Dr.  Vikram  Kumar
Hydrology Division, Government of Bihar,  India

Title: Low-Cost Sensing for High-Impact Hydrology: Plot-Scale Insights

Abstract:

Recent decades have witnessed a marked increase in hydrometeorological hazards across the Himalayan and adjoining regions of India, driven by climate variability, land-use change, and intensifying monsoon rainfall. Observational records indicate a rise in short-duration extreme rainfall events across the Indian subcontinent, with central and eastern India experiencing a significant increase in hourly and sub-daily rainfall extremes, contributing to flash floods and localized inundation. Globally, flood-related disasters now account for over 40% of all natural hazard events, with mountain and monsoon-dominated regions showing the highest sensitivity to rainfall intensity and antecedent wetness conditions. In India, recent flood events in Uttarakhand, Himachal Pradesh, Assam, and Bihar highlight the growing vulnerability of catchments characterized by rapid runoff response and limited hydrological buffering.

This study investigates preferential flow and rainfall–runoff response using high-frequency soil moisture measurements at the plot scale across two contrasting hillslope landscapes in Gaya district, Bihar, India. The landscapes represent a forested hillslope with structured soilsand abarren hillslope dominated by sandy textures, typical of degraded land-use conditions in the region. Soil moisture sensors installed at multiple depths were used to examine subsurface response during monsoon rainfall events. Event-based hydrograph analysis reveals pronounced contrasts between the two landscapes. The forested hillslope exhibits longer runoff lag times (30–60 min), reduced peak discharge (30–45% lower), lower runoff coefficients (0.18–0.25), and extended recession periods, indicating enhanced infiltration, subsurface storage, and macropore-driven preferential flow. In contrast, the barren sandy hillslope shows rapid hydrograph rise (<15 min), higher peak discharge, runoff coefficients ranging from 0.35–0.50 during high-intensity rainfall (>20 mm h⁻¹), and shorter recession limbs, reflecting limited surface protection and rapid subsurface connectivity. Antecedent soil moisture further modulates hydrograph shape and peak response across both hillslopes.

The results provide quantitative insights into land-use–controlled runoff generation processes under data-limited conditions. These findings can improve parameterization of hydrological models and enhance flood early warning and decision-support systems. Future work will focus on upscaling these process relationships to catchment scale and integrating them with remote sensing and climate projections to support hazard-resilient water management.

Keywords: Soil moisture; Land-use impacts; runoff coefficients; Antecedent Soil Moisture

Biography:

Dr. Kumar Vikram is a Scientist in the Hydrology Division, Government of Bihar, India. He holds a Master’s degree in Hydraulics and Water Resources Engineering and a Ph.D. focused on Himalayan hydrological processes, emphasizing field instrumentation across catchment areas.

He has previously served as Head of the Department of Civil Engineering at Gaya College of Engineering, Gaya, and at Poornima Group of Institutions, Jaipur, where he also led Research and Development initiatives. Earlier in his career, he worked as a Planning Engineer with a South Korea–based construction firm on a major stay cable bridge project.