Lakes are important water resources in Inner Mongolia and play essential roles in flood storage, water source maintenance, aquaculture, water volume regulation, and the regional ecological balance. However, most lakes in Inner Mongolia have undergone significant shrinkage over the past few decades. In order to quantify the lake changes in Inner Mongolia and analyze the factors associated with these changes, information about 546 lakes in seven years (1990, 1995, 2000, 2005, 2010, 2015, and 2018) was retrieved using 30 m resolution Landsat images taken of the entire region over 29 years (1989–2018). In addition, water census data from 2010 and 1:250,000 geological maps were used as references. The analysis revealed that the lakes in Inner Mongolia exhibited rapidly decreasing trends during the past three decades, with both the area and the number of lakes decreasing to a minimum by 2010. The number of lakes with areas of >1 km2 decreased from 384 in 1990 to 301 in 2018; the total area of lakes with individual areas of >1 km2 decreased from 4905.74 km2 in 1990 to 4187.45 km2 in 2018. With respect to the lake distribution among different geomorphological units, the analysis revealed that the lake shrinkage was most pronounced on the West Liaohe Plain, followed by the northern Inner Mongolian Plateau. Furthermore, in relation to different climatic zones, lake shrinkage primarily occurred in the mid-temperate semi-arid zone, wherein the lake area decreased by 776.6 km2. We hypothesize that the changes in the lake number and area in Inner Mongolia resulted from the combined effects of natural conditions and anthropogenic disturbances; possibly, lake shrinkage was mainly driven by the rising temperature and decreasing precipitation, along with water regulation projects, agricultural irrigation, mining development, and population growth that also had non-negligible effects on the lakes.

Under the dual influences of global climate change and human activities, inland lakes in arid areas are shrinking and drying up, and a large area of bare lake bed has become the source of the release of chemical dust. The aim of this study is to study the control of groundwater on the distribution and development of natural vegetation and the effects of the groundwater conditions on soil salinization. In this study, a typical modern dry lake in northern China, Chahan Lake, was taken as the study area. Through field investigations, field sampling and analysis, and statistical analysis, the influence of groundwater on the ecosystem of this dry lake was studied. The results revealed that the vegetation communities in the lakeside zone were Kalidium foliatum, Nitraria tangutorum, Suaeda glauca, Leymus chinensis, Chloris virgata, and Carex duriuscula communities from the dry lake bed outwards. The groundwater table suitable for vegetation growth in Chahan Lake is 2.0–3.0 m deep. The groundwater table suitable for the growth of Kalidium foliatum vegetation is 1.5–2.5 m deep. The groundwater table suitable for the growth of Leymus chinensis vegetation is 3.0–4.0 m deep. In Chahan Lake, the critical groundwater depth and total dissolved solids (TDS) for moderate salinization, severe salinization, and saline soil occurrence are 4.0 m and 2.0 g/L, 3.0 m and 3.0 g/L, and 1.5 m and 4.0 g/L, respectively. Regarding the prevention and control of salt-dust storms, the ecological threshold of the groundwater, which can effectively increase the vegetation coverage and prevent soil salinization, is groundwater depths of 2.0–4.0 m and TDS values of <2 g/L.