Lake Malawi

 

1. Description of Water Resource

2.Hydrological Description

3. Socio-Economic Issues

4.Transboundary Issues

 

1. Description of Water Resource

 

 Lake_Malawi.jpg

 

Figure 1. Map of Malawi

1.1. Geographical Description

 

1.1.1. Location

Lake Malawi Basin is located at latitude -12° 0' 0" (-12.0000) and longitude 34° 30' 0" (34.5000).

1.1.2. Riparian states

Lake Malawi/Nyasa/Niassa is a transboundary basin shared between Malawi, Tanzania and Mozambique. The majority of the catchment, 64%, lies within Malawi. 28% of the catchment lies in Tanzania and 8% in Mozambique[1].  The percentage distribution of inflow into the lake by country is as follows[2]:

  • Tanzania: 44%
  • Malawi: 46%
  • Mozambique: 10%

 

Summary of Calculated Basin Areas from SRTM Elevation Data[3]

Country

Area (km2)

Tanzania

26,600

Malawi

64,373

Mozambique

6,768

Total Land Area

87,471

Lake Malawi

30,898

Total Basin Area

97,740

 

The catchment area of Lake Malawi is 97,740 km2, of which 64,373 km2 lies in Malawi (70% of Malawi’s land area), 26,600 km2 in Tanzania, and 6,768 km2 in Mozambique (Department of Water/UNDP, 1986).

1.1.3. Topography

Lake Malawi/Nyasa is the ninth largest, and third deepest, freshwater lake on Earth. In its deepest regions the lake is underlain by more than 4 km of sediment, reflecting its great age which has been estimated at several million years.

The lake is long, relatively narrow, and deep. The lake basin consists of a series of half-grabens (blocks of earth that have tilted and dropped during rifting). Some parts of the lakeshore are bordered by steep mountains, while in other parts the mountains that define the edges of the rift valley are separated from the lake by extensive lakeshore plains. As a result, near shore topography varies between gently sloping beaches and steep, rocky coastline.

Although some of the plateau regions around the lake contain thick colluvial soils, the drainage basin is dominated by metamorphic and igneous gneiss, schist and granite. The northern two-thirds of the watershed are predominantly a mixture of woodlands (evergreen, Brachystegia) and agriculture. The southern third is woodland on the Mozambique coast, but almost completely cultivated land within the Malawi portion of the watershed, with the exception of the steep hillsides on the western side of the rift valley, which are forest covered

Within the watershed, the population density is greatest in the southern Malawian portion, although it is also relatively high at the northern end, in the Songwe and Kiwira River catchments. The watershed is more densely populated than that of Lake Tanganyika, but less so than that of Lake Victoria.

While only around 28% of the catchment lies within Tanzania, land use in Tanzania may have a disproportionate effect on the lake, because annual rainfall is greater at the northern end of the lake, and therefore river inputs are greater.

Figure_2.jpg 

Figure 2. Map of Lake Malawi and its watershed, showing lake bathymetry and major tributaries[4]

Approximately 20 % of annual river inflow to the lake comes from the Ruhuhu River in Tanzania, the largest tributary, with a catchment area of 14,070 km2(5,432 mi2). The second largest tributary is the South Rukuru in Malawi with a catchment area of 12,110 km2(4,676 mi2). The Bua and Linthipe Rivers of Malawi also are significant tributaries, with catchment areas of 10,700 km2 (4,141 mi2) and 8,560 km2 (3,305 mi2), respectively. Other tributaries include the Kiwira, Songwe and North Rukuru Rivers, with the area of all these catchments being less than 5,000 km2 (1,931 mi2) each.

