Quantitative assessment of exogenous manifestations of karst-suffusion processes south of Lake Ebeyty

Abstract

This study presents a geoecological assessment of agricultural land degradation in the southern Omsk region caused by karst-suffosion processes and anthropogenic activities. A quantitative analysis of three key study sites (U-1, U-2, and U-3) shows that 8.6-9.2% of agricultural land is unsuitable for cultivation due to karst-suffosion processes. A total of 79 exogenous objects of varying sizes were documented at the sites. Geological surveys revealed soluble minerals (carbonates, gypsum, sulfates, and chlorides) in subsurface sediments at depths of 0.2-10.4 m, creating favorable conditions for dissolution. Boreholes document light loams with calcareous inclusions, clays with sandy interlayers, and fragmented calcareous concretions. These lithological characteristics, combined with a shallow groundwater table (2.1-8.1 m) and chemically aggressive groundwater (3.5-4.5 g/L of sulfate and chloride anions), create optimal conditions for accelerated development of karst-suffosion processes. Climatic analysis indicates a humidity coefficient of 0.6 with annual precipitation of 350 mm, which creates periodic infiltration pulses during spring snowmelt and summer thunderstorms. This cyclic regime promotes carbonate dissolution during high-humidity periods and salt accumulation during dry seasons. Paleogeological factors, including remnants of the Paleogene Zhuravskoye Sea, provide the material basis for ongoing dissolution processes. Analysis of satellite images (2004-2022) demonstrates progressive expansion of existing depressions, with the area of one basin increasing from 0.48 km² to 0.66 km² over 18 years. Anthropogenic factors, particularly violations of water resource protection standards due to agriculture near water bodies, accelerate these processes through increased infiltration and runoff from slopes. The forecast assessment indicates continued intensification and spatial expansion of karst and suffosion manifestations in the coming years. The study area will experience a gradual reduction in agriculturally suitable land as these processes expand. Enhanced geoecological monitoring is necessary, including: (1) drilling new boreholes for comprehensive subsurface diagnostics; (2) analysis of groundwater depth and chemical composition; (3) annual monitoring using remote sensing; and (4) field studies. Such studies are crucial for monitoring hazardous exogenous processes in the context of global climate change and anthropogenic impact. Detailed quantitative analysis provides an important tool for assessing land resources, identifying risk zones, and developing mitigation measures to increase agricultural sustainability in the region. Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interests.