Printed on recycled paper

Back cover 8-1/2" 11" 
Cover photograph: Barchan dunes on the Sar-o-Tar agricultural plain, Sistan, Afghanistan.
Geology, Water, and Wind in the Lower 

Helmand Basin, Southern Afghanistan

By John W. Whitney

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

Scientific Investigations Report 2006–5182

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2006

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

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.
Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................3

Physiography of the Lower Helmand Basin ..............................................................................................4

Tectonic Origin of the Helmand Basin........................................................................................................6

Late Cenozoic History of the Lower Helmand Basin................................................................................8

Late Tertiary History .............................................................................................................................8

Quaternary History..............................................................................................................................11

The Modern Desert Environment..............................................................................................................15

Climate..................................................................................................................................................15

Desert Winds and Eolian Environment............................................................................................18

1998–2005 Drought..............................................................................................................................19

Hydrology of the Helmand River System ................................................................................................22

Drainage Features and Discharge...................................................................................................22

1885 Flood ............................................................................................................................................25

Water Quality.......................................................................................................................................26

Channel Changes in the Sistan Depression ...................................................................................26

The Helmand Valley Project .............................................................................................................30

An Unknown Future ....................................................................................................................................32

Acknowledgments.......................................................................................................................................34

References Cited...........................................................................................................................35

iii
Figures

 1. Landsat 5 image showing the lower Helmand Basin in southern Afghanistan..................2

2. Map showing geography of the lower Helmand Basin showing the location

of physical features and streams...............................................................................................3

3. Map showing tectonic setting of the Helmand Basin and adjacent areas.........................4

4. Photograph showing the two main stream terraces of the Helmand River

downstream from the junction of the Arghandab and Helmand Rivers .............................5

5. Photograph showing multiple episodes of subsidence in the Sistan depression

are recorded in the tilted basin-fill sediments (dipping to right) and uplifted

erosional surfaces along the Afghan-Pakistan border near Jali Robat..............................7

6. Geologic map of the lower Helmand Basin..............................................................................9

 7. Photograph showing a 13.6-meter-thick section of Sistan beds exposed south

of Rudbar at the northern edge of the Gaud-i Zirreh............................................................10

8. Map showing eolian deposits and wind directions in the lower Helmand Basin............13

9. Graph showing monthly and annual pan evaporation rates for the lower

Helmand Basin ............................................................................................................................15

10. Climate diagrams for the Helmand Basin and adjacent areas ...........................................17

11. Graph showing mean monthly wind velocities for Zaranj and Lashkar Gah ...................19

12. Photographs showing landsat images of the Sistan delta and hamuns in 1976

and 2001........................................................................................................................................20

13. Photograph showing MODIS image (weather satellite) of dust deflation from

 the dry hamuns in Sistan on September 13, 2003.................................................................21

14. Diagram showing stream profile of the Helmand River with mean annual

discharges shown along the profile ........................................................................................22

15. Graphs showing monthly maximum, median, and minimum discharges of the

Helmand River from the Kajakai Reservoir and of the Arghandab River from

the Arghandab Reservoir .........................................................................................................23

16. Graph showing average annual discharge of the Helmand River from the

Kajakai Reservoir and of Arghandab River from the Arghandab Reservoir.....................24

17. Graph showing annual peak discharges of the Helmand River at Chahar Burjak ..........25

18. Map showing channel changes on the Helmand River delta in the Sistan

depression ...................................................................................................................................29

19. Map of agricultural lands irrigated by the Kajakai and Arghandab Dams of the 

Helmand Valley Project..............................................................................................................31

20. Photograph showing Kajakai Reservoir on the Helmand River in 1976.............................32

21. Photograph showing a tamarisk band (a porous dam) on the Helmand River

raises the water level in order to irrigate on the flood plain...............................................33

22. Photograph showing a small village on the Helmand River flood plain near

Qala-i Fath at the head of the delta is engulfed by dunes ...................................................34

Table

1. Calculations of flood discharges for the 1885, 1903, 1904, and 1905 floods by

T.R.J. Ward...................................................................................................................................27

iv
Multiply By To obtain

Length

mile (mi) 1.61 kilometers (km)

Area

acre 4,047 square meter (m2)

square foot (ft2) 0.09290 square meter (m2)

Volume

cubic foot (ft3) 28.32 cubic decimeter (dm3)

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

Multiply By To obtain

Length

kilometer (km) 0.62 mile (mi)

meter (m) 3.28 foot (ft)

Area

hectare (ha) 2.471 acre

square meter (m2) 10.76 square foot (ft2)

Volume

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter (m3) 264.2 gallon (gal)

Flow rate

meter per second (m/s) 3.281 foot per second (ft/s)

1 gallon per second = 646,316.9 gallons per day

1 gallon per second for one year = 723.97 acre-feet per year

1 cubic foot = 7.48 gallons

1 million gallons = 3.07 acre-feet

1 acre-foot = 1.233 million liters = 1.233 megaliters

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F–32)/1.8

Conversion Factors

v
Preferred (translation) Other transliterations

Chahar Burjak Char Burjak

Chankhansur Chakansur

Dasht-i Margo Dasht-e Margo, Daste Margo, Margo Desert, Margow Desert

Gaud-i Zirreh Goud-e Zirreh, Gawd-e Zireh, Gowd-e-Zereh, Zirreh or Zereh Depression

Hamun (lake) Hamoon, Hamoun

Hamun-i Helmand Hamoon Hirmand, Daryacheh-ye Sistan

Hamun-i Puzak Hamoon-e Puzak, Hamun-e Puzak, Hamoon-e-Puzak

Hamun-i Sabari Hamoon-e Saberi, Hamoun-e Saburi, Hamun-e-Saberi

Harirud Hari Rud

Helmand Hirmand, Hilmand

Kabul Kabol

Kajakai Dam Band-e Kajakai

Kandahar Qandahar

Koh-i Kannesin Koh-e Khan Nassin, Koh-i Kannasin, Kuh-e Khannesin

Registan Rigistan, Rigestan

Rud (river) Rod

Sar-o-Tar Tar-o-Sar

Shahr-i Shahr-e

Shela Rud Rud-e Shela, Rud-e Shelah, Shile River

Sistan Seistan, Sejestan

Zabol Zabul

Southern Afghanistan Orthography (spelling of locations)

vi
from the Helmand accumulates in several hamuns (shallow 

lakes) in the Sistan depression. The wetlands surrounding 

these hamuns are the largest in western Asia and are directly 

affected by droughts and floods on the Helmand. Average 

annual discharge on the Helmand is about 6.12 million megaliters (million cubic meters), and the annual discharge varies 

by a factor of five. In 2005, the region was just beginning to 

recover from the longest drought (1998–2005) of record back 

to 1830. Annual peak discharges range from less than 80 cubic 

meters per second in 1971 to nearly 19,000 cubic meters per 

second in 1885. Large floods fill each hamun to overflowing 

to create one large lake that overflows into the normally dry 

Gaud-i Zirreh basin. The interaction of flooding, active subsidence, and wind erosion causes frequent channel changes on 

the Helmand delta. 

A major development effort on the Helmand River was 

initiated after World War II with substantial aid from the 

United States. Two dams and several major canals were completed in the 1950s; however, poor drainage conditions on the 

newly prepared agricultural fields caused extensive waterlogging and salinization. New drains were installed and improved 

agricultural methods were implemented in the 1970s, and 

some lands became more productive. Since 1980, Afghanistan 

has endured almost constant war and civil and political strife. 

In 2005, the country was on a path to rebuild much of its 

technical infrastructure. Revitalization of agricultural lands in 

the lower Helmand Basin and improved management of surface- and ground-water resources are crucial to the country’s 

reconstruction efforts.

Introduction

Sistan is the depression that receives the discharge of the 

Helmand River in the lower Helmand Basin and was often 

described by explorers, military men, and natural scientists 

of the 19th and early 20th centuries as one of the most desolate deserts on Earth. It still is. A large and remote desert 

basin, extremely arid and known for its windstorms, extreme 

floods, and droughts, the lower Helmand Basin in Afghanistan 

(fig. 1) is considered to be the easternmost extension of the 

Iranian Highlands. The closed basin receives the waters of the 

Helmand River, the only major perennial river in western Asia 

Geology, Water, and Wind in the Lower Helmand Basin, 

Southern Afghanistan

By John W. Whitney

Abstract

This report presents an overview of the geology, hydrology, and climate of the lower Helmand Basin, a large, closed, 

arid basin in southern Afghanistan. The basin is drained by the 

Helmand River, the only perennial desert stream between the 

Indus and Tigris-Euphrates Rivers. The Helmand River is the 

lifeblood of southern Afghanistan and has supported desert 

civilizations in the Sistan depression for over 6,000 years.

The Helmand Basin is a structurally closed basin that 

began to form during the middle Tertiary as a consequence of 

the collision of several Gondwanaland fragments. Aeromagnetic studies indicate the basin is 3–5 kilometers deep over 

basement rocks. Continued subsidence along basin-bounding 

faults in Iran and Pakistan throughout the Neogene has formed 

the Sistan depression in the southwest corner of the basin. 

Lacustrine, eolian, and fluvial deposits are commonly exposed 

in the basin and were intruded by latest Miocene–middle 

Quaternary volcanoes, which indicates that depositional environments in the lower Helmand Basin have not substantially 

changed for nearly 10 million years.

Lakes expanded in the Sistan depression during the 

Quaternary; however, the size and extent of these pluvial lakes 

are unknown. Climate conditions in the lower Helmand Basin 

likely mirrored climate changes in the Rajasthan Desert to the 

east and in Middle Eastern deserts to the west: greater aridity 

during global episodes of colder temperatures and increased 

available moisture during episodes of warmer temperatures. 

Eolian processes are unusually dominant in shaping the 

landscape in the basin. A strong wind blows for 120 days each 

summer, scouring dry lakebeds and creating dune fields from 

annual flood deposits. Nearly one-third of the basin is mantled 

with active or stabilized dunes. Blowing winds combined 

with summer temperatures over 50o Celsius and voluminous 

insect populations hatched from the deltaic wetlands create an 

environment referred to as the “most odious place on earth” by 

19th century visitors. During dry years, large plumes of dust 

originating from Sistan are recorded by weather satellites.

The Helmand River drains about 40 percent of Afghanistan and receives most of its moisture from melting snow and 

spring storms. Similar to many desert streams, the Helmand 

and its main tributary, the Arghandab River, are characterized 

by large fluctuations in monthly and annual discharges. Water 
as the early 16th century A.D. After the early 16th century, Sistan has not been restored to its former prosperity. At present, a 

large field of active barchan dunes overlies most of the agricultural plain on the Afghan side of the Helmand delta. This plain 

was once the most prosperous and densely populated tract in 

the delta region.

In 1949 the United States initiated a new program for the 

improvement of underdeveloped areas of the world. The damming of the Helmand River in southern Afghanistan became 

one of the showcase projects of U.S. foreign aid in the “Third 

World” after World War II. Set up as the Helmand-Arghandab 

Valley Authority (HAVA), dams were built on the Helmand 

River and its main tributary the Arghandab River during the 

1950s. The project goals were to provide hydroelectric power, 

increased agricultural productivity through irrigation, and 

land reclamation. The Arghandab dam, located northwest of 

the city of Kandahar, was completed in 1952 with a height of 

145 feet (44.2 meters) and storage capacity of 388,000 acrefeet (478.6 million cubic meters). The larger Kajakai dam 

on the Helmand was completed a year later with a height of 

300 feet (91.4 meters) and length of 919 feet (280 meters) and 

Figure 1. Landsat 5 image showing the lower Helmand Basin in southern Afghanistan.

between the Tigris-Euphrates and Indus Rivers. The Helmand 

and its tributary streams drain the southern Hindu Kush Mountains of Afghanistan and flow into an otherwise waterless 

basin of gravel plains and sandy tracts before terminating in 

Sistan (also Seistan, British spelling), a depression containing 

the large delta of the Helmand River and a series of shallow, 

semiconnected playas at the western edge of the basin (fig. 2). 

Extensive archeological ruins in the Helmand Valley, on 

the Helmand delta, and around the terminal lakes are evidence 

that the Helmand River was a major focal point for the development of early civilizations in western Asia. In fact, archeological excavations at Shahr-i Sokhta (Tosi, 1973, 1976), 

located at the edge of the Hamun-i Helmand (hamun is a lake) 

(fig. 2), revealed that human societies developed rudimentary 

irrigation systems and lived in protourban settings by

3,200 B.C., several centuries before the great Harappan cities of the Indus Valley civilization appeared on the cultural 

horizon.

Sistan is known historically as the “breadbasket of western Asia’’ (Goldsmid, 1876). Agricultural civilizations have 

occupied the deltaic plains in Sistan intermittently and as late 

 Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
storage capacity of 1,495,000 acre-feet (1,844 million cubic 

meters). About 300 miles (482.8 kilometers) of concrete-lined 

canals were built to distribute the reservoir waters.

Purpose and Scope

This report presents a synthesis of the geology, climate, 

and surface hydrology in the lower Helmand River Basin 

as a foundation for future exploration and development of 

water and mineral resources. Very little technical work has 

been done in the region since the late 1970s. At that time, the 

Afghans (Mujahidin) began a protracted war and successfully 

repelled the Soviet occupation forces in 1988. In 1996, after 

years of civil war fighting among warlords, the Taliban, an 

alliance of Pashtun clans, captured Kabul and instituted a conservative Islamic regime. The Taliban ruled for 5 years until 

the American military invaded the country in response to the 

Taliban’s accommodation and support of al Qaeda, an extremist Islamic group that has conducted international terrorism, 

including the attack on the World Trade Center in New York in 

hamun flood l mi it

506

467

Koh-i

Chakab

Shahr-i Sawari

Shahr i Sokhta

Ram Rud

P u l a n K u h

Kacha Kuh

Jali

 Robat

Shela Rud

Shah-i Mardan

Khaimah

Barang

Kuh-i

Chakhansur

Shelah Charkh

Qala

Surkh

Dasht-i Amiran

Jahannum

Shahr-i Gholghola

Kona

 Qala Rud-i

Khusk

Koh-i Khannesin

Khaneh Gohar

Darweshan

Godar-i Rud

Golichah

Ribat Rud

Sana Rud

Khwaja

Rud-i

Gamak

Rud-i Pariun

Siksar

Zaranj

old canal

Qala-i

Fath R e g i s t a n

Zabol

Chahar

Burjak

Sistan

610

472

512

914

610

1219

477

488

507

500

488

500

542

523

914

1279

914

1524

1524

1524

1219

1829

610

463

914

610

610

576

610

793

696

q214 q198

q169

640

775

803

803

753

610

1420

690

1219

914

2333

1829

1219

1524

2460 1829

850

750

Mandeh

E X P L A N AT I O N

Farah Rud

Hamun-i

Sabari

Hamun-i

Puzak

Hamun-i Helmand

Zahedan

Rud-i Biyaban

Khuspas Rud

Khash Rud

Dor Rud

Sar-o-Tar

Rudbar

Gaud-i Zirreh

D a s h t - i M a r g o

Bust

H e l m a n d R u d

C h a g a i H i l l s

K o h - i - S u l t a n

Harut Rud

E l e v a t i o n i n f e e t

50 100 MILES

0 100 KILOMETERS

0

Figure 2. Geography of the lower Helmand Basin showing the location of physical features and streams.

Introduction 
Physiography of the Lower Helmand 

Basin

Afghanistan is a landlocked country composed of rugged 

mountain terrain, vast barren plains, and isolated basins. This 

harsh and remote landscape is dominated by the Hindu Kush 

Mountains, which are the western extension of the Karakoram-Himalayan mountain chain. The Hindu Kush ranges 

trend and generally decrease in altitude to the southwest from 

the Pamir Knot, a complicated mountain mass that formed 

where the northern tip of the Indian continental plate collided 

with the Russian plate (fig. 3). Nearly all the major mountain 

valleys follow faults or fault systems; earthquakes and multiple surfaces in these valleys are evidence of continuing uplift 

in these ranges.

Chaman Fault

0

0 300 KILOMETERS

300 MILES x x

x

x

x

xx x

x x

x

x

x

x

x

x

x x

x x

x

x

x

x

x

x

x

x x x

x x x

x

x xx x

CASPIAN

SEA

PERSIAN

GULF

ARABIAN SEA

TEHRAN

Russian Plate

Indian

Plate

KARACHI

Afghan

Microplate

Central

Iran

Lut

Block

Zagros System

Kavir-Doruneh Fault Nayband Fault

O

man Lin

e

50E 60E 70E

30N

Harirud (Herat) Fault KABUL

Farah Fault

Figure 3. Tectonic setting of the Helmand Basin and adjacent areas. Major structural trends are shown and principal fault systems 

are labeled. Areas of volcanic activity shown by an “x.”

2001. In 2005 Afghanistan continued slowly to rebuild, after 

more than two and a half decades of war, with its first elected 

government. Most of the country’s infrastructure, including 

water resources, needs repair or restoration. Defining the oil 

and gas potential of the Sistan depression is also a 21st century 

priority.

Field data presented in this report were collected from 

1973 to 1977 when the author was a graduate student and a 

member of the Smithsonian Institution’s archeological expedition to Sistan and the lower Helmand River region. 

The Smithsonian’s project ceased in dramatic fashion 

in 1979 when the Soviets invaded Kabul, and the American 

Ambassador, Adolf Dubs, was kidnapped and murdered. New 

technical information was added to this report in 2005 from 

available sources where possible.

 Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
The Helmand Basin is approximately 310,000 square 

kilometers in area and drains about 40 percent of Afghanistan. 

Physiographically, it is the easternmost basin of the Iranian 

Highlands (Fisher, 1968). To the north, the basin is confined 

by the southern Hindu Kush ranges, on the west by the East 

Iranian ranges; and on the south and east by the mountain 

ranges in Baluchistan province of Pakistan. Culturally, the area 

south and west of the Kandahar-Lashkar Gah agricultural area 

is loosely referred to as being part of Baluchistan (also spelled 

Balouchistan, Baloochistan), a region that extends south and 

west into northwestern Pakistan and eastern Iran. The nearly 

500 tribes, about 1.5 million people, who live in this region are 

culturally connected by the Baluchi (Balouchi) language.

The Helmand River (also spelled Hilmand, Hirmand) 

is the main stream in the basin (figs. 1, 2) and its headwaters 

are in the high Koh-i Baba Range. The river begins its nearly 

1,300-kilometer journey about 90 kilometers west of Kabul, 

then flows southwestward through steep, narrow valleys of 

the Hazarajat Mountains (fig. 1) before entering the vast, open 

basin that appears to the traveler as endless gravel plains with 

little relief (fig. 4); desert vegetation on these plains is limited 

to small depressions and areas where local runoff collects.

The Helmand River has several tributary streams whose 

headwaters are located in the eastern Hazarajat Mountains. 

The Tarnak and Arghastan streams flow into the Dor Rud 

(rud is Persian for river or stream), which in turn flows into 

the Arghandab River. The Arghandab joins the Helmand just 

downstream from the ancient site of Bust near the town of 

Lashkar Gah (figs. 1, 2). These tributaries would naturally 

contribute about 15–20 percent of the discharge received in 

the Sistan depression; however, most of the water is presently 

diverted for irrigation and domestic use (U.S. Agency for 

International Development, 1976).

