Ephemeral Lakes: Fascinating Fleeting Oases

A lake is a large body of water surrounded by land and not connected to a sea or ocean… but there are thousands of lakes that, for the most part, hold no water?

These are known as ephemeral lakes, and despite arguably not being a lake much of the time, these temporary water bodies are vital to many of the world’s ecosystems and cultures.

What are Ephemeral Lakes?

Merriam-Webster defines ephemeral as, “lasting a very short time” — and that’s exactly what ephemeral lakes do!

Also known as playas, pans, chottes, and sebkas, ephemeral water bodies flood episodically, but are dry for extended periods. When there’s abundant rainfall and runoff, water flows and fills the basin. In dry periods when evaporation exceeds inflow, the lake shrinks until all that’s left is a dried lake bed. Some flood seasonally, others only fill a few times a century.

Ephemeral lakes are mostly found in semiarid and arid environments around the world. Low precipitation and high evaporation in deserts promote the infrequent formation and inevitable desiccation of these lakes.

Why are They Important?

Despite their fleeting nature, ephemeral lakes are incredibly important to both people and the planet.

"If there is one generalization that can be made about arid and semiarid environments, it is that episodic events have a greater impact on the ecosystems and landscapes than the cumulative effect of 25–30 years of events within the 'average range.'"

Ecology of Desert Systems (p. 99)

This is known as a “pulse-reserve paradigm”. During extended periods of drought, desert organisms limit their activity. Life proliferates or pulses with abundant rainfall. The gains made during these brief favourable periods carry organisms through harsher times. Infrequent, intense rainfall events turn ephemeral water bodies into temporary oases.

Ephemeral Water Bodies

Kati Thanda-Lake Eyre

Region: Simpson Desert, South Australia

Nation(s): Australia

Climate: Extremely Arid (~127mm rainfall annually)

Basin: Lake Eyre Basin (1,400,000km²)

Lake Type: Endorheic (Saline-Hypersaline)

Area: ~9,700km²

Main Tributary(ies): Georgina and Diamantina rivers (via the Warburton River), Cooper Creek (including the Thomson River). Many of the rivers in the basin dry out before reaching Kati Thanda-Lake Eyre.

Status: Protected as part of Kati Thanda-Lake Eyre National Park.

Kati Thanda-Lake Eyre is the largest ephemeral lake in the world and the largest lake of any kind in Australia — When it’s full, which has only happened a few times in the 160 years since recording began.

The lake lies within Australia’s arid region, specifically the Simpson Desert. Temperatures in the area range from 21-37C, and evaporation rates exceed 3,500mm per year.

FUN FACT: With its lowest portion lying 15m below sea level, Kati Thanda-Lake Eyre is the lowest point in Australia!

When full Kati Thanda is about as salty as seawater, but becomes hypersaline as it dries and salt concentrates. When the lake dries it leaves a thick salt crust exposed that is 15 inches thick in some places.

The first recorded fill occurred in 1950, with the others occuring in 1974 and 1984. Partial fills happening more frequently. As of May 2026, Kati Thanda is currently filling and it may overflow in the coming months.

This hostile environment around Kati Thanda is not entirely desolate. The surrounding floodplains, waterholes and wetlands sustains the life tough enough to stake its claim in the outback

Mammals: Red Kangaroo (Osphranter rufus), Hill Kangaroo (Osphranter robustus), Short-beaked echidna (Tachyglossus aculeatus), Dingo (Canis lupus dingo, Canis dingo), Fat-tailed Dunnart (Sminthopsis crassicaudata), Kultarr (Antechinomys laniger), Spinifex hopping Mouse (Notomys alexis), Long-haired rat (Rattus villosissimus), Inland broad-nosed bat (Scotorepens balstoni), Little brown-nosed bat (Scotorepens greyii), Gould’s wattled bat (Chalinolobus gouldii)

The most devastating invasive species in Australia (and the Lake Eyre Basin) is the domestic cat — which kills billions of small mammals, birds and reptiles annually.
Feral camels are another introduced species that degrade the environment and outcompete native species by eating the scarce plant life in the basin.