 

 Figure3.jpg

Figure.3. Map of Lake Malawi[5]

Despite its large size, the lake does not have a high volume of outflow. Of the approximately 68 km3 of water that enters the lake annually, only about 16% flows out the Shire River[B1] ; the remainder is evaporated directly from the lake surface. As a result, the lake has a very long flushing time. This distillation effect results in the lake water being more concentrated with regard to conservative ions than are its inflowing rivers. The long flushing time has important ramifications for water quality. Any nutrients or other chemicals that enter the lake essentially become trapped in the lake, and can only be removed by burial in sediment, loss to the atmosphere (if the chemical has a gaseous phase), or the very slow process of outflow through the Shire River.

The dominance of precipitation and evaporation in the lake’s hydrological cycle mean that it is also very susceptible to changes in climate. A small increase in the precipitation: evaporation ratio can result in flooding, as occurred in 1979-80, while a small decrease in the ratio can result in the basin becoming closed with no outflow, as was the case between 1915 and 1937[6]. In recent years, lake level has again been declining, and the lake came near to being closed at the end of 1997.

2. Hydrological Description

2.1. Rainfall

The hydrology of Lake Malawi is dominated by distinct dry and wet seasons. Almost 90% of rainfall occurs between December to March, with no rain at all between May to October over most of the catchment.

The catchment receives an average annual rainfall of 996 mm but the distribution is uneven. The northern half of the catchment receives an average of 1,1103 mm while further northern areas particularly in eastern lakeshore areas and escarpments in Malawi and northern escarpments in Tanzania receive higher than 1,540 mm annually on average.

The rainfall over the lake averages about 1,410 mm (estimated from land rain gauges along the shore). Both the land catchment and the lake rainfall peak in March, with monthly totals of about 220 and 300 mm, respectively.

Owing to the migration of the Inter-Tropical Convergence Zone (ITCZ), the climate of the basin is more heavily affected by annual precipitation-evaporation than temperature. The zone of rising air, which migrates southward from the equator to the southern shores of Lake Malawi, brings moisture from the Indian Ocean and produces a wet-dry monsoonal cycle. The wet season extends from November to April, with the dry season extending from May to October. The dry season is characterized by strong south-easterly trade winds (locally known as the Mwera) that blow over the lake, while during the wet season the winds are generally north-easterly (the Mpoto) and weaker.

 

Physical Characteristics of Lake Malawi

Surface Areas (km2)

29,500

Maximum depth (m)

700

Mean depth (m)

264

Volume (km3)

7,775

Altitude (m a sl)

474

Drainage area (km2)

100,500

River Inflow (km3/yr)

29

River outflow (km3/yr)

12

Rainfall (km3/yr)

39

Evaporation (km3/yr)

57

Residence Time (years)

1144

 

2.2. Runoff

The mean annual runoff for the catchment is 588m3/s[7]. The major rivers in the basin are the Shire, Bua, Songwe , Linthipe, North Rukuru, South Rukuru, Dwangwa and Ruo. The Shire is the only outlet of Lake Malawi and is also the largest of the rivers. The other rivers drain into either the Shire River or Lake Malawi[8].

 

Contribution of Run-off Water to Lake Malawi[9]

 

Malawi

Tanzania

Mozambique

Total

Catchment area of lake km2

64 372

26 600

6 768

97 740

Flow (m3/s)

391

486

41

918

Percentage area (%)

65.9

27.2

6.9

100

Percentage Flow (%)

42.6

52.9

4.5

100

 

2.3. Surface Water

The catchments that drain into the lake are located in Malawi, Tanzania and Mozambique; although Malawi provides the greatest land area, over 52% of the inflow is from catchments in Tanzania and Mozambique.

The total inflow into the Lake is calculated to be 920 m3/s out of which 400 m3/s are from Malawi, 486 m3/s are from Tanzania and 41 m3/s are from Mozambique[10].

2.4. Ground Water

Little is known about the groundwater in the basin. Groundwater inflow and outflow has been ignored in previous studies because of lack of piezometric data quantifying groundwater flow around the lake (Kumambala and Ervine, 2010[11]).