The Helmand River is incised from 70 to 100 meters 

below the surface of the basin fill, and its valley width varies 

from 2 to 5 kilometers. As the river approaches the southwestern part of the basin, its direction curves sharply to the north 

as it enters the Sistan depression and terminates in several of 

the semiconnected lakes (the local term hamuns is used in 

this report) and wetlands that straddle the Afghan-Iran border. 

There are two principal stream terraces in the Helmand Valley 

(fig. 4); however, as many as four terrace remnants are found 

in the Koh-i Khan Nashin area, where the valley is wide. The 

highest terrace coincides with the top of the basin fill, and the 

main lower terrace, which is 20–30 meters above stream level, 

appears to be graded to an old delta of the Helmand River that 

is now incised by four distributary channels: the Sana Rud, 

Rud-i Biyaban, Rud-i Khusk, and the main channel (fig. 2; 

also see fig.19).

North of the Helmand Valley is the extensive Dasht-i 

Margo (“desert of death”), a remarkably flat and waterless plain that is broken up only by the shallow, southwestward-trending valleys of the Khash and Dor Ruds and several 

small fields of active dunes. South and east of the Helmand 

Valley is the Registan (“land of sand”), where a large, inactive 

sand sea has accumulated at the eastern edge of the basin. The 

inactive dunes are more than 75 meters high and strikingly red 

in color. Small, white-tan active dunes appear to be moving 

across the older stabilized dunes (Neil Munro, United Nations 

Environmental Programme consultant, written commun., 

2005). Farther to the west in the Registan, the dunes are active, 

smaller in height, and lighter in color. Two other areas of 

active dunes are located in the Sistan depression: the Sar-o-Tar 

dunefield and the Gardan Reg. Parts of the Dasht-i Margo and 

much of the Registan have not been explored for scientific 

purposes except by aerial reconnaissance and remote sensing.

Figure 4. The two main stream 

terraces of the Helmand River 

downstream from the junction 

of the Arghandab and Helmand 

Rivers. Remnants of the upper 

terrace have been streamlined by 

wind erosion.

Physiography of the Lower Helmand Basin 
are exposed along complex suture zones near Kandahar and 

Farah in ophiolite complexes that are interlayered in Cretaceous limestones (Krumsiek, 1980).

The Kopet Daghah and Alborz Mountains in Iran were 

formed by a similar sequence of Alpine events: the Iranian 

microcontinents, assumed to be the Lut and Tabas blocks, collided northward with the Russian plate (Stocklin, 1974). The 

Alborz Mountains, however, have also been interpreted as a 

former volcanic island arc complex (Forster, 1978).

At about the same time (Early Cretaceous), or slightly 

earlier, the Indian plate broke away from Gondwanaland and 

began a 5,000-kilometer journey northward. Collision initiated 

with the Eurasian continental landmass sometime between the 

late Paleocene and the early Eocene (Molnar and Tapponnier, 

1975; Klootwijk and Pierce, 1979). As the Indian plate continued northward, it converged westward against the Afghan and 

Iranian microcontinents. The amount of northward penetration 

of the Indian plate into Eurasia could be accommodated by 

tectonic thickening in the Asian mountain belts, or by underthrusting of continental crust; therefore, much of the crustal 

shortening took place by lateral movement of large crustal 

blocks away from the area of collision (Molnar and Tapponnier, 1975). Central and southwestern Afghanistan, the Afghan 

microplate (Afghan Block) including the Helmand Basin, is 

one of these wedge-shaped, crustal blocks and is shown in 

figure 3.

The Afghan block is defined by two major wrench faults, 

the Chaman and Herat faults (fig. 3), that resulted from the 

crustal shortening on the west side of the Indian plate. The 

Chaman and Herat faults meet at a point about 70 kilometers 

north of Kabul and join the Ghorband-Panser fault, which 

continues northeast into the Pamir Mountains in Pakistan. The 

intersection of these three faults is a triple junction between 

the Russian, Indian, and Afghan-Iran crustal plates and blocks 

(Krumsiek, 1980). The Afghan block began displacement to 

the southwest during the late Eocene. This displacement has 

continued up to the present in response to continued northward 

thrusting of the Indian plate.

The 800-kilometer-long, north-south-trending Chaman 

(also called Moqur-Chaman) fault forms the eastern boundary of the Afghan block and is considered by Auden (1974) to 

be the transform fault that bounds the northwest edge of the 

Indian plate. The fault is active and is a principal source of 

earthquakes in Afghanistan (Abdullah, 1979). A major earthquake in 1892 displaced a set of railroad tracks by nearly a 

meter and created a surface rupture more than 200 kilometers 

long (McMahon, 1897). Based on the offset of isotopically 

dated volcanic rocks, a sinistral displacement rate of 2.5–

3.5 cm/year for the last 2 million years has been calculated for 

movement on the Chaman fault (Beun and others, 1979).

The east-west-trending Harirud fault system forms the 

northern boundary of the Afghan crustal block (Wheeler and 

others, 2005). The fault extends more than 1,100 kilometers 

from northeast Afghanistan to Iran, where it may be connected 

with the Kavir-Doruneh fault system in Iran across a system 

of north-south fault systems that separates the Lut Block from 

Sistan is actually an 18,000-square-kilometer depression 

within the lower Helmand Basin. The floor of the depression, commonly called the Sistan Basin or Sistan Proper, is 

situated 200–300 m below the surface of the Dasht-i Margo 

and is occupied by the modern, arable Helmand delta and the 

terminal hamuns. Three main hamuns and wetlands are situated roughly at the termini of the deltaic distributary channels. 

Water in the hamuns is rarely more than 3 meters deep; in 

fact, during the 1970s local inhabitants still poled reed boats 

(called tutins) around the hamuns to fish and to harvest the 

reeds, which abound in the marshes (called naizar) that fringe 

most of the open-water areas. The size of the hamuns varies 

both seasonally and from year to year. Maximum expansion 

takes place in late spring, following snowmelt and spring 

precipitation in the mountains. All but 10 percent of the annual 

basin runoff enters Sistan between February and June. In 

years of exceptionally high runoff, the hamuns overflow their 

low divides and create one large lake that is approximately 

160 kilometers long and 8–25 kilometers wide. Overflow from 

this lake is carried southward into the normally dry Gaud-i 

Zirreh (fig. 2), the lowest playa (463-meter altitude) in the Sistan depression. Mountain runoff varies considerably from year 

to year; in fact, the hamuns have completely dried up at least 

three times during in the 20th century. The maximum extent of 

the hamuns following large floods is shown in figure 2.

Several intermittent streams enter Sistan from the north 

and west. Runoff from the mountains in Iran and Pakistan 

percolates through the alluvial fans that rim the southwestern 

edge of Sistan. Runoff from the Paropamisus and western 

Hazarajat Ranges discharges into the northern hamuns through 

the Harut, Farah, Khash, and Khuspas Ruds. The combined 

discharge of all these sources (before irrigation diversion) is 

less than 20 percent of that contributed by the Helmand River 

(Brigham, 1964; U.S. Agency for International Development, 

1976).

Tectonic Origin of the Helmand Basin

The Helmand Basin is a large, structurally closed basin 

that began to form during the middle Tertiary as a consequence of the collision of several former Gondwanaland 

fragments. Paleomagnetic studies in Afghanistan (Krumsiek, 

1976, 1980) and in central Iran (Becker and others, 1973; Soffel and others, 1975) indicate that at least two, but probably 

more, continental fragments (referred to as microcontinents 

or microplates) broke away from the supercontinent Gondwanaland sometime during the Late Permian. These microcontinents drifted northward toward their present positions while 

rotating in a counterclockwise motion that is characteristic of 

Gondwanaland fragments. Collision of the Afghan microplate 

with the Eurasian continent, also called the Russian plate, was 

complete by Early Cretaceous and created the Paropamisus 

Range. This range forms part of the northern boundary of the 

Helmand Basin. Remnants of ocean floor and plate margins 

 Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
the Afghan Microplate (also referred to as the Sistan Block) 

(fig. 3). Auden (1974) described the Harirud fault, then called 

the Herat fault (Wellman, 1966) before it was renamed by 

Russian geologists during the 1980s, as a fault system consisting of fault troughs containing deformed Neogene and 

Quaternary sediments. Trifonov (1978) reported offsets of 

60–100 meters of probable Holocene-age fill along this fault, 

as well as similar displacements in Quaternary deposits in 

parallel fault valleys to the north. Wellman (1966) measured 

60–100 m of dextral stream displacement along the fault north 

of Kabul. Holcombe (1978) has calculated an average rate of 

movement on the fault of 1.04 centimeters per year based on a 

total displacement of 620 kilometers along the Harirud fault.

Faults within the Afghan block are subparallel to, but do 

not exhibit displacements as great as, the Harirud and Chaman 

faults. Basic dikes along one of these internal faults, the Farah 

fault, are offset dextrally about 80 kilometers (Auden, 1974). 

The faults within the Afghan block exert structural control on 

the streams that drain into the lower Helmand Basin. Wheeler 

and others (2005) have compiled a seismotectonic map of 

Afghanistan and annotated bibliography on the basis of published sources and seismicity.

As the fault-bound Afghan block was squeezed southwestward away from India, the Afro-Arabian plate was moving to the north; the intervening regions in Iran were thus subjected to intensive collisional compression and deformation. 

The East Iranian ranges that form the west-to-southwest edge 

of the Helmand Basin were formed when western remnants of 

the former Tethys sea were closed and marine rocks as young 

as Eocene were intensely folded, faulted, and uplifted, while 

ultramafic rocks were tectonically emplaced into the marine 

sedimentary sequence. The intensity of this collision is seen in 

the zones of blueschist metamorphism that are found in these 

highly deformed rocks between the Afghan and Lut blocks 

(Stocklin and others, 1972).

The southwest-trending faults and mountain ranges in 

the Afghan block terminate abruptly against north-trending 

systems in Iran and the East Iranian ranges. This collision or 

suture zone between the Afghan and Lut block has been active 

since the late Eocene; dextral movement has been an apparent 

response to the continued movement of the Afro-Arabian plate 

(Forster, 1976, 1978; Freund, 1970). Late TertiaryQuaternary-age volcanoes erupted along the fault, and the fault 

is the locus of major earthquakes in eastern Iran (Gansser, 

1971; Berberian, 1976). 

The Sistan depression is situated at the junctions of the 

Harirud fault and the southwest-trending faults within the 

Afghan block. Middle to late Tertiary subsidence of basement 

blocks led to the formation of the lower Helmand Basin

(Schreiber and others, 1971), and continued subsidence along 

the active Harirud fault has formed the Sistan depression during the late Tertiary and Quaternary (fig. 5). Ongoing movement of the Arabian plate from the southwest is recorded by 

continued seismic activity around the Iranian microplates 

(Berberian, 1976, 1981; Nowroozi, 1972, 1976).

Volcanic activity was also associated with the complex 

tectonic activity associated with the Afro-Arabian plate movement and closing of the Tethys sea (Forster, 1978). The Chagai 

Hills at the south edge of the lower Helmand Basin in Pakistan 

are, for example, one of the late Eocene volcanic fields that 

are found around the microcontinents. Volcanic flows and sills 

covered and intruded the Pliocene basin and lake sediments 

with olivine basalt and olivine dolerite in both Iran and the 

lower Helmand Basin (Gansser, 1971; Lang, 1971). A small, 

7.3 ± 0.2 million-year-old basalt flow caps the 121-meter-high 

Kuh-i Khwaja mesa located in the Hamun-i Helmand (fig. 2) 

in Iranian Sistan (Jux and Kempf, 1983). This dated basalt 

flow overlies lakebeds, which indicates that the Sistan depression began to form, and lakes were present, in the Neogene, 

Figure 5. Multiple episodes of 

subsidence in the Sistan depression 

are recorded in the tilted basin-fill 

sediments (dipping to right) and 

uplifted erosional surfaces along the 

Afghan-Pakistan border near Jali 

Robat. View to the east.

Tectonic Origin of the Helmand Basin 
area. The Sistan beds are exposed where stream incision and 

scarp retreat have undercut or eroded away colluvium and (or) 

overlying gravels.

Younger gravel deposits are chiefly distributed along 

the basin edge or adjacent to volcanic mountains; generally, 

these gravels underlie pediments and alluvial fans. A few loess 

deposits generally are present near the stream valleys and on 

some of the mountain hillslopes that border the basin. Modern 

lacustrine deposits are present around the hamuns in the Sistan 

depression.

Late Tertiary History

Late Tertiary basin sedimentation was controlled primarily by late Tertiary subsidence of basement blocks, by the 

supply of detritus from the surrounding mountains, and by 

the Neogene climates that controlled transport processes in 

the basin. Sedimentation patterns in the basin are predictably 

similar to other Asian intermontane basins: coarser grained 

sediments are deposited closer to the edge of the basin, and 

fine-grained sediments are deposited in the lower reaches of 

the basin (Blanford, 1873; Dickey, 1968). The exact patterns 

of sedimentation in any closed basin are dictated by the number and position of streams and local base levels or depressions. The depressions are controlled by the location and 

activity of the major basin-controlling faults (Reeves, 1977).

The depositional history of the lower Helmand Basin is 

imprecisely known because little detailed fieldwork has been 

done on the stratigraphy of this remote area, and subsurface 

geologic data are not available. All earlier investigators, 

including this author, have either studied one area in some 

detail or several outcrops across widely separated localities.

Aeromagnetic surveys (Schreiber and others, 1971) 

indicate that the sediment thickness above the Precambrian 

basement blocks varies from 3,000 meters to more than 

5,000 meters. Basin deposition likely began following Oligocene subsidence; Neogene and Quaternary sediment thickness 

is estimated to be approximately 1,000 meters (Weippert and 

others, 1970) and is believed to be greater near the western 

edge of the basin where subsidence has continued to the present. However, only the uppermost 250 meters of sediment 

is exposed along the cliffs of the lower Helmand Valley and 

Sistan depression. The exposed stratigraphy is remarkably 

uniform and flat-lying except along the Iranian and Pakistani 

mountain fronts. In fact, the horizontal aspect and apparent 

continuity of individual beds led some investigators to believe 

that tectonic activity played only a minor role in the depositional history of the basin (Blanford, 1873; Huntington, 1905; 

Jux and Kempf, 1983; Smith, 1974).

The Neogene basin fill is composed of two informal 

units: the Sistan beds (Lang, 1971; Jux and Kempf, 1983), 

which consist chiefly of fluvial and eolian sand units and 

lacustrine sandy and clayey silts; and beds of coarse to fine 

gravels, which overlie and, near the basin edge, interfinger 

with the Sistan beds. The cliffs around Sistan expose nearhorizontal lake and fluvial units of the Sistan beds; however, 

although the original flow surface has probably subsided an 

unknown amount since deposition.

The most recent episode of widespread volcanic activity 

took place during the Pliocene and early Quaternary, when the 

Zagros Mountains of western Iran were formed from severe 

compression and uplift due to the northeast rotation of the 

Arabian plate. Three large volcanoes, Koh-i Sultan, Koh-i 

Taftan, and Koh-i Bazman, are located just south of the lower 

Helmand Basin and lie in a southwesterly trend just south of 

the border with Pakistan (fig. 4). The Quaternary-age volcanic 

rocks intruded into folded Eocene melange as well as older 

eroded volcanic complexes. These young volcanic centers 

still show signs of activity, although no historical flows are 

known. The Quaternary lavas are more intermediate to silicic 

in composition than the Eocene lavas. The line of these volcanoes does not follow the strong structural surface trends of the 

region, which may point to the existence of large discrepancies 

between the surface and deeper subsurface structures (Gansser, 

1971).

One isolated volcano, Koh-i Khannesin, in south-central 

Helmand Basin is situated on the south bank of the Helmand 

River (fig. 2). It is a carbonatite volcano and apparently is 

unrelated to the Koh-i Sultan complex located to the southwest or to the older Chagai Hills located directly to the south 

(Abdullah and others, 1975). Although Koh-i Khannesin was 

considered Pliocene to early Quaternary in age because of the 

eroded appearance of the crater (Vikhter and others, 1978), a 

lava flow on the southeast flank of the volcano erupted during the middle Quaternary. A potassium-argon (K-Ar) date 

of 0.61 ± 0.05 million years was obtained on leucite crystals 

separated from a collected sample of a leucite phonolite (Richard Marvin, U.S. Geological Survey, written commun., 1977). 

The flow appears to be one of the youngest flows from the 

volcano; the center of the crater is now highly eroded. Afghan 

and Russian geologists discovered rare-earth metals associated 

with the volcanic rocks at Koh-i Khannesin (Shareq and others, 1977; Shareq, 1981) and evaluated the economic potential 

of the mountain.

Late Cenozoic History of the Lower 

Helmand Basin

The upper Cenozoic deposits of the lower Helmand Basin 

are shown in figure 6, which is a geologic map of the basin 

revised after Wittekindt and Weippert (1973) on the basis 

of fieldwork, interpretation of Landsat images, and recent 

geologic map compilations by O’Leary and Whitney (2005a, 

b). Basin stratigraphy is dominated by three units: the Sistan 

beds, coarse gravels that overlie the Sistan beds, and eolian 

sands. Eolian sand distribution is controlled by the locations of 

flood sands, which are reworked by northwesterly to westerly winds. The distribution of coarse gravels on the Dasht-i 

Margo reflects the deposition of coarse debris off the southern 

Hazarajat Mountains, which lie just to the north of the map 

 Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
it is not known how deep these deposits extend. The overlying 

gravels vary from less than a meter to more than 15 meters 

thick and were deposited on an erosional surface.

The Sistan beds exposed along the northern edge of the 

Sistan depression consist mainly of flat-lying, alternating units 

of oxidized (tan to pink) and unoxidized (light green) clayey 

silt. Fluvial sand units also are present in outcrops visited 

in the Helmand Valley and Gaud-i Zirreh. The presence of 

these lakebeds led several investigators to hypothesize that the 

entire lower Helmand Basin was at one time filled by a very 

large lake. Furthermore, the age of the lake was assumed to 

be Pleistocene because of the position of beds at the top of the 

basin fill and the known worldwide fluctuations in Quaternary 

climate (Anderson, 1973; Blanford, 1873; Huntington, 1905; 

Smith, 1974).

The existence of a Pleistocene basinwide lake is unlikely 

for two reasons. First, the thick lacustrine deposits are confined to exposures in the western one-third of the lower 

Helmand Basin, and second, the dated Neogene volcanic rocks 

in the Sistan beds indicate deposition primarily during the 

Neogene. Exposed Sistan beds along the Helmand Valley from 

Lashkar Gah to the Rudbar area consist chiefly of eolian and 

fluvial sands that contain rare, thin, interbedded units of tuff 

(Lang, 1971). Between Koh-i Khannesin and Chahar Burjak, the number of interbedded, 1- to 3-meter-thick lakebeds 

increases from one to two, or to possibly three; the rest of 

the exposed section is eolian and fluvial sand. At the western 

edge of the Dasht-i Margo at a location east of the Sar-o-Tar 

archeological plain, a 97-meter section of the Sistan beds was 

measured that consists of 88 meters of crossbedded sands and 

7 meters of gypsiferous lacustrine silt. At the top of the section is 2 meters of well-rounded gravel. South of the Helmand 

River, the cliffs along the north edge of the Gaud-i Zirreh are 

composed chiefly of fluvial and eolian sands with one interbedded lacustrine unit (fig. 7). Thus, the exposed Sistan beds 

located outside the Sistan depression indicate that the principal 

Figure 6. Geologic map of the lower Helmand Basin. Revised from Wittekind and Weippert (1973) and O’Leary and Whitney (2005a, b).

