Lag times as indicators of hydrological mechanisms responsible for NO$_3$-N flushing in a forested headwater catchment

Lebar, Klaudija (author), Vidmar, Andrej (author), Bezak, Nejc (author), Rusjan, Simon (author)

Understanding the temporal variability of the nutrient transport from catchments is essential for planning nutrient loss reduction measures related to land use and climate change. Moreover, observations and analysis of nutrient dynamics in streams draining undisturbed catchments are known to represent a reference point by which human-influenced catchments can be compared. In this paper, temporal dynamics of nitrate-nitrogen (NO$_3$-N) flux are investigated on an event basis by analysing observed lag times between data series. More specifically, we studied lag times between the centres of mass of six hydrological and biogeochemical variables, namely discharge, soil moisture at three depths, NO$_3$-N flux, and the precipitation hyetograph centre of mass. Data obtained by high-frequency measurements (20 min time step) from 29 events were analysed. Linear regression and multiple linear regression (MLR) were used to identify relationships between lag times of the above-mentioned processes. We found that discharge lag time (LAG$_Q$) and NO$_3$-N flux lag time (LAG$_N$) are highly correlated indicating similar temporal response to rainfall. Moreover, relatively high correlation between LAG$_N$ and soil moisture lag times was also detected. The MLR model showed that the most descriptive variable for both LAG$_N$ and LAG$_Q$ is amount of precipitation. For LAG$_N$, the change of the soil moisture in the upper two layers was also significant, suggesting that the lag times indicate the primarily role of the forest soils as the main source of the NO$_3$-N flux, whereas the precipitation amount and the runoff formation through the forest soils are the main controlling mechanisms.

• Language: English
• Keywords: hydrological processes, soil moisture, precipitation, runoff, nitrate flux, forested catchment, time lag
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2020
• Number of pages: 13 str.
• Numbering: Vol. 12, iss. 4, art. 1092
• PID: 20.500.12556/RUL-128465
• UDC: 556
• ISSN on article: 2073-4441
• DOI: 10.3390/w12041092
• COBISS.SI-ID: 9113441
• Publication date in RUL: 14.07.2021

Record is a part of a journal

• Title: Water
• Shortened title: Water
• Publisher: Molecular Diversity Preservation International - MDPI
• ISSN: 2073-4441
• COBISS.SI-ID: 36731653

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 12.04.2020

Secondary language

• Language: Slovenian
• Keywords: hidrološki procesi, vlažnost tal, padavine, odtok, gozdnato porečje, čas zakasnitve

Projects

• Funder: ARRS - Slovenian Research Agency
• Funding programme: PhD grant

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0180
• Name: Vodarstvo in geotehnika: orodja in metode za analize in simulacije procesov ter razvoj tehnologij