Birds:

Waterfowl: black swan (Cygnus atratus), Australian pelican (Pelecanus conspicillatus), great cormorant (Phalacrocorax carbo), grey teal (Anas gracilis), hardhead (Aythya australis), pink-eared duck (Malacorhynchus membranaceus), black-winged stilt (Himantopus himantopus), banded stilt (Cladorhynchus leucocephalus), red-necked avocet (Recurvirostra novaehollandiae), masked lapwing (Vanellus miles), red-capped plover (Anarhynchus ruficapillus), common greenshank (Tringa nebularia), marsh sandpiper (Tringa stagnatilis), silver gull (Chroicocephalus novaehollandiae).
Other: White-bellied sea eagle (Icthyophaga leucogaster).

Reptiles: inland taipan (Oxyuranus microlepidotus), western brown snake (Pseudonaja mengdeni), black-headed python (Aspidites melanocephalus), carpet python (Morelia spilota), woma python (Aspidites ramsayi), perentie monitor (Varanus giganteus), central netted dragon (Ctenophorus nuchalis), gibber earless dragon (Tympanocryptis intima), bearded dragon (Pogona spp.), sand goanna (Varanus gouldii), long-necked turtle (Chelodina longicollis), blue-tongued Lizard (Tiliqua spp.).

Amphibians: desert tree frog (Colleeneremia rubella), water-holding frog (Cyclorana platycephala), Main’s frog (Cyclorana maini), striped burrowing frog (Cyclorana alboguttata), common spadefoot toad (Pelobates fuscus),

Fish: Hyrtl’s catfish (Neosilurus hyrtlii), desert goby (Chlamydogobius spp.), rainbowfish (Family Melanotaeniidae), bony bream (Nematalosa erebi), golden perch (Macquaria ambigua), spangled perch (Leiopotherapon unicolor).

Invertebrates:

Dunaliella salina is a salt-loving green algae that is responsible for turning Kati Thanda-Lake Eyre’s waters pink and red. Cyanobacteria (Nodularia spp.) are blue-green algae that fix atmospheric nitrogen, making Kati Thanda’s waters nutrient-rich which enables life in the lake.
Aquatic invertebrates including brine shrimp, fairy shrimp, water fleas, copepods, ostracods live in Kati Thanda-Lake Eyre’s salty waters.

Kati Thanda lies within the traditional territories of several Australian Aboriginal peoples, who have lived in and cared for the area for at least 40,000. The Arabana people hold modern land title to the lake, but Kati Thanda also lies within the traditional territories of the Dieri and Wangkangurru. Though distinct, these groups are related linguistically and culturally, and have shared kinship, trade and ceremonial connections.

Their way of life is governed by the natural cycles of the basin. The intimate relationship and understanding Kati Thanda’s aboriginal peoples have with the land allowed them to survive despite the extreme environment.

British explorer and colonial officer Edward John Eyre became the first European to see the lake in 1840 — and is whom the lake is named after.

Despite being the first European to see Kati Thanda-Lake Eyre, the lake would have been dry at the time. It would be over a century after Eyre saw the lakebed that the first recorded fill would occur.

Today about 60,000 people live in the Lake Eyre basin — in aboriginal communities, large towns, small settlements, and isolated homesteads on grazing properties. Despite the lack of surface water resources, the Lake Eyre basin lies on top of the Great Artesian Basin, which provides a steady supply of groundwater to inhabitants through wells and aquifers.

Major threats to the basin include invasive species and resource extraction. In 2024 the Queensland government introduced the Regional Planning Interests (Lake Eyre Basin) Amendment Regulation, which bans new oil and gas developments within the Basin — an important step in protecting the Kati Thanda and all its inhabitants.

Sambhar Lake

Region: Thar Desert, Rajasthan

Nation(s): India

Climate: Arid

Basin: 5,600km²(Could not find a name for the basin)

Lake Type: Endorheic (Hypersaline)

Area: ~230km²

Main Tributary(ies): Mendha and Rupangarh Rivers

Status: Protected under the Ramsar Convention. The lake is threatened by industry, namely salt production.

Sambhar Lake is the largest inland salt lake in India. It is located in the state of Rajasthan, and lies withing the Thar desert. This large desert is named after the rolling sand dunes found within.

Sambhar Lake typically floods during monsoon season when there’s enough rainfall and runoff. The average depth is about one metre.

A 5.16km stone-earthen dam divides the lake in two sections. The western portion of the lake is largely undisturbed habitat, while the eastern portion of the lake is developed for salt extraction. During the dry season when the lake evaporates, thick salt sheets are exposed on the lake bed.