Late Cenozoic History of the Lower Helmand Basin 
ostracods, however, do indicate that the chemistry, depth, and 

temperature of the lakes at that time were similar to conditions 

in the present hamuns. These paleoenvironmental data correlate well with the arid climatic conditions that are inferred 

from the eolian sand units in the Sistan beds exposed outside 

the Sistan depression. In fact, the crossbedding directions in 

the sand units suggest that sand deposition took place under a 

wind regime similar to present conditions (Lang, 1971; Smith, 

1974).

The gravels overlying the Sistan beds are a puzzlement 

because the surfaces of deposition appear to have gradients 

Figure 7. A 13.6-meter-thick section of Sistan beds exposed south of Rudbar at the northern 

edge of the Gaud-i Zirreh. The four principal units from bottom to top are eolian sand, fluvial 

sand with mud chips, fluvial sand, and lacustrine silt. A 2-meter scale is at the cliff base.

depositional environments were eolian and fluvial; lacustrine 

deposition was infrequent and short-lived. Without close topographic and lithologic control, it is impossible to tell whether 

or not the few lacustrine beds located outside the depression 

were deposited in isolated lakes or in a lake that expanded 

from the Sistan depression. 

A major problem in describing the stratigraphy of the Sistan beds is the lack of index fossils and marker beds. Jux and 

Kempf (1983) identified ostracods from the lacustrine units 

exposed just north of the hamuns and found that the species 

indicate an indeterminate age of Neogene to Pleistocene. The 

10 Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
that are too low for gravel transportation. Smith (1974) proposed that the mode of deposition was by pebbly mudflows. 

However, Jux and Kempf (1983) observed that the gravels 

increase in thickness toward the mountains and interfinger 

with mountain-front fans. Gravel outcrops commonly display 

fluvial crossbedding that indicates fluvial deposition. Jux and 

Kempf reported a 50-meter-thick channel deposit of gravel 

near Koh-i Chakab, located in Iranian Sistan west of the 

north end of Hamun-i Sabari, which the authors believed was 

deposited in response to an episode of subsidence in the Sistan 

depression.

The gravel cover on the surface (dasht) of the basin fill 

most likely has a complex depositional history. Gravels were 

deposited by streams from the Hazarajat Mountains that 

flowed across the gentle Dasht-i Margo plain before the Sistan 

depression and present Helmand Valley were formed. The 

deposition of gravel instead of finer grained sediment may 

have been in response to relatively rapid uplift in the mountains or to increased runoff due to climatic change, or possibly 

to both factors. The gravel was probably distributed unevenly 

on the surface, and subsequent reworking and surface erosion, 

including strong deflation, over a long time period has formed 

a lag gravel cover over most of the Dasht-i Margo. The local 

reworking of gravel deposits would explain the fact that gravels are very thin or absent in some places and 1–3 meters thick 

in other places. Pias (1976) noted thick gravel deposits west of 

the present Helmand Valley that he believed were deposited by 

the Helmand River before the present valley was incised.

Reworking of gravel by local runoff continued in the 

lower Helmand Basin long after the Helmand River incised 

into the basin fill. In fact, most, if not all, of the gravel found 

on all surfaces below the Dasht-i Margo has been reworked 

from the gravels that were originally deposited on top of the 

Sistan beds. The gravel is transported to lower surfaces by 

slope retreat processes that leave behind a lag deposit and by 

local runoff. In Sistan, it is common to see concentrations of 

gravel at multiple levels on the eroding slopes of the Sistan 

beds; each gravel concentration represents the position of a 

former runoff channel. Pebble counts on three different surfaces at Chahar Burjak by Jux and Kempf (1983) illustrate this 

principle well; the percentage of limestone pebbles decreased 

from 15 percent on the highest surface to 6.5 percent on the 

middle surface to 1 percent on the lowest surface, while the 

percentage of resistant quartz pebbles had a corresponding 

increase from higher to lower surfaces.

The Sistan beds and overlying dasht (surface) gravels 

have been intruded by volcanic rocks at Koh-i Khannesin, 

Kuh-i Khwaja, and Koh-i Chakab, volcanoes located along 

the western edge of Sistan in Iran (fig. 6). Koh-i Khannesin is 

reported to be between 1.4 and 2.8 to 5.0 million years old by 

Shareq and others (1977), although the methods of dating were 

not given. Jux and Kempf (1983) obtained whole rock, potassium-argon ages of 7.3 ± 2 million years and 8.2 ± 6.0 million 

years on basalt from Kuh-i Khwaja and Koh-i Chekab. These 

age determinations may be somewhat older than the rocks 

due to argon loss or because lavas were contaminated slightly 

by older rock; however, the ages of all three volcanic eruptions indicate that the underlying Sistan beds and gravels are 

Neogene.

The late Miocene age of Kuh-i Khwaja, a basalt flow 

that overlies lakebeds, also indicates that the Sistan depression existed by that time. The base of volcanic flow is situated only 55–60 meters above the present lake plain, whereas 

the depression is about 255 meters deep. Assuming the late 

Miocene age determination is correct, the Sistan depression 

was about 200 meters deep and the Helmand Valley was established when the upper Miocene lava was deposited. However, 

it is unlikely that the Helmand was incised to its present depth 

before the middle Pleistocene because more than 35 meters 

of downcutting has taken place below the 0.6 ± 0.01 millionyear-old leucite phonolite flow at Koh-i Khannesin. The total 

depths of the depression and resultant valley incision are not 

known because of the unknown sediment thickness underlying 

the delta and hamuns in Sistan.

Quaternary History

The Quaternary history of the lower Helmand Basin is 

primarily recorded in the Helmand Valley and Sistan depression because the top of the basin fill has been an erosional 

surface since the deposition of Neogene gravels above the 

Sistan beds. Quaternary deposition outside the valleys and 

depression was chiefly confined to gravel deposition at the 

mountain fronts and to dune accumulation in the Registan. 

Fluvial and lacustrine deposition in the Sistan depression and 

inflowing valleys has been continuous from the late Tertiary 

to the present, although the patterns of deposition and erosion 

were controlled by local tectonic movements and by fluctuating climatic conditions. No stratigraphic break between 

the Tertiary and Quaternary deposits has been identified in 

the Sistan depression. A lack of age control is the principal 

impediment to deciphering Quaternary history in the basin. 

The major reason for few dated deposits is that several dating 

methods available in 2005 were not available in the 1970s 

when these studies were conducted: luminescence dating, 

which would be well suited for eolian sands and lake silts; 

cosmogenic dating, useful for determining exposure ages; and 

uranium-series dating, which can now be used to analyze ages 

of soil carbonates. Until a clear distinction is drawn between 

the Neogene and Quaternary sediments underlying the delta 

and conterminous lake basins, reconstruction of the early and 

middle Quaternary basin history is imprecise. Available data 

for a climatic reconstruction of the late Quaternary in Sistan 

are few; thus, the climatic framework presented here is heavily 

based on correlations with better dated stratigraphic sequences 

in Iran and India.

In an attempt to define the Tertiary-Quaternary boundary 

in Sistan, Jux and Kempf (1983) obtained three 9-meter-long 

cores from the dry lakebeds of the Hamun-i Sabari and the 

Hamun-i Puzak (fig. 2) during the 1971 drought. Gastropods, 

ostracods, and pelecypods collected from the cores characterize a lacustrine environment of generally fresh or slightly 

Late Cenozoic History of the Lower Helmand Basin 11
sediments rest on deformed strata of Koh-i-Khannesin, the 

extinct volcano south of the Helmand River, and that the 

eroded mountain is likely to be early or middle Tertiary in age. 

Although Smith allowed that faulting may have occurred at the 

west edge of the basin, he hypothesized that the Sistan depression was formed almost entirely by deflation; the mountains at 

the southern edge of the basin deflected northwesterly winds 

to the east, which caused increased turbulence in the area of 

the Gaud-i-Zirreh depression. Although not stated explicitly, 

Smith implied that the deflation must have taken place during 

dry interglacial intervals of the Pleistocene because the Sistan 

hamuns would have expanded during glacial times of lower 

mean annual temperatures.

The idea of accelerated wind erosion during an interglacial climate was first applied in Iran by Bobek (1963, 1969) 

to explain a large field of yardangs (positive-relief landforms 

carved by wind erosion) in the Lut Basin. Bobek, however, 

believed that the magnitude of climatic changes was much 

smaller in the arid basins of eastern Iran than in northern and 

western Iran; otherwise, the Lut yardangs would have been 

altered or destroyed by either runoff or lake deposition during 

significantly wetter conditions.

The existence of large, basinwide Quaternary lakes, as 

proposed by Huntington (1905) and Smith (1974), is discredited on the basis of Neogene-dated volcanics that are located 

both on the top of the basin fill and within the Sistan depression (Jux and Kempf, 1983). However, Jux and Kempf (1983) 

did agree with Smith’s deflation mechanism for the origin of 

the Sistan depression. Flat-lying Sistan beds and lack of visible faulting led Jux and Kempf to believe that tectonic activity 

played a minor role in the geomorphic history of the basin. 

They constructed the following climatic hypothesis to account 

for the origin of the depression: wind erosion occurred during 

cold, glacial episodes when water was held in storage by ice 

and snow in the upper drainage basin, and shallow lakes would 

flood Sistan during warmer interglacial episodes when snow 

and ice would melt in spring and summer. Within this climatic 

model, Jux and Kempf (1983) also proposed that three stream 

terraces along the lower Helmand River constituted evidence 

of the episodic lowering of the depression by deflation; each 

terrace was interpreted to represent an episode of lake stability 

in the depression.

Abundant eolian landforms and deposits in the basin 

(fig. 8) attest to strong eolian activity, both past and at present. 

However, wind erosion is localized and cannot occur in the 

hamuns and surrounding wetlands when they contain water. 

In order to create the Sistan depression by deflation, the 

climate during most of the Quaternary must have been much 

drier than present hyperarid conditions. Considering the large 

size of the Helmand drainage basin with significant runoff 

from high mountains and known Quaternary fluctuations from 

adjacent areas such as the Caspian and Black Seas (Degens 

and Paluska, 1979; Paluska and Degens, 1979), it is highly 

unlikely the Sistan depression was dry during most of the Quaternary. Jux and Kempf cited Quaternary wind erosion in the 

brackish water. Jux and Kempf argued that the Quaternary lake 

deposits must be very thin, in some places less than 5 meters, 

because of the presence of one ostracod, Cyprideis torosa, 

which predominates in the lower sections of the cores but is 

absent in the upper sections. This species is associated with 

brackish water conditions and is a common ostracod in the 

Neogene Sistan beds that are exposed in the nearby cliffs. The 

species Cyprideis torosa, however, is alive at present (present, 

for example, in the Dead Sea). Therefore, the presence of the 

species cannot be considered an indicator of Neogene-age sediments, nor can the species be said to live in an environment 

that does not exist in Sistan today (I.G. Sohn, U.S. National 

Museum, written commun., 1976). Jux and Kempf did not 

consider an alternative explanation that Quaternary fluctuations in lake size and changing lake positions may account 

for fluctuating conditions of sedimentation and salinity. The 

thickness of Quaternary deposits in the present lakebeds cannot be determined on the presence or absence of one species 

of ostracod that has persisted from the early Neogene to the 

present; thus, the thickness of Quaternary fill is still an open 

question.

Ellsworth Huntington (1905) was the first investigator to describe a Quaternary history in the Sistan depression. 

Although he was limited to fieldwork in Iranian Sistan and 

did not visit the Helmand Valley, he proposed that the exposed 

pink and green lacustrine sediments resulted from alternate 

expansions and contractions of a large lake in Sistan controlled 

by Quaternary climatic fluctuations. Huntington calculated 

that 10 pluvial-to-arid cycles, interrupted by an episode of 

volcanic activity, would account for nearly all the observed 

features present in the Sistan basin. Huntington also noted that 

distorted shorelines were evidence that warping (deformation) 

has continued to recent times; however, the influence of tectonic activity was all but excluded from Huntington’s geologic 

reconstruction of the basin. From a historical point of view, a 

major objective of the 1900 Carnegie Expedition, which also 

included noted American geographers Raphael Pumpelly and 

W.M. Davis, was to expound on the nature of climatic changes 

in Central Asia. Thus, Huntington’s climatic reconstruction 

was almost certainly influenced by his earlier observations in 

the glaciated drainage basins in Turkestan.

Huntington did perceive and discuss alternative geological mechanisms to account for the rhythmic nature of 

the stratigraphic units. He considered a “diversion” theory 

whereby a river was diverted back and forth across a basin 

and concluded that such behavior must be due to a systematic 

cause such as warping or climatic change. He decided that 

rhythmic warping was implausible and could not account for 

the exposed lake sediments as well as a climatic mechanism 

that would cause the hamuns to expand and contract. Had 

Huntington known that the Sistan beds were Neogene in age 

instead of Pleistocene, perhaps he might have more strongly 

considered his tectonic model of basin sedimentation.

Because of the lack of dating control on the Sistan beds, 

Smith (1974) also assumed that all exposed deposits in the 

Helmand Basin are Quaternary in age. He stated that basin 

12  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
Lut Basin as an analog to the Sistan depression; however, the 

Lut Basin is not fed by a major perennial flowing river.

There are several reasons why deflation alone is not 

the process that formed the Sistan depression. First, strong 

evidence for a tectonic origin of the depression has been discussed herein. The fact that recent tectonic activity is concentrated along the margins of the lower Helmand Basin, while 

the center contains flat-lying sedimentary beds, is not unique. 

Both the Tarim Basin in southwest China (Norin, 1941) and 

the Lut Basin in Iran (Conrad and Conrad, 1970a,b) exhibit the 

same geologic relationship. Furthermore, the hamun shapes 

are arcuate around the edge of the depression and coincide 

with the position of basin-controlling faults. Sar-o-Tar plain 

and the wind-scoured area to the south (known as Jehanum or 

Hell) are the only areas in the depression that are elongated 

parallel to the wind, and wind erosion is presently active in 

these areas. Second, if the Sistan depression was lowered 

during each Quaternary glacial episode, then there should 

be many more than three terraces in the Helmand Valley that 

would have recorded the sequential lowering of the base level. 

Third, nearly all fans, terraces, and basin surfaces are mantled 

by a layer of gravels that prevents significant deflation. Curiously, Jux and Kempf (1983) ignored the fact that the depression was chiefly formed during the late Tertiary; the middle 

terrace in Helmand Valley (35 meters above stream level) 

cannot be middle-late Quaternary in age if their proposed late 

Miocene surface of the depression at Kuh-i Khwaja was only 

55–60 meters above the present basin floor.

The question of climatic conditions during global 

episodes of glacial activity is the key to understanding the 

Quaternary history of the lower Helmand Basin. Was the 

basin occupied by pluvial lakes, as proposed by Huntington 

(1905) and Smith (1974), or was the Sistan depression dry, as 

suggested by Jux and Kempf (1983)? One factor overlooked 

by previous investigators is the lack of glacial deposits in 

the upper Helmand Basin. The north side of the Koh-i Baba 

Range, just west of Kabul, was glaciated several times during 

the Pleistocene (Grotzbach and Rathjens, 1969); however, no 

evidence of glaciation has been observed on the south side 

of the range, which drains into the Helmand Basin (Balland 

and Lang, 1974; Lang, 1975). The snowline on south-facing 

mountain slopes is as much as 400 meters higher than on 

north-facing slopes (Horvath, 1975), which illustrates the 

increased insolation received by south-facing slopes. However, 

increased insolation was not the sole reason for the absence of 

glacier buildup. The snowline during glacial episodes was as 

much as 1,000 meters lower (Grotzbach and Rathjens, 1969) 

than the present snowline. Lack of snow and ice accumulation during glacial episodes was due to a lack of moisture and 

must have been a major factor. Norin (1932) recognized a 

similar situation in the Tarim Basin; the north-draining Kunlun 

Mountains contained evidence of multiple glaciation, while no 

KHASH RUD

HELMAND

RUD

ARGHANDAB RUD

Dasht-i

Margo

Registan

Eolian deposits

EXPLANATION

Wind direction

Figure 8. Eolian deposits and wind directions in the lower Helmand Basin.

Late Cenozoic History of the Lower Helmand Basin 13
Sistan depression; however, this contribution is considered 

to be minor relative to late Tertiary and Quaternary tectonic 

subsidence of the depression.

Two former shorelines at altitudes of about 3 meters and 

10 meters above the Iranian hamuns were found and interpreted by Huntington (1905) to represent temporary stillstands 

during the progressive desiccation of the last Pleistocene 

high lake stand. Because the Neogene age of the Sistan beds 

negates this interpretation, these shorelines must represent 

either expansion of the late Quaternary hamuns into larger 

lakes or, possibly, evidence of Quaternary subsidence of the 

lake floor. Radiocarbon dating of calcium carbonate-rich 

lacustrine sediments in Afghan Sistan and along the Khash 

Rud by Pias (1972, 1974a,b, 1976) indicates that Quaternary lake expansions did take place in the Sistan depression 

during global interglacial climates. Pias obtained an age of 

9,030 ±125 years before present on a lake deposit exposed 

by wind erosion in the floodable land tract east of Zaranj. 

He also obtained ages of 30,300 ±1,050 years before present 

and 33,200 ±1,600 years before present on calcareous sediments that he collected on small mounds located at the mouth 

of, and many kilometers upstream in, the Khash Rud valley. 

Unfortunately, Pias did not give stratigraphic descriptions of 

these samples, their altitudes, or their exact localities. It is 

also not clear whether Pias dated soil carbonate or carbonate 

precipitated in lake sediments. Thus, it is impossible to ascertain whether these dates represent lake expansions that were 

responsible for the two low shorelines. Smith (1974) and Jux 

and Kempf (1983) rejected the radiocarbon dates; however, 

the dates do correlate with well-known episodes of increased 

moisture in the subtropical deserts of Australia (Bowler, 

1978), North Africa (Williams and Faure, 1980; Street and 

Grove, 1976), Arabia (Whitney, 1983; Whitney and others, 

1983), and Pakistan and India (Allchin and others, 1978; 

Singh and others, 1972). Although the geologic data from the 

Sistan depression is at best circumstantial, a tentative correlation with pluvial deposits of similar ages in deserts located 

both to the east and west of the Helmand Basin suggests that 

Quaternary lake expansion in Sistan was probably synchronous with interstadial (interglacial) climates. If this correlation is correct, then the Holocene climate in Sistan, beginning 

approximately 10,000 years before present, was relatively 

wet in comparison to the last glacial episode (approximately 

18,000 years before present). The lowest shoreline around the 

depression may then represent an early to middle Holocene 

expansion of the hamuns. Future radiometric, cosmogenic, and 

(or) luminescence dating will eventually refine or revise the 

lake history in Sistan.

