THE UNITED REPUBLIC OF TANZANIA

Ministry of WaterWater Resources Division

Physiographic Profile

143,200 km2Basin Area (inside Tanzania)

9No. of Sub-basins

7No. of Major Lakes

107

52,827 Km2

Protected Areas

No.

Area

Sandy LoamDominant Soil Texture

Migmatite/

Granitoide/

Meta-Sediment

Complexes

Dominant Productive

Formation

0.25Mean Vegetation Index

-1.52 %/yrForest Cover Change (2000-2015)

4.6%Average Slope

5,895 m.a.s.l*

573 m.a.s.l

1,312 m.a.s.l

Altimetry

Highest

Lowest

Mean Elevation

Water Resources Fact SheetThe Internal Drainage Basin

Map of the Internal Drainage Basin

Socio-Economic Profile (2019)

7.47 millionPopulation52 person/km2Population Density

933 m3/yrWater per Capita

Hydro-Climatic & Water Resources Profile*

701 mm/yrAverage Precipitation21.7 CAverage Temperature

1,667 mm/yr

646 mm/yr

Average Evapotranspiration

Potential

Actual6,968 mcm/yr

6,084 mcm/yr

884 mcm/yr

Average Renewable Water

Resources

Surface Water

Groundwater

5,634 mcm/yr

1,087 mcm/yr

Water Demands

Averaged Total

Human Consumptive

16 %Water Resources

Vulnerability Index

Tanzania mainland is comprised of nine hydrologic basins. The Transboundary Internal Drainage Basin is Tanzania’s 2nd Largestbasin (considering total area of the basin shared with Kenya); however, regarding part of the basin that is located inside Tanzania,it is the 3rd largest basin that encompasses more than 15% of the area of the country. The basin is stretched from central parts ofTanzania to the north-east, where it crosses borders with Kenya. Waters that run from precipitation, flow into several lakes andswamps scattered in the basin.

19%

45%

13%

6%

6%3% 1% 4% 3%

Area of Subbasins (%)Bahi Swamp

Lake Eyasi

Lake Manyara

Lake Natron

Masai Steppe

Monduli A

Monduli B

Namanga

Olduvai

71% of basin area lies between 1000-1500 m.a.s.l

* m.a.s.l: meters above mean sea level

Internal Drainage Basin Water Demands Key Figures

The Falkenmark Water Stress Indicator

Water ResourcesDivision

20

9.5

84

.5

51

.9

30

.5

29

.9

28

.9

13

.0

6.5

5.6

0

50

100

150

200

250

Irri

gate

d A

rea

(1,0

00

ha)

Area of Irrigation Schemes in Basins

11%

89%

Share of Irrigated Area

Internal Drainage

Other Basins

9,5

80

2,1

86

1,9

73

1,3

74

1,1

53

96

2

92

0

80

3

62

8

0

2,000

4,000

6,000

8,000

10,000

Cu

bic

me

ters

pe

r ye

ar

Renewable Water Resources per Capita in Sub-Basins (2019)

IndicationAvailable Renewable

Water per Capita (m3/yr)

Water Stress< 1700

Water Scarcity< 1000

Absolute

Water Scarcity< 500

Country Average: 2,250 m3/yr/cap

3%12%

1% 2%2%

80%

Water Demands by Sector (%)Internal Drainage Basin

Domestic (200 mcm)

Irrigation (687 mcm)

Hydropower (47 mcm)

Livestock & Aquaculture (99 mcm)

Industries & Mining (101 mcm)

Ecosystem & Wildlife (4,547 mcm)

0 200 400 600 800

Lake Eyasi

Lake Manyara

Bahi (Manyoni)

Namanga

Lake Natron

Masai Steppe

Olduvai

Monduli A

Monduli B

mcm per year

Water Demands in Sub-Basins*(human consumptive demands)

* exclusive of environmental & hydropower demands

Ecosystem is the largest water user in the Internal Drainage Basin. About 65% of the renewable water resources in the basin isrequired for replenishment of environmental demands, and nearly 16% is currently utilised for domestic, industries, irrigation, andlivestock sectors. In the latter portion, Irrigation sector accounts for about 63% of human-consumptive uses, which makes it thesecond rank in total water demands.

3 rd

Ị

* According to the Internal Drainage Basin IWRMDP, 2015

Internal Drainage Basin:

Rank in Irrigated Area3 rd Tanzania,s Total Irrigated Area:

460,300 ha

8%

92%

Human Consumptive Water Demands

Internal Drainage

Other Basins

0 10 20 30 40 50

0 10 20 30 40 50 60 70

500-750750-1000

1000-12501250-15001500-17501750-20002000-22502250-25002500-30003000-40004000-6000

Area Percentage (%)

Area (thousand km2)

Ele

vati

on

Cla

sse

s (m

.a.s

.l)

Land Hypsometry○ 17% of people in IDB are experiencing water stress.

○ 80% of people in IDB are confronted with water scarcity.

