Abstract
Climate change and land use are rapidly changing the amount and temporal distribution of recharge in northern aquifers. This paper presents a novel method for distributing Monte Carlo simulations of 1-D sandy sediment profile spatially to estimate transient recharge in an unconfined esker aquifer. The modelling approach uses data-based estimates for the most important parameters controlling the total amount (canopy cover) and timing (thickness of the unsaturated zone) of groundwater recharge. Scots pine canopy was parameterized to leaf area index (LAI) using forestry inventory data. Uncertainty in the parameters controlling sediment hydraulic properties and evapotranspiration (ET) was carried over from the Monte Carlo runs to the final recharge estimates. Different mechanisms for lake, soil, and snow evaporation and transpiration were used in the model set-up. Finally, the model output was validated with independent recharge estimates using the water table fluctuation (WTF) method and baseflow estimation. The results indicated that LAI is important in controlling total recharge amount. Soil evaporation (SE) compensated for transpiration for areas with low LAI values, which may be significant in optimal management of forestry and recharge. Different forest management scenarios tested with the model showed differences in annual recharge of up to 100 mm. The uncertainty in recharge estimates arising from the simulation parameters was lower than the interannual variation caused by climate conditions. It proved important to take unsaturated thickness and vegetation cover into account when estimating spatially and temporally distributed recharge in sandy unconfined aquifers.
| Original language | English |
|---|---|
| Pages (from-to) | 1961-1976 |
| Number of pages | 16 |
| Journal | Hydrology and Earth System Sciences |
| Volume | 19 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 23 Apr 2015 |
Bibliographical note
Acknowledgements. This study was made possible through fundingfrom the EU 7th Framework programme GENESIS (contract
number 226536), AQVI project (no. 128377) in Academy of
Finland AKVA research programme, the Renlund Foundation,
VALUE doctoral school and Maa- ja vesitekniikan tuki ry. We
would like to express our gratitude to Geological survey of Finland,
Finnish Forest Administration (Metsähallitus) and Finnish Forest
Centre (Metsäkeskus), Finnish meteorological institute, Finnish
environmental administration and National land survey of Finland
for providing data sets and expert knowledge that made this study
possible in its current extent. To reproduce the research in the
paper, data from above-mentioned agencies can be made available
for purchase on request from the corresponding agency, other data
can be provided by the corresponding author upon request. We
thank Per-Erik Jansson for his assistance with the CoupModel
and Jarkko Okkonen (GTK), anonymous reviewer, and Angelo
Basile for their critical comments that significantly improved the
manuscript.
Access to Document
- Estimation of temporal and spatial variations in groundwater recharge in unconfined sand aquifers using Scots pine inventories
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