The Caspian, Black, and Aral Seas all expanded and 

filled to their highest shorelines during the time of maximum 

ice expansion (Ehlers, 1971), although active Quaternary 

subsidence in these basins makes it difficult to estimate how 

much larger the seas were (Paluska and Degens, 1979). These 

inland seas were models for Huntington’s (1905) lake history for Sistan. However, these lakes greatly increased in 

size because they were fed by glacial meltwater; Sistan and 

evidence of glaciation was found in the south-draining Tien 

Shan Mountains on the other side of the basin.

An apparent moisture decrease in the southern Hindu 

Kush Mountains during glacial episodes is also suggested by 

palynological studies in the Hindu Kush (Pias, 1974b, 1976) 

and by similar glacial-age precipitation decreases in Iran (Van 

Zeist and Bottema, 1977), in lake basins in the Near East (Bottema, 1978; Van Zeist and Bottema, 1982), and in the Rajasthan Desert (Singh and others, 1972, 1974). The correlation 

with Iranian and Near Eastern lake basins is especially strong 

because the Hindu Kush receives its moisture from the same 

source area and same winter depressions (cyclonic storms) that 

pass over these areas.

The primary reason that precipitation did not increase 

over these regions is a 5oCelsius water-temperature drop in the 

Mediterranean Sea during times of worldwide glacial activity 

(Emiliani, 1955; Thunnell, 1979); hence, less moisture was 

picked up by eastward-moving storms. Also, fewer storms 

may have invaded southwest Asia because an expanded winter 

high pressure system existed over the Eurasian continent during glacial times; this high pressure cell may have deflected 

storms to the south (Lamb, 1977).

The combination of a somewhat reduced glacial-age 

precipitation and lower evaporation rates probably had a counterbalancing effect that may account for the fact that nearly all 

the closed basins in Iran did not experience major geomorphic 

changes during the late Quaternary (Bobek, 1963; Krinsley, 

1970, 1972). However, another important climatic factor to be 

considered in the Helmand and Lut Basins is wind activity.

The great volume of dunes in the lower Helmand Basin 

may be evidence of enhanced wind erosion during times of 

reduced, glacial-age precipitation. The dunes in the large 

Registan sand sea (fig. 8) were found to be stabilized and 

oxidized; therefore, they provide evidence of a past episode, 

or episodes, of accelerated eolian sand movement and deposition in the basin. Although the dunes were not directly dated, 

4,000-year-old pottery was found in 1976 on the surface of 

dunes located at the eastern edge of the dunefield by members of a Smithsonian archeological team, which indicates 

that the dunes have been stable for at least the late Holocene. 

Stabilized sand seas in other subtropical deserts were active 

during the last glacial episode (Bowler, 1978; Whitney and 

others, 1983), including the dunefields in the nearby Thar and 

Rajasthan deserts (Allchin and others, 1978; Singh and others, 1972, 1974). Thus, until the dunes can be dated directly 

by luminescence methods, it is reasonable to suggest that the 

stabilized dunes in the Registan were also last active during 

the last Pleistocene glacial episode.

Increased windiness in the Helmand Basin was not a 

consequence of low precipitation but probably was caused 

by the presence of cold, high-pressure air over Soviet Central 

Asia. The gradient between high-pressure arctic air and the 

low-pressure summer thermal cell over the lower Helmand 

Basin was likely greater during glacial episodes than at present 

and resulted in winds of greater velocity and frequency. Thus, 

wind erosion has undoubtedly enhanced the formation of the 

14  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
other Iranian playas were not. Sources of moisture for the 

expanded pluvial lakes of Central Asia were not the same for 

the stable-to-drier lakes of Southwest Asia. Precipitation in the 

southern Hindu Kush and Iranian highlands was insufficient 

to form large accumulations of ice or to increase runoff within 

the lower Helmand Basin. Low precipitation was characteristic over most of the Soviet Union during the glacial maximum. Velichko (1984) has estimated that precipitation was 

25–50 percent of present totals and that active loess deposition 

took place during the glacial maximum.

In Afghanistan, Pias (1974a) stated that arboreal pollen 

was reduced to less than 5 percent during the last glacial maximum, and the nonarboreal pollen was predominantly steppe 

vegetation characterized by Artemisia and chenopoddominated, marshy, saline flood plains. This vegetation association is similar to the present vegetation in the mountains of 

Afghanistan.

When the large continental ice sheets disappeared 

18,000–13,000 years ago, subtropical deserts began to receive 

increased precipitation. The melted continental ice filled the 

oceans to near present sea level during early-middle Holocene. 

By mid-Holocene, sea level was actually a meter or so higher 

than at present (Fairbridge, 1961; Woodruff and Horton, 

2005), which expanded the water surface area available for 

winds to pick up moisture. Sea surface temperatures rose to 

levels 1o–2oCelsius greater than they were in the late 20th century (Emiliani, 1955; Thunnell, 1979), which in turn increased 

the amount of moisture evaporating into the air in the warm 

tropics and subtropics. This increased Holocene moisture is 

reflected in the vegetation changes that are recorded in pollen 

profiles in western Iran (Van Zeist and Bottema, 1977), the 

Thar and Rajasthan Deserts (Allchin and others, 1978; Allchin 

and Goudie, 1978; Goudie and others, 1973), the Sahara

(Williams and Faure, 1980), and Saudi Arabia (Schulz and 

Whitney, 1986). Precipitation steadily increased over these 

regions from the beginning of the Holocene to between 6,000 

and 5,000 years before present. In Iran, precipitation levels 

since that time have not significantly declined; however, 

aridity did increase in the Rajasthan about 3,000 years ago. 

This difference is undoubtedly due to two different moisture 

sources: moisture in the Rajasthan comes from the monsoon; 

whereas, Iran and the Helmand Basin are supplied by Mediterranean moisture.

The mid-Holocene return of forests to the Zagros Mountains (Van Zeist and Bottema, 1977) roughly correlates in 

time with the expansion of Mesopotamian civilizations along 

the Tigris-Euphrates. The transition from the Neolithic to the 

protourban settlements of the Ubaid, and later Sumer, cultures 

in Mesopotamia occurred between 7,000 and 6,000 years ago 

when climatic conditions in the Near East were “optimal” 

(Butzer, 1978). Relatively wetter conditions in Sistan during 

the mid-Holocene may have played been instrumental in the 

construction of early settlements such as Shahr-i Sokhta

(Tosi, 1973, 1976); however, no geologic data presently 

exist to prove climatic conditions and water supply about 

6,000 years ago were significantly different from the present 

(Costantini and Tosi, 1978). Enzel and others (1999) found 

that middle Holocene lakes in the Thar Desert dried up about 

4,800 14C years before present, about 1,500 years before the 

Harrapan civilization flourished. Thus, a wetter climate did not 

coincide with the growing and expanding civilization in the 

Indus Valley. 

The Modern Desert Environment

Climate

The harsh extremes of temperature, winds, and even 

precipitation leave an indelible impression upon the visitor to 

Sistan. Sir Frederic Goldsmid (1876) referred to the Helmand 

delta region as being the “most odious” place on the face of 

the Earth. Many instances of the effects of extreme temperatures and fierce windstorms on man and beast are recorded in 

the reports of the various Sistan boundary commissions. For 

instance, McMahon (1906) recounted one 4-day blizzard in 

1905 that resulted in the death of more than 200 camels. In 

1975, our own expedition was forced to close its field season 

early because of a sudden and unusually forceful gale that 

destroyed three tents before we were able to take them down. 

From 1998 until early in 2005, the Helmand Basin experienced the longest drought in 175 years of historical record.

The climate of the Helmand Basin is hyperarid except at 

the edges of the basin, where it is arid. According to UNESCO 

(1979) definitions, arid and hyperarid zones are distinguished 

O N D J F M A M J J A S

800

700

600

500

400

300

200

100

0

MONTH

PAN EVAPORATION IN SISTAN, IN MILLIMETERS

CHAKHANSUR

Annual rate 4,306

LASHKAR GAH

Annual rate 2,772

KANDAHAR

Annual rate 1,752

Figure 9. Monthly and annual pan evaporation rates for the 

lower Helmand Basin. Data from Brigham (1964).

The Modern Desert Environment 15
the sun sets, which causes ground and air temperatures to drop 

rapidly on cloudless evenings.

Winter temperatures in the lower Helmand Basin are 

somewhat colder than in most subtropical deserts. Freezing 

temperatures can occur from November to March; thus, the 

growing season averages only about 270 days a year, which is 

generally too short and cold for tropical and subtropical vegetation. During the mid-1970s I saw only two small date palms 

in the Helmand Valley; however, only 100 km to the south in 

Baluchistan these palms are common near springs and irrigation canals. Sleet and snow accompany these low temperatures 

on occasion because winter is the main precipitation season. 

According to residents in the basin, snow rarely lasts the day 

and apparently falls only once every 2 or 3 years. Published 

data on yearly snowfall are not available.

Because of the relatively cold winters, the mean annual 

temperature range in the lower Helmand Basin is 27o Celsius, 

whereas the range in most Middle Eastern deserts is from 

15o to 20o Celsius (Beaumont and others, 1976). High annual 

temperature ranges are also common to the north in the deserts 

of Iran and in the former Union of Soviet Socialist Republics. 

In this respect, the climate of the lower Helmand Basin more 

closely resembles that of the Asian continental deserts than the 

subtropical deserts of the Middle East and Africa.

The lower Helmand Basin exhibits two other characteristics of continental deserts: the basin is situated a great distance 

from its moisture sources, and it is rimmed by mountains that 

prevent the invasion of many moist air masses. For example, 

the East Iranian and Makran Ranges in Baluchistan prevent the 

northward penetration of the summer monsoon.

The position of air masses over Asia in winter appears 

to be related to the sudden shift of the westerly subtropical jet 

stream from the north side of the Himalaya Mountains to the 

south side (Beaumont and others, 1976). Summer conditions, 

on the other hand, occur when the subtropical jet stream shifts 

back to the north. Fall and spring are relatively short transitions between the winter and summer conditions. Summer 

climatic conditions last from April to October, and winter 

conditions last from November to April.

Accompanying the winter shift of the subtropical jet 

stream is the southward shift of the polar front, that is, the 

boundary between polar and tropical air masses. Wave 

disturbances are commonly generated along this front over 

the North Atlantic Ocean and the Mediterranean Sea. These 

frontal disturbances, or cyclones, travel along eastward tracks 

from the eastern Mediterranean area and penetrate much of 

western Asia and the Middle East, regions that are dominated 

by dry descending air in summer (Beaumont and others, 1976; 

Ganji, 1968; Lydolph, 1977). This winter regime of Mediterranean-type precipitation is responsible for virtually all the 

moisture that falls in the Helmand Basin.

Precipitation reaching Sistan must travel at least 

2,600 kilometers from the eastern Mediterranean area and 

cross several areas of higher relief that deplete the cyclones of 

most of their moisture. Precipitation totals from Mediterranean 

storms are greatest over the high Zagros ranges in western 

by the ratio of mean annual precipitation (P) to mean annual 

potential evapotranspiration (ETp). Arid zones are defined 

by P/ETp of less than 0.20 and greater than 0.03, and hyperarid zones have less than 0.03 P/ETp. At the meteorological 

stations that have published annual totals of potential evaporation (fig. 9), the P/ETp is 0.027 at Lashkar Gah, 0.016 at 

Chakhansur, and 0.08 at Kandahar.

Climate diagrams (Walter, 1973) were constructed from 

the meteorological data available for the basin and adjacent 

areas (fig. 10). These diagrams illustrate the relative periods of 

wetness and drought during the year by plotting temperature 

and precipitation on the same graph for each month. Periods 

of effective moisture exist when monthly precipitation (in millimeters) is greater than twice the air temperature in degrees 

Celsius. The climate diagram for Herat shows the standard 

units of 10o Celsius increments for temperature on the left side 

of the diagram and 20-millimeter increments of precipitation 

on the right side. The stations in the lower Helmand Basin 

and farther south in Pakistani Baluchistan clearly show that 

drought conditions (shown in orange color) dominate almost 

year round; very small amounts of effective moisture (blue 

color) are available during January and February, a time when 

it is too cold for agriculture. Outside the hyperarid zone, at 

Herat and Kandahar, the relatively humid season lasts from 

November to April.

The lower Helmand Basin is situated between 29o and 

32o north latitude on the north edge of the subtropical dry 

zone, a belt of aridity that extends from northwest Africa (the 

Saharan-Arabian Deserts) eastward to the Thar-Rajasthan Deserts of Pakistan and India. This arid climatic zone is the result 

of worldwide circulation patterns of air that create semipermanent cells of high pressure (Hadley cells) in the general region 

of the tropics. Cold, dry, polar air descends from high altitudes 

and is subjected to compressional heating at the adiabatic rate 

of 10o Celsius per 1,000 meters. Because it is hot and dry, the 

air is incapable of producing clouds or rain when it reaches the 

Earth’s surface. The low percentage and frequency of cloud 

cover together with the clarity of dry air allow a great deal of 

solar radiant energy to reach the ground, which results in very 

high ground temperatures. The heated ground returns much of 

this heat to the atmosphere in the form of long waves of radiant energy. High daytime air temperatures that are characteristic of most deserts are primarily due to heating of the lower 

atmosphere by terrestrial radiation.

Summer temperature maximums of greater than 

50o Celsius (122o Fahrenheit) have been recorded in the delta 

region of Sistan (Afghan Institut de Meteorologie, 1971; U.S. 

Agency for International Development, 1976). Temperature 

maximums decrease outside the delta region because the land 

surface steadily rises in altitude toward the mountains that rim 

the basin. At Zaranj, the provincial capital of Nimruz Province in Sistan, the midsummer daily air temperature range is 

nearly 20o Celsius. A daily range as great as 32o Celsius and a 

monthly range of 43o Celsius has been reported by the Afghan 

Institut de Meteorologie (1971). These high diurnal temperature ranges occur because terrestrial radiation continues after 

16  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
964 m

16.2

211 mm

660 m

20.5

77 mm

780 m

19.4

75 mm

495 m

20.8

73 mm

490 m

20.7

72 mm

1,005 m

19.1

141 mm

585 m

20.9

73 mm

1,369 m

17.9

75 mm

679 m

24.5

39 mm 21.6

84 mm

Herat

Farah

Zabol

Zaranj

Gaud-i Zirreh

IRAN

Zahedan

Nok

Kundi

Mashkel

Dalbandin

Deshu

Chakhansur

Lashkar

Gah

J J D

Kandahar

Nushki

Lora

AFGHANISTAN PAKISTAN

13

7

4

28

10

30

6

20

16

33

Farah

Harut

Khuspas

Helmand

Khash

Kajaki

Dori

Tarnak

Arghastan

Arghandab

50 100 MILES

0 100 KILOMETERS

0

964 meters

16.2o Celsius

211 millimeters J F M A M J J A S O N D

oC

millimeters

of

precipitation

30

10

60

20

13

Month

Total years

of record

Altitude

of station

Average

annual

temperature

Average annual

precipitation

EXPLANATION

Figure 10. Climate diagrams for the Helmand Basin and adjacent areas.

The Modern Desert Environment 17
Pakistan near the town of Sibi, on the Indus plain. The position of this heat low over the basin explains the pattern and 

direction of dunes in the basin; wind streamlines, as observed 

on Landsat images of southwestern Afghanistan, curve in a 

counterclockwise motion from the Sar-o-Tar area to the Registan (fig. 8). Low, isolated mountains along the southern edge 

of the basin cannot alone account for such a massive wind 

deflection. Thus, wind directions are a direct consequence of 

the Dasht-i Margo thermal low. In a strict sense, the “Wind of 

120 Days” is a trade wind that is accelerated and deflected by 

a local heat low before the dry, originally polar air can reach 

the Intertropical Convergence Zone, which is located over the 

north-south-striking Sulaiman Mountains of Pakistan.

The Sulaiman Mountains and the mountains along the 

Makran coast also serve as a southern barrier to the moisture-bearing monsoons. Occasionally, monsoons do invade the 

high mountainous areas of eastern Afghanistan and cause summer floods (Sivall, 1977). Some of this precipitation may enter 

Sistan from eastern tributaries of the Helmand River.

The “Wind of 120 Days” is stronger in Sistan than over 

the rest of the Helmand Basin. Mean monthly wind velocities 

are given for Lashkar Gah and Zaranj in figure 11. A striking increase in wind velocity occurs from May to September 

at Zaranj but not at Lashkar Gah, which is located about 

200 kilometers to the east. Stronger winds are concentrated 

along the west edge of the basin because the wind accelerates 

along a long, narrow corridor between the mountains of Iran 

and Afghanistan. The “Wind of 120 Days” is felt farther south 

in Baluchistan; however, the intensity is not as great. The 

maximum, mean monthly wind speed at Nok Kundi, Pakistan, 

is 4 meters per second (Takahashi and Arakawa, 1981) and is 

about 6 meters per second at Zaranj (Brigham, 1964). Comparison of these two stations is tenuous, however, because data 

probably were collected by different methods and over different time periods.

According to members of the Sistan Arbitration Commission, who lived in Sistan from 1903 to 1905, the “Wind 

of 120 Days” blows almost constantly day and night during 

the hottest months of the year. Sustained, hurricane-force 

winds of 29–36 meters per second (65–80 miles per hour) 

were experienced frequently. One storm in 1905 recorded an 

average velocity of 39.3 meters per second (88 miles per hour) 

for a 16-hour period. During that storm, a maximum velocity 

of 53.6 meters per second (120 miles per hour) was recorded 

(McMahon, 1906). The pebbles, sand, dust, and debris carried 

by the wind, plus its continual noise, make living conditions 

particularly undesirable during the summer. Violent windstorms are by no means limited to one season and were a 

subject of considerable interest to most early foreign visitors 

to this area (for example, Tate, 1910–12).

The approach of a windstorm is the same in summer as 

in winter. The days preceding the arrival of the storm become 

slightly, but detectably, warmer and the air becomes still, or 

a slight breeze may blow from the southeast. Less than a day 

before the gale arrives, small cirrus clouds usually appear in 

the northwest. Strong winds may arrive suddenly, in the space 

Iran and lowest over the interior desert basins of eastern Iran 

(Ganji, 1968). Annual precipitation averages about 75 millimeters per year over most of the lower Helmand Basin 

(fig. 10). Precipitation in the mountains north of Herat and in 

the eastern Helmand Basin at Kandahar averages about two 

to three times that received on the desert plains and on the 

delta. The driest and warmest region is not on the Helmand 

delta, but farther south in Baluchistan at the village of Nok 

Kundi, Pakistan. The annual temperature at Nok Kundi is 

almost 4o Celsius warmer than at Zabol (Iran) or Chakhansur, 

Afghanistan, and the annual rainfall is only 39 millimeters. 