BahiSwamp

Internal Drainage Basin Water Resources Key Figures

Annual Renewable Water Resources: 6.97 km3

19

19.5

20

20.5

21

21.5

22

22.5

23

19

001

905

19

101

915

19

201

925

19

301

935

19

401

945

19

501

955

19

601

965

19

701

975

19

801

985

19

901

995

20

002

005

20

102

015

Tem

per

atu

re (

°C)

Historic Average Air Temperature (1900-2016)

Averaged for the Internal Drainage Basin; Source: Climatic Research Unit, University of East Anglia, UK; http://www.cru.uea.ac.uk/data

Long Term Rainfall Variation

703 mmRainfall Average 1900-1930

680 mmRainfall Average 1985-2016

- 23 mmDifference in Long-term Average

Long Term Temperature Variation

21.30 CTemperature Average 1900-1930

22.32 CTemperature Average 1985-2016

+ 1.02 CDifference in Long-term Average

Difference in Rainfall*: - 3.3% Difference in Temperature*: + 4.8%

* Over 85 Years (30-yr average values, centered on 1915-2000)

87%

13%

Surface Water

Groundwater

The Internal Drainage Basin receives in average an annual precipitation of 100 km3 out of which as much as ca. 93 km3 returnsback to the atmosphere and 6.97 km3 (about 7%) turns into surface and ground water as renewable freshwater resources.

27

09

12

90

12

00

11

44

20

2

15

0

11

9

11

6

40

0

500

1000

1500

2000

2500

3000

An

nu

al V

olu

me

(m

cm) Average Total Renewable Water

Resources in Sub-Basins

6%

94%

Total Water Resources

Internal Drainage

Other Basins

Share of Internal Drainage Basin in Tanzania’s Renewable Water Resources

15%

85%

Basin Area

Internal Drainage

Other Basins

0102030405060708090

100

Spe

cifi

c R

un

off

(m

m) Average Surface Water

Runoff in Sub-Basins Average Country-wide Specific Runoff: 111 mm

Water ResourcesDivision

There is a large variation of runoff production within different sub-basins in the Internal Drainage Basin:• Lake Natron sub-basin as high as 221% of average• Namanga sub-basin as low as 44% of average

(6.08 km3)

(0.89 km3)(inside Tanzania borders)

Internal Drainage Basin Water Infrastructure Key Figures

Water Infrastructure Profile

11,957

16,285

Water Points

No. of Water Points

No. of Taps

5

57

46

31

No. of Monitoring Stations:

Weather

Rainfall

Hydrological

Hydrogeological

119No. of Dams and Reservoirs

119.2 mcmReservoirs Capacity

315

51,872 ha

Irrigation Schemes

No.

Area

30%Irrigation Efficiency

Maize, Sorghum,

Wheat, Beans

Main Crops (irrigated)

37%

23%

17%

11%

1%2%

9%

Water Points by Sources of Water

Borehole Shallow WellSpring River/ StreamLake DamRainwater Harvesting

Functioning Water Taps: 11,820 73%

CED Pumps: Conventional Energy-Driven Pumps (includes Thermal Electricity, Hydroelectricity, Gasoline & Diesel)

NCD Pumps: Non-Conventional Energy -Driven Pumps (includes Solar Electricity, Windmill(

Hand Pumps: (includes Lever Pumps, Mono Pumps, Rope Pumps, Play Pumps)

Water supply access in Tanzania – mainly in rural areas – is realised through "water points", i.e. usually a public place for peopleto obtain clean water.Water from water points is potable water consumed for the people or livestock. Means of access to water at the supply points areusually in form of communal standpipes. However, other shapes of access to water are present such as water kiosks, water tanks,hand pumps, developed or undeveloped springs, and cattle troughs.

Water Points Supplied by Groundwater and Springs

Water Points that Need Energy for Extraction of Water 62%

Water ResourcesDivision

0 10 20 30 40

0 5 10 15 20

2-3

3-4

4-5

5-6

6-7

7-8

8-9

9-10

10-11

11-12

12-13

13-14

Cumulative Reservoir Capacity (mcm)

Count of Dams

He

igh

t o

f D

ams

(m)

Count

Volume

There are 119 man-made dams constructed in the Internal Drainage Basin with a total reservoir capacity of about 119.2 mcm. The largest reservoir belongs to Mwamapuli Dam with a height of 10 m and capacity of 28 mcm on Cheli River, Tabora Region.

Statistics of Dams in the Basin

77%

20%

1%

41%

38%

Extraction Technologies at Water Points

CED Pumps

NCD Pumps

Hand Pumps

Gravity

400

500

600

700

800

900

1000

1100

19

001

905

19

101

915

19

201

925

19

301

935

19

401

945

19

501

955

19

601

965

19

701

975

19

801

985

19

901

995

20

002

005

20

102

015

Pre

cip

itat

ion

(m

m)

Historic Annual Precipitation (1900-2016)

IDB average = 43 mmAverage Internal Drainage

Basin’s Specific Runoff: 43 mm

Average Gross Area per Water Point: 12 km2