Sambhar Lake is an oasis in the Thar Desert during the wet season. It’s one of the largest flamingo habitats in India, second only to the Great Rann of Kutch. Sambhar lake’s rich biodiversity led to it being designated as a Ramsar site in 1990.

The Ramsar Convention is a international environmental treaty recognizing wetlands of international importance. But the lake is not only important to the region's wildlife

Mammals: leopard (Panthera pardus), striped hyena (Hyaena hyaena), golden jackal (Canis aureus), bengal foxes (Vulpes bengalensis), rhesus monkeys (Macaca mullatta), and hanuman langurs (Semnopithecus entellus), Indian Grey Mongoos (Herpestes edwardsii), Indian hare (Lepus nigricollis)

There are an estimated 7 million domestic animals including domestic cats, dogs, pigs, cattle, sheep, buffalo, camels, goats, donkeys, and horses.

Birds: greater flamingo (Phoenicopterus roseus), lesser flamingo (Phoeniconaias minor), cattle egret (Ardea ibis), black-crowned night heron (Nycticorax nycticorax), Indian pied heron (Ardeola grayii), Eurasian teal (Anas crecca), gadwall (Mareca strepera), pied avocet (Recurvirostra avosetta), black-winged Stilt (Himantopus himantopus), white-breasted kingfisher (Halcyon smyrnensis)

Reptiles: Caspian cobra (Naja oxiana), common krait (Bungarus caeruleus), Indian sand boa (Eryx johnii), Indian rat snake (Ptyas mucosa), Indian chameleon (Chamaeleo zeylanicus), Indian star tortoise (Geochelone elegans)

Amphibians: green pond frog (Euphlyctis hexadactylus), Bufo spp.

Fish:

Several freshwater fish species have been reported Sambhar Lake, entering through streams and rivers during the rainy season. However, these species die out due to the lake’s salinity.

Invertebrates:

Zooplankton are an essential component of this lake’s ecosystem. Various Protozoa, Rotifers and crustaceans inhabit Sambhar.
Several species predatory aquatic beetles (Including Cybister tripunctatus & Eretes sticticus)

For centuries Sambhar Lake has been important to people both culturally and economically.

Traditionally the lake is said to be created by the goddess Shakambari, which is a form of the deity Durga, and consort to one of the three supreme Hindu gods, Shiva. There is a temple devoted to Shakambari along the southern shore of the lake.

Sambhar Lake is also mentioned in the Mahabharata — an ancient Sanskrit text. It’s said to have once been part of the kingdom of Vrishparva — a Danava or demon king in Hindu mythology. The lake is also where the wedding of King Yayati and Devayani, the daughter of priest Sukracharya, took place.

People have been extracting salt from Lake Sambhar for at least 1500 years. The town of Sambhar was founded by the Chauhan dynasty is 551CE. Later, various groups including the Sindhias, Marathas and Mughals harvested salt from Sambhar. In 1709 the lake fell under the control of the Jaipur and Jodhpur princely states, who leased the lake to the British in 1870.

Salt extraction continues to be an important industry today, though it also threatens the lake.

Hamoun Wetlands

Region: Iranian Plateau

Nation(s): Afghanistan, Iran, Pakistan

Climate: Extremely Arid (~60mm rainfall annually)

Basin: Sistan Basin (370,000km²)

Lake Type: Freshwater marshes and wetlands

Area: ~2,000km²

Main Tributary(ies): Helmand River Delta

Status: Critical. Protected under the Ramsar Convention, however, extreme drought lasting several decades has completely dried the wetland.

The Sistan Basin is an endorheic basin that spans across Afghanistan, Iran, and Pakistan. Roughly two thirds of the wetland is located in Afghanistan along with most of the water sources, the remaining third in Iran. Most of the information here comes from the Iranian side.

"Despite the importance of the Hamoun wetlands, field surveys on the status of the ecosystem and its health and integrity are difficult and rare due to its location between Iran and Afghanistan and conflicts in Afghanistan. Most studies have been focused on the Iranian side of the wetlands."

Maleki et al. p. 610

The lakes experience seasonal fluctuations in water levels, expanding in the spring following snow melt in the Hindu Kush mountains, though water levels rarely exceed three metres in depth.

Unsustainable water use and variations in year-to-year runoff and precipitation has caused Hamoun lakes and wetlands to dry up completely multiple times in the 20th and 21st centuries.

