Prepared under the auspices of the U.S. Agency for International Development

Historical and Hypothetical Future Sedimentation and Water 

Storage in Kajakai Reservoir, Central Afghanistan

Summary

Sedimentation has reduced water storage in Kajakai Reservoir. If current sedimentation rates continue, hypothetical future reservoir water volumes at the spillway elevation of 1,033.5 meters could be reduced about 22 percent from 2006 to 2057. Even if the spillway elevation is raised to 1,045 meters, a severe drought could result in large multiyear irrigation-supply deficits in which reservoir 

water levels remain below 1,022 meters for more than 4 years. Hypothetical climate change and sedimentation could result in greater 

water-supply deficits. The chance of having sufficient water supplies in Kajakai Reservoir during the worst month is about 47 percent.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2008–3002

January 2008 Printed on recycled paper

Kajakai Reservoir, Kajakai Dam complex, and spillway.

Introduction

The management of natural resources, especially water, is 

important for improving the economy of Afghanistan. Irrigation is essential to many crops in Afghanistan; therefore, people 

commonly live close to rivers and reservoirs to maintain easy 

access to water (Favre and Kamal, 2005). During periods of low 

water levels, people moved to the shores and onto the sediment 

beds of Kajakai Reservoir on the Helmand River in central 

Afghanistan to farm and possibly reside (Blue, 2006). Proposed 

economic development and future improvements to Kajakai 

Dam may include increases in reservoir storage for increased 

hydropower production and downstream irrigation. However, 

increased water volumes and water levels in Kajakai Reservoir 

could necessitate the resettlement of people who live near the 

reservoir. This fact sheet, which is based on information from 

Vining and Vecchia (2007), is intended to provide Afghanistan 

authorities with information on historical and hypothetical 

future sedimentation and water storage in Kajakai Reservoir that 

could be used to make decisions concerning reservoir operation 

and economic development along the Helmand River.

Central Afghanistan and Kajakai Reservoir

Central Afghanistan is mostly hilly to mountainous arid 

rangeland and a small percentage of the area is devoted to 

cultivated agriculture (Favre and Kamal, 2004, 2005). Annual 

precipitation ranges from about 100 to 400 millimeters and falls 

mostly at higher elevations during winter and spring (Favre and 

Kamal, 2004). A prolonged drought from about 1999 to 2005, 

which likely reduced streamflows in the Helmand River and 

runoff to reservoirs, resulted in the drying of wetlands on the 

Afghanistan-Iran border (Whitney, 2006).

Kajakai Reservoir, which is a major water body in central 

Afghanistan, formed after the completion of Kajakai Dam on 

the Helmand River in 1952 (Perkins and Culbertson, 1970; 

fig. 1). The main purpose of the reservoir is to supply irrigation 

water to areas downstream from Kajakai Dam. Hydropowergeneration facilities were added to the dam in 1975. Currently 

(2007), Kajakai Dam impounds water to the spillway elevation of 1,033.5 meters. Proposed improvements to the spillway 

include the construction of gates to impound water to an elevation of 1,045 meters (U.S Army Corps of Engineers, written 

commun., 2005).
4,501 - >5,000

4,001 - 4,500

3,501 - 4,000

3,001 - 3,500

2,501 - 3,000

2,001 - 2,500

1,501 - 2,000

1,001 - 1,500

501 - 1,000

0 - 500

ELEVATION, IN METERS

Kajakai

Reservoir

0 60 120 180 Kilometers

30 ̊

34 ̊

64 ̊ 68 ̊

River

Iran Helmand

72 ̊

Kajakai Dam

5

10

15

20

25

30

35

40

45

5 Approximate distance, in kilometers, upstream from Kajakai Dam

5 Kilometers

38 ̊

Kabul

Historical and Hypothetical Future Sedimentation in 

Kajakai Reservoir

Sediment deposition has occurred in Kajakai Reservoir 

since the reservoir formed. A topographic survey in 1953 

indicated Kajakai Reservoir had an original volume of about 

1,844 million cubic meters at the current spillway elevation 

of 1,033.5 meters (Perkins and Culbertson, 1970). In 1968, 

a sedimentation survey indicated the reservoir had lost about 

7 percent of its volume to about 1,715 million cubic meters 

(Perkins and Culbertson, 1970). By 2005, sedimentation had 

likely reduced the reservoir volume by about 26 percent to an 

estimated 1,360 million cubic meters at the current spillway 

elevation (Whitney, 2006).

