Land use influences on suspended sediment yields and event sediment dynamics within two headwater catchments, Waikato, New Zealand

Abstract. Climatic changes are expected to fundamentally alter discharge and sediment dynamics in glaciated high alpine areas, e.g. through glacier retreat, prolonged snow-free periods and more frequent intense rainfall events in summer. However, how exactly these hydrological changes will affect sediment dynamics is not yet known. In the present study, we aim to pinpoint areas and processes most relevant to recent sediment and discharge dynamics on different spatial and temporal scales in the Ötztal Alpine Region in Tyrol, Austria. Therefore, we analyze observed discharge and relatively long suspended sediment time series of up to 15 years from three gauges in a nested catchment setup. The catchments range from 100 to almost 800 km2 in size with 10 to 30 % glacier cover and span an elevation range of 930 to 3772 m a.s.l.. The investigation of satellite-based snow cover maps, glacier inventories, mass balances and precipitation data complement the analysis. Our results indicate that mean annual specific discharge and suspended sediment fluxes are highest in the most glaciated sub-catchment and both fluxes correlate significantly with annual glacier mass balances. Furthermore, both discharge and suspended sediment loads show a distinct seasonality with low values during winter and high values during summer. However, the spring onset of sediment transport is almost synchronous at the three gauges, contrary to the spring rise in discharge, which occurs earlier further downstream. A spatio-temporal analysis of snow cover evolution indicates that the spring increase in sediment fluxes at all gauges coincides with the onset of snow melt above 2500 m elevation. Zones above this elevation include glacier tongues and recently deglaciated areas, which seem to be crucial for the sediment dynamics in the catchment. Precipitation events in summer were associated with peak sediment concentrations and fluxes, but on average accounted for only 21 % of the annual sediment yields of the years 2011 to 2020. We conclude that glaciers and the areas above 2500 m elevation play a dominant role for discharge and sediment dynamics in the Ötztal area, while precipitation events play a secondary role. Our study extends the scientific knowledge on current hydro-sedimentological changes in glaciated high alpine areas and provides a baseline for investigations on projected future changes in hydro-sedimentological system dynamics.

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SPATIAL AND TEMPORAL VARIABILITY IN SUSPENDED SEDIMENT YIELDS OF NORTH ISLAND BASINS, NEW ZEALAND

JAWRA Journal of the American Water Resources Association ◽

10.1111/j.1752-1688.1982.tb00038.x ◽

1982 ◽

Vol 18 (4) ◽

pp. 575-584 ◽

Cited By ~ 33

Author(s):

George A. Griffiths

Keyword(s):

New Zealand ◽

Suspended Sediment ◽

Temporal Variability ◽

Spatial And Temporal Variability ◽

Sediment Yields

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Impact of Land-Use Changes on Spatiotemporal Suspended Sediment Dynamics within a Peri-Urban Catchment

Water ◽

10.3390/w12030665 ◽

2020 ◽

Vol 12 (3) ◽

pp. 665 ◽

Cited By ~ 5

Author(s):

C.S.S. Ferreira ◽

R.P.D. Walsh ◽

Z. Kalantari ◽

A.J.D. Ferreira

Keyword(s):

Land Use ◽

Suspended Sediment ◽

Urban Area ◽

Land Use Changes ◽

Suspended Sediments ◽

Sediment Dynamics ◽

Storm Event ◽

Rainfall Condition ◽

Urban Catchments ◽

The Impact

Understanding sediment dynamics in peri-urban catchments constitutes a research challenge because of the spatiotemporal complexity and variability of land-uses involved. This study investigates differences in the concentration of total sediments (TSC) and suspended sediments (SSC) in the small peri-urban Mediterranean Ribeira dos Covões catchment (40% urban area) in central Portugal. Suspended sediment responses at the catchment outlet (E) and in three upstream sub-catchments, during periods of urbanization (2011–2013) and stabilizing land-use (2017–2018) are compared for storm-event datasets encompassing similar ranges of rainstorm sizes and antecedent rainfall condition. The Quinta sub-catchment, with the lowest urban area (22%) but subject to major construction activities affecting 17% of its area, led to highest TSC and SSC during urbanization (attaining 4320 mg/L and 4184 mg/L, respectively), and a median reduction of 38% and 69%, respectively, during stabilization. Espírito Santo sub-catchment, with highest urban area (49%) and minor construction activities, displayed similar median TSC in both periods (258–240 mg/L) but highest SSC reduction (76%), highlighting the impact of the anthropogenic disturbance mainly on fine-particle sediments and a good connectivity with the stream. Porto Bordalo sub-catchment, with 39% urban area and subject to the construction of a four-line road covering 1.5% of its area, showed the lowest TSC and SSC concentrations and the lowest median reductions in both periods (31% and 64%, correspondingly), mainly because of the impact of an unplanned retention basin established with soil from the construction site. Overall, median TSC and SSC reduced 14% and 59% at E, from urbanization to stabilization. Information about sediment dynamics should guide stakeholders in establishing strategies to reduce sediment loads and mitigate the impacts on urban aquatic ecosystems.

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SOME SUSPENDED SEDIMENT YIELDS FROM SOUTH ISLAND CATCHMENTS, NEW ZEALAND

JAWRA Journal of the American Water Resources Association ◽

10.1111/j.1752-1688.1981.tb01274.x ◽

1981 ◽

Vol 17 (4) ◽

pp. 662-671 ◽

Cited By ~ 55

Author(s):

George A. Griffiths

Keyword(s):

New Zealand ◽

Suspended Sediment ◽

Sediment Yields

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How does the suspended sediment yield change in the North Caucasus during the Anthropocene?

10.22541/au.162428232.28195434/v1 ◽

2021 ◽

Author(s):

Anatolii Tsyplenkov ◽

Valentin Golosov ◽

Pelagiya Belyakova

Keyword(s):

Land Use ◽

Suspended Sediment ◽

Sediment Yield ◽

Weather Conditions ◽

Sediment Flux ◽

Northern Caucasus ◽

Land Use Impacts ◽

North Caucasus ◽

Sediment Yields ◽

Suspended Sediment Yield

Quantifying and understanding catchment sediment yields is crucial both from a scientific and environmental management perspective. To deepen the understanding of land use impacts and climate change on sediment load, we explore mechanisms of the suspended sediment yield formation in the Northern Caucasus during the Anthropocene. We examine how sediment flux of various river basins with different land-use/landcover and glacier cover changes during the 1925-2018 period. Our analysis is based on observed mean annual suspended sediment discharges (SSD, kg·s−1) and annual fluxes (SSL, t·yr−1) from 33 Roshydromet gauging stations (Russia). SSL series have been analyzed to detect statistically significant changes during the 1925-2018 period. The occurrence of abrupt change points in SSD was investigated using cumulative sum (CUSUM) charts. We found that SSL has decreased by −1.81% per year on average at most gauges. However, the decline was not linear. Several transition years are expected in the region: increasing trends from the 1950s and decreasing trends from 1988-1994. Correlation analyses showed that variation in SSL trend values is mainly explained by gauging station altitude, differences in land use (i.e., the fraction of cropland), and catchment area. Nonetheless, more accurate quantifications of SSL trend values and more refined characterizations of the catchments regarding (historical) land use, soil types/lithology, weather conditions, and topography may reveal other tendencies.

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