Lower Volta and the Volta delta: Ghana’s river flood hotspot
Eight of the 13 districts that stay at the top of Ghana’s modelled river flood ranking lie on the lower Volta, its delta and the Keta lagoon: Keta, South, North and Central Tongu, Anloga, Ada East, Ada West and Ketu South. Together they hold about half of the modelled damage to homes and of the people exposed.
- 8 lower Volta and Keta lagoon Act districts
- 252 other districts
How to read this: the orange districts run from North Tongu, below the Akosombo dam, down to the sea at Ada and east along the Keta lagoon to Aflao. Each stays in Ghana’s top 20 for modelled river flood damage under every assumption I tested. River flooding only; not an official priority list.
- of Ghana’s 13 Act districts lie on the lower Volta, its delta and the Keta lagoon
- 8
- of Ghana’s modelled annual river flood damage to homes, about GHS 2.78 billion a year (derived from the model)
- 54%
- people inside the modelled 1-in-100-year river flood in these eight districts, 48% of the national total (derived from the model)
- 566,674
- of low ground connected to the sea at the 1-in-100-year level in the same districts today, two-thirds of the national total (derived)
- 87.1km²
Why does the lower Volta top Ghana’s river flood ranking?
Because many people and homes sit on low, flat ground beside Ghana’s biggest river and its lagoons. In the model, a 1-in-100-year flood reaches about 566,700 people in these eight districts, nearly half the national total. Keta and South Tongu never fall below fourth in Ghana for modelled damage in any of the nine tests. derived from the model
Below the Akosombo and Kpong dams the Volta runs past Juapong, Battor, Adidome and Sogakope to the sea at Ada. East of the mouth, the Keta lagoon lies behind a narrow sand bar that carries Anloga, Keta and the road to Aflao. Towns, farms and fishing communities sit close to the water along the whole stretch.
I ranked all 260 districts by modelled damage to homes under nine combinations of flood edge and damage curve. These eight stay in the national top 20 every time. Their sums are mine: about GHS 2.78 billion a year of modelled damage, 54% of the national figure, and 566,674 people, including about 200,800 children derived from the model.
The eight lower Volta districts hold nearly half the people in Ghana’s river flood zone
How to read this: the map opens on the stretch from Accra to Keta, with the eight lower Volta and Keta lagoon districts outlined. Colours show people living inside the modelled 1-in-100-year flood, as in the key. Switch to damage, to the priority class or to the whole country; tap a district, or a row of the table, to read its figures.
Modelled river flooding. People live inside the modelled 1-in-100-year flood; damage is to homes and their contents, a yearly average. “Nearly half” is my sum of the district results derived from the model.
Sources
My independent consultancy (2025–26), also my Oxford MSc dissertation. Hazard: JRC global river flood hazard maps v2 (CC BY 4.0). Buildings: Google Open Buildings v3. People: WorldPop (CC BY 4.0). Boundaries: OCHA/HDX COD-AB (Ghana Statistical Service).
| District | Region | Damage to homes a year, GHS m (median) | People in the 1-in-100-year flood extent | National rank across 9 combinations | Class |
|---|---|---|---|---|---|
| Keta Municipal | Volta | 598.6 | 112,294 | 1st–3rd | Act |
| South Tongu | Volta | 476.4 | 89,113 | 2nd–4th | Act |
| Ketu South | Volta | 421.3 | 101,768 | 4th–6th | Act |
| Ada East | Greater Accra | 371.6 | 63,149 | 5th–6th | Act |
| Anloga | Volta | 369.6 | 63,481 | 4th–7th | Act |
| North Tongu | Volta | 307.4 | 66,672 | 7th–8th | Act |
| Ada West | Greater Accra | 130.6 | 42,492 | 8th–12th | Act |
| Central Tongu | Volta | 107.8 | 27,705 | 9th–17th | Act |
Damage: median expected annual damage to homes and contents, floods from 1 in 10 to 1 in 500 years, flood extent as mapped. Rank: best and worst national rank for damage across the nine combinations. All 13 Act and 13 Investigate districts: flood-prone districts in Ghana.
Which lower Volta districts are most at risk of flooding?
Keta and South Tongu, which rank between first and fourth in Ghana for modelled damage under every assumption. Keta also has more people inside the 1-in-100-year river flood than any district in Ghana, about 112,300. Ketu South, Anloga and Ada East follow, all within the national top seven.
- Keta Municipal
- 1st to 3rd for damage. About 112,300 people in the flood zone, the most in Ghana, and about 8,300 people aged 65+, also the most.
- South Tongu
- 2nd to 4th. Sogakope and the lower river; about 89,100 people in the flood zone.
- Ketu South
- 4th to 6th. The eastern end of the Keta lagoon to Aflao; about 101,800 people, and the most children of any district, about 37,400.