The main reason the temperature is warmer in Baluchistan 

than in the lower Sistan depression is that Sistan is subject to 

stronger summer winds than Nok Kundi. The very low precipitation at Nok Kundi is due to a rain shadow effect; mountains 

surround the village on three sides. Both meteorological stations at Dalbandin and Nok Kundi record a slight amount of 

summer precipitation, which is evidence of the northernmost 

invasion of monsoon moisture in Baluchistan. Residents in 

Baluchistan speak of the destructive flash floods that accompany the rare invasions of monsoon storms from the Indian 

Ocean. Nok Kundi received 16.5 millimeters of precipitation 

in 24 hours during one July storm (Takahashi and Arakawa, 

1981). The Chagai, Koh-i Sultan, Saindak, and Kacha Mountains, however, serve as a barrier to monsoon precipitation in 

the Helmand Basin.

Another continental aspect of Sistan’s winter weather is 

the frequency with which the region is subjected to waves of 

cold, polar air (Asiatic High) from the interior of Central Asia. 

Winter insolation effects are weak and tend to be dominated 

by these invasions of cold air. It is common for the air temperature to drop several degrees after the passage of a rain-bearing cyclone because the cyclonic low pressure (depression) 

tends to pull in the dry, cold, northern air.

Desert Winds and Eolian Environment

Winds are the most notable and frequently described 

feature of the lower Helmand Basin, especially in Sistan. Violent sandstorms may occur at any time of the year; however, 

winds blow with a great regularity from May to September. 

This summer wind blows steadily from the northwest and is 

locally called the bad-i-sad-o-bist ruz, or “Wind of 120 Days.” 

This wind has a significant effect on the landscape and the 

lives of the basin’s inhabitants: eolian erosional and depositional landforms dominate much of the desert basin outside the 

Helmand Valley, and drifting sand has been a principal natural 

determinant in changing irrigation patterns and the location of 

agricultural endeavors throughout historical times.

The position of the summer low-pressure (monsoon) system over the mountains in Pakistan is the principal reason that 

high-pressure air (the Azores High) is drawn in to Sistan from 

the Caspian Sea region (Ganji, 1968; Kendrew, 1961). Sivall’s 

(1977) compilation of pressure data in Afghanistan, however, 

shows that a significant heat low develops over the Dasht-i 

Margo independent of the heat low centered over western 

18  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
of only a few minutes, or the winds may build strength over 

half a day. A marked rise in temperature accompanies the 

wind; however, when the strong winds abate, normally after 

several days, the air temperature is noticeably cooler. After an 

interval of time, calm days begin to become more frequent and 

the temperature begins to rise again, seemingly initiating the 

next windstorm cycle.

In the summer, daily winds blow about 9–11 meters per 

second (20–25 miles per hour), with gusts up to 18–22 meters 

per second (40–50 miles per hour) (U.S. Agency for International Development, 1976). Evidence that these strong winds 

existed in historical times is attested to by dated deposits of 

eolian sand and by the standing remains of windmills that are 

found both in and outside the delta region. The most commonly found windmills were built in the 14th–15th centuries 

and were used to grind grain (Whitney and Trousdale, 1982, 

1984).

The presence of exceptionally strong winds for long durations has a marked effect on the potential evaporation rates 

in the Helmand delta region (fig. 9). Because the “Wind of 

120 Days” is strongest in Sistan, where Chakhansur village 

is located, evaporation totals are higher there than elsewhere 

in the Helmand Basin, as is shown by lower totals at Lashkar Gah and Kandahar (Brigham, 1964). Measurements at 

Chakhansur that exceed 4,000 millimeters per year were 

recorded by the Afghan Institut de Meteorologie (1971). This 

potential evaporation rate is 2.5 times greater than rates in 

the eastern part of the basin and is among the highest rates 

recorded around the globe.

1998–2005 Drought

The Helmand Basin has recently experienced an unusually long 5-year drought from 2000 through early 2005 

(United Nations Environment Programme, 2003, 2006). 

Combined with war and severe political disruption over the 

past 2 decades, the 5-year drought has created conditions of 

widespread famine that affected as many as 6 million people 

in central and southern Afghanistan. A suggested climatic 

forcing mechanism has been proposed for the recent drought 

by Barlow and others (2002). A prolonged ENSO (El NiñoSouthern oscillation) cold phase (known as La Niña) from 

1998 to 2001 and unusually warm ocean waters in the western 

Pacific appear to have contributed to the prolonged drought. 

The unusually warm waters (warm pool) resulted in positive precipitation anomalies in the Indian Ocean and negative 

anomalies over central Afghanistan (Barlow and others, 2002). 

The hamuns, nearly 4,000 square kilometers in extent, in 

both Iranian and Afghan Sistan went completely dry in

Average

Lashkar Gah

Zaranj

Maximum

1,200

1,000

800

600

400

200

0

O N D J F M A M J J A S

14.0

12.0

10.0

8.0

6.0

4.0

2.0

0

WIND VELOCITY, IN KILOMETERS PER DAY

METERS PER SECOND

MONTH

Figure 11. Mean monthly wind velocities for Zaranj and Lashkar Gah. Maximum monthly wind 

velocities are shown for Zaranj. 

The Modern Desert Environment 19
1976 2001

Figure 12. Landsat images of the Sistan delta and hamuns in 1976 and 2001. 1976 was a relatively wet year and 2001 was a drought year and the hcompletely dry.
wherever vegetation is not supported by irrigation or ground 

water. The topography in Sistan has been and continues to be 

dominated by the interplay of eolian and fluvial processes in 

the depression. Wind-eroded yardangs (McCauley and others, 1977) and dunefields are common features in the lower 

Helmand Basin. Active dunes presently cover most of the 

agricultural fields that supported multiple historical societies over the past 3,000 years (Whitney and Trousdale, 1982, 

1984). Sistan inhabitants adapted to these winds during historical times: nearly all structures were constructed with their 

long walls parallel to the north-northwest wind direction, and 

during medieval times uniaxle windmills were constructed for 

grinding grain. In modern Iranian Sistan, small wind intakes 

(bad geres) are built on the top of village houses as a form of 

air conditioning during the summer. 

MODIS satellite images of Sistan taken during the recent 

drought capture striking evidence of strong eolian erosion 

and dust generation in the depression (fig. 13). Dust from the 

area of dry hamuns and delta can be traced on satellite images 

moving across Pakistan and over the Arabian Sea. When the 

Figure 13. MODIS image (weather satellite) of dust deflation from the dry hamuns in Sistan on September 13, 2003.

2001–2002: a human and natural catastrophe. A contrast 

between a relatively wet year in 1976 and the nearly dry 

hamuns in 2001 in shown in figure 12. Millions of fish and 

untold numbers of wildlife and cattle died. Agricultural fields 

and approximately 100 villages were abandoned, and many 

succumbed to blowing sand and moving dunes (Partow, 2003). 

Although one flood occurred in April 2003, about one-half 

of the 1997 population had left Sistan by November of that 

year. Finally, in March 2005, melting snow in combination 

with strong spring rains flooded the Helmand Valley and delta 

and partially refilled the hamuns. In 2006, the United Nations 

Environment Programme released a study of environmental 

change in Sistan from 1976 to 2005 that documents hydrologic 

and vegetation changes on the delta based on satellite image 

analysis.

Sistan is one of the windiest deserts in the world. Except 

in the immediate areas of active fluvial and lacustrine deposition, the landscape in the lower Helmand Basin is dominated 

by eolian erosional and depositional landforms. In the Sistan 

depression, active wind erosion and(or) sand movement occurs 

The Modern Desert Environment  21
Helmand’s largest tributary. Downstream from the junction, 

the volume of streamflow steadily diminishes because of irrigation diversions, evapotranspiration losses, and ground-water 

seepage. The Helmand flows nearly 500 kilometers beyond its 

junction with the Arghandab through a desert with little to no 

local runoff. Previous investigators have stated that groundwater seepage was the major reason for decreasing annual 

downstream discharges (Radermacher, 1974, 1976; Jux and 

Kempf, 1983); however, water diversions for domestic use and 

agriculture are the main siphons of water from the river. There 

are more than 750 kilometers of irrigation canals maintained 

by the Government of Afghanistan in the Helmand Basin, and 

this figure does not include local village canals downstream 

from Darweshan (U.S. Agency for International Development, 

1976). About 78 kilometers downstream from Chahar Burjak 

(figs. 2, 14), 45–55 percent of the Helmand’s discharge is 

diverted into Iranian Sistan at the Band-i Sistan. The balance 

of the discharge flows toward Zaranj in what was once called 

the Nad-i Ali channel, and at Zaranj, the Helmand flows into 

the Shelah Charkh channel, which empties eventually into the 

Hamun-i Puzak.

The river is 1,100 kilometers long if one considers the 

Hamun-i Puzak to be the terminus; but in years of exceptionally high flows, the Helmand waters spill from the Hamun-i 

HELMAND RIVER

DOWNSTREAM DISTANCE FROM HEADWATERS, IN KILOMETERS

DISCHARGE, IN CUBIC METERS PER SECOND

ALTITUDE, IN METERS

Mean annual discharge

Water

diverted

to Iran

Canals

Vertical exaggeration 10:1

Streambed

profile

250

200

150

100

50

SW NE

0

3,400

2,800

2,200

1,600

1,000

400

1,300 1,100 900 700 500 300 100 0

Guad-i

Zirreh Hamun-i

Puzak

Chahar

Burjak Junction with

Arghandab

Rud

Base of

Kajakai

Dam

Ghezab

Koh-i

Baba

Mtns

Figure 14. Stream profile of the Helmand River with mean annual discharges shown along the profile.

hamuns are dry, Sistan becomes a major contributor of global 

aerosols. Middleton (1986) discovered that over 30 dust 

storms per year originate in Sistan, more than from any other 

area in south or southwest Asia. 

Hydrology of the Helmand River System 

Drainage Features and Discharge

The Helmand River drains the southern one-half of 

Afghanistan and supplies about 80 percent of the waters 

that empty into the Sistan depression. The headwaters of the 

Helmand River originate about 90 kilometers west of Kabul on 

the southern flank of the Koh-i Baba and on the western slopes 

of the Paghman Ranges, where individual mountains reach 

altitudes of 4,400 meters. The profile of the river is illustrated 

in figure 14, and the mean annual downstream discharges 

of the Helmand are superimposed on the stream profile 

(Brigham, 1964; U.S. Agency for International Development, 

1976). The river steadily increases its volume from the steep 

headwaters to its junction with the Arghandab River, the 

22  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
Puzak into the Hamun-i Sabari, which in turn merges with the 

Hamun-i Helmand in Iran and subsequently overflows to the 

south into the Gaud-i Zirreh, the lowest, and normally dry, 

hamun basin. When the Helmand floodwaters reach the Gaud-i 

Zirreh, the river has increased its length another 200 km 

(fig. 14). Local residents in Sistan stated that the hamuns overflow into the Gaud-i Zirreh once every 20–25 years. After the 

flood of 1885, the largest flood on record, the Gaud-i Zirreh 

did not dry up until 1898 (Ward, 1906).

The extent and volume of the hamuns varies substantially 

from season to season and from year to year. The hamuns 

expand during the spring and reach a maximum size in late 

May or June and then steadily shrink to a minimum size in the 

late fall because of the high evaporation rates and low summer 

inflow. In years of low discharge, the hamuns can dry up for 

as long as 3–4 months. This happened in 1902 (Ward, 1906) 

and, on the basis of a conversation with Ghulam Khan (the 

oldest villager interviewed in 1975), it appears that the hamuns 

went dry twice from 1905 to 1946, a time period for which no 

hydrologic records or documented observations exist. Construction of the Kajakai Dam in 1952 on the upper Helmand 

River has reduced the frequency of the river failing in its 

lower reaches, except during extremely dry years. During the 

1998–2005 drought, however, the hamuns were dry or nearly 

dry on several occasions.

Snowmelt and spring precipitation in the mountainous, 

upper regions of the basin are the main sources of runoff. 

Maximum, median, and minimum discharges for the Helmand 

and Arghandab Rivers for 1948–60 are shown in figure 15 

(Brigham, 1964). These discharges are releases from the Kajakai and Arghandab Reservoirs, which have introduced a slight 

lag effect into the data, especially during early spring when 

the reservoirs are filling and during periods of low flow when 

some storage water is released. Stream discharges are highest in the months of March through May, during the spring 

thaw in the mountains; in fact, one-half of the annual runoff 

occurs during April and May. After May, stream discharges 

commonly fall by a factor of five during the months of August 

through December.

An interesting characteristic of both the Helmand and 

Arghandab Rivers is the large variation in annual discharge 

from year to year. On the Helmand, maximum spring runoff 

was about six times larger than the minimum spring discharge 

(fig. 15); on the Arghandab, the maximum discharge was 

about eight times larger than the minimum (Brigham, 1964). 

The highest average monthly flows occurred in April on 

both rivers, but the largest monthly discharges did not occur 

in the same month: maximum flows took place in May on 

the Helmand and in April on the Arghandab. This difference 

may be due to later snowmelt in the higher Helmand Valley 

headwaters or to late spring storms that did not penetrate far 

enough east into the Arghandab drainage basin.

Annual discharges of the Helmand and Arghandab 

Rivers from 1948 to1975 are shown in figure 16 (Brigham, 

1964; Childers, 1974; U.S. Agency for International Development, 1976). The 25-year average annual discharge of the 

D I S C H A R G E , I N C U B I C M E T E R S P E R S E C O N D D I S C H A R G E , I N C U B I C M E T E R S P E R S E C O N D

3,000

2,500

1,000

500

0

1,000

500

0

1,500

O N D J F M A M J J A S

O N D J F M A M J J A S

MONTH

MONTH

HELMAND RIVER

ARGHANDAB

RIVER

Maximum

Median

Minimum

Figure 15. Monthly maximum, median, and minimum discharges 

of the Helmand River from the Kajakai Reservoir and of the 

Arghandab River from the Arghandab Reservoir. 

Hydrology of the Helmand River System  23
streams in arid regions. The unpredictability of streamflow 

from year to year has a marked effect on the inhabitants of 

Sistan. During dry years, inhabitants in the lower valley and 

on the delta suffer great hardship; not only do they lose most, 

if not all, of their crops that year, but the low spring runoff 

may also result in the destruction of agricultural fields and 

choking of irrigation channels by increased deflation and 

moving dunes. The British tell of great swarms of insects that 

hatched when the hamuns dried up in 1902, which made life 

nearly unbearable and caused a great loss of animal life in 

Sistan (McMahon, 1906; Tate, 1910–12). Unusual outbreaks 

of insects may well have been responsible for episodes of 

pestilence in the past.

Sistan residents must adjust to regular flooding as well 

as to droughts. Floods are potentially more destructive than 

droughts because they can occur without warning and quickly 

destroy life and property. The destruction of canals, channels 

(juis), villages, and fields can be substantial.

A sudden temperature increase in a year of heavy snowfall or a sudden warming combined with a large precipitation event in the upper drainage basin can create very high 

magnitude floods in the Helmand Valley and on the delta. 

Annual peak discharges on the Helmand River at Chahar 

Burjak are summarized in figure 17. For available data through 

AVERAGE ANNUAL DISCHARGE, IN MEGALITERS

WATER YEAR

12,000

10,000

8,000

6,000

4,000

2,000

0

48 50 52 54 56 58 60 62 64 66 68 70 72 74

Helmand River

KAJAKAI

RESERVOIR

ARGHANDAB

RESERVOIR

6,124.6

1,251.3

25 year

average

Figure 16. Average annual discharge of the Helmand River from the Kajakai Reservoir and of Arghandab River from the 

Arghandab Reservoir: 25 years of data compiled from Brigham (1964), Childers (1974), and U.S. Agency for International 

Development (1976).

Arghandab is 1,251.3 megaliters and the Helmand River discharge is 6,124.6 megaliters, about five times more water than 

flows down the Arghandab River. Annual discharge has varied 

by a factor of five over 28 years of continuous record on the 

Helmand, and the pattern of yearly discharge is very irregular. 

Years of average flow are not common; in fact, abrupt differences in total discharge from year to year are the rule. Thus, 

the erratic behavior of the Helmand and the Arghandab is a 

characteristic of these streams; droughts and floods are not 

rare events in the lower Helmand Basin. All available stream 

discharge data for the Helmand Basin have been digitized and 

are available on the USGS Web site http://afghanistan.cr.usgs.

gov/gagingstations.asp (access date August 21, 2005). 

The irregularity of precipitation events in the Hindu Kush 

Mountains is illustrated in figure 16. During 1951, 1964, and 

1969, major increases in annual discharge took place in the 

Helmand Basin but not in the Arghandab Basin; whereas, during 1959 and 1974, the Helmand River experienced decreases 

in flow from the year before, while flows in the Arghandab 

River remained the same or increased slightly. However, there 

was likely some control of outflow from the dams on these 

rivers.

The large variation in month-to-month discharge and the 

variation in annual discharges are common characteristics of 

24  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
1970 annual peak discharges range from a low of 80 cubic 

meters per second in 1971 to a high of 18,917 cubic meters 

per second (668,000 cubic feet per second, English units) 

in 1885 (Ward, 1906; International Engineering Co., 1972; 

U.S. Agency for International Development, 1976). At least 

eight floods during the 20th century had peak discharges 

of 3,000 cubic meters per second or more and were at least 

6 times larger than the average May flood discharge on the 

Helmand. These flood years stand in contrast to 6 years 

between 1948 and 1971 when peak discharges were less than 

the average May discharge; once every 4 years, large spring 

floods did not occur.

The destructive effect of high flood discharges is 

enhanced because of the very low stream gradient in the lower 

Helmand Valley and on the delta. The average gradient from 

the Rudbar area to the Hamun-i Puzak is 0.00035, or a drop of 

0.35 meter per kilometer. Also shown on the profile are elevations of the water in the valley at Chahar Burjak during peak 

flood discharges of 10,000 and 24,000 cubic meters per second. These flood levels decrease in height downstream as the 

valley opens onto the delta, but they emphasize the effect of 

large floods on the distributary channels. At the junction of the 

Helmand and Rud-i Biyaban, the water depths of these floods, 

which are approximately equivalent to the 80- and 200-year 

floods, are estimated to be about 7.5 meters and 10.5 meters, 

respectively, above the present channel on the basis of the 

valley width at Chahar Burjak (International Engineering Co., 

1972). Discharges of this magnitude will flood all distributary 

channels on the old and new deltas and cause significant damage and, most likely, extensive loss of life.

1885 Flood 

The closed depression of Sistan contains four shallow 

basins that receive the Helmand discharge. Three basins lie 

along the edges of the delta: Hamun-i Puzak on the northeast, 

which also receives water from the Khash Rud and Farah 

Rud; Hamun-i Sabari to the north with its large surrounding 

wetlands (Naizar); and Hamun-i Helmand to the west. South 

of the present delta is a separate and lower depression that 

contains the Gaud-i Zirreh, which receives floodwaters only 

when the other three hamuns fill, merge into one very large 

lake, and overflow southward through the normally dry Shela 

Rud (fig. 2). Floodwaters fill the Gaud-i Zirreh infrequently, 

on the order of once every decade or two. Satellite images of 

the depression, however, do show small amounts of water in 

the Gaud-i Zirreh in some nonflood years, which indicates that 

183018851903190419311939194819501952195419561958196019621964196619681970

0

1,000

2,000

3,000

5,000

9,000

13,000

19,000

 ANNUAL PEAK DISCHARGE, IN CUBIC METERS PER SECOND

YEAR

?

