of water in the Blue Nile, alongside a limited decline in the water-covered area within the river channel. The change is visible in a July 15 image compared with another image from June.

A chronological sequence of Sentinel-2 images shows a clear decline in the area since July 2022, which coincided with the third phase of filling the GERD reservoir. Available evidence indicates that water levels increased relatively in 2025 but declined again in July 2026.

However, 2026 was not the worst year in that area. Dry areas within the river channel appeared more prominently in 2024. That year saw the fifth and final phase of filling the GERD reservoir, which began on July 17, before Ethiopia announced its completion by early October.

Flood Season Begins With Below-Average Flows

The observed decline in Nile waters at several locations in Sudan coincided with the beginning of the flood season, while rainfall data indicate a clear deficit in parts of the Blue Nile Basin, the Nile's most important tributary and the one with the greatest impact on seasonal flows.

The main rainy season over the Ethiopian Highlands typically runs from June through September, during which flows in the Blue Nile rise in Sudan. The Blue Nile provides the largest share of Nile waters during the flood season, accounting for up to around 80% or more of flows at their peak, while its contribution decreases during the dry season.

Preliminary data extracted from CHIRPS maps show a negative rainfall anomaly, meaning below-average precipitation, over parts of the Ethiopian Highlands, including the area around Lake Tana, where the Blue Nile originates, during June and July 2026.

Rainfall anomaly refers to the difference between the amount of precipitation recorded during the observed period and the average rainfall in the same area over a historical reference period. In this analysis, the reference average was calculated for the period from 1981 to 2020. Given how recent the observed period is, 2026 data remain preliminary and subject to updates.

The data show that rainfall recorded during June and July 2026 was about 230 millimeters below the historical average, compared with a deficit of 96.82 millimeters during the same period in 2025. By contrast, rainfall in 2024 exceeded the average by about 81.17 millimeters.

Although the July data provided by CHIRPS maps remain preliminary and subject to updates, the size of the deficit provides an early indication of a weak rainy season. A comparison of June data, which are complete for all three years, also shows that rainfall recorded in June 2026 was the lowest compared with the same month in 2024 and 2025, as well as with the historical average of 482.48 millimeters, based on the geographic range and reference period used in the analysis.

This trend is consistent with estimates from the Climate Prediction Center of the U.S. National Oceanic and Atmospheric Administration (NOAA), which indicate that the El Niño phenomenon will persist during the second half of 2026 and is likely to continue through the winter of 2026-2027.

According to monitoring by the Famine Early Warning Systems Network (FEWS NET), the start of the June-September rainy season has been disrupted in parts of Sudan and South Sudan, as well as in Ethiopia's Kiremt rainfall areas. Large areas recorded rainfall below 45% of normal levels between early June and July 10, 2026.

Climate model forecasts indicate that below-average rainfall could persist across large parts of West, East, and North Africa during August and September, alongside above-average temperatures. The combination of the two factors could accelerate evaporation and evapotranspiration and deplete soil moisture and surface-water resources.

Alongside this rainfall deficit, satellite imagery showed a slight decline in the visible water surface area of the GERD reservoir in July 2026 compared with the same month in 2025. However, this comparison alone is insufficient to attribute the change to reduced rainfall, as the reservoir's surface area may also be affected by water releases, dam operating procedures, and evaporation rates.

Satellite imagery indicates that the GERD reservoir began forming in July 2020. This followed an official Ethiopian announcement on June 27 stating that the filling process would begin within two weeks. On July 22, Addis Ababa announced the completion of the first phase of filling, after storing about 4.9 billion cubic meters of water.

Reservoir filling continued through five seasonal phases between 2020 and 2024. In October 2024, Ethiopian authorities announced the completion of the fifth and final phase of filling, along with the completion of the dam's civil works.

Since the reservoir reached its largest observed extent in 2024, the satellite images analyzed by Misbar have not shown any further expansion in its water surface area. Instead, images from July 2025 showed limited areas of exposed land along the reservoir's edges, before the decline in visible water coverage became more pronounced in June 2026.

This pattern coincides with differences in rainfall levels across the three seasons, with 2024 recording more rainfall than 2025 and 2026 within the geographic area studied. However, this correlation alone is insufficient to establish that reduced rainfall was the direct cause of the reservoir's decline, as visible water surface area is also affected by storage levels, water releases, turbine operations, evaporation, and the topography of the lake's edges.

Lack of Rainfall or GERD Operations?

On July 29, 2026, Ethiopian Minister of Water and Energy Habtamu Itefa said the Ethiopian Highlands had experienced a significant decline in rainfall during the current season and that the amount of water entering the GERD reservoir was determined by rainfall rather than operational decisions. The minister attributed the decline in water flows toward downstream countries to natural hydrological fluctuations and denied that dam operations were responsible.

Sudan's Ministry of Agriculture and Irrigation, however, offered a different explanation. In a statement published on July 17, 2026, the ministry referred to a "temporary decline" in Nile water levels in several parts of the country and attributed it to reduced Blue Nile inflows resulting from a decline in GERD releases between July 7 and 9.

The ministry stressed that fluctuations in river levels between recession and flooding are a natural phenomenon but noted that the construction of the GERD had altered the hydrological characteristics of the Blue Nile, requiring Sudan to manage its reservoirs according to flows received from the Ethiopian dam.

Egypt did not issue an official statement at the time blaming the GERD alone for the decline observed in Sudan. However, Egyptian Minister of Water Resources and Irrigation Hani Sewilam linked disruptions in flows reaching Sudan to the continued unilateral operation of the dam in the absence of a binding agreement and a mechanism for exchanging data.

Sewilam said the incoming water was a "black box" for Sudanese dam operators because they did not know in advance how much water would reach them. He explained that the absence of data could prompt them to reduce storage levels as a precaution, affecting the dams' capacity to store water and generate electricity.

On July 21, Egyptian Foreign Minister Badr Abdelatty expressed a similar position, saying Ethiopia had begun operating the dam unilaterally and that the lack of coordination over water storage and releases had created risks affecting the two downstream countries, particularly Sudan.

Satellite imagery alone cannot settle the dispute between the two accounts. The absence of an increase in the GERD reservoir's surface-water area does not necessarily mean that no additional water was retained, because surface area does not correspond directly to storage volume. Outflows are also affected by turbine and gate operations and reservoir levels.

However, Sudanese data provide direct evidence of a short-term change in flows. According to a statement from Sudan's Ministry of Agriculture and Irrigation, daily inflows into the Roseires Reservoir fell from 207 million to 129 million cubic meters between July 7 and 9, a difference of 78 million cubic meters per day. This coincided with a decline in releases downstream of the Roseires Dam by about 100 million cubic meters per day, and downstream of the Sennar Dam by 82 million cubic meters between July 7 and 10.

Sentinel-1 imagery supports the observation of the impact of this change, with an image captured on July 8, 2026, showing a slight reduction in the visible water surface area of the Roseires Reservoir compared with an image from June 25.

Read More

Satellite Images Reveal Likely Site of First International Base Inside Gaza

At the Gate of the Northern Jordan Valley: Misbar Tracks Two Settlement Projects Near Tayasir Checkpoint