Landsat images taken in about 2000 and obtained from 

Google Earth in 2007 (fig. 1) indicated possible sedimentation 

upstream from a reservoir narrows (near kilometer 15) where 

farming plots and possible settlements appear (upstream from 

kilometer 25). The combination of satellite photography and 

past reservoir surveys indicated the elevation of sediments in 

the far northern portion of the reservoir might at least equal the 

spillway elevation of 1,033.5 meters. Using this information, a 

reservoir sediment profile for 2006 was estimated (fig. 2). For 

2006, the reservoir incremental volume between elevations of 

1,030 and 1,045 meters was estimated to be about 1,140 million 

cubic meters (fig. 3), which compares well to an estimated 

1,230 million cubic meters determined by using a digital elevation model (Blue, 2006).

Historical and Hypothetical Future Water Storage in 

Kajakai Reservoir

Historical water volumes in Kajakai Reservoir, calculated 

from published and estimated information (Perkins and Culbertson, 1970; Whitney, 2006), indicate a storage loss of about 

365 million cubic meters (about 21 percent) from 1968 to 2006 

at the current spillway elevation (fig. 3). If sedimentation into 

the reservoir continues at the historical rate, hypothetical future 

reservoir water volumes at the current spillway elevation could 

be reduced another 22 percent from 2006 to 2057 (fig. 3).

Investigations of hypothetical future water storage in 

Kajakai Reservoir included a spillway elevation of 1,045 meters, 

continued sedimentation, climate change, and irrigation development (Vining and Vecchia, 2007). Some studies suggest that 

precipitation decreases of about 10 percent (Milly and others, 

2005) and temperature increases of about 2 degrees Celsius 

(Vining and Vecchia, 2007) could occur in central Afghanistan 

by about 2057. In addition, irrigated area below Kajakai Reservoir could increase from about 234,000 hectares (Favre and 

Kamal, 2004) to about 420,000 hectares (U.S. Army Corps of 

Engineers, written commun., 2005), resulting in a possible near 

doubling of irrigation demand.

Figure 1. Location of Kajakai Reservoir, central Afghanistan (adapted from Afghanistan Information Management 

Services, 2006, and U.S. Geological Survey Landsat imagery obtained from Google Earth in 2007).
 

960 970 980 990 1,000 1,010 1,020 1,030 1,040 1,050 1,060

0

500

1,000

1,500

2,000

2,500

3,000

3,500

ELEVATION, IN METERS

VOLUME, IN MILLION CUBIC METERS

1968

2006

2057

Current spillway elevation

1,033.5 meters

The effects of doubled downstream irrigation demand, 

hypothetical monthly temperature increases of 2 degrees 

Celsius, reservoir sedimentation estimated at 2057 levels, and 

10-percent decreases in monthly precipitation on hypothetical future water levels in Kajakai Reservoir indicate reservoir 

levels are likely to decline and supply deficits are more likely 

to occur (Vining and Vecchia, 2007). For example, with current sedimentation and climate conditions and doubled downstream irrigation demand, water-supply deficits in July would 

occur 10 percent of the time (once every 10 years, on average) 

compared to 28 percent of the time (more than once in 4 years, 

on average) with future sedimentation and potential climate 

change (fig. 5). In September and October, water-supply deficits would occur once every 5 years, on average, with current 

Reservoir water levels initialized at the conservation elevation of 990 meters were used to investigate the effects of irrigation demand on hypothetical water-level probabilities during 

reservoir filling (Vining and Vecchia, 2007). Calculations using 

existing and doubled downstream irrigation demand indicate 

that the reservoir has about a 75-percent chance and about 

a 50-percent chance, respectively, of filling to 1,045 meters 

within 2 years (fig. 4). During a severe drought, however, 

large multiyear irrigation-supply deficits could occur in which 

water levels remain below 1,022 meters for more than 4 years 

before increasing to 1,045 meters (Vining and Vecchia, 2007). 

Although the chance of such a severe drought is estimated to be 

1-in-100 during the next few years, the impacts of the drought 

on downstream agriculture could be substantial.

Figure 2. Kajakai Reservoir sediment profiles for 1953 and 

1968, and estimated sediment profile for 2006 (adapted from 

Perkins and Culbertson, 1970).