Average May discharge

Average annual discharge

Figure 17. Annual peak discharges of the Helmand River at Chahar Burjak.

Hydrology of the Helmand River System  25
tude has occurred on the Helmand up to year 2006, although 

Ward (1906, p. 46) mentions a flood in 1830 (fig. 17) that was 

believed to be almost as large as the 1885 flood. 

The 1885 flood filled all four hamuns to overflowing and 

merged them into one huge lake, which, in turn, overflowed 

and spilled southward through the Shela Rud (also Rud-i 

Shela, fig. 2) and created a lake in the normally dry Gaud-i 

Zirreh basin. Average hamun depths in 1903–1905 were 1.2–

1.5 meters (4–5 feet) with maximum depths of 3.7–4.9 meters 

(12–16 feet). During the 1885 flood, based on mapping of 

the 1885 lake level, the hamun average depth was 2.4 meters 

(8 feet) and maximum depth was 5.8–6.4 meters (19–21 feet). 

At these depths, the lake overflowed into the Gaud-i Zirreh. In normal years, water depths in the Gaud-i Zirreh are 

0–1.8 meters (0–6 feet); during 1885 the lowest point in the 

basin contained a water depth of 10.4 meters (34 feet), and the 

lake lasted for about 3 years before it completely evaporated. 

A total of 24.9 million acre-feet or 30 billion cubic meters of 

water flowed into the hamuns during April 1885 (Ward, 1906). 

The overflow channel into Gaud-i Zirreh, 10.7 meters (35 feet) 

deep and 304.8 meters (1,000 feet) wide, was active for nearly 

2 years before drying up.

Water Quality

One important aspect of the Helmand River is its very 

low content of total dissolved solids (Anderson, 1973; Forster, 

1976; Perkins and Culbertson, 1970). Water purity is probably the major reason why salts do not concentrate heavily in 

the hamuns. The hamuns are normally about 1.5–3.0 meters 

deep and will overflow into the Gaud-i Zirreh after their depth 

increases an additional 1.5 meters. However, if the very high 

evaporation rates on the delta area are accurate, then some 

salt concentration is expected. One possible explanation for 

the relatively fresh water is that some alkaline salts are drawn 

down into the ground water. Alternatively, several investigators believe that the salts are dissolved during periods of high 

flow, are flushed into the Gaud-i Zirreh, and then deflated out 

of the basin when the hamun is dry (McMahon, 1906; Anderson, 1973; Jux and Kempf, 1983). Deflation of salts probably 

occurs more frequently because the hydrologic records of the 

Helmand River indicate that the individual hamuns drastically 

shrink, or completely dry up, once or twice a decade, which is 

more frequent than previously described. Another possibility 

is that salt is rapidly buried by a high sediment influx during floods. In any case, the Sistan hamuns remain the only 

free-standing bodies of relatively fresh water in Southwest 

Asia that are not artificially created or located in mountainous 

terrain.

Channel Changes in the Sistan Depression

The Helmand River enters the Sistan depression about 

20 kilometers downstream from the village of Chahar Burjak. 

At this location the Helmand bifurcates into two channels: 

ground water seeps into that basin from the alluvial fans in 

Baluchistan to the south.

During the late 19th century Britain offered to arbitrate international boundary issues in Sistan between Iran 

and Afghanistan. In 1872 the British Commissioner, Major 

General Goldsmid, presented the lands of Sistan east of the 

Helmand River below the village of Kohak (a former village near the present Khwabgah in fig. 2), including the three 

eastern hamuns, to Iran. Lands to the west of the Helmand and 

much of the northern delta were awarded to Afghanistan. Both 

countries accepted this division of land; however, in 1896 the 

Helmand and a couple of tributaries changed their courses during a flood and reignited land and water disputes between the 

countries. So, in 1903 a second British mission was dispatched 

to Sistan from India to once again arbitrate the boundary and 

water disagreements. This mission stayed until 1905 and did 

thorough studies on the delta, lakes, hydrology, and history 

of the area (McMahon, 1906; Tate, 1910–12; Ward, 1906). 

The collection of detailed geographic and hydrological data 

by T.R.J. Ward (1906) in his Revenue and Irrigation Reports 

to the British Government is an unsung classic in desert 

literature. Unfortunately only a handful of copies of these 

documents were published, and they were originally classified “Secret.” This commission suggested that Iran receive 

one-third of the total volume of the annual Helmand River 

discharge and warned that future changes in the position of 

the lower Helmand and its distributaries were likely. Both 

countries refused to accept the commission’s suggestions. In 

1972 an agreement between Iran and Afghanistan was written 

that would provide 26 cubic meters per second to Iran from 

the Helmand; however, the Afghan Government never ratified 

this agreement. Friction over water deliveries to Iranian Sistan 

has continued to the present (2006) and has become especially 

contentious during droughts.

Ward and his crew of Indian surveyors measured many 

hydrologic properties in Sistan in order to characterize the 

Helmand River and available water on the delta and in the 

hamuns. They even measured daily flows into Sistan from 

1903 to April 1905 on all streams entering the depression 

(by soundings on boats) and calculated volumes for each 

lake through detailed land surveys. Water years 1903 and 

1904 were then compared to the extraordinary flood in 1885 

(table 1; Ward, 1906, p. 48). Local residents and earlier 

travelers through Sistan described the unusual 1885 flood, 

and high water marks from the flood and hamuns were still 

visible in 1903. Ward reconstructed discharges for the 1885 

flood by calculating the cross-section area of the flow in the 

lower Helmand Valley just above the delta (downstream from 

Chahar Burjak village) and in a few distributaries. Flood 

heights for the 1885 flood were 4.6 meters (15 feet) higher 

than those during 1903. During the flood a new distributary, 

the Rud-i Pariun, was excavated by flood scour of a former 

canal. Calculated discharge in cusecs (cubic feet per second) 

at four sites on the lower Helmand ranged from about 650,000 

to 693,000 cubic feet per second (18,406–19,624 cubic meters 

per second). No flood of similar size or even half that magni-

26  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
Table 1. Calculations of flood discharges for the 1885, 1903, 1904, and 1905 floods by T.R.J. Ward.
the Rud-i Biyaban, which flows west, and the main Helmand 

channel, which flows north. About 18 kilometers farther 

downstream another distributary stream, the Sana Rud (also 

spelled Sena Rud), branches off to the northwest from the 

main Helmand channel. The Rud-i Biyaban and the Sana Rud 

are incised about 15–30 meters below a low, erosional, gravel 

plain that is confined on the east by the Helmand River Valley. 

The deltaic shape of this erosional plain suggests that it is the 

surface of an old delta of the Helmand; the deltaic streams are 

incised because continued subsidence of the depression has 

lowered their base level.

The main Helmand channel continues north to the village 

of Khwabgah, where the flood plain is no longer confined by a 

high valley wall on the east. Just beyond Khwabgah, the edge 

of the “old delta” on the west terminates in an erosional scarp 

(possibly a fault scarp), and the Helmand enters the “modern 

delta,” a region locally referred to as “Sistan Proper” because 

the majority of the population live on this plain.

At the head of the modern delta, just south of Khwabgah, 

the Helmand is divided into two channels by a modern dam 

(the Band-i Sistan): the Rud-i Sistan, which flows into Iranian 

Sistan, and Shelah Charkh, which flows north to Zaranj and 

then northwest into the Hamun-i Puzak. The present distribution of Helmand waters on the modern delta is well controlled 

against all but the most severe floods because the river is now 

regulated by three dams and distributed through several irrigation schemes. Sedimentation in these reservoirs and channels, 

however, is expected to decrease due to regulation of Helmand 

discharge by releases from Kajakai Dam (Perkins and Culbertson, 1970). Before the large dams were built in the early 

1950s, channel changes in the Sistan depression were frequent. 

In fact, it is not an exaggeration to say that the human history 

of Sistan is a history of human struggle to control the deltaic 

distribution of the Helmand River (Whitney and Trousdale, 

1982).

Deltaic processes were described by the Arab geographer 

Istakhri, who visited Sistan about A.D. 900. He wrote about 

the change of the provincial capital: “It is said that the ancient 

capital of the province, in the time of the first Persian dynasty, 

was. . .named Ram-Shahristan, and the canal of Sejestan 

(Sistan) flowed to it; but owing to the bursting of the dyke on 

the Helmand, the water of this canal was lowered and cut off 

from it, so that its prosperity diminished, and the inhabitants 

removed from it and built Zaranj” (Rawlinson, 1873). Water 

on the 10th century delta was distributed by seven major canals 

and channels; agriculture and habitation on the delta were 

robust.

The changing position of stream channels and important 

canals on the delta was noted by several 19th century British explorers and military officers and is illustrated in figure 18. In 1840, Conolly reported that a similar catastrophe 

had befallen occupants on the western delta; a major flood 

in 1830 had caused the Helmand to abandon a west-flowing 

channel (labeled 1800 in figure 18) and to occupy a small 

east-flowing branch or canal (labeled 1830–40 in figure 18) 

that was scoured during the flood. Although the inhabitants 

tried to reclaim the old channel by building a mound in the 

new one, the next flood washed away their efforts and the river 

remained in the new channel. Thus, the channel change forced 

another local population shift. Chaos on the delta probably 

followed major channel changes: efforts to reclaim a channel 

or build new canals to old fields; agricultural losses; construction of new villages and forts to protect them; digging new 

canals and preparing agricultural fields; and certain political 

strife among land-holding tribes when old channels became 

uninhabitable. Similar desert relationships of early societies 

to shifting stream channels have occurred on other rivers in 

Central Asia (Gerasimov, 1978).

The Helmand River changed its principal deltaic channel 

three more times before the Rud-i Pariun was established in 

1896 (Sykes, 1902; Tate, 1910–12). In fact, the 1896 channel change created an international furor because the border 

between Afghanistan and Iran was partly located along the 

former channel (labeled 1866–96 in fig. 18) (Goldsmid, 1876; 

McMahon, 1906). The Rud-i Pariun persisted as the main 

channel until the early 1950s, and by 1954 the Helmand was 

flowing in its present channel, the Shelah Charkh.

The channel change to Shelah Charkh was partly caused 

by dam construction in 1953 across the Rud-i Sistan to control 

water distribution in Iranian Sistan. Diversion of floodwaters 

apparently caused increased scour in the Shelah Charkh; this 

scour deepened the channel, which resulted in less discharge 

in the Rud-i Pariun. The deeper channel also caused agricultural problems because the channel was downcut below the 

irrigation diversions, necessitating expensive rebuilding of 

takeoff canals (International Engineering Co., 1972). Dunes 

were noted in the Rud-i Pariun channel, but it is not known if 

the dunes were emplaced before or after the channel change.

The pre-19th century channel history is more difficult to 

reconstruct. Rawlinson (1873) described some of the canals 

and channels that are mentioned in the writings of early 

geographers and historians, and these channel positions are 

included in figure 18. The position of channels during the 

times of earlier civilizations is based on archeological site 

locations. Fairservis (1961) plotted the location of presumed 

Achaemenid and pre-Achaemenid sites in Sistan on the basis 

of his studies in Afghanistan and those of Stein (1928) and 

Hedin (1910) in Iran. The earliest known sites in the Sistan 

depression are Khaima Barang, which is located along the 

lower Shela Rud (fig. 2), and Shahr-i Sokhta in Iran (fig. 18). 

Both of these sites were supplied by water that came down 

the Rud-i Biyaban. Khaima Barang was discovered by the 

Smithsonian Institution’s Helmand-Sistan Project in 1976. 

Charcoal from this unexcavated site was radiocarbon-dated 

at 5,925 ± 65 years before present (lab no. SI 3164). Shahr-i 

Sokhta, discovered by Stein (1928) and excavated by an Italian team (Tosi, 1973, 1976), was occupied from 2800 B.C. 

to 1500 B.C., which is roughly equivalent in age to the Indus 

Valley civilization. Archeological surveys in Afghan Sistan 

have failed to find sites older than 1500 B.C. on the modern 

delta or on the adjacent Sar-o-Tar plain, which suggests that 

the Rud-i Biyaban was the principal distributary during the 

28  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
Lake Limit

H A M U N S

Shahr-i Sawari

KUH-I KHWAJA

Shahr-i Sokhta

Khwabgah

Chahar Burjak

Shahr-i

Gholghola Qala-i Fath

Qala-i Gawak

Sar-o-Tar

Zarkhan Canal

Zorkhan Canal

Chakhansur

130 0–750 B.C.

20 0 B.C.–A.D. 40 0

A.D. 80 0–1550

Canals in use

ZABOL 

R U D - I B I Y A B A N

H E L M A N D R U D

R U D - I K H U S K

K H A S H

R U D

R U D - I PA R I U N

R U D - I S I S TA N

S A N A

R U D

Prehistoric

Prehistoric

1954–present

70 0

1830–40

1866–96

1860

1690

1896–1953

1760

1845

180 0

40 0 0 B.C.

250 B.C.–A.D. 40 0

1400–1550

3000 – 1500

B.C.

1845

70 0

180 0–45

0

0 30 KILOMETERS

30 MILES

Figure 18. Channel changes on the Helmand River delta in the Sistan depression. 

Hydrology of the Helmand River System  29
elevated, and the water is driven to some other 

place. It necessarily results, that the level of the 

country must constantly be altering, and that as the 

whole bed of the lake is thus gradually filling up, 

the waters spread themselves over a large surface 

every year. This extension is much assisted by the 

deposits which take place in the beds of the rivers 

at their mouths, which deposits are of course ever 

on the increase as the current becomes less rapid, 

when layer after layer of settling earth diminishes 

the slope. In consequence of this filling up of their 

beds, nearly all these rivers overflow their banks on 

entering Seistan.

The behavior of the lower Helmand River in historical 

times demonstrates that major hydrologic changes took place 

that directly affected the survival of ancient settlements in 

the Sistan depression; furthermore, these changes were not 

uncommon and were not ostensibly controlled by an external 

factor such as climate change. Channel change, or channel 

shifting, is a natural process during the growth of a delta.

The Helmand Valley Project 

“In Seistan, as in Egypt, there is no cultivation without 

irrigation, both owe their existence to the fertility brought 

to an almost rainless tract by surplus waters of a far distant 

catchment....” (from the introduction to T.R.J. Ward’s 1906 

study of the lower Helmand River, delta, and lakes in Seistan 

for the Afghan Commission). 

Numerous visitors to the lower Helmand Basin in the 

19th and early 20th centuries were impressed by the remnants of vast irrigated fields and archeological ruins along the 

Helmand Valley and especially in Sistan. People have been living in the lower Helmand Basin for over 5,000 years (Dupree, 

1980). The Government of Afghanistan became interested in 

expanding agriculture in the 1930s, and a few ancient canals 

were rebuilt by German and later Japanese engineers in the 

middle Helmand Valley. The Afghan Government continued 

canal construction during World War II and hired the American firm of Morrison-Knudsen, Inc. in 1946 with U.S. Government funding to build two diversion dams on the Helmand and 

Arghandab Rivers, to enlarge canals, and to build roads in the 

valleys (Caudill, 1969; Zakhilwal, 2004). The Afghan Government put a strong emphasis on the project in hopes of resettling a large portion of the nomad population and augmenting 

agricultural exports, as well as supplying electrical power to 

the southern provinces in order to modernize the country.

Afghanistan found itself the beneficiary of Cold War politics between the Soviet Union and the United States. During 

the 1950s and 1960s Afghanistan “received one of the highest 

levels of per capita aid of any country in the world”—about 

$1.2 billion up to 1972 (Nyrop and Seekins, 1986, p. 147), 

which is equivalent to over $7.4 billion in 2005 dollars. After 

World War II the U.S. Government took an interest in underdeveloped, independent nations and used the Tennessee Valley 

Authority (TVA) as a model for economic development

middle Holocene. It should be emphasized, however, that the 

delta region has not been extensively surveyed. It is possible 

that pre-1500 B.C. sites exist but will not be recognized until 

some of the large, unexamined sites (tepes) are excavated, 

because younger settlements were commonly constructed over 

ruins of earlier cultures.

The earliest archeological evidence of water flowing in 

the main Helmand channel toward the modern delta is derived 

from three sites on the Sar-o-Tar plain, discovered by the 

Helmand-Sistan Project; these sites were inhabited as early as 

1300 B.C. The abandonment of Shahr-i Sokhta about

1500 B.C. and the occupation of the Sar-o-Tar plain about 

1300 B.C. suggests at least one major channel shift from the 

Rud-i Biyaban to the main, north-flowing Helmand channel 

sometime in the intervening 200 years; in fact, a major channel 

shift to the modern (northern) delta may have been a primary 

reason for the abandonment of Shahr-i Sokhta.

Archeological surveys and excavations by the 

Helmand-Sistan Project identified three periods of occupation 

on the Sar-o-Tar plain: 1300 B.C.–750 B.C., 200 B.C.–A.D. 

400, and A.D. 800–1550. Canals were extensively used during 

each period, and many of the younger canals either followed 

older canal traces or the older canals were reused. ParthianSassanian sites (250 B.C.–A.D. 400) are also found on the 

Rud-i Biyaban delta (fig. 18), which indicates that water was 

flowing in both the main Helmand Valley and Rud-i Biyaban 

at that time; the larger concentration of Parthian-Sassanian 

sites on the modern delta and Sar-o-Tar plain would seem to 

indicate that the main channel flowed north, while the Biyaban sites were supplied by a major diversion canal. A similar 

situation existed during medieval Islamic times (A.D. 1400–

1550); a small number of Timurid sites were built in the Rud-i 

Biyaban Valley and along the Shela Rud, while hundreds of 

Timurid buildings were constructed on the modern delta and 

on the Sar-o-Tar plain.

Channel changes during historical times were undoubtedly far more complex than it is possible to reconstruct from 

the fragmentary archeological and written records. The 

frequency of natural channel change indicates that the processes causing these changes were not controlled by long-term 

factors, such as climate change or tectonic activity, although 

individual events, such as a decade-long drought or a local 

fault movement in a stream valley, may have contributed to a 

specific channel change. Instead, the processes that cause the 

Helmand to shift channels are channel aggradation, common 

on all low-gradient deltas, and the frequent high-magnitude 

floods that characterize this desert basin. Conolly (1840) 

described this process of channel change in 1840: 

It requires but little knowledge of physical geography, to judge of the effect of a large body of water 

discharged in this manner, with varying velocity, 

into a basin, incapable, from its nature, of offering 

the slightest resistance to its progress. The water 

hurries away to the lowest spots, and there, when its 

turbulence has subsided, drops its load of earth, till 

in the process of time these low spots have become 

30 Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
(Cullather, 2002). U.S. aid and assistance focused on three 

areas: transportation and communications, infrastructure, 

and agricultural development. The United States concentrated development efforts in the southern half of the country, 

primarily the lower Helmand Basin, while the Soviet Union 

created and oversaw projects in the north, including oil and 

gas exploration and development.