- Anloga
- 4th to 7th. On the sand bar between the lagoon and the sea; about 63,500 people.
- Ada East
- 5th to 6th. The Volta mouth and the Songor lagoon; about 63,100 people, and the largest coastal flood area in Ghana.
- North Tongu
- 7th to 8th. Juapong and Battor, just below the dams; about 66,700 people.
- Ada West
- 8th to 12th. The coast and lagoon edges west of the Volta mouth; about 42,500 people.
- Central Tongu
- 9th to 17th. Adidome and the middle reach; about 27,700 people.
Two more Act districts sit higher up the same river. Asuogyaman holds the Akosombo dam; Shai Osudoku faces North Tongu across the Volta. Nearby, Ketu North, Akatsi South and Lower Manya are Investigate districts: they reach the national top 20 under some assumptions but not all.
Where do river and sea flooding meet on the lower Volta?
At Ada and along the Keta lagoon. At the 1-in-100-year sea level, Ada East and Ada West hold about 85 km² of low ground connected to the sea today, nearly two-thirds of Ghana’s total. Keta and Anloga have little today, but in a stress test the Keta lagoon connects to the sea and floods widely. derived from the model
With a 0.25 m sea-level rise scenario for 2050, Ada East grows from about 45 km² to 77 km². At Keta the same rise changes little in the screen, 0.86 km² to 0.93 km². Only when the stress test adds a further 0.5 m does the lagoon connect: about 385 km² in Keta and 162 km² in Anloga.
The river screen and the coastal screen were run separately. Nothing here models a river flood and a high sea arriving together, which is exactly what can happen at a delta. That combined picture needs a 2D model of the river, the lagoons and the sea boundary.
The coast’s biggest connected flood area is at the Volta mouth, by Ada
How to read this: the chart shows the eastern end of the coast, from Prampram to Aflao, and opens on section 47, at the Songor lagoon near Ada; the lower Volta and the Keta lagoon are the sections to its right. Switch to 2050 or the stress test and watch the Keta sections. Tap the chart, or use the arrow keys, to move along the coast.
The last 136 km of Ghana’s 566 km coast, in 14 of its 57 sections, west to east; the total in the panel is for the whole coast. Top: the 1-in-100-year sea level. Bottom: low ground connected to the sea at that level. Static screening; forcing provisional.
Sources
My analysis (2026), independent consultancy. Water levels: GTSM hourly reanalysis; waves: ERA5 (Copernicus Climate Change Service). Terrain: FABDEM v1-2 (Fathom and University of Bristol, CC BY-NC-SA 4.0).
| District | Today, km² | 2050, +0.25 m, km² | Stress test, +0.75 m, km² |
|---|---|---|---|
| Keta Municipal | 0.86 | 0.93 | 384.57 |
| South Tongu | 0.00 | 0.00 | 61.90 |
| Ketu South | 0.46 | 0.51 | 55.53 |
| Ada East | 45.13 | 77.08 | 133.63 |
| Anloga | 1.21 | 1.33 | 162.41 |
| North Tongu | 0.00 | 0.00 | 6.47 |
| Ada West | 39.42 | 41.95 | 47.67 |
| Central Tongu | 0.00 | 0.00 | 10.41 |
| All eight derived from the model | 87.08 | 121.80 | 862.59 |
Stress test: 2050 sea level plus a further 0.5 m for wave processes, 0.75 m above today; a sensitivity, not a forecast. Part of its flooding along the Volta channel is an artefact of the static method. More: Ghana’s coast to 2050.
Do the 2023 dam spillage and the 2026 floods match the model?
They are not a test of it. The flood maps do not represent how the dams are operated, so releases from the Akosombo and Kpong dams, lagoon gates and sand bars are not in them. What the reports do show is how many kinds of flooding these districts face, most of which a national river screen leaves out.
These are reports by others, given as background:
- 2023, Akosombo dam spillage. The UN in Ghana estimated 35,857 people displaced, and a UN rapid assessment team covered North, Central and South Tongu (UN in Ghana, 6 November 2023).
- April 2026, Fuveme. The Ghana News Agency reported tidal waves breaking through the sand bar at Fuveme, and concern that the sea could open a second estuary into the Keta lagoon.
- June 2026, Keta. The Ghana News Agency reported the Keta lagoon overflowing into Havedzi, Kedzi and nearby communities. Residents linked it to continuous rain and controlled spillage from Akosombo, and asked for the Havedzi flood gate to be opened.
- June 2026, the Tongu districts. The Ghana News Agency reported floods displacing residents in South, Central and North Tongu after heavy rain, with local leaders pointing to poor drainage.
Only part of this is river flooding as my national screen sees it. The Tongu floods of June 2026 were described as rain and drainage flooding, which the screen does not model. The Keta reports involve lagoon levels, gates and sand bars. That mix is the strongest argument for a local study that brings them together.
