Chapter 16
Desert lakes: playa lakes and sebkhas
1. Main features
Large areas of desert regions are characterized by endorheic drainage and, consequently,
waters collect in the lower topographic areas creating lakes of different sizes and origins.
Lakes can last if water input (surface run-off, ground waters, rivers) is higher than output
(mostly evaporation). If solute discharge increases, the lake becomes saline. Lakes from
arid zones can dry out during long periods of time, although in most cases, they show a
seasonal regime, drying out during the summer season. Only the Aral, Caspian, and Dead
Sea (Figure 16.1) are permanent water bodies, as their main water input is derived from
nearby mountains or far-away areas. The Dead Sea, fed by the Jordan River, outlet of the
Sea of Galilee, has a very high salinity (300,000ppm TDS), which impedes the
development of life in its waters. Saline lakes with a salinity of about 5000 mg/1 are
relatively common in arid and semi-arid areas (Shaw and Thomas, 1997). This figure,
mainly based on biological tolerance, is considered the boundary between fresh and saline
water bodies (Euster and Hardie, 1978).
There is a very wide terminology referring to closed depressions developed in arid
environments, largely due to the use of vernacular names (Tricart, 1969; Cooke and
Warren, 1973; Neal, 1975; Cooke et al., 1993; Currey, 1994; Rosen, 1994; Shaw
and Thomas, 1997; Briere, 2000; Guti6rrez, 2001). The term playa has a Spanish origin
and was introduced in the English language from the exploration of the North American
southwest by the Spaniards (Guti6rrez, 2001; Guti~rrez et al., 2002) (Figure 16.2).
Recently, Briere (2000) presented a thorough compilation of names used to designate
these depressions. This author proposes the use of the term playa for intracontinental
depressions with a negative water balance that remain dry more than 75% of the year,
and playa lake, a transition between playa and lake, for depressions that host water from
25 to 75% of the year. In many cases these definitions may be difficult to apply since the
hydrologic regime of the playas may change substantially in successive years.
Tchakerian (1999a), in the Encyclopaedia of the Deserts, defined playas as depressions
typical of arid and semi-arid zones, affected by flooding by ephemeral surficial waters or
fluctuations in the water table. The definition of pan given by Dregne (1999) is very
similar to the previous one. Several authors consider both terms as synonyms (Shaw and
Thomas, 1997; Goudie, 2004b). On the other hand, the word sabkha has clear geographic
meaning restricted to depressions located in coastal plains (Tchakerian, 1999b; Briere,
2OOO).
Other synonyms are sebkha, an Arabic term used in northern Africa and sabkha,
common in the Arabian Peninsula (Figure 16.3). In Iran, kavir denotes depressions rich
in salts. Another Arabic word, chott, means a saline basin with groundwater input, and is
Desert lakes: playa lakes and sebkhas
1. Main features
Large areas of desert regions are characterized by endorheic drainage and, consequently,
waters collect in the lower topographic areas creating lakes of different sizes and origins.
Lakes can last if water input (surface run-off, ground waters, rivers) is higher than output
(mostly evaporation). If solute discharge increases, the lake becomes saline. Lakes from
arid zones can dry out during long periods of time, although in most cases, they show a
seasonal regime, drying out during the summer season. Only the Aral, Caspian, and Dead
Sea (Figure 16.1) are permanent water bodies, as their main water input is derived from
nearby mountains or far-away areas. The Dead Sea, fed by the Jordan River, outlet of the
Sea of Galilee, has a very high salinity (300,000ppm TDS), which impedes the
development of life in its waters. Saline lakes with a salinity of about 5000 mg/1 are
relatively common in arid and semi-arid areas (Shaw and Thomas, 1997). This figure,
mainly based on biological tolerance, is considered the boundary between fresh and saline
water bodies (Euster and Hardie, 1978).
There is a very wide terminology referring to closed depressions developed in arid
environments, largely due to the use of vernacular names (Tricart, 1969; Cooke and
Warren, 1973; Neal, 1975; Cooke et al., 1993; Currey, 1994; Rosen, 1994; Shaw
and Thomas, 1997; Briere, 2000; Guti6rrez, 2001). The term playa has a Spanish origin
and was introduced in the English language from the exploration of the North American
southwest by the Spaniards (Guti6rrez, 2001; Guti~rrez et al., 2002) (Figure 16.2).
Recently, Briere (2000) presented a thorough compilation of names used to designate
these depressions. This author proposes the use of the term playa for intracontinental
depressions with a negative water balance that remain dry more than 75% of the year,
and playa lake, a transition between playa and lake, for depressions that host water from
25 to 75% of the year. In many cases these definitions may be difficult to apply since the
hydrologic regime of the playas may change substantially in successive years.
Tchakerian (1999a), in the Encyclopaedia of the Deserts, defined playas as depressions
typical of arid and semi-arid zones, affected by flooding by ephemeral surficial waters or
fluctuations in the water table. The definition of pan given by Dregne (1999) is very
similar to the previous one. Several authors consider both terms as synonyms (Shaw and
Thomas, 1997; Goudie, 2004b). On the other hand, the word sabkha has clear geographic
meaning restricted to depressions located in coastal plains (Tchakerian, 1999b; Briere,
2OOO).
Other synonyms are sebkha, an Arabic term used in northern Africa and sabkha,
common in the Arabian Peninsula (Figure 16.3). In Iran, kavir denotes depressions rich
in salts. Another Arabic word, chott, means a saline basin with groundwater input, and is