Decadal changes in size, salinity, waterbirds, and fish in lakes of the Konya Closed Basin, Turkey, associated with climate change and increasing water abstraction for agriculture

Abstract

The Konya Closed Basin (KCB) in Turkey has a cold semiarid to warm Mediterranean climate and hosts the largest Turkish freshwater lake, Lake Beyşehir, and the iconic saline Lake Tuz. Using published as well as our own ground-truth and remote sensing data, we provide (1) a brief description of the paleoenvironmental changes in the KCB; followed by (2) a detailed description of the changes in land use, crop farming, groundwater and surface water levels, and climate; and (3) associated changes in lake water surface area and salinity as well as in waterbird and fish communities during the past 40 years. The KCB is intensively farmed; thus, the farming of mainly water intensive crops has increased substantially, especially since 2000. This, combined with climate warming, has led to a substantial reduction of the groundwater level (up to 1 m/yr) and the surface area of the lakes and wetlands, followed by an increase in salinisation, and even complete loss of several wetlands. Three globally threatened waterbird species face extinction in the basin, and 18 of the 62 previous breeding species have already been lost. The KCB has 38 fish species, of which 74% are endemic and 61% are considered threatened or near threatened. Modelling projections using various climate and land use scenarios predict serious additional reductions of the water level in the future due to climate change, leading to deterioration (or complete loss) of lake ecosystems and the services they provide.

Impact of soil compaction and irrigation practices on salt dynamics in the presence of a saline shallow groundwater: An experimental and modelling study

“…Recent years have experienced unsustainable increase in irrigated lands and a shift to more profitable water-demanding crops (Yılmaz et al, 2021). The basin suffers from high levels of soil salinization arising from shallow WT under high evaporative conditions with poor drainage conditions.…”

Documenting the impacts of increasing salinity in freshwater and coastal ecosystems: Introduction to the special issue

“…Climate change and associated sea‐level rise, coupled with groundwater extraction, leads to saltwater invading coastal freshwater ecosystems (Roy and Zahid 2021), with predicted effects across more and more regions in the future (Loáiciga et al 2012; Dai 2013; Olson 2019). Increasing temperatures and decreases in precipitation due to climate change are predicted to lower water levels and increase drought frequency, thereby reducing the salt dilution capacity of many lakes and wetlands: these impacts will be widespread but are expected to be more drastic in human populated, arid regions of the world (e.g., Great Plains of North America, Covich et al 1997; Mediterranean zone, Jeppesen et al 2015; Yilmaz et al 2021; wetlands in Southern Australia, Nielsen and Brock 2009). …”

Feedback between climate change and eutrophication: revisiting the allied attack concept and how to strike back

“…In the latter situation, despite the resulting reduction in runoff and potentially lower net loads of nutrients, water nutrient concentrations may remain high because a more prolonged residence time can enhance sediment-water column exchange and internal nutrient cycling (Özen et al 2010). In arid and semi-arid climates, climate warming also enhances drought through higher evaporation and evapotranspiration rates (Trenberth et al 2014;IPCC 2021), with strong implications for water level and salinity in lakes (Beklioğlu et al 2011;Yılmaz et al 2021).. If prolonged or extreme, drought can transform permanent lakes and ponds into more transient systems (Beklioğlu et al 2007) or they may disappear altogether.…”

“…If prolonged or extreme, drought can transform permanent lakes and ponds into more transient systems (Beklioğlu et al 2007) or they may disappear altogether. Even if the water bodies remain permanent, they may become saline to different degrees, with negative effects on aquatic diversity (Brucet et al 2012) and trophic web structure and functioning (Vidal et al 2021;Yılmaz et al, 2021). This process may be accelerated when water extraction is increased by enhanced bank filtration for drinking water production (Gillefalk et al 2019;Yılmaz et al 2021).…”

“…Water-demanding fast-growing crops are expected to increase in locations where precipitation is already increasing or expected to increase in coming years (Olesen et al 2007). In places where access to water will be limited or more variable in time and space, the selection of drought resistant crops or crop variants, as well as agricultural practices, are to be expected, although the reverse pattern (i.e., more water demanding crops fed by irrigation) has unfortunately also been seen in recent decades (Yılmaz et al, 2021). In contrast, climate change-mitigation policies, such as land-use changes towards reforestation or even afforestation may eventually lead to improved water quality (Daneshmand et al 2020), depending on local conditions.…”