A study by Rashki et al, grouped yearly variations in the Hamouns into four periods:

A low-water period from 1985 to 1988. There was some inflow into the basin at this time, but the lakes shrunk almost every year.
A high-water period from 1989 to 1993. Abundant inflow in the basin kept water levels high for the most part.
A moderate period from 1994 to 1999. During this time a balance between inflow and outflow maintained moderate water levels year-to-year.
A dry period from 2000 to 2005. Where a dramatic decrease in inflow caused a severe drought. A flood in 2005 provided brief reprieve, but the hamouns dried out shortly thereafter.

Made up of a complex of shallow permanent and seasonal freshwater lakes, lagoons and marshes, the Hamouns were an oasis in the dry Sistan basin. Dense reedbeds provide habitat for over 20,000 birds during breeding season and winter time.

Mammals: golden jackals (Canis aureus), red foxes (Vulpes vulpes), caracal (Caracal caracal), striped hyena (Hyaena hyaena), wild boar (Sus scrofa).

Birds:

Waterfowl: great white pelican (Pelecanus onocrotalus), dalmation pelican (Pelacanus crispus), great egret (Egretta alba), grey heron (Ardea cinera), purple heron (Ardea purpurea), Eurasian bittern (Botaurus stellaris), common crane (Grus grus), whooper swan (Cygnus cygnus), greylag goose (Anser anser), common shelduck (Tadorna tadorna), mallard (Anas platyrhynchos), Eurasian coot (Fulica atra), great crested grebe (Podiceps cristatus), western swamphen (Porphyrio porphyrio), pied avocet (Recurvirostra avocetta), black-tailed godwit (Limosa limosa), Little tern (Sterna albifrons), clamorous reed warbler (Acrocephalus stentoreus)
Other: White-tailed eagle (Haliaeetus albicilla), Easter imperial eagle (Aquila heliaca), Cinerous vulture (Aegipius monachus), Western marsh harrier (Circus aeruginosus)

Reptiles: Desert monitor (Varanus griseus)

The Hamoun Wetlands and Mount Khajeh are the cradle of millenia of history. The island Mount Khajeh contains some of Iran’s most important archaeological sites. A 2014 study analyzing pottery shards found there were three main settlement periods of Mount Khajeh:

Parthian period: from 247 BCE to 224 CE.
The Sassanid period: from 224 to 651 CE.
The Islamic period: ~1200 to 1400 CE* (6th-8th century AH**)

*Gregorian date range calculated from provided Hijri date range. Online converters from Hijri to Gregorian only went back a couple centuries. I tried my best with the math based off my research (please feel free to correct)

**AH means After Hijri in the Islamic calender.

Located in the middle of a vast desert, these lakes, wetlands, and reed beds provided for the region’s inhabitants for thousands of years. The Hamouns are so important to people and the planet that they were designated as a wetland of international importance under the Ramsar Convention in 1975.

The Baloch are a nomadic and pastoral ethnic group that live in villages along the shoreline of Hamoun-e-Puzak. The Baloch use reeds from the Hamouns as forage for livestock, to construct boats known as “tutans”, as a fuel source for cooking and heating, and to create windbreaks protecting settlements from the intense dust storms churned up by the 120-day wind.

The majority of the region’s inhabitants work in agriculture, fisheries, and handicraft production. Fishing and hunting are important sources of income and sustenance. Their entire way of life depends on the water resources and ecosystem services the Hamoun wetlands provide…

… or they did.

While water levels naturally fluctuate in the basin, prolonged drought conditions led to the wetlands drying up in 2001. Though they’ve partially flooded since, these events have not been able to counteract the environmental and economic effects of ongoing drought.

So what caused this?

For millenia the Hamoun Wetlands were an oasis in the arid and remote Iranian Plateau. The rich resources provided by the ecosystem sustained civilizations, from the Parthians to the Baloch. However, the effects of a warming climate, environmental degradation, resource mismanagement, and political conflicts in the region have desiccated the wetlands and decimated the communities that relied on them.

Learn more about the destruction of the Hamoun wetlands in the video for more.

Ephemeral Lakes: Fascinating Fleeting Oases

A lake is a large body of water surrounded by land and not connected to a sea or ocean… but there are thousands of lakes that, for the most part, hold no water?

Table of Contents

What are Ephemeral Lakes?

Why are They Important?