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𝗡𝗘𝗪 𝗔𝗥𝗧𝗜𝗖𝗟𝗘 𝗣𝗨𝗕𝗟𝗜𝗦𝗛𝗘𝗗
Morphometric Determinants of Dry Season Flow in Small Upstream Watersheds of Mts. Banahaw-San Cristobal Protected Landscape, Philippines

Authors:
𝗥𝗼𝗻𝗮𝗹𝗱 𝗖. 𝗚𝗮𝗿𝗰𝗶𝗮, Rex Victor O. Cruz, Nathaniel C. Bantayan, Canesio D. Predo, & Cristino L. Tiburan, Jr

Department of Forestry and Environmental Science, College of Agriculture, Southern Luzon State University, Lucban, Quezon, 4328, Philippines

Published by: Journal of Hydrology and Hydromechanics
Indexing: Scopus Q2 & Web of Science

𝗔𝗯𝘀𝘁𝗿𝗮𝗰𝘁
Geomorphology influences hydrologic response behavior of watersheds but seasonal responses such as dry season flow are rarely given focused more so their availability, quality, and spatiotemporal distribution. This is crucial for sustaining hydrologic ecosystem services (HES). This study assessed the influence of watershed morphometry on dry season flow volume and its selected physicochemical characteristics. Spot measurements of stream flow and its dissolved oxygen (DO), electric conductivity (EC), total dissolved solids (TDS), and Salinity levels from 56 small upstream watersheds in the Mts. Banahaw – San Cristobal Protected Landscape (MBSCPL) was determined. Principal Component Analysis (PCA) for variable reduction of geomorphological parameters and two-stage Random Forest Regression were used to determine the drivers of dry season flow occurrence and characteristics. Results showed that small upstream watersheds can exhibit sustained dry season flow with acceptable levels of EC, TDS, and Salinity. Total stream length (Tlu), Bifurcation ratio (Rb), area, and slope were the most important variables in predicting dry season flow volume, but its model showed poor validation performance and slightly overfit (R2= 0.527, p = 0.011). Models for water quality parameters showed acceptable performance for DO, EC, Salinity, and TDS levels (R2= 0.824, 0.713, 0.623, and 0.722, respectively) with flow volume (Q2018) as the most important driver, followed by Basin relief (Bh), watershed area, and slope.
Access the article here: https://doi.org/10.2478/johh-2025-0025


SDG 6: Clean Water and Sanitation
Focuses on sustaining water availability and quality (DO, EC, TDS, salinity) during dry season flows, which directly supports access to safe water resources.

SDG 13: Climate Action
understanding geomorphology helps in climate adaptation strategies for water resource management.

SDG 15: Life on Land
Situated in a protected landscape (MBSCPL), highlighting the role of watershed morphometry in sustaining hydrologic ecosystem services essential for biodiversity and terrestrial ecosystems.

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