Spatial-Geomorphological Analysis of Kuhrang Glacial Cirques and Their Impacts on Hydrological Sustainability and Water Management

Glacial cirques in the Kuhrang Basin, located in the Central Zagros Mountains, serve as vital natural water reservoirs, contributing to hydrological sustainability and offering valuable records for paleoclimate reconstruction. This study investigates the spatial distribution and geomorphological characteristics of 55 cirques to evaluate their hydrological potential and paleoclimatic significance. Data were derived from 1:50,000 topographic maps, Sentinel-2 imagery (2023), and field surveys conducted between 2022 and 2024. Analytical methods included descriptive statistics, kernel density estimation (KDE), KMeans spatial clustering, and advanced data visualizations (heatmaps, violin plots) implemented in Python. Snow cover was assessed using the Normalized Difference Snow Index (NDSI), while the Wright and Porter methods estimated the Quaternary snowline at 2,650–2,673 m. Results indicate that north-facing cirques (N, NE, NW), with a mean elevation of ~3,000 m, function as key hydrological sources, sustaining the Kuhrang River—an essential water supply for agriculture and local communities. In contrast, south-facing cirques (S, SE) at lower elevations (2,149–2,600 m) are more susceptible to climate-induced reductions in seasonal water availability. The equilibrium-line altitude (ELA), calculated using the Accumulation Area Ratio (AAR) method, was 3,609 m for east-facing and 3,680 m for west-facing cirques, reflecting regional climatic gradients. The 1,451 m difference between the Quaternary (2,650 m) and current snowline (4,101 m) suggests a paleotemperature approximately 8.71°C cooler than present. The study highlights the need to prioritize conservation of high-elevation, north-facing cirques and to implement adaptive water management strategies for more vulnerable southern slopes. These findings provide critical insights for climate change adaptation and sustainable water resource planning in the Zagros region.
 
Extended Abstract
1-Introduction
Glacial cirques, distinctive geomorphological formations found in mountainous terrains, offer valuable insights into past climatic conditions and function as natural reservoirs that contribute to hydrological sustainability. The Kohrang region, situated in the Central Zagros Mountains of Iran, contains a notable concentration of these landforms and holds strategic hydrological importance as the source area for one of the Iranian Plateau’s most significant rivers. The Kuhrang Basin, encompassing 55 glacial cirques at elevations ranging from 2,149 to 3,550 meters, is particularly vital due to its role in sustaining the Kuhrang River and its potential for reconstructing paleoclimatic conditions. This study investigates the spatial distribution, geomorphological attributes, and hydrological capacity of these cirques to support sustainable water resource management and enhance understanding of Quaternary paleoclimate dynamics.
 
2-Materials and Methods
The study employed a hybrid methodology combining field observations, remote sensing techniques, and computational analyses. Data sources included 1:50,000 topographic maps, Sentinel-2 satellite imagery (2023), and field surveys conducted between 2022 and 2024. Key variables collected encompassed geographic coordinates (49.9°–50.6°E, 32.0°–32.6°N), elevation, slope aspect, and morphometric parameters such as length, width, and area.
To monitor snow cover, the Normalized Difference Snow Index (NDSI) was calculated using the formula:
Snow-covered areas were identified where NDSI values were ≥ 0.4. Statistical analyses included descriptive metrics (mean, standard deviation) and kernel density estimation (KDE), expressed as:
Spatial clustering was conducted using the KMeans algorithm based on Euclidean distance:
The optimal number of clusters (k = 3) was determined using the Elbow Method. Data visualization was performed using Matplotlib, Seaborn, Plotly, Holoviews, and Altair, generating heatmaps (via Gaussian functions), violin plots, and 3D scatter plots.
A central objective of the study was to estimate the Equilibrium Line Altitude (ELA), a key paleoclimatic indicator. The ELA was calculated using the Accumulation Area Ratio (AAR) method:
with AAR set to 0.67. The Wright and Porter methods were applied to estimate the Quaternary snowline (2,650 m) and ELA (2,673 m). Past temperature conditions were reconstructed using a lapse rate-based thermal gradient:
To refine ELA estimates, the elevation data of cirques across different slope aspects were analyzed, enabling aspect-specific calculations for eastern and western exposures.
 
3- Results and Discussion
The glacial cirques in the Kuhrang region are predominantly situated above 2,500 meters, with an average elevation of approximately 3,000 meters, and are primarily concentrated on northern-facing slopes (N, NE, NW). Their distribution—particularly the clustering between 3,000 and 3,500 meters and on northern aspects—reflects a complex interaction of topographic, climatic, and geological influences during the Pleistocene epoch. Heatmap analyses revealed a higher density of cirques in the northeastern portion of the basin, especially along elevated ridgelines. North-facing cirques, which receive reduced solar radiation, function as critical water reservoirs, contributing to a stable discharge into the Kuhrang River. This flow is essential for sustaining agricultural activities, livestock, and domestic water supply in the region. In contrast, south-facing cirques (S, SE), located at lower elevations (2,149–2,600 meters), are more susceptible to the impacts of global warming, posing risks to seasonal water availability. Violin plot analyses confirmed a concentrated elevation distribution among northern aspects, while southern aspects exhibited broader elevation ranges. A notable 1,451-meter difference between the Quaternary snowline (2,650 m) and the present snowline (4,101 m) suggests a paleoclimatic cooling of approximately 8.71°C. This temperature shift aligns with reconstructed precipitation estimates of 2,043–2,418 mm, compared to the current average of 1,137.6 mm. The calculated Equilibrium Line Altitudes (ELA)—3,609 meters for east-facing cirques and 3,680 meters for west-facing cirques—further validate the presence of regional climatic gradients and underscore the importance of aspect-specific analysis in paleoclimatic reconstruction.
 
4- Conclusion
The spatial distribution of cirques in the Kuhrang region reflects the influence of a cold, humid Quaternary climate in conjunction with regional topographic controls. Northern aspects, characterized by reduced solar radiation and enhanced snow accumulation, promoted intensified glacial erosion. Cirques located at higher elevations on these shaded slopes demonstrate greater hydrological stability, underscoring their importance for conservation. In contrast, southern and southeastern cirques, situated at lower elevations, are more vulnerable to the impacts of climate change and may require adaptive strategies such as artificial water storage systems.Comparative analysis with global studies (Riese et al., 2025; Kumar et al., 2025) reveals that the Kuhrang cirques exhibit morphological and spatial patterns similar to those observed in the Himalayan and Tibetan glacial systems, suggesting broader regional climatic parallels. Methodological limitations included the 30-meter resolution of the Digital Elevation Model (DEM) and intermittent cloud cover in Sentinel-2 imagery; however, these were mitigated through field-based calibration and validation.
This study highlights the critical role of Kuhrang’s glacial cirques in supporting hydrological sustainability and reconstructing Quaternary paleoclimate. North-facing cirques, due to their hydrological resilience, should be prioritized for protection against disruptive activities such as mining and infrastructure development. To enhance predictive capacity, the application of hydrological models (e.g., SWAT) and high-resolution monitoring tools (e.g., LiDAR) is recommended for assessing water yield and long-term sustainability. These findings are essential for informing climate-resilient water management policies in the Zagros region and lay the groundwork for future interdisciplinary research.