Author: USAID/Sustainable Water Partnership (SWP)
Site of publication: globalwaters.org
Type of publication: Country profile
Date of publication: 25 August 2021
Ghana Water Resources Profile Overview
Ghana has abundant water resources and is not considered water stressed overall. The total volume of freshwater withdrawn by major economic sectors amounts to 6.3 percent of its total resource endowment, which is lower than the water stress benchmark. Total renewable water resources per person of 1,949 m3 is also above the Falkenmark Index threshold for water stress. However, water availability is influenced by management decisions and abstractions from upper-basin countries as almost half of its freshwater originates outside the country.
The Volta Basin covers most of the country and is critical to hydroelectric generation, agriculture, and fisheries. However, water availability for hydropower generation and agriculture is vulnerable to drought and depends on upper basin dam releases and abstractions in Burkina Faso. Flood risks are amplified by uncoordinated floodgate releases from upstream dams. Transboundary cooperation is needed to reconcile basin development plans and address flood mitigation and drought contingencies in the Volta Basin.
Ghana is one of the most flood prone countries in West Africa. Climate change is worsening flooding, particularly in the north, while rising seas threaten coastal wetlands, biodiversity, and communities. Drought frequency and severity are increasing in the Volta Basin, impacting hydroelectric power generation, irrigation water supply, and agricultural and fishery production. Flood risks are worsened by poor urban planning and low enforcement of land use policies and could be alleviated by harnessing green infrastructure for flood management.
Surface Water Resources
Ghana has three main basins that outlet to the Gulf of Guinea: the Volta, Southwestern, and Coastal Basins. The transboundary Volta Basin contributes almost twothirds of total runoff, and is divided into the Black Volta, White Volta, Oti River, and Lower Volta Basins. The Black Volta joins the White Volta at the northwestern corner of Lake Volta, which is formed by the Akosombo Dam (147,960 MCM capacity) and is one of the largest artificial reservoirs in the world. The Black Volta is characterized by high seasonal variability, with average wet season flows ten times higher than in the dry season.
Ghana is one of the most flood prone countries in West Africa
The White Volta Basin is smaller, however, the River’s flow is higher and covers more of Ghana. The White Volta’s flows are moderated by Burkina Faso’s Bagre Dam and seasonal flows of its tributaries. The Oti River joins the Volta River near Kete Krachi and contributes 40 percent of Lake Volta’s annual inflows. The Lower Volta Basin consists of numerous small rivers and Lake Volta. The Southwestern Basin is relatively small but contributes almost one-third of Ghana’s total runoff due to high precipitation within the Bia, Tano, Ankobra and Pra Basins. The Coastal Basin contributes six percent of Ghana’s total runoff, with the Densu Basin sustaining the Densu Delta, a key Ramsar Site.
Most groundwater is contained in basement complexes or consolidated sedimentary formations and are not very productive. Basement complexes cover 54 percent of the country, mostly in the west, south central, and the north. Consolidated sedimentary formations are present in most of the Volta Basin. Aquifer depth is shallow (10-60 meters) while well yields are generally low. More productive limestone aquifers exist along the southeastern and southwestern coasts at greater depths (120-300 meters) with high average well yields, but these systems only underlie one percent of the country. Groundwater recharge is generally low and highly variable, ranging from 1.5 to 19 percent of rainfall, with higher rates in the upper Volta Basin.
Surface Water Outlook
The agricultural sector is the largest water user (73 percent of total withdrawals), followed by municipal/ domestic (20 percent), and industry (7 percent). Most withdrawals are from surface water. Most agriculture is rainfed and only 30,900 hectares irrigated nationwide, less than 2 percent of its total irrigation potential. Large public irrigation systems in the Volta Basin and small reservoirs and dugouts in the north are the main mechanisms of abstraction and use of surface water for livestock watering and small-scale irrigation.
Ghana produces one-fifth of global cocoa and recent investments may double national output. Ghana lost eight percent of remaining primary forest (2002- 2019), mostly from cocoa expansion. Between 2017 and 2018, Ghana’s deforestation rate of primary forests increased by 60 percent, faster than any country in the world. Agricultural encroachment (mostly from cocoa) degrades 30 to 60 percent of forests in reserves and the degraded area has increased tenfold since 2010.
Approximately 60 percent of surface water is polluted nationwide and is most severe in the Southwestern and Coastal Basins, especially downstream of Kumasi and Accra
Heavy metals, mainly from small-scale gold mining, pollute rivers and key drinking water sources throughout the Southwestern Basin. Heavy metal pollution from gold mining has been observed in Southwestern Basin’s Tano and Ankobrah Basins, but is worst in the Pra Basin where gold mining is concentrated. Gold mining has led to water service disruptions in several towns due to extreme contamination of surface water. Arsenic levels near Prestea (Pra Basin) have also been detected at nearly 800 times the WHO guideline limit for drinking water, most likely from gold mining.
Untreated industrial, municipal, and domestic waste deplete oxygen levels in rivers while high turbidity in the wet season can disrupt water treatment and service delivery. Approximately 60 percent of surface water is polluted nationwide and is most severe in the Southwestern and Coastal Basins, especially downstream of Kumasi and Accra. Municipal and industrial effluent has led to high concentrations of fecal coliforms and “dead zones” from deoxygenation in the Subin River in Kumasi. High turbidity in the Pra basin has significantly increased water treatment costs and left some plants inoperable for several months each year. The lower Volta River also has high chromium levels that likely derive from industrial and municipal pollution.
