Combined Impacts of Climate and Land-Use/Land-Cover Changes on the Flow Regime and Ecological Diversity in the Songkhram River Basin, A Tributary of the Mekong River
Abstract
Climate change (CC) and land-use/land-cover (LU/LC) alterations are among the most pervasive drivers of hydrological and ecological change in river basins worldwide, yet their combined impacts on fluvial ecological diversity remain insufficiently quantified, particularly in data-scarce tropical regions. This study presents a novel integrated framework that jointly evaluates the individual and combined effects of projected CC and LU/LC change scenarios on flow regimes and aquatic ecological diversity in the Songkhram River Basin, a critical tributary of the Mekong River in northeast Thailand. The Soil and Water Assessment Tool (SWAT) was calibrated and validated on a daily timescale for streamflow simulation. Bias-corrected and downscaled CMIP6 climate projections (2026–2055) under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) were combined with scenario-based LU/LC projections to simulate future flow regimes. Ecologically relevant flow alterations were assessed using hydrological alteration indices, and fluvial ecological diversity was quantified through the Shannon Diversity Index (SI). Results reveal that CC alone will significantly reduce annual streamflow (up to 22%), shift seasonal water availability, and intensify hydrological extremes - reducing low flows by up to 75% and amplifying short-duration flood events by up to 59%. CC substantially reduces ecological diversity, with the SI declining by 23.04% under SSP2-4.5 and 30.55% under SSP5-8.5. In contrast, conservation-oriented LU/LC scenarios support biodiversity recovery, increasing the SI by up to 20.66%; however, these gains are insufficient to offset CC-driven losses. When stressors are combined, CC effects dominate, resulting in net declines in ecological diversity of 18.62%-23.87% relative to the baseline. These findings provide robust scientific evidence that underscores the urgency of integrated land and water management strategies to build landscape resilience and safeguard riverine biodiversity across the Mekong region in a rapidly changing climate.
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BibTeX
@article{baghel2026combined,
title = {{Combined Impacts of Climate and Land-Use/Land-Cover Changes on the Flow Regime and Ecological Diversity in the Songkhram River Basin, A Tributary of the Mekong River}},
author = {Triambak Baghel and Mukand S Babel and Dibesh Khadka and Guillaume Lacombe and Sonu Kumar},
journal = {Earth Systems and Environment},
year = {2026},
month = sep,
doi = {10.1007/s41748-026-01331-z},
url = {https://hal.science/hal-05749840v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Combined Impacts of Climate and Land-Use/Land-Cover Changes on the Flow Regime and Ecological Diversity in the Songkhram River Basin, A Tributary of the Mekong River
AU - Triambak Baghel
AU - Mukand S Babel
AU - Dibesh Khadka
AU - Guillaume Lacombe
AU - Sonu Kumar
PY - 2026
DA - 2026/09/10
JO - Earth Systems and Environment
DO - 10.1007/s41748-026-01331-z
UR - https://hal.science/hal-05749840v1
AB - Climate change (CC) and land-use/land-cover (LU/LC) alterations are among the most pervasive drivers of hydrological and ecological change in river basins worldwide, yet their combined impacts on fluvial ecological diversity remain insufficiently quantified, particularly in data-scarce tropical regions. This study presents a novel integrated framework that jointly evaluates the individual and combined effects of projected CC and LU/LC change scenarios on flow regimes and aquatic ecological diversity in the Songkhram River Basin, a critical tributary of the Mekong River in northeast Thailand. The Soil and Water Assessment Tool (SWAT) was calibrated and validated on a daily timescale for streamflow simulation. Bias-corrected and downscaled CMIP6 climate projections (2026–2055) under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) were combined with scenario-based LU/LC projections to simulate future flow regimes. Ecologically relevant flow alterations were assessed using hydrological alteration indices, and fluvial ecological diversity was quantified through the Shannon Diversity Index (SI). Results reveal that CC alone will significantly reduce annual streamflow (up to 22%), shift seasonal water availability, and intensify hydrological extremes - reducing low flows by up to 75% and amplifying short-duration flood events by up to 59%. CC substantially reduces ecological diversity, with the SI declining by 23.04% under SSP2-4.5 and 30.55% under SSP5-8.5. In contrast, conservation-oriented LU/LC scenarios support biodiversity recovery, increasing the SI by up to 20.66%; however, these gains are insufficient to offset CC-driven losses. When stressors are combined, CC effects dominate, resulting in net declines in ecological diversity of 18.62%-23.87% relative to the baseline. These findings provide robust scientific evidence that underscores the urgency of integrated land and water management strategies to build landscape resilience and safeguard riverine biodiversity across the Mekong region in a rapidly changing climate.
SN - 2509-9434
SN - 2509-9434
ER -