2.5      Water use 

The major water uses in the Lake Malawi basin are irrigated agriculture and water supply for domestic, municipal and industrial use. In addition, fishing plays an important role in the livelihoods of those who dwell around the basin and the wider economy. As much as 98% of electricity produced in Malawi comes from hydroelectric plants on the Shire River, which drains the lake.

Total annual average water demand is estimated at 2,900 Ml/d. In average rainy season this increases by 26% to 3,900 Ml/d (see graph below). Arable agriculture accounts for 72% of usage (2,088Ml/d) and domestic use makes 19% of water usage or 812Ml/d[12].

Surface water quality is considered generally tolerable for industrial, recreational and agricultural uses. However, water resource degradation remains a challenge in the catchment area. Contributors to poor water quality are population pressure, deforestation and poor agricultural practices resulting in siltation problems downstream. Other detrimental results emerging from the agricultural sector include the unwarranted use of heavy agrochemicals, and unchecked disposal of industrial and domestic waste.

3. Socioeconomic Issues

3.1. Demographics

Population density is greatest in the southern part of the catchment within Malawi. The total population of Malawi in 2014 is 17.4 million, with an annual growth rate of 3.33% (CIA World Factbook). 53% of the population, 9.2 million, resides in the Northern and Central regions of the country that make up the Malawian portion of the catchment. The 9.2 million Malawians make up 80% of the residents of the catchment. Malawi’s population density in the basin is 106 persons per km2. In contrast, the Tanzanian and Mozambican regions of the catchment, at 24 persons per km2 and 33 persons per km2 are very sparsely populated owing to the remoteness of the region from urban and administrative centres.

3.2. Income and Occupations

Malawi is designated a low income nation and has a gross per capita national income of USD383.00 – the equivalent of USD1.05 per day. Approximately 54% of the population in the basin lives below the poverty line. The majority of the population are rural dwellers. Of the 9.2 million Malawians who reside in the basin, the majority are subsistence farmers, with a few small scale entrepreneurs.

 

Key Socio-economic Indicators[13]

 

Malawi

Mozambique

Tanzania

Total area (km2)

118,480

801,590

945,090

Total Population (millions)

17.4

25.8

31.2

Population density (persons/km2)

106

24

33

GDP per capita USD)

238

168

162

Population below the poverty line

54

 

51

 

3.3. Economic sectors active in Sub-basin

The main economic sectors active in the basin include: hydropower, industry, navigation, agriculture, tourism and fisheries[14]. The top use is agricultural irrigation, followed by municipal water supply and industry. 68% of the population is considered economically active and of these: 78% are subsistence farmers and 13% are formally employed.

The fisheries industry is not insignificant, contributing 2% of GDP and employing over 300,000 people. Fish makes up 70% of dietary animal protein intake in the basin and most of it is fished from Lake Malawi.

3.4. Development Potential

A number of government initiatives have been put in place which will have a bearing on water demand in the catchment area. One of these is the Green Belt Initiative (GBI), established in 2010, which has resulted, and will continue to result, in an increase in water usage for irrigation purposes. The Initiative was put in place to reduce dependence of rain fed irrigation, which left farmers vulnerable to the vagaries of drought years and climate variance.

The Government of Malawi (Ministry of Mining) awarded an exclusive exploration license to Sacoil, a South African oil exploration company to conduct hydrocarbon prospecting in 2012. The discovery of oil is likely to impact both water quality and water usage.

4. Transboundary Issues

Formal management activities have taken place on the Lake for decades, but most have been nationally-driven and focused on fisheries management.  However, there are a number of issues that must be dealt with in the transboundary management of the basin:

