Ghana: Water resources

A significant number of households (~40 %) depend on groundwater especially in the north [20], [21]. In particular after mid-century, climate change will reduce the recharge into groundwater reservoirs (aquifers), while increased requirements for agricultural water use under dry periods can lead to water scarcity. This risk is significant for closed basins such as Lake Bosomtwi, which has a small catchment [22]. In the south, sea level rise and storm surges will also increase the risk of salt water intrusion in freshwater especially in aquifers. Model results from the literature for the impacts of climate change on the Volta river basin in Ghana indicate that extreme flows will be more frequent [23], [24]. This means there is a likely increase of periods with either relatively higher or lower mean annual discharge than in the past, sometimes in consecutive years, affecting availability of fresh water for agriculture, sanitation, generation of hydropower and other economic activities.

Per capita water availability

Figure 9: Projections of water availability from rainfall per capita and year with national population held constant at year 2000 level (A) and changing according to SSP2 projections (B) for different GHG emissions scenarios, relative to the year 2000.

Current projections for water availability in Ghana display high uncertainty under both GHG emissions scenarios. Assuming a onstant population level, multi-model median projections suggest a slight decline in per capita water availability over Ghana by the end of the century under both RCP2.6 and RCP6.0 (Figure 9). Yet, when accounting for population growth according to SSP2 projections², per capita water availability for Ghana is projected to decline by about 70 % by 2080 relative to year 2000 (Figure 9, B). While this decline is not primarily driven by climate change but population growth, it highlights the urgency to invest in water saving measures and technologies for future water consumption.

Spatial distribution of water availability

Looking at the spatial distribution of future water availability projections within Ghana, it becomes evident that water saving measures will become especially important after 2050 in the north of the country (Figure 10). For all other parts of Ghana, water availability projections are too uncertain to make any such statement.

Figure 10: Water availability from precipitation (runoff) projections for Ghana for different GHG emissions scenarios.

² Shared Socio-economic Pathways (SSPs) outline a narrative of potential global futures, including estimates of broad characteristics such as country-level population, GDP, or rate of urbanisation. Five different SSPs outline future realities according to a combination of high and low future socio-economic challenges for mitigation and adaptation. SSP2 represents the “middle of the road”-pathway.


[20] P. Gyau-Boakye and S. Dapaah-Siakwan, “Groundwater as source of rural water supply in Ghana,” J. Appl. Sci. Technol., vol. 5, no. 1, pp. 77–86, 2000.
[21] E. Obubie and B. Barry, “Ghana,” in Groundwater availability and use in Sub-Saharan Africa: a review of 15 countries, P. Pavelic, M. Giordano, B. Keraita, T. Rao, and V. Ramesh, Eds. Colombo, Sri Lanka: International Water Management Institute (IWMI), 2012, p. Ch. 4, pp.43–64.
[22] B. F. Turner, L. R. Gardner, and W. E. Sharp, “The hydrology of Lake Bosumtwi, a climate-sensitive lake in Ghana, West Africa,” J. Hydrol., vol. 183, no. 3–4, pp. 243–261, Sep. 1996.
[23] K. Owusu, P. Waylen, and Y. Qiu, “Changing rainfall inputs in the Volta basin: implications for water sharing in Ghana,” GeoJournal, vol. 71, no. 4, pp. 201–210, Apr. 2008.
[24] L. Murken et al., “Climate Risk Analysis for Identifying and Weighing Adaptation Strategies in Ghana’s Agricultural Sector,” 2019.

Ghana: Climate


Figure 2: Air temperature projections for Ghana for different GHG emissions scenarios, relative to the year 1876.

In response to increasing greenhouse gas (GHG) concentrations, air temperature over Ghana is projected to rise by 0.7 – 2.7°C (very likely range) by 2080 relative to year 2000, depending on the future GHG emissions scenario. Compared to 2000 levels, median climate model temperature increases over Ghana amount to approximately 0.8°C in 2030, 1.1°C in 2050, and 1.2°C in 2080 under the low emissions scenario RCP2.6. Under the medium/high emissions scenario RCP6.0, median climate model temperature increases amount to 1.0°C in 2030, 1.5°C in 2050, and 2.3°C in 2080.

Very hot days

Figure 3: Projections of the annual number of very hot days (daily maximum temperature greater than 35 °C) for Ghana for different GHG emissions scenarios.

In line with rising annual mean temperatures, the annual number of very hot days (days with daily maximum temperature greater than 35°C) is projected to rise substantially in particular over northern Ghana. Under the medium/high emission scenario RCP6.0, on average over all of Ghana, the median climate model projects 34 more very hot days per year in 2030 than in 2000, 55 more in 2050, and 94 more in 2080. In some parts, especially in the North of Ghana, this amounts to about 300 days per year by 2080.