Work in the Helmand and Arghandab Valleys, known as 

the Helmand Valley Project (HVP), was the largest agricultural 

development project in the country and in the early 1950s was 

financed by U.S. Technical Assistance Grants (fig. 19). Morrison-Knudsen, Inc., completed the 44.2-meter-high (145 feet) 

Arghandab Dam with its storage capacity of 388,000 acrefeet of water (18 miles northeast of Kandahar) in 1952. A 

few months later in April 1953 the Kajakai Dam (72 miles 

upstream from Lashkar Gah) was finished. The rock-fill dam 

was 91.4 meters high (300 feet) and 26.5 meters long (87 feet) 

with a 51.5-kilometer-long (32 miles) reservoir and a capacity 

of almost 1.5 million acre-feet of water (fig. 20). Before the 

dams were constructed, appropriate soil and topography studies were not conducted before designing irrigation tracts on 

new (previously not irrigated) lands designed for agricultural 

development (Michel, 1972). A 1950 United Nations report 

(cited in Zakhilwal, 2004) cast doubt on the economic soundness of the project, and later Bureau of Reclamation engineers 

cautioned that the project would require “extraordinary (that 

is, expensive) protective installations (soil drains) and maintenance, and extensive releveling of the newly irrigated lands” 

(Bureau of Reclamation, 1954).

Two negative effects occurred relatively quickly when 

irrigation waters were spread across both new and traditional 

agricultural lands. A strongly cemented conglomerate underlies the newly irrigated lands and impeded infiltration of 

irrigation waters which in turn caused the local water table to 

rise 4.9 meters (16 feet) within 3–4 years of opening the main 

Boghra canal (Michel, 1972). Because of high evaporation 

rates and lack of persons experienced in irrigation management, large areas of the new lands became salinized and 

unsuitable for farming. In other areas, especially on traditional 

agricultural lands, increased water on the land resulted in 

waterlogging and loss of crops. The Bureau of Reclamation was brought in to install drainage systems and redesign 

some of the irrigation schemes, and some of these salinized 

and waterlogged lands were reclaimed. The U.S. Geological 

Survey set up surface- and ground-water monitoring programs 

(Taylor, 1976), and this work continued until the United States 

was forced out of the country in the late 1970s.

The Helmand Valley Project cost roughly $150 million (about $850 million in 2005 dollars), half of which was 

directly financed by the United States (Clapp-Wincek, 1983). 

Of the target of 540,000 acres to be irrigated in the project, 

about 170,000 (31 percent) received irrigation water by the 

0

0 50 KILOMETERS

50 MILES

PAK ISTAN

IRAN

AFGHANISTAN

DARWESHAN AREA

KAJAKAI DAM

D A S H T - I - M A R G O

D E S E R T

R E G I S T A N D E S E R T

NAD-I-ALI

Chakhansur

Basin

DIVERSION DAM

DIVERSION DAM

DIVERSION DAM

Kandahar

Irrigated areas

EXPLANATION

Lashkar Gah

Girishk

GARMSEL

MARJA

TARNAK

Seraj

CENTRAL ARGHANDAB

ARGHANDAB DAM

NORTH

ARGHANDAB

HELMAND R IVER

Baghra Canal

HELMAND RIVER

ARGHANDAB RIVER

ARGHASTAN R.

D OR I R .

TARNAK RIVER

30o

31o

32o

62o 63o 64o 65o 66o

Kandahar

Herat Kabul

AFGHANISTAN

IRAN

PAKISTAN

TURKMENISTAN

INDIA

TAJIKISTAN CHINA

UZBEKISTAN

30o N

60o E 70o E

35o N

THE HELMAND VALLEY

PROJECT

Figure 19. Map of agricultural lands irrigated by the Kajakai and Arghandab Dams of the Helmand Valley Project. Modified from

Michel (1972).

Hydrology of the Helmand River System  31
hamuns and adjacent wetlands, especially in drier years when 

a greater proportion of the annual discharge has been withheld upstream. Less water also results in lower water tables 

on the main delta and poorer water quality. More lands have 

experienced salinization, and lack of fresh annual sediment 

has decreased soil fertility. Another consequence of less water 

on the delta is less vegetation holding the soil: local residents 

interviewed in 1977 claimed that sand movement across 

deltaic agricultural lands (fig. 22) had increased since the 

dams were completed. These negative environmental effects 

in the lower valley, along with waterlogging and salinization 

downstream from the dam, have not been calculated as indirect 

costs of the Helmand Valley Project. 

 During the first 15 years of operation, the Kajakai 

reservoir received an annual average of 194 cubic meters per 

second of water and trapped an average of 9,625,060 cubic 

meters of sediment (340 x 106 cubic feet) (Perkins and 

Culbertson, 1970). If patterns of discharge on the Helmand 

have been roughly the same since the late 1960s, then about 

405,860 acre-feet of sediment has accumulated behind 

the dam by 2005, which implies that storage capacity has 

decreased by 27 percent.

An Unknown Future 

This report presents an overview of the geology, hydrology, and climate of the lower Helmand Basin—an earth 

science base upon which future studies can improve both 

knowledge and resource management in southern Afghanistan. Nearly all the work discussed here was accomplished 

before 1980 because Afghanistan has been through nearly 

Figure 20. Kajakai Reservoir on 

the Helmand River in 1976. View is 

upstream.

mid-1970s, and some of those lands were previously under 

cultivation (Zakhilwal, 2004). By 1970, HVP lands were 

producing 100,000 tons of wheat per year. This amounted 

to only 4 percent of the national wheat production, yet the 

project consumed over one-third of the total public investment 

in agriculture (Nyrop and Seekins, 1986). By the mid-1970s, 

however, the region was producing cotton, fruits, and nuts for 

export, although the volumes were not as high as anticipated. 

More than 2 decades of war and intense political strife 

have left Afghanistan as one of the poorest nations on Earth. 

The principal Helmand Valley cash crop during the early years 

of the 21st century is opium. Since the late 1990s, Afghanistan 

is the world’s largest producer of opium (more than 80 percent 

of 2004 world supply) and has become the major supplier 

of heroin to Europe. In 2003 opium brought in $1.2 billion 

to Afghanistan, roughly one-half its gross domestic product 

(Robyn Dixon, Los Angeles Times, October 5, 2003). In 2002 

the Helmand Province had 30,000–35,000 hectares under 

poppy production, the most of any province in the country.

No HVP provisions or plans were made for improved irrigation on the Helmand delta in Sistan, site of several former 

civilizations (Tate, 1910–12; Tosi, 1973). Several negative 

effects of the dams and water distribution schemes in the lower 

Helmand Valley and the delta were, in fact, observed by the 

author during the mid-1970s. The foremost effect in the valley 

was increased incision by the Helmand River into its flood 

plain due to decreased sediment delivery and lower discharges 

in the river. Villagers and farmers were forced to extend their 

irrigation canals several kilometers upstream in order to bring 

water up onto the flood plain (fig. 21). Water and sediment 

trapped behind the dams has also affected the delta. Smaller 

volumes of water to the delta have resulted in shrinking 

32  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
constant political and civil strife for the past 25 years. One of 

the poorest nations in the world, the country has been at or 

near survival-level conditions for a generation. Much time and 

effort are needed to rebuild the nation’s technical infrastructure before new insights can be gained into the geology and 

geomorphology of the lower Helmand Basin.

Few details of the geologic history of the lower Helmand 

Basin are available. Exposed basin fill and dated volcanic 

rocks are of Neogene age, and the southern part of the basin 

has continued to subside throughout the Quaternary to form 

the Sistan depression. The active faults bounding the southwestern basin and depression are located across the international boundaries with Iran and Pakistan and are yet to be 

studied in detail. Sistan receives the discharge of the Helmand 

River, which supplies a semicircular chain of hamuns around 

the north end of the delta. Delta position and stream incision 

have responded through the late Quaternary to active subsidence in the depression. Scour by the unusual wind conditions 

unique to Sistan and eastern Iran has deflated dry lakebeds and 

flood deposits and spread vast seas of eolian sand across the 

southern and eastern parts of the basin. Planned airborne geophysical surveys of the Helmand Basin in 2006 by the USGS 

will provide new data for an improved picture of the basin 

tectonic setting and for oil and gas resource assessment.

The Helmand River and its tributaries are the lifeblood of 

southern Afghanistan. Water supports Kandahar, the second 

largest city in the country, and the irrigated fields along the 

Helmand and Arghandab Rivers provide food for much of 

the country. Thirty years ago, agricultural products from the 

lower Helmand Basin were abundant enough to be one of the 

major sources of foreign exchange for the country. Now, out 

of desperation, the main source of foreign exchange is opium. 

Rebuilding a sustainable agricultural economy of southern 

Afghanistan is a high priority of the Afghan Government. 

In order to accomplish this goal, management of the surface 

and ground waters in the lower Helmand Basin, along with 

improved agricultural methods and land reclamation, will be 

critical. 

Sistan was home to many historic civilizations; however, the delta region was left out of the first Helmand Valley 

Project. A reevaluation of and reinvestment in the agricultural 

potential of Sistan may provide more productive agricultural 

lands for the country. Maintenance of the hamuns and extensive wetlands around the delta would help to preserve the 

unique ecological setting and niche for human inhabitants, 

birds, and animals (United Nations Environment Programme, 

2006). 

The Helmand River is the only perennial river between 

the Indus and Tigris-Euphrates Rivers. A typical desert river, 

the Helmand is fed by melting snow from high mountains 

and infrequent storms. Great fluctuations in discharge—from 

tremendous floods to years of successive drought—can be 

expected. Intelligent management of water distribution for 

irrigation, power generation, and human consumption is essential in this arid environment. More than 50 years have passed 

since the Kajakai and Arghandab Dams were completed. 

Afghanistan can build on its vast experiences, good and bad, 

with irrigation and drainage schemes, land reform, agricultural 

methods, power requirements, and environmental costs to 

upgrade and to improve the water distribution system of the 

lower Helmand Basin. The reinvestment costs to upgrade dams 

and irrigations systems will be significant; however, improved 

water management in the lower Helmand Basin will be a critical element in the reconstruction of the country. 

Figure 21. A tamarisk band (a 

porous dam) on the Helmand River 

raises the water level in order to 

irrigate on the flood plain. 

An Unknown Future  33
1973

1974

USGS Afghanistan Project, which has been funded by the U.S. 

Agency for International Development (USAID) Mission in 

Kabul through an Interagency Agreement. The author appreciates careful reviews and suggestions by Michael Chornack, 

Patrick Tucci, and Thomas Judkins. Lisa Rukstales greatly 

improved the figures in this report and Mary Kidd enhanced 

the clarity of the text by her editing.

Figure 22. A small village on the Helmand River flood plain near Qala-i Fath at the head of the 

delta is engulfed by dunes.

Acknowledgments

The author acknowledges his original support from the 

Smithsonian Institution and from William Trousdale, the 

effective and insightful director of the Helmand-Sistan Project 

during the 1970s. The present study was prepared for the 

34  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
References Cited

(hard-to-find references are marked with an *)

Abdullah, Shareq, 1979, The Chaman-Moqur fault: Tectonophysics, v. 52, p. 345–346.

Abdullah, J., Bordet, P., Carbonnel, J.-P., and Pias, J., 1975, 

Sur l’existence d’un dome récent de carbonatites dans le 

Registan: Comptes Rendus de l’Académie des Sciences 

Paris, v. 281, p. 1801–1804.

Afghan Institut de Meteorologie, 1971, Meteorological records 

of Afghanistan for 1970: Kabul, open-file data, 37 p. *Most 

of these data are summarized in U.S. Agency for International Development 1976 report on the Helmand Basin.

Allchin, Bridgit, and Goudie, A., 1978, Climatic change in the 

Indian Desert and north-west India during the late Pleistocene and early Holocene, in Brice, W.C., ed., The Environmental history of the Near and Middle East: London, 

Academic Press, p. 255–260.

Allchin, Bridget, Goudie, A., and Hedge, M., 1978, The 

prehistory and palaeogeography of the Great Indian desert: 

London, Academic Press, 339 p.

Anderson, A.O., 1973, Pleistocene geology and archeological problems of the Seistan Basin, southwest Afghanistan: 

Albuquerque, University of New Mexico, Master’s thesis, 

105 p.

Auden, J.B., 1974, Afghanistan-West Pakistan, in Spencer, 

A.M., ed., Mesozoic-Cenozoic orogenic belts: Geological 

Society of London, p. 235–253.

Balland, Viviane, and Lang, Jacque, 1974, Les rapports 

géomorphologique Quaternaires et actuels du bassin de 

Bamyan et de ses bordures montagneuses (Afghanistan 

central): Revue de géographie et de géologie dynamique, 

v. 16, p. 327–350.

Barlow, Matthew, Cullen, H., and Lyon, B., 2002, Drought 

in central and southwest Asia: La Niña, the warm pool, 

and Indian Ocean precipitation: Journal of Climate, v. 15, 

p. 697–701.

Beaumont, Peter, Blake, G.H., and Wagstaff, J.M., 1976, The 

Middle East—A geographical study: London, Wiley, 572 p.

Becker, H., Forster, H., and Soffel, H.,1973, Central Iran, a 

former part of Gondwanaland—Paleomagnetic evidence 

from Infracambrian rocks and iron ores of the Bafq area, 

central Iran: Zeitschrift fur Geophysics, v. 38, p. 953–963.

Berberian, Manuel, 1976, The seismicity of Iran—Preliminary 

map of epicentres and focal depths: Tehran, Geological 

Survey of Iran, scale 1: 2,500,000.

Berberian, Manuel, 1981, Active faulting and tectonics of 

Iran, in Gupta, H.K., and Delany, F.M., eds., Zagros, Hindu 

Kush, Himalaya—Geodynamic evolution: Washington, 

D.C., American Geophysical Union and Geological Society 

of America (Boulder Geodynamic series), v. 3, p. 33–69.

Beun, Noel, Bordet, P., and Carbonnel, J.P., 1979, Premières 

données quantitatives Relatives au Coulissage du Décrochement de Chaman (Afghanistan du Sud-Est): Comptes Rendus de l’Académie des Sciences Paris, v. 288, p. 931–934.

Blanford, W.T., 1873, On the nature and probable origin of 

the superficial deposits in the valleys and deserts of central 

Persia: Geological Society of London Quarterly Journal, 

v. 29, p. 493–503.

Bobek, Hans, 1963, Nature and implications of Quaternary 

climatic changes in Iran: UNESCO-WHO Symposium on 

changes of climate, October 1961, Rome, p. 403–413.

Bobek, Hans, 1969, Zur Kenntnis der Sudlichen Lut: Mittlungen der Oesterreichischen Geographischen Gesellschaft, 

v. 3, p. 155–192.

Bottema, Sytze, 1978, The late glacial in the eastern Mediterranean and the Near East, in Brice, W.C., ed., The environmental history of the Near and Middle East: London, 

Academic Press, p. 15–28.

Bowler, J.M., 1978, Glacial age aeolian events at high and low 

latitudes—A southern perspective, in Van Zinderen Bakker, 

E.M., Antarctic glacial history and world palaeoenvironments: Rotterdam, A.A. Balkema, p. 149–172.

Brigham, R.H., 1964, Compilation of hydrologic data, 

Helmand River valley, Afghanistan, through September 

1960: U.S. Geological Survey Open-File Report, 236 p.

Bureau of Reclamation, 1954, Drainage and related problems 

of irrigation development in the Helmand Valley of Afghanistan: Reconnaissance Report, Foreign Operations Administration, 35 p. (C.R. Maierhofer, writer) *Available at Bureau 

of Reclamation library, Denver, Colorado.

Butzer, K.W., 1978, The Late Prehistoric environmental history of the Near East, in Brice, W.C., ed., The environmental history of the Near and Middle East: London, Academic 

Press, p. 5–12.

Caudill, Mildred, 1969, Helmand-Arghandab Valley: USAID/

Afghanistan, Lashkar Gah, 70 p. * Available in libraries 

that are repositories for U.S. Government reports.

Childers, Dallas, 1974, Compilation of streamflow records, 

Helmand River valley and adjacent areas, Afghanistan, 

1961–1968: U.S. Geological Survey Open-File Report (no 

number), 144 p.

References Cited  35
Fairservis, W.A., 1961, Archaeological studies in the Seistan 

basin of southwestern Afghanistan and eastern Iran: New 

York, Anthropological Papers of the American Museum of 

Natural History, v. 58, p. 1–128.

Fisher, W.B., 1968, Physical geography, in Fisher, W.B., The 

land of Iran—The Cambridge history of Iran, I: Cambridge 

University Press, v. 1, p. 3–110.

Forster, Hansgeorg, 1976, Continental drift in Iran in relation 

to the Afar structures, in Pilger, A., and Rosler, A., eds., 

Afar between continental and oceanic rifting—Proceedings of an international symposium on the Afar region and 

related rift problems held in Bad Bergzabern, F. R. Germany, April 1–6, 1974: Stuttgart, E. Schweizerbart’sche 

Verlagsbuchhandlung, v. 2, p. 180–190.

Forster, Hansgeorg, 1978, Mesozoic-Cenozoic metallogenesis 

in Iran: Journal of the Geological Society of London, v. 135, 

p. 443–455.

Freund, Raphael, 1970, Rotation of strike slip faults in Sistan, 

southeast Iran: Journal of Geology, v. 78, p. 188–200.

Ganji, M.H., 1968, The climate of Iran, in Fisher, W.B., ed., 

The land of Iran—The Cambridge history of Iran, I: Cambridge, University Press, p. 212–245.

Gansser, Augusto, 1971, The Taftan volcano (SE Iran): Ecologae Geologicae Helvetiaev, v. 64, no. 2, p. 319–334.

Gerasimov, I.P., 1978, Ancient rivers in the deserts of Soviet 

Central Asia, in Brice, W.C., ed., The environmental history 

of the Near and Middle East: London, Academic Press, 

p. 319–334.

Goldsmid, Sir Frederic, 1876, Eastern Persia: London, Macmillan and Co., 2 volumes.

Goudie, A.S., Allchin, B., and Hedge, K.T.M., 1973, The former extensions of the Great Indian Sand Desert: Geographical Journal, v. 139, p. 243–257.

Grotzbach, E., and Rathjens, C., 1969, Die heutige and jung 

Pleistozane Vergletcherung des Afghanischen Hindukush: 

Zeitschrift fur Geomorphologie, Supplement band 8, 

p. 58–75.

Hedin, S.A., 1910, Zu Land nach Indien durch Persien, 

Seistan, Belutschistan: Leipzig, Brochaus, 2 volumes.

Holcombe, C.J., 1978, Intraplate wrench deformation in Iran, 

Afghanistan and western Pakistan: Geologische Rundschau, 

v. 67, p. 37–48.

Horvath, Eva, 1975, Glaciers of the Hindu Kush, in Field, 

W.O., Mountain glaciers of the northern hemisphere: Cold 

Regions Research and Engineering Laboratory, Hanover, 

N.H., v. 1, p. 361–370.

Clapp-Wincek, Cynthia, 1983, The Helmand Valley Project 

in Afghanistan: A.I.D. Evaluation Special Study no. 18, 

U.S. Agency for International Development PN–AAL–028, 

29 p. *Available in libraries that are repositories for U.S. 