4.1. Border Dispute between Malawi and Tanzania

The major legal issue surrounding the Lake is the ongoing border dispute between Malawi and Tanzania.  The dispute actually dates back several decades.  Following independence, Tanzania reaffirmed the border established by the Heligoland Agreement between Britain and Germany, which stipulates that the border lies on the Tanzanian border of the Lake, leaving the whole of the body of the Lake within Malawi.  In the years following independence, however, local leaders began to petition the government to seek a more equitable division of the resources and amend the Agreement.  While there was considerable debate, the motion was not carried.  The matter was re-ignited in 1961 when Nyerere announced that then-Tanganyika would honor bilateral treaties executed by the colonial powers for only two years and they would then be considered lapsed in absence of additional action between the relevant States.  The matter of the Lake was specifically raised again in 1962 in the National Assembly, but was again defeated when the Prime Minister declared that, despite the disadvantages posed to Tanganyika by the border position, it would not be possible to negotiate with Britain on the matter.  Prime Minister Kawawa felt that it would be necessary, instead, to wait for the independence of then-Nyasaland (Malawi), thus holding out the promise of future negotiations.

Following the independence of Malawi, however, the relationship with Tanzania became strained as Banda suspected Tanzania of harboring exiles that were planning to mount an invasion against him.  The northern portion of the Lake provided an ideal route for such ingress, and thus contributed to Banda’s firm stance that the Lake belonged in full to Malawi.

Despite a statement at the 1963 Organisation of African Unity Summit that pre-colonial borders would remain intact following independence, the issue came to a head once more in 1967 following severe flooding of the northern Lakeshore that impacted the land of many Tanzanians.  It is also likely that political issues contributed to the renewed claim of Tanzania that the border was inequitable.  Malawi’s growing relationship with Mozambique and South Africa triggered fears in Tanzania that the Portuguese would have access to the northern part of the Lake to pursue Frelimo to their sanctuaries across the Rovuma River.   Moreover, the fact that Malawi was seen to be supporting South Africa and Portugal was antithetical to Tanzania’s regional policies.  All of these political factors likely contributed to Nyerere’s claim that the Lake border was unacceptable and that Tanzania now recognized the median line as the “legal and just delineation between the two countries.” 

Banda’s response was unequivocal: “As to the claim that the Lake should be divided between Malawi and another neighboring country, I should like to say here and now that we will never recognize or accept this claim; we will never agree to the suggested or proposal.  The Lake has always belonged to Malawi.”  From there, the situation disintegrated into Malawi making threats to place gunboats in the Lake and Tanzania embarking on a military and political education campaign among communities on the Lakeshore. 

Over time, tensions dissipated between the two countries, though the dispute was never resolved.  In 2002 and again in 2007, the African Union passed resolutions which upheld the colonial agreement because of the emphasis on member states maintaining colonial borders.  Despite this, a resurgence of the dispute was triggered in 2012 when Malawi contracted with a British company, Surestream Petroleum, to start gas and oil exploration on the eastern portion of the Lake.  In response, Tanzania announced plans to purchase a $9 million ferry to cross the Lake’s waters, a move that Malawi claimed was not legal as the ownership and border are still under dispute.  Tanzania responded that Malawian fishing and tourism activity in that portion of the Lake were encroachments on Tanzanian territory.   The two countries entered into mediation talks, which came to a deadlock.  Currently, mediation is continuing, and both countries have agreed that if they fail to come to an agreement through diplomatic talks, they will submit the case to the International Court of Justice (ICJ).

Critically, because of the lack of resolution on the Lake border issue, Malawi has also thus far failed to ratify the Zambezi Commission Agreement, and can only participate in planning and decision-making meetings of the ZAMCOM and its Member States as an observer.  This places Malawi at a distinct disadvantage in the Basin as it cannot vote on issues of crucial importance to the development and protection of this Basin.  

Malawi is, however, signatory to a number of international treaties and conventions, including the SADC Protocol on Shared Watercourses. Within the SADC region, Malawi is also part of other initiatives such as the SIDA initiative and the FAO-supported Convention on the Management of Lake Malawi/Nyasa for Sustainable Development.