Sea level rise

Figure 4: Sea level rise projections for the coast of Ghana for different GHG emissions scenarios, relative to the year 2000.

In response to globally increasing temperatures, the sea level off the coast of Ghana is projected to rise. Until 2050, very similar sea levels are projected under different GHG emissions scenarios. Under RCP6.0 and compared to year 2000 levels, the median climate model projects a sea level rise by 11 cm in 2030, 20 cm in 2050, and 39 cm in 2080. This threatens Ghana’s coastal communities and may cause saline intrusion in coastal waterways and groundwater reserves.


Figure 5: Annual mean precipitation projections for Ghana for different GHG emissions scenarios, relative to the year 2000.

Future projections of precipitation are substantially more uncertain than projections of temperature or sea level rise. Detecting trends in annual mean precipitation projections is complicated by large natural variability at multi-decadal time scales and considerable modelling uncertainty (Figure 5). Of the four climate models underlying this analysis, one projects a decline in annual mean precipitation over Ghana. According to the other three models, there will be no change. Therefore, our best estimate is that there will be almost no change in total precipitation per year until 2080 irrespective of the emissions scenario, yet this result is highly uncertain.

Heavy precipitation events

Figure 6: Projections of the number of days with heavy precipitation over Ghana for different GHG emissions scenarios.

In response to global warming, extreme precipitation events are expected to become more intense in many parts of the world due to the increased water vapor holding capacity of a warmer atmosphere. At the same time, the number of days with heavy precipitation is expected to increase. This tendency is also found in climate projections for Ghana, with climate models projecting a slight increase in the number of days with heavy precipitation events, from 7 days/year in 2000 to 8 days/year under RCP2.6 or 9 days/year under RCP6.0 by 2080. Central Ghana is subject to increased heavy precipitation, while for the far north, no change is projected by the multi-model mean.

Soil moisture

Figure 7: Soil moisture projections for Ghana for different GHG emissions scenarios, relative to the year 2000.

Soil moisture is an important indicator for drought conditions. In addition to soil parameters, it depends on both precipitation and evapotranspiration and therefore also on temperature as higher temperature translates to higher potential evapotranspiration. Annual mean top 1-m soil moisture projections for Ghana show a decreasing tendency. This tendency is stronger than the corresponding precipitation change projections, which reflects the influence of temperature rise on evapotranspiration.

Potential evapotranspiration

Figure 8: Potential evapotranspiration projections for Ghana for different GHG emissions scenarios, relative to the year 2000.

Potential evapotranspiration is the amount of water that would be evaporated and transpired if there were sufficient water available at and below the land surface. Since warmer air can hold more water vapor, it is expected that global warming will increase potential evapotranspiration in most regions of the world. In line with this expectation, hydrology projections for Ghana indicate a stronger rise of potential evapotranspiration under RCP6.0 than under RCP2.6. Specifically, under RCP6.0, compared to year 2000 levels, potential evapotranspiration is projected to increase by 3.2% in 2030, 4.6% in 2050, and 7.4% in 2080.

Adaptation to climate change in Ghana

Many options exist for farmers in Ghana to adapt to climate change. In the climate risk analysis for Ghana conducted within the Agrica project, five promising adaptation strategies were analysed in detail: crop insurance, post-harvest management, irrigation, rainwater harvesting and improved crop varieties. Those strategies were selected based on stakeholder interest, links to existing climate change adaptation plans in Ghana and suitability for analysis within crop models. Yet, they only present a small subset of possible and suitable adaptation strategies, in addition to them, many different adaptation strategies can be useful and the local context and communities’ needs are key for ultimately deciding on the strategies to pursue. The strategies portrayed are thus meant as indications only, for which adaptation measures may provide a useful start and hold potential at a wider scale.

Post-harvest management can be recommended for wider implementation across Ghana, as the analysis shows high potential for upscaling and attainment of adaptation goals. Crop insurance is particularly well-suited for upscaling and, as a risk-transfer strategy, crucial for complementing risk-reduction measures, which equally can be recommended for uptake in the whole of Ghana. Rainwater harvesting is a low-cost strategy with potential for autonomous uptake and additional agricultural production. Both improved crop varieties and irrigation are rather costly strategies, requiring much institutional support. Their implementation feasibility and suitability varies according to location in Ghana, irrigation is generally only recommended for areas suffering from insufficient or highly variable precipitation levels but can offer improved agricultural production levels in dry areas, if other water use interests can be reconciled with water demand for irrigation. Improved crop varieties are judged to have better prospects for transforming agriculture, also given the mostly sufficient precipitation levels in Ghana. However, improved seeds always need to cater to the requirements of local agro-ecologies, thus they cannot be recommended for the whole of Ghana. Employing multiple adaptation strategies can be useful, especially the combination of risk-reducing and risk-transferring strategies is promising. Risk-reduction measures like irrigation and improved crop varieties are important for addressing risk that can be mitigated, whereas risk-transfer strategies such as insurance are needed for managing risk that cannot be reduced.