What would a local flood study on the lower Volta involve?
A detailed model of the river, the Keta and Songor lagoons and the sea boundary, run with dam-release scenarios and high tides together. It would be checked against the 2023 flood, use surveyed floor levels and the communities’ own flood records, and end with options people can act on and warning levels agreed with the agencies.
This is a proposal, not a planned project. In practice it would run in five parts:
- Flows. River flows for a range of flood sizes, with release scenarios from the Akosombo and Kpong dams agreed with the operator.
- Model. A linked 1D–2D model at 10–30 m, with the coastal screen’s hourly tide, surge and waves at the sea boundary.
- Check. Against satellite maps and reported impacts of the 2023 flood, the way I checked the national maps against the White Volta in 2020.
- Who and what. Floor levels, schools, clinics and roads, and what residents say about past floods.
- Decide. Options compared on one basis, and trigger levels for warnings.
It is the same sequence I followed at Hamstall Ridware in England, on a much smaller river: my own hydrology, a 1D–2D model built jointly with an Environment Agency colleague, then an appraisal of the options. There, the farmers built an earth bund.
What does the national screen not show here?
No dams, gates or barsReservoir releases, the Keta sea defence and its flood gates, and the sand bars at river and lagoon mouths are not represented.
River flooding onlyRain and drainage flooding, like that reported in the Tongu districts in June 2026, is not modelled. A low figure is not “no risk”.
No combined floodingRiver floods and high seas are screened separately, never together.
Screening, not street levelThe 90 m river grid and the 30 m coastal grid compare districts and stretches of coast. They cannot say whether one house floods.
Not officialIndependent consultancy; the river work is also my Oxford MSc dissertation, presented for discussion with the World Bank. Not an official priority list of the Government of Ghana or the World Bank.
Questions people ask
Is Keta at risk from the river or the sea?
Both, in different ways. In the river screen Keta ranks between first and third in Ghana for modelled damage and has the most people in the flood zone. In the coastal screen it is barely touched today, but the Keta lagoon connects to the sea in the stress test.
Does the model include releases from the Akosombo dam?
No. The global flood maps it uses do not represent how the dams are operated. Release scenarios agreed with the dam operator would be one of the first inputs to a local study.
How many people live in the lower Volta flood zone?
About 566,700 people live inside the modelled 1-in-100-year river flood in the eight lower Volta and Keta lagoon districts, including about 200,800 children. That is my sum of the district results, 48% of Ghana’s total. People at risk of flooding in Ghana.
Will the Keta lagoon flood more as the sea rises?
In this static screen, a 0.25 m rise changes little at Keta. With a further 0.5 m the lagoon connects to the sea. Whether that happens in reality depends on the sand bar, the inlets and the gates, which only a 2D model with surveyed defences can test.
Is this an official list of priority districts?
No. It is my independent analysis, also my Oxford MSc dissertation, presented for discussion with the World Bank. It is not an official priority list of the Government of Ghana, NADMO or the World Bank.
Sources
- Nuhu, H. (2026). National fluvial flood-risk assessment and priority stability under uncertainty in Ghana. MSc dissertation, University of Oxford. Independent consultancy, presented for discussion with the World Bank. Method and results.
- Nuhu, H. (2026). Ghana national coastal flood hazard: total water level, extreme-value analysis and connected inundation. Independent consultancy. Method and results.
- European Commission Joint Research Centre. Global river flood hazard maps, version 2 (CC BY 4.0). JRC data catalogue.
- WorldPop, University of Southampton. Gridded population, 2026 (CC BY 4.0). worldpop.org.
- Google Research. Open Buildings v3 building footprints. Open Buildings.
- Copernicus Climate Change Service. Hourly tide and surge levels (GTSM) and ERA5 waves. Water levels; ERA5.
- Fathom and University of Bristol. FABDEM v1-2, 30 m terrain (CC BY-NC-SA 4.0). Data record.
- UN in Ghana (6 November 2023). UN in Ghana reaffirms its support to Ghana in the wake of the Akosombo dam spillage disaster. Article.
- Ghana News Agency (29 April 2026). President Mahama visits tidal waves hit Fuveme in Volta Region. Article.
- Ghana News Agency (24 June 2026). Keta residents demand opening of Havedzi flood gate, dredging of lagoon to stem perennial flooding. Article.
- Ghana News Agency (June 2026). Floods displace residents, destroy property in Tongu districts. Article.
- Ghana Statistical Service / OCHA. Ghana subnational administrative boundaries (COD-AB). Humanitarian Data Exchange.
Work with me
Preparing flood work on the lower Volta or the Keta lagoon?
I can scope a local study, build the river and coastal evidence it needs, and turn the results into options and warning levels people can use. Remote or in-country.