TY - JOUR

T1 - Riparian Lowlands in Clay Till Landscapes

T2 - Part I—Heterogeneity of Flow Paths and Water Balances

AU - Petersen, R. J.

AU - Prinds, C.

AU - Iversen, B. V.

AU - Engesgaard, P.

AU - Jessen, S.

AU - Kjaergaard, C.

PY - 2020

Y1 - 2020

N2 - Riparian lowlands act as interfaces between the streams and upland areas. This study identified and quantified local flow paths in four transects of a 26 ha Danish riparian lowland in a glacial till landscape. The riparian lowland was fed by drain water from the upland agricultural drainage catchments. Precipitation, stream stage, and drainage discharge into the riparian lowland were measured continuously, while groundwater hydraulic heads were measured in piezometer pipes twice per month. A water balance model was developed to quantify water fluxes leaving the riparian lowland area via evapotranspiration, leakage to a deeper aquifer, and via groundwater flow, drain flow, and overland flow to the adjacent stream. Overland flow originating from the tile drains was the main flow path in all four transects, and also fluxes to the stream via groundwater or lowland tile drains were significant in some subareas. The presence of a secondary tile drainage network within parts of the riparian lowland reduced overland flow and increased interaction with the riparian lowland soils. Area-normalized fluxes varied greatly between transects, largely reflecting variations in hydraulic loading rate (ratio of water input rate to the area of the receiving riparian lowland). This, combined with the significance of groundwater flow and riparian lowland tile drain flow in some of the investigated transects, revealed a heterogeneous distribution of flow paths within the small headwater lowland. The rate of overland flow was highly correlated to the hydraulic loading rate, which in turn was dominated by the drainage discharge rate at the hillslope boundary.

AB - Riparian lowlands act as interfaces between the streams and upland areas. This study identified and quantified local flow paths in four transects of a 26 ha Danish riparian lowland in a glacial till landscape. The riparian lowland was fed by drain water from the upland agricultural drainage catchments. Precipitation, stream stage, and drainage discharge into the riparian lowland were measured continuously, while groundwater hydraulic heads were measured in piezometer pipes twice per month. A water balance model was developed to quantify water fluxes leaving the riparian lowland area via evapotranspiration, leakage to a deeper aquifer, and via groundwater flow, drain flow, and overland flow to the adjacent stream. Overland flow originating from the tile drains was the main flow path in all four transects, and also fluxes to the stream via groundwater or lowland tile drains were significant in some subareas. The presence of a secondary tile drainage network within parts of the riparian lowland reduced overland flow and increased interaction with the riparian lowland soils. Area-normalized fluxes varied greatly between transects, largely reflecting variations in hydraulic loading rate (ratio of water input rate to the area of the receiving riparian lowland). This, combined with the significance of groundwater flow and riparian lowland tile drain flow in some of the investigated transects, revealed a heterogeneous distribution of flow paths within the small headwater lowland. The rate of overland flow was highly correlated to the hydraulic loading rate, which in turn was dominated by the drainage discharge rate at the hillslope boundary.

KW - drain water

KW - infiltration

KW - overland flow

KW - peat

KW - riparian lowland

KW - water balance

U2 - 10.1029/2019WR025808

DO - 10.1029/2019WR025808

M3 - Journal article

AN - SCOPUS:85079219959

VL - 56

JO - Water Resources Research

JF - Water Resources Research

SN - 0043-1397

IS - 4

M1 - e2019WR025808

ER -