The first study (Schulz et al., 2020) deals with the quantification of the water balance components of Lake Urmia and their temporal development over the last five decades. It shows that the fluctuations in the water level of Lake Urmia in the period we studied were mainly triggered by climatic changes. However, under current climatic conditions, agricultural water abstraction is significant compared to the remaining inflow of surface water. Changes in agricultural water abstraction would have a significant impact on the lake volume and could lead either to a stabilisation of the lake or to its complete collapse. The second study deals with the construction and testing of a low-cost climate chamber for simulating warm climate conditions (Darehshouri et al., 2020). The climate chamber enables reliable regulation of temperature and relative humidity in a typical range of warm climate conditions. Climate chambers are widely used in various disciplines (e.g., salt weathering of rocks, nutrient leaching in soils, water repellency of soils or in evaporation studies, as well as in testing monitoring equipment, etc.). This study also includes step-by-step instructions for building a low-cost DIY climate chamber. The use of the climate chamber allowed us to conduct a series of evaporation experiments to estimate evaporation from the lake surface (Schulz et al., 2020) and the dried lake bed (Darehshouri et al., 2022) of the Lake Urmia and accordingly determine a better water balance for the lake. In the third study (Darehshouri et al., 2022) we quantified the amount of evaporation from the dried up lake bed of Lake Urmia. The decline in the lake's water level between 1998 and 2020 has formed an area of more than 4,000 km² (i.e., in September 2015) of dried up lake bed, which is covered with precipitated salt on the surface. Although several studies have analysed the water balance of the lake in recent decades, evaporation from the dried up lake bed has not been taken into account. Considering that large areas dried up, we assumed that evaporation from the dried up lake bed might also play a role in the overall water balance of the lake. We applied a transferable multi-methods approach using laboratory column experiments and field data to determine the evaporation from the dried up lake bed of Lake Urmia. The column experiment was conducted with undisturbed soil columns taken from the dried up lake bed of Lake Urmia. The columns were placed in a climate chamber and exposed to daily temperature and humidity cycles to simulate the climatic conditions of Lake Urmia, while monitoring weight and water level changes due to evaporation. Our results show that the estimated evaporation from the dried up lake bed during the dry season (June to August) ranges from 0.12 mm per day to 0.2 mm per day, accounting for up to more than 6% (0.07 km³) of the total evaporation from Lake Urmia, depending on the lake level.

ISI publications that are part of this cumulative thesis:

Schulz, S., Darehshouri, S., Hassanzadeh, E., Tajrishy, M., Schüth, C., 2020. Climate change or irrigated agriculture – what drives the water level decline of Lake Urmia. Scientific Reports 10 (1): 236 https://doi.org/10.1038/s41598-019-57150-y

Darehshouri, S., Michelsen, N., Schüth, C., Schulz, S., 2020. A low‐cost environmental chamber to simulate warm climatic conditions. Vadose Zone Journal 19 (1): 1–6 https://doi.org/10.1002/vzj2.20023

Darehshouri, S., Michelsen, N., Schüth, C., Tajrishy, M., Schulz, S., 2022. Evaporation from the dried-up lake bed of Lake Urmia, Iran. Science of The Total Environment: 159960 https://doi.org/10.1016/j.scitotenv.2022.159960