Current spillway elevation, 1,033.5 meters

0 5 10 15 20 25 30 35 40 45

1,050

1,040

1,030

1,020

1,010

1,000

990

980

970

APPROXIMATE DISTANCE UPSTREAM FROM DAM, IN KILOMETERS

ELEVATION, IN METERS

1953 profile

1968 profile

2006 profile

Figure 4. Percentiles of generated monthly reservoir levels for a 36-month conditional simulation period and an initial reservoir level of 990 

meters assuming A, existing (2006) downstream irrigation demand and B, a doubling of downstream irrigation demand.

Figure 3. Published and estimated storage volumes 

for 1968 and 2006 for Kajakai Reservoir, and hypothetical 

storage volumes for 2057.

980

990

1,000

1,010

1,020

1,030

1,040

1,050

RESERVOIR LEVEL, IN METERS

OCT JAN APR JULY OCT JAN APR JULY OCT JAN APR JULY OCT

YEAR 1 YEAR 2 YEAR 3

980

990

1,000

1,010

1,020

1,030

1,040

1,050

RESERVOIR LEVEL, IN METERS

EXPLANATION

90

10

25

50

75

PERCENTILE

Proposed spillway elevation

Conservation elevation

A

B
sedimentation and climate conditions compared to about once 

every 2 years, on average, with future sedimentation and potential climate change. Stated another way, the chance of having 

sufficient water supplies in Kajakai Reservoir during the worst 

month (October) is about 47 percent.

References

Afghanistan Information Management Services, 2006, 

Afghanistan physical map, accessed May 2007 at 

http://www.aims.org.af

Blue, A.C., 2006, Kajakai Dam inundation study—Kajakai 

Dam and Reservoir, Helmand Province, Afghanistan: 

U.S. Army Corps of Engineers Report to U.S. Agency for 

International Development, September 2006, 23 p.

Favre, R., and Kamal, G.M., 2004, Watershed atlas of 

Afghanistan: Afghanistan Information Management 

Service, Kabul, Afghanistan, 183 p.

Favre, R., and Kamal, G.M., 2005, Watershed atlas of 

Afghanistan—Book 2, Watershed maps: Afghanistan Information Management Service, Kabul, Afghanistan, 145 p.

Milly, P.C.D., Dunne, K.A., and Vecchia, A.V., 2005, Global 

pattern of trends in streamflow and water availability in a 

changing climate: Nature, v. 438, no. 17, p. 347–350.

Perkins, D.C., and Culbertson, J.K., 1970, Hydrographic and 

sedimentation survey of Kajakai Reservoir, Afghanistan: 

U.S. Geological Survey Water-Supply Paper 1608–M, 43 p.

Vining, K.C., and Vecchia, A.V., 2007, Water-balance 

simulations of runoff and reservoir storage for the Upper 

Helmand watershed and Kajakai Reservoir, central 

Afghanistan: U.S. Geological Survey Scientific Investigations Report 2007–5148, 16 p.

Whitney, J.W., 2006, Geology, water, and wind in the lower 

Helmand Basin, southern Afghanistan: U.S. Geological 

Survey Scientific Investigations Report 2006–5182, 40 p.

Figure 5. Percentiles of hypothetical monthly reservoir levels for 

A, conditions in 2006 but doubled downstream irrigation demand, 

and B, conditions in 2057 that include a 2-degree-Celsius increase 

in temperature, sedimentation estimated at 2057 levels, and a 

10-percent decrease in precipitation and doubled downstream 

irrigation demand.

USGS Afghanistan Project Product Number 176.

This study was funded by Interagency Agreement 07C442100KB 

between the U.S. Agency for International Development and the 

U.S. Geological Survey.

Photographs courtesy of Donald C. Houk, advisor to the U.S. 

Agency for International Development; Verne R. Schneider, 

U.S. Geological Survey; and John W. Whitney, U.S. Geological 

Survey.

Assistance in development of fact sheet courtesy Tara A. Banse

(20) (2) (1) (2) (5) (8) (2) (1) (4) (10) (17) (20)

980

990

1,000

1,010

1,020

1,030

1,040

1,050

RESERVOIR LEVEL, IN METERS

(53) (4) (2) (4) (17) (28) (11) (10) (17) (28) (40) (47)

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

980

990

1,000

1,010

1,020

1,030

1,040

1,050

RESERVOIR LEVEL, IN METERS

EXPLANATION

(20) Percent chance 

 of supply deficit

90

10

25

50

75

PERCENTILE

Proposed spillway elevation

Conservation elevation

—Kevin C. Vining and Aldo V. Vecchia

A

B