Understanding the impact of anthropogenic climate variability on the surface inundation dynamics in the wetlands of drylands: A case study of Ile-Balkhash Delta, Kazakhstan.

Understanding the impact of anthropogenic climate variability on the surface inundation dynamics in the wetlands of drylands:  A case study of Ile-Balkhash Delta, Kazakhstan.

Kanchan Mishra^1*, Philip Weber¹, Kathryn E. Fitzsimmons²

¹Department of Geosciences, University of Tübingen, Schnarrenbergstrasse 94-96, 72076 Tübingen, Germany.

²School of Earth Atmosphere and Environment, Monash University, Clayton VIC, Australia

(^*Email: kanchan.mishra@uni-tuebingen.de)

The Ile-Balkhash Delta, a Ramsar wetland of international importance in southeastern Kazakhstan, is one of the largest deltas in arid Central Asia (ACA). Like other waterbodies in dryland regions, the Ile-Balkhash delta faces degradation and desertification driven by anthropogenic climate change and human-induced alterations. These changes disrupt the structure, function, and distribution of wetlands, resulting in ecological and socio-economic impacts, including habitat loss, declining water quality and quantity, and reduced carbon sequestration. Despite their sensitivity to environmental changes, the surface water dynamics of these wetlands remain poorly understood in arid settings.

This study aims to assess the seasonal surface inundation patterns (SIP) and their spatio-temporal dynamics in the Ile-Balkhash Delta from 1992 to 2024 using remote sensing, GIS, and logistic regression analysis. Climatic and anthropogenic drivers of wetland dynamics are identified, while a new classification algorithm quantifies degradation patterns and transitions under the current regulated hydrological regime, offering insights into physical processes and conservation strategies.

The study reveals a strong seasonal variability, with persistent water coverage peaking in spring (15.4%) and declining in summer (10.4%), reflecting substantial reductions during drier months. Interannual variability shows peaks in wetland areas during years such as 2000, 2004, 2010, 2016, and 2018, likely linked to upstream discharge and snowmelt. However, a marked decline in coverage post-2018 suggests potential shifts in the hydrological conditions of the wetlands. The analysis further highlights that upstream inflows and hydrological connectivity exert a stronger influence on wetland dynamics than localized rainfall and temperature, which primarily regulate evaporation rates. Across the entire delta (27,791 km²), total lost (231.95 km²) and gained (246.04 km²) areas are nearly balanced. However, persistent water remains limited (617.28 km², 10.6%), while seasonal and temporary water has expanded, emphasizing the dominance of temporary water areas. Regionally, the coastal region (SR-1, 2,750 km²) shows a net increase in inundation, with gains (117.84 km²) far exceeding losses (7.99 km²), resulting in dynamic seasonal water coverage. In contrast, the main Central Ile River Delta (SR-2, 5,357 km²) shows a net areal decline, with losses (127.35 km²) surpassing gains (40.70 km²), despite heightened seasonal fluctuations. Similarly, the southern arid inland regions (SR-3, 1,039 km²) exhibit modest gains (11.64 km²) dominated by larger losses (37.46 km²), indicating a shift toward ephemeral water occurrences. The findings highlight the complex and dynamic nature of water variability in the Ile-Balkhash Delta, emphasizing the need for integrated water management strategies to address ongoing hydrological changes and support wetland conservation under evolving climate and human pressures.