Government reports.

Conolly, E., 1840, Sketch of the physical geography of 

Seistan: Journal of the Asiatic Society of Bengal, v. 9, 

p. 710–726.

Conrad, Georges, and Conrad, J., 1970a, Le Tertiare continental des monts de Kerman et du Lout (Iran oriental): 

Comptes Rendus de l’Académie des Sciences Paris, v. 270, 

p. 1421–1423.

Conrad, Georges, and Conrad, J., 1970b, L’évolution quarternaire de la dépression du Lut (Iran oriental): Comptes 

Rendus de l’Académie des Sciences Paris, v. 270,

p. 1672–1674.

Costantini, Lorenzo, and Tosi, M., 1978, The environment 

of southern Sistan in the Third Millennium B.C., and its 

exploitation by the Proto-urban Hilmand civilization, in

Brice, W. C., ed., The environmental history of the Near and 

Middle East: London, Academic Press, p. 165–182.

Cullather, Nick, 2002, Damming Afghanistan—Modernization in a buffer state: Journal of American History, v. 89, 

p. 512–537.

Degens, E.T., and Paluska, A., 1979, Tectonic and climatic 

pulses recorded in Quaternary sediments of the Caspian–

Black Sea region: Sedimentary Geology, v. 23, p. 149–163.

Dickey, P.A., 1968, Contemporary nonmarine sedimentation 

in Soviet Central Asia: American Association of Petroleum 

Geologists Bulletin, v. 52, p. 2396–2421.

Dixon, Robyn, 2003, Opium production spreading in Afghanistan: Los Angeles Times, October 5, 2003, newspaper 

article.

Dupree, Louis, 1980 (1973 revised), Afghanistan: London, 

Oxford University Press, 804 p.

Ehlers, Eckart, 1971, Die historischen Spiegelschwankeungen des Kaspischen Meeres und Probleme ihrer Deutung: 

Erkunde, v. 25, p. 241–248.

Emiliani, Cesare, 1955, Pleistocene temperature variations in 

the Mediterranean: Quarternaria, v. 2, p. 87–98.

Enzel, Yahuda, Ely, L.L., Mishra, S., Ramesh, R., Amit, R., 

Lazar, B., Rajaguru, S.N., Baker, V., and Sandler, A., 1999, 

High-resolution Holocene environmental changes in the 

Thar Desert, northwestern India: Science, v. 284,

p. 125–128.

Fairbridge, R.W., 1961, Eustatic changes in sea level: Physics 

and chemistry of the earth, v. 4, p. 99–185.

36  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
Huntington, Ellsworth, 1905, The basin of eastern Persia and 

Sistan, in Pumpelly, Raphael, Explorations in Turkestan: 

Washington, D.C., Carnegie Institution, v. 26, 219–316.

International Engineering Company, 1972, Preliminary assessment of providing flood control in Chakhansur, Afghanistan: Report to the Asian Development Bank, Philippines, 

134 p. *Available in Kabul at the Ministry of Water and 

Energy. IECO was the engineering company subsidiary 

of Morrison-Knudsen Corporation, which is the heritage 

company of Washington Group International.

Jux, Ulrich, and Kempf, K.E., 1983, Regional geology of 

Afghan Sistan, in Tosi, M., ed., Prehistoric Sistan: Rome, 

Istituto Italiano per il Medio ed EstremoOriente, Reports 

and Memoirs, v. 19, p. 5–60.

Kendrew, W.G., 1961, The climate of the continents: New 

York, Oxford University Press, 5th ed., 608 p.

Klootwijk, C.T. and Pierce, J.W., 1979, India’s and Australia’s 

pole path since the late Mesozoic and the India-Asia collision: Nature, v. 282, p. 605–607.

Krinsley, D.B., 1970, A geomorphological and paleoclimatological study of the playas of Iran: Bedford, Mass., U.S. Air 

Force Cambridge Research Laboratories, 486 p.

Krinsley, D.B., 1972, The paleoclimatic significance of Iranian 

playas: Paleoecology of Africa and of the surrounding 

islands and Antarctica, v. 6, p. 114–120.

Krumsiek, Klaus, 1976, Zur Bewegung der Iranisch-Afghanistan Platte: Geologische Rundschau, v. 65, p. 909–930.

Krumsiek, Klaus, 1980, Zur plattentectonischen Entwicklung 

des Indo-Iranischen Raumes (Resultate palaomagnetischer 

Untersuchungen in Afghanistan): Stuttgart, Geotektonische 

Forschungen, band 60, 223 p.

Lamb, H.H., 1977, Climate—Present, past and future: London, 

Methuen and Company, volume 2 (Climatic history and the 

future), 335 p.

Lang, H.O., 1971, Uber das Jungtertiar und Quartar in SudAfghanistan: Beihefte zum Geologischen Jahrbuch, heft 96, 

p. 167–208.

Lang, Jacques, 1975, Les bassins intramontagneux Cenozoiques de l’Afghanistan central: Nancy, Sciences de la Terre, 

Tome XX, no. 1, 115 p.

Lydolph, P.E., 1977, Climates of the Soviet Union: Amsterdam, Elsevier Scientific Publishing Co., p. 7–33 and 

151–189.

McCauley, J.F., Grolier, M.J., and Breed, C.S., 1977, Yardangs, in Doehring, D.O., ed., Geomorphology in arid 

regions: Proceedings, 8th Annual Geomorphology Symposium, Binghamton, State University of New York, p. 233–

269.

McMahon, A.H., 1897, The southern borderlands of Afghanistan: Journal of the Royal Geographical Society, v. 19, 

p. 931–934.

McMahon, Henry, 1906, Recent survey and exploration in 

Seistan: Journal of the Royal Geographical Society, v. 28, 

p. 209–228 and 333–352.

Michel, A.A., 1972, The impact of modern irrigation technology in the Indus and Helmand Basins of southwest Afghanistan, in Farvar, M.T., and Milton, J.P., eds., The careless 

technology: Garden City, N.Y., Natural History Press, 

p. 257–275.

Middleton, N.J., 1986, A geography of dust storms in southwest Asia: Journal of Climatology, v. 6, p. 183–196.

Molnar, Peter, and Tapponnier, P., 1975, Cenozoic tectonics 

of Asia—Effects of a continental collision: Science, v. 189, 

p. 419–426.

Norin, Erik, 1932, Quaternary climatic changes in the Tarim 

Basin: Geographical Review, v. 107, p. 591–598.

Norin, Erik, 1941, Geological reconnaissance in Chinese 

Turkestan: Stockholm, Reports of the Sino-Swedish Expedition, publication no. 16, p. 186–190.

Nowroozi, A. A., 1972, Focal mechanism of earthquakes in 

Persia, Turkey, West Pakistan, and Afghanistan, and plate 

tectonics of the Middle East: Bulletin of the Seismological 

Society of America, v. 62, p. 823–850.

Nowroozi, A. A., 1976, Seismotectonic provinces of Iran: 

Bulletin of the Seismological Society of America, v. 66, 

p. 1249–1276.

Nyrop, R.F., and Seekins, D.M., eds., 1986, Afghanistan—A 

country profile: Washington, D.C., American University 

Foreign Area Studies, 408 p.

O’Leary, D.W., and Whitney, J.W., 2005a, Geological map of 

quadrangles 3062 and 2962, Charbuiak (609), Khannesin 

(610), Gawdezereh (615) and Galach (616), Afghanistan: 

U.S. Geological Survey Open-File Report 2005–1122A, 

scale 1:250,000.

O’Leary, D.W., and Whitney, J.W., 2005b, Geological map of 

quadrangles 3164, Lashkargah (605) and Kandahar (606), 

Afghanistan: U.S. Geological Survey Open-File Report 

2005–1119A, scale 1:250,000.

References Cited  37
Shareq, Abdullah, 1981, Geological observations and geophysical investigations carried out in Afghanistan over the 

period of 1972-1979, in Gupta, H.K., and Delany, F.M., 

Zagros, Hindu Kush, Himalaya—Geodynamic evolution: 

Washington, D.C., American Geophysical Union and Geological Society of America (Boulder), Geodynamic series, 

v. 3, p. 75–86.

Shareq, Abdullah, Chmyriov, V.M., Stazhilo-Alekseev, K.F., 

Dronov, V.I., Gannon, P.J., Lubemov, B.K., Kafarskiy, 

A.Kh., and Malyarov, E.P., 1977, Mineral resources of 

Afghanistan (2d ed.): Kabul, United Nations Development 

Programme, 429 p.

Singh, Gurdip, Joshi, R.D., and Singh, A.B., 1972, Stratigraphic and radiocarbon evidence for the age and development of three salt lake deposits in Rajastan, India: Quaternary Research, v. 2, p. 496–505.

Singh, Gurdip, Joshi, R.D., Chopra, S.K., and Singh, A.B., 

1974, Late Quaternary history of vegetation and climate of 

the Rajastan desert, India: Philosophical transactions of the 

Royal Society, series B, v. 267, p. 467–501.

Sivall, T.R., 1977, Synoptic-climatological study of the Asian 

summer monsoon in Afghanistan: Geografiska Annaler, 

v. 59, p. 67–87.

Smith, G.I., 1974, Quaternary deposits in southwestern 

Afghanistan: Quaternary Research, v. 4, p. 39–52.

Soffel, Heinrich, Forster, H., and Becker, H., 1975, Preliminary polar wander path of Central Iran: Zeitschrift fur 

Geophysics, v. 41, p. 541–543.

Stein, Sir M.A., 1928, Innermost Asia—Detailed report of 

explorations in Central Asia, Kan-su, and eastern Iran: 

Oxford, Oxford University Press, 3 volumes.

Stocklin, Jovan, 1974, Possible ancient continental margins 

in Iran, in Burke, K., and Drake, C., eds., The geology of 

continental margins: New York, John Wiley, p. 873–887.

Stocklin, Jovan, Eftekhar-nezhad, J., and Hushmand-zadeh, 

A., 1972, Central Lut reconnaissance, east Iran: Tehran, 

Geological Survey of Iran, report no. 22, 61 p.

Street, F.A., and Grove, J., 1976, Late Quaternary lake level 

fluctuations in Africa—Environmental and climatic: Nature, 

v. 261, p. 385–390.

Sykes, P.M., 1902, Ten thousand miles in Persia, or eight years 

in Iran: London, John Murray, 481 p.

Takahashi, Koichiro, and Arakawa, H., ed., 1981, Climates of 

southern and western Asia: Elsevier Publishing Company 

(World Survey of Climatology, v. 9), 333 p.

Paluska, Antonin, and Degens, E.T., 1979, Climatic and 

tectonic events controlling the Quaternary in the Black Sea 

region: Geologische Rundschau, v. 68, p. 284–301.

Partow, Hassan, 2003, Sistan oasis parched by droughts, in

Atlas of global change: United Nations Environmental Programme, Oxford University Press, p. 144–145.

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.

Pias, Jean, 1972, Signification geologique, pedologique et 

paleoclimatique de formations paleolacustres et deltaiques 

au Seistan: Comptes Rendus de l’Academie des Sciences 

Paris, v. 274, p. 1143–1146.

Pias, Jean, 1974a, Genese de croutes et encroutements calcaires en Afghanistan au Quarternaire Recent: International 

Congress of Soil Sciences, Transactions, no. D, v. 6, pt. 2 

(commission 5), p. 394–401.

Pias, Jean, 1974b, Pedogeneses et accumulations calcaires 

successives en Afghanistan au cours des quarante derniers 

millenaires: Comptes Rendus de l’Academie des Sciences 

Paris, v. 278, p. 2625–2621.

Pias, Jean, 1976, Formations superficielles et sols 

d’Afghanistan: Paris, Travaux et Documents de

l’O.R.S.T.O.M. (Institut Français de Recherche Scientifique 

pour le Développement en Coopération), no. 55, 315 p.

Radermacher, Helmut, 1974, Historical irrigation systems in 

Afghan Sistan—Their origin, their decline and possibilities 

of their reconstruction: Annual Bulletin of the International 

Commission on Irrigation and Drainage, p. 34–42.

Radermacher, Helmut, 1976, Historische und gegenwartige 

Bewasserungssysteme, in Fischer, K., ed., Nimruz—

Archaologische landesaufnahme in Sudwest Afghanistan: 

Bonn, Rudolf Habelt Verlag, p. 159–213.

Rawlinson, Henry, 1873, Notes on Seistan: Journal of the 

Royal Geographical Society, v. 43, p. 272–294.

Reeves, C.C., 1977, Intermontane basins of the arid western 

United States, in Doehring, D.O., ed., Geomorphology in 

arid regions: Binghamton, N.Y., 8th Annual Geomorphology Symposium proceedings, p. 7–25.

Schreiber, Alfred, Weippert, D., Wittekindt, H._P., and 

Wolfart, R., 1971, Geology and petroleum potentials of 

central and south Afghanistan: The American Association 

of Petroleum Geologists Bulletin, v. 56, p. 1494–1519.

Schulz, Erhard, and Whitney, J.W., 1986, Upper Pleistocene 

and Holocene lakes in the An Nafud, Saudi Arabia: Hydrobiologia, v. 143, p. 175–190.

38  Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
Tate, G.P., 1910–12, Seistan, A memoir on the topography, 

ruins, and people: Calcutta, Superintendent of Printing, 

4 volumes, 374 p. *Available at a few American research 

libraries. 

Taylor, G.C., 1976, Historical review of the international 

water-resources program of the U.S. Geological Survey, 

1940–70: U.S. Geological Survey Professional Paper 911, 

p. 62–65.

Thunnell, R.C., 1979, Eastern Mediterranean Sea during the 

last glacial maximum—An 18,000-years B.P. reconstruction: Quaternary Research, v. 11, p. 353–372.

Tosi, Maurizo, 1973, L’industria litica e italiana; lavorazione 

degli element, di collana a Shahr-i-Sokhta (Iran): GeoArcheologia, v. 1, p. 23–29.

Tosi, Maurizo, 1976, A topographical and stratigraphical 

periplus of Sahr-e Suxteh, in Bagherzadeh, F., ed.: Proceedings of the 4th Annual Symposium an Archeological 

Research in Iran, 3−8 November, Tehran, 1975, p. 130–158.

Trifonov, V.G., 1978, Late Quaternary tectonic movements of 

western and central Asia: Geological Society of America 

Bulletin, v. 89, p. 1059–1072.

United Nations Educational, Scientific, and Cultural Organizations, 1979, Map of the world distribution of arid 

regions—Man and the biosphere technical notes no. 7: 

Paris, UNESCO, 54 p.

United Nations Environment Programme, 2003, Afghanistan—Post conflict assessment: Switzerland, United Nations 

Environment Programme, 180 p.

United Nations Environment Programme, 2006, History of 

environmental change in the Sistan Basin based on satellite 

image analysis, 1976–2005: Geneva, Switzerland, United 

Nations Environment Programme, 56 p.

U.S. Agency for International Development, 1976, Helmand 

River Basin—Soil and water survey study report: Open File 

Report in Kabul, 180 p. *Available in Kabul at the Ministry 

of Water and Energy library.

Van Zeist, Willem, and Bottema, S., 1977, Palynological investigations in western Iran: Palaeohistoria, v. 19, 

p. 19–85.

Van Zeist, Willem, and Bottema, S., 1982, Vegetational history of the eastern Mediterranean and Near East during the 

last 20,000 years, in Bintliff, J.L., and Van Zeist, W., eds., 

Paleoclimates, paleoenvironments and human communities in the eastern Mediterranean region in later prehistory: 

Oxford, British Archeological Reports, v. 133 (part 2), 

p. 277–321.

Velichko, A.A., 1984, Late Pleistocene spatial paleoclimatic 

reconstructions, in Velichko, A.A., ed., Late Quaternary 

environments of the Soviet Union: Minneapolis, University 

of Minnesota Press, p. 261–285.

Vikhter, B. Ya., Yeremenko, G.K., Chmyrev, V.M., and Abdullah, D., 1978, Pliocene-Quaternary volcanism of Afghanistan: International Geology Review, v. 20, p. 525–536.

Walter, Heinrich, 1973, Vegetation of the earth (translated by 

J. Wieser): New York, Springer-Verlag, 237 p.

Ward, T.R.J., 1906, Seistan—Revenue reports and notes 

(vol. 1), Irrigation report (vol. 2): Simla, India, Government 

Central Printing Office. *Available in Great Britain.

Weippert, Dietrich, Wittekindt, H., and Wolfart, R., 1970, Zur 

geologischen Entwicklung von Zentral- und Sudafghanistan: Kabul, Beihefte zum Geologischen Jahrbuch, heft 92, 

99 p.

Wellman, H.W., 1966, Active wrench faults of Iran, Afghanistan, and Pakistan: Geologische Rundschau, band 55, 

p. 716–735.

Wheeler, R.L., Bufe, C.G., Johnson, M.L., and Dart, R.L., 

2005, Seismotectonic map of Afghanistan, with annotated 

bibliography: U.S. Geological Survey Open-File Report 

2005–1264, 31 p.

Whitney, J.W., 1983, Erosional history and surficial geology 

of western Saudi Arabia: Jiddah, Kingdom of Saudi Arabia, 

Deputy Ministry of Mineral Resources Technical Record 

TR–04–01, 90 p. (U.S. Geological Survey Interagency 

Report 621). *Available at U.S. Geological Survey library.

Whitney, J.W., Faulkender, D.J., and Rubin, M., 1983, The 

environmental history and present condition of the Saudi 

Arabia’s northern sand seas: U.S. Geological Survey OpenFile Report 83–749, 42 p.

Whitney, J.W., and Trousdale, W., 1982, Catastrophic floods, 

wind erosion, and historical occupation on the Helmand 

River delta, southwest Afghanistan: American Quaternary 

Association, 7th biennial conference, June 28–30, Seattle, 

Wash., p. 180.

Whitney, J.W., and Trousdale, W., 1984, Man versus sand in 

southwest Afghanistan: Geological Society of America 

Abstracts with Programs, v. 16, no. 7, p. 693.

Williams, M.A.J., and Faure, H., eds., 1980, The Sahara and 

the Nile: Rotterdam, A. A. Balkema, 607 p.

Wittekindt, Hans, and Weippert, D., compilers, 1973, 

Geologische Karte von Zentral- und Sudafghanistan: 

Hannover, Bundesanstalt fur Bodenforschung, 4 sheets, 

scale 1:500,000.

References Cited  39
Zakhilwal, Omar, 2004, The Helmand Valley Project: Institute 

for Afghan Studies, archived article at http://www.institutefor-afghan-studies.org/Foreign%20Affairs/us-afghan/

helmand_0.htm (accessed Oct. 3, 2005).

Over 25 years of war and political strife have left an 

indelible impact on the Afghan people and have become 

a common theme in their famed handmade carpets.

Woodruff, S.A., and Horton, B.P., 2005, Holocene sea-level 

changes in the Indo-Pacific: Journal of Asian Earth

Sciences, v. 25, p. 29–43.

40 Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan
Back cover photograph: Spring and oasis on the alluvial fan that drains northward into the Gaud-i Zirreh at Kirtaka in Pakistan.
Back cover 8-1/2" 11" 

Printed on recycled paper