Sediment Yield and Pollution from Small Watersheds under Changing Climatic Conditions

The aim of this paper is to quantify the spatial distribution of suspended sediment yield in the Baltic Sea drainage basin, and to quantify the suspended sediment inflow to the Baltic. The sediment yield in the studied area varies in accordance with the potential erosion conditions in the morphological sub-units and reaches values from below 2 to almost 1,000 t/km2/yr. Topographical, pedological and climatic conditions are decisive for the sediment yield variations. The suspended sediment yield increases generally from north to south, and reaches maximum values in the lower parts of the Carpathians. In contrast, the Scandinavian mountains are characterized by low suspended sediment yield. The suspended sediment load derived from the source areas decreases during its transport to the Baltic as a result of sedimentation processes. In the largest rivers of the area no more than 20 to 30% of the sediment amount flowing from tributaries to the main rivers ends up in the Baltic Sea. The total mass of suspended material flowing to the Baltic Sea is 4,455,000 t/yr, 37% of which is carried into the Baltic proper. 20% of the total supply to the Baltic Sea comes from the Vistula river.

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Modelling streamflow and sediment yield from two small watersheds of Kashmir Himalayas, India

ISH Journal of Hydraulic Engineering ◽

10.1080/09715010.2021.2015463 ◽

2022 ◽

pp. 1-10

Author(s):

Sarvat Gull ◽

Shagoofta Rasool Shah

Keyword(s):

Sediment Yield ◽

Small Watersheds ◽

Kashmir Himalayas

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Sediment Regimes in South Korea

10.22541/au.162671158.89460854/v1 ◽

2021 ◽

Author(s):

Chun-Yao Yang ◽

Woochul Kang ◽

Jai Hong ◽

Pierre Julien

Keyword(s):

South Korea ◽

Sediment Yield ◽

Measurement Data ◽

Cumulative Distribution ◽

Watershed Area ◽

Flow Duration ◽

Small Watersheds ◽

Flow Duration Curves ◽

Large Floods ◽

Sedimentation Processes

This study provides a comprehensive review of the existing river measurement data of South Korea. The specific sediment yield in the country is 5–1,500 tons/km ·year. The watershed area decisively affects the shapes of the curves for flow duration, sediment rating, and cumulative distribution of water and sediment discharge, and it can determine the effects of topographic and anthropogenic characteristics on erosion and sedimentation processes. Regarding flow regime, small watersheds have flashy hydrographs and high sediment concentrations at a given flow discharge. The coefficient of the sediment rating curves for various rivers decreases from 1 to 0.02 as the watershed area increases from 100 to 20,000 km , with the exponent of the curves ranging from 1.5 to 2.0. Moreover, sediment transport in small watersheds depends on large floods. The half-yield discharge typically ranges from 5 to 40 times the mean discharge, and it decreases with increasing watershed area. This study proposes equations to calculate the annual discharges, flow duration curves, sediment yield, and cumulative distribution curves of the flow and sediment, as well as the sediment yield at reservoirs in South Korea. Additionally, the sediment regimes in the country are compared to those in other continental regions.

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Temporal Variation in Snowcover Area During Melt in Prairie and Alpine Environments

Hydrology Research ◽

10.2166/nh.1993.0021 ◽

1993 ◽

Vol 24 (2-3) ◽

pp. 183-198 ◽

Cited By ~ 34

Author(s):

K. Shook ◽

D.M. Gray ◽

J.W. Pomeroy

Keyword(s):

Temporal Variation ◽

Edge Length ◽

Climatic Conditions ◽

Frequency Characteristics ◽

Aerial Photographs ◽

Canadian Prairies ◽

Small Watersheds ◽

Snow Covered Area ◽

Covered Area ◽

Alpine Environments

Information on the temporal variation in snow-covered area of watershed during melt is requisite for accurate predictions of runoff. The amount of the gross watershed area that is snow-covered affects runoff primarily in two ways: a) it influences the melt rate, because patches of bare ground affect the energy balance of the snow field, and b) it governs the contributing area of runoff. This paper examines the area-frequency and perimeter-area characteristics of soil and snow patches that form during ablation of seasonal snowcovers in Prairie and Alpine environments. It uses fractal geometry as a basis for quantifying these properties. Image analyses are applied to aerial photographs taken during snowmelt on two small watersheds: one in the West-central part of the Province of Saskatchewan in the Canadian Prairies, the other in the alpine region of the Austrian Alps. The results of the study suggest that the soil and melting snow patches behave as fractals, that is their perimeter-area and area-frequency characteristics can be described by simple power equations with patch area. The perimeter-area ratio of the soil and snow patches decreases with increasing size of patch, but at a smaller rate than for Euclidean objects. The area-frequency characteristics of snow patches follow a hyperbolic distribution with relatively few large patches and numerous small patches. It is suggested that the soil and snow patches have the same fractal dimension. It is concluded that snow patches are not random and their size distribution is predictable. The variation in the edge length of a snow field per unit basin area during ablation is demonstrated. A maximum value of the ratio is reached when a basin has 45-65 % snowcover. With snow coverage in this range the potential for local advection increasing melt under a specific set of climatic conditions is greatest.

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