Previous initiatives to establish a Lake Basin Institution met with political intransigence and other difficulties.   From 1994-1999, the Global Environment Facility funded the Lake Malawi/Nyasa Biodiversity Conservation Project, the objective of which was to assist Malawi, Mozambique and Tanzania in “creating the scientific, educational, and policy basis required to ensure conservation of the biological diversity and unique ecosystem” of the Lake.  The project consisted of seven components over four main areas: (1) building riparians’ fisheries research capacity; (2) undertaking basic data collection through surveys of the Lake, its fish stocks and water quality; (3)reviewing legislation of all three riparians to identify necessary amendments and areas for harmonization; and (4) creation of strategic management plans for the Lake and for other special areas in Malawi. 

While an independent review of the project found that the research and capacity building components were mostly successful in achieving high international standards, national budgets were insufficient to maintain active Lake research once the project ended.  Moreover, the management planning process was incomplete and what was meant to be an exercise in joint planning ultimately polarized the riparians.  This was attributed to funding being channeled through Malawi and to the sense that there was insufficient objective review of the management process.  It was also noted that the planning and consultation necessary for the effective creation of a regional institution for international water management was not undertaken and there was a need for trilateral agreement in the form of a legal framework with protocols on communication, etc.   The project resulted in agreement on the need for a trilateral Lake Basin Commission.  However, this has not been accomplished to date. 

4.2.     Fisheries and Biodiversity

Lake Malawi/Nyasa is home to rich biodoversity and is one of the most species-rich lakes in the world.  There are 11 fish families in the Lake, but Cichlidae make up 90% of the species present, most of which are endemic.  Lake Malawi contributes between 40-50% of Malawi’s annual catch and fish accounts for more than 60% of Malawian’s protein intake.  There is also a small, but profitable export industry based on trade in ornamental fish from the Lake.

Total fish catch in the Lake is difficult to estimate, as the majority of fishers (approximately 90% in Malawi) are small-scale and the governments are limited in their capacity to collect the necessary data.  The commercial sector has both large- and small-scale components.  The large-scale commercial fisheries operate mainly the in southern portion of Lake Malawi.

None-the-less, fish landings have declined considerably since the 1990s, from approximately 60,000 metric tonnes in 1976-1990 to 49,000 from 1993-2003.  This decline is attributed to population growth, over-fishing and lack of effective enforcement of fisheries regulations.

While several programs have been undertaken in each of the countries to establish co-management along the Lakeshore fisheries, the major attempt at an integrated approach (see GEF Biodiversity Conservation Project description above) was unsuccesful in establishing a sustainable mechanism for data collection and integrated management.

4.3 Catchment erosion and water quality decline

Upper catchment degradation and deforestation has resulted in high levels of siltation and increasingly high levels of nutrient inflows into the Lake. 

 4.4 Climate Change 

 

 

[1] Hydrology Report: Preparation for an Integrated Water Resources Management and Development Plan for the Lake Nyasa Basin (May 2013)[2] Lake Nyasa Basin Water Board.

[3] Malawi Department of Water

[4]Source: Bootsma and Jorgensen (2003).Lake Basin Management Initiative: Lake Malawi/ Nyasa Brief

[5] Sourced at: http://kodu.ut.ee/~olli/eutr/malawiFig1.gif on 5 October 2014.

[6] Kidd, 1983.

[7] Chipofya, V. et al (2009). Integrated Water Resources Management – Key to Sustainable Development and Management of Water Resources: Case of Malawi, pp152 - 153.

[8] Chipofya, V. et al (2009). Integrated Water Resources Management – Key to Sustainable Development and Management of Water Resources: Case of Malawi.

[9] Ministry of Water Development

[10] Government of Malawi

[11] Kumambala, P.G and Ervine, A. 2010 Water Balance Model of Lake Malawi and its Sensitivity to Climate Change. The Open Hydrology Journal, 2010, 4, 152-162

[12] Government of Malawi, 2011. Malawi Water Resource Investment Strategy Report, Main Report.

[13] UNEP (2008). Freshwater Under Threat

[14] UNEP