This evaluation is only to be viewed as a careful model-based and expert assessment, which can by no means replace a thorough analysis for specific project design and local implementation planning. It gives an indication of the overall feasibility and suitability of the selected adaptation strategies in Ghana. Actual selection of adaptation strategies, however, should always be based on specific needs and interests of local communities.

Crop insurance

While most adaptation strategies seek to minimize risks stemming from climate change, not all risks can be eliminated. Weather perils such as droughts, storms or erratic precipitation represent so-called systemic risks that go beyond the farmers’ coping ability. Thus, mechanisms are needed that distribute residual risks to avoid that certain groups or individuals lose their livelihoods. One such risk transfer solution is crop insurance, which allows farmers to insure their crop yields against weather-induced losses. While insurance usually is based on indemnity assessment, this model is problematic for smallholder farmers due to the high transaction costs which insurance schemes usually entail. Thus, a more suitable approach for smallholder farmers are weather index-based insurances (WII), a scheme that uses a weather index, such as precipitation, to determine a payout. Alternative index-based insurance schemes can also be useful, such as area-yield index insurance.

Generally, insurance schemes are rather costly adaptation strategies, at least when considering the overall costs and with progressing climate change increasing the overall risk to the agricultural sector. However, insurance schemes have an important role to play for securing livelihoods: They can stabilize farm incomes and can prove to be very cost-effective for farmers when a hazard occurs.

According to the Ghana Agricultural Insurance Pool (GAIP), area-yield index insurance (AYII) as an alternative to WII has shown the biggest potential for smallholder farmers in Ghana as of yet. GAIP is a pioneer in implementing AYII in Ghana, insuring since 2011 successfully some 3000 – 4000 smallholder farmers’ cereal crops[1] on over 18,000 acres of land. In 2017, GAIP made payouts to nearly half its insured parties.

Although AYII is a promising development, farmers’ uptake of AYII in Ghana remains limited. Balmalssaka et al. (2016), who examined the willingness of farmers in northern Ghana to participate in insurance schemes, found access to credit as well as education and experience with insurance to be important factors determining farmers’ engagement with crop insurance (Balmalssaka et al., 2016).

This indicates the need for additional incentives or financial support for taking out insurance, underlined also by Aidoo et al. (2014) who determined farmers’ willingness to pay for crop insurance in one municipality in Ghana. He concluded there was a need for government subsidies to implement it in the country (Aidoo et al., 2014). While subsidies are one strategy, experts also suggested to bundle insurance with inputs, where possible, to increase uptake.

Overall, crop insurance is a promising strategy for transferring climate risk also in Ghana. There is high interest in Ghana and demand-based roll-out of insurance pilots can be recommended. However, careful design is crucial to ensure affordability and financial sustainability.

Post-harvest management

Effective post-harvest management is crucial to avoid food loss along the value chain. Investments in scaling technologies for improved post-harvest management have high potential for reducing crop losses, also and especially under climate change. With climate change altering growing and harvesting seasons, post-harvest management is important to cope with increased uncertainty. It is a risk-reducing strategy that lowers the vulnerability of crop production to climate impacts. Next to main staple crops such as maize and beans, post-harvest loss (PHL) of easily perishable horticulture crops could be avoided. Numerous effective and low-cost technologies exist that can prevent or reduce PHL.

Ghana’s NDC Implementation and Investment plan lists post-harvest management as a priority for adapting agriculture to climate change, with interviews confirming wide-spread interest in such strategies. A concrete post-harvest technology with promising results in the context of maize production in Ghana have been so-called PICS bags (Purdue Improved Cowpea Storage): simple and affordable yet effective hermetic storage bags originally developed for storing cowpea. Implementation of improved post-harvest management strategies can be recommended across the country as a low-hanging fruit, since better post-harvest management can increase agricultural production considerably.

Furthermore, as the economic analysis confirmed, most post-harvest management measures are rather low cost interventions, with most intervention types being “no regret” strategies because even in the absence of climate change, the improvement in crop handling will lead to lower crop losses and higher agricultural output, being economically sensible. Figure XX shows the net value of maize production under different post-harvest management scenarios, compared to scenarios of maize production without adaptation – both with (CC) and without climate change (BAS). Except for the highest cost scenario (MAX), all other PHM scenarios do not only make up for the maize losses under climate change, but are also able to surpass maize production under the baseline scenario (without climate change and without adaptation). This shows their high economic viability.

[1] The main insured crops are: maize, sorghum, millet and groundnut.

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