Groundwater is widely used for communitylevel drinking water supply as it is more reliable, particularly in periods of drought, and often does not require much treatment. Approximately 41 percent of the population depend on groundwater for household use, although this rate is much higher in rural areas (59 percent) than in urban areas (16 percent). Groundwater dependency is highest in northern Ghana due to low seasonal availability of surface water. Groundwater abstraction for irrigation and animal husbandry occur primarily in the northern Volta Basin, and for industry in the south around Accra, but these abstractions are nominal compared to domestic use.
Shallow groundwater is increasingly susceptible to pollution from inadequate sanitation systems in cities, and from sea level rise and over pumping in coastal aquifers. Only one-third of wastewater is safely disposed of in Accra, while sewerage systems only receive 10 percent of all wastewater. As of 2014, poor maintenance limited Accra’s wastewater treatment plants to one-fifth their design capacity. Shallow groundwater is widely contaminated by sources such as bathhouses, landfills, latrines and septic tanks, and animal waste from pigs and poultry. There are over 45,000 hand dug wells in Ghana and only half are suitable for drinking due to water quality problems from high turbidity, nitrates, and fecal coliforms. Salinity is a growing problem in coastal aquifers due to seawater intrusion. In the greater Accra region, high salinity has limited the use of boreholes for drinking and irrigation in small farming communities. In the Densu Basin, salinity is likely caused by seawater intrusion as result of concentrated abstractions.
Water Resources and Climate
Declining rainfall and higher evapotranspiration will reduce water availability in the transboundary Volta Basin and increase vulnerability to drought. Northern Ghana is semi-arid and experiences one rainy season (May-September) while southern Ghana has two rainy seasons (April-July, and September-November). Mean annual rainfall is approximately 1,200 mm however total annual rainfall ranges between 1100 mm/year in the north to 2,100 mm/year in the southwest. Climate change is expected to raise average annual temperatures by 1.7-3.5 °C by the end of the century. While the impact on total precipitation is uncertain, higher temperatures will increase evaporation and cause water losses.59 Climate change impacts on upper Volta Basin countries, particularly Burkina Faso, will also impact water resources in Ghana.
Flood risks are increasing with climate change, particularly in urban areas and riverine communities in northern Ghana
Higher temperatures and increasing water stress in the Volta Basin threaten hydropower generation and inland aquaculture at Lake Volta, as well as agriculture across northern Ghana. Hydropower generated at the Akosombo Dam is highly sensitive to changes in Lake Volta’s water level. Most shortfalls in hydroelectric power generation derive from rainfall variability, which disrupt industry and cause economic losses of several hundred million dollars. Over the past few decades, drought has caused national hydroelectric production to fall to 33 percent of capacity in some cases. Ghana’s fisheries are also considered highly vulnerable to climate change, and inland fisheries in Lake Volta have been declining due to increasing temperatures.
Flood risks are increasing with climate change, particularly in urban areas and riverine communities in northern Ghana. Sea level rise is reducing freshwater availability and harming coastal wetlands. Between 1988 and 2010, Ghana experienced 15 major floods that displaced hundreds of thousands of people. In 2010, 700,000 people were displaced after heavy rainfall destroyed a dam and in 2015 flash flooding in Accra killed more than 150 people and caused over $100 million in damage. Precipitation is becoming more variable and intense, which is increasing flood severity and impact. Coastal populations, which comprise one-quarter of the population and include five major cities, will become more exposed to flooding.
Water Policy and Governance
Understaffing, low technical capacity, limited funding, and hydrological and water quality data constraints hinder basin planning and management. Government funding for the WRC has amounted to only 3 percent of total funding in recent years. Total allocations to the WRC declined between 1997 to 2009 and disbursements are often late. Resource constraints have delayed the establishment of new Basin Secretariats and IWRM Plans. The 2012 National IWRM Plan set a target of updating six existing IWRM Basin Plans and developing six new plans within 10 years. However, as of 2018, only seven IWRM Basin Plans have undergone development, revision, and implementation. Resource constraints also affect the WRC’s ability to monitor and manage water use permits and data on surface and groundwater availability and quality. Limited technical resources also impede the development and use of flood and drought monitoring and early warning systems. Research on climate change impacts on water resources, such as droughts and floods, are not adequately incorporated into national mitigation strategies.
Water Quality Monitoring
Systematic groundwater quality monitoring does not occur and a broader framework for water quality monitoring is lacking. The MSWR’s Water Directorate oversees the WRC, which is responsible for bulk water quality monitoring. The CWSA supports water quality monitoring for rural drinking water sources, while the PURC monitors drinking water quality for urban providers. These monitoring efforts are supplemented by crosscutting surface and groundwater quality research from the WRI. While the WRC has routinely monitored surface water quality since 2005, systematic groundwater quality monitoring does not occur. The WRC monitors basic physio-chemical parameters for surface water in all of its three basins through 32 river monitoring stations and nine reservoir/lake stations. However, parameters such as dissolved oxygen and microbial indicators are not monitored. Further, the WRC lacks a national water quality monitoring framework. PURC lacks the equipment and logistical capacity to independently monitor urban drinking water quality, and instead relies on the GWCL to support this mandate.
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