Annual water, sediment, nutrient, and organic carbon fluxes in river basins: A global meta‐analysis as a function of scale

Mutema, Macdex; Chaplot, Vincent; Jewitt, Graham; Chivenge, Pauline; Blöschl, Günter

doi:10.1002/2014wr016668

Cited by 50 publications

(69 citation statements)

References 166 publications

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“…Differences in catchment characteristics, including land use/cover, soil properties, and topography, as well as precipitation characteristics, are clearly the reason for the spatial patterns in the precipitation-sediment yield relationship (Morera et al, 2013;Mutema et al, 2015). The lower vegetation cover was the main reason for the greater effects of precipitation on sediment yield in the northwestern part.…”

Section: Discussionmentioning

confidence: 98%

“…Notable decreases in sediment yields have been observed in approximately 50 % of the world's rivers (Walling and Fang, 2003;Syvitski et al, 2005). Many studies have investigated the dynamics of streamflows and sediment yields at different spatial and temporal scales (Mutema et al, 2015;Song et al, 2016;Gao et al, 2016). In addition to climate variability, LUCC, soil and water conservation measures (SWCMs) and construction of reservoirs and dams have substantially contributed to the sediment load reductions (Walling, 2006;Milliman et al, 2008;Wang et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to climate variability, LUCC, soil and water conservation measures (SWCMs) and construction of reservoirs and dams have substantially contributed to the sediment load reductions (Walling, 2006;Milliman et al, 2008;Wang et al, 2011). While previous studies have certainly provided valuable insights into the streamflow and sediment load changes, the distinctive roles of LUCC and precipitation variability in changing sediment loads still need further investigation in large domains and across gradients of climate and land surface conditions (Walling, 2006;Mutema et al, 2015). A particularly useful approach to the development of generalizable understanding of the effects of precipitation variability and LUCC is a comparative analysis approach focused on extracting spatio-temporal patterns of sediment yields based on observations in multiple locations within the same region, or even across different regions.…”

Section: Introductionmentioning

confidence: 99%

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Spatio-temporal patterns of the effects of precipitation variability and land use/cover changes on long-term changes in sediment yield in the Loess Plateau, China

Gao

Zhang

Liu

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. Within China's Loess Plateau there have been concerted revegetation efforts and engineering measures since the 1950s aimed at reducing soil erosion and land degradation. As a result, annual streamflow, sediment yield, and sediment concentration have all decreased considerably. Humaninduced land use/cover change (LUCC) was the dominant factor, contributing over 70 % of the sediment load reduction, whereas the contribution of precipitation was less than 30 %. In this study, we use 50-year time series data , showing decreasing trends in the annual sediment loads of 15 catchments, to generate spatio-temporal patterns in the effects of LUCC and precipitation variability on sediment yield. The space-time variability of sediment yield was expressed notionally as a product of two factors representing (i) the effect of precipitation and (ii) the fraction of treated land surface area. Under minimal LUCC, the square root of annual sediment yield varied linearly with precipitation, with the precipitation-sediment load relationship showing coherent spatial patterns amongst the catchments. As the LUCC increased and took effect, the changes in sediment yield pattern depended more on engineering measures and vegetation restoration campaign, and the within-year rainfall patterns (especially storm events) also played an important role. The effect of LUCC is expressed in terms of a sediment coefficient, i.e., the ratio of annual sediment yield to annual precipitation. Sediment coefficients showed a steady decrease over the study period, following a linear decreasing function of the fraction of treated land surface area. In this way, the study has brought out the separate roles of precipitation variability and LUCC in controlling spatio-temporal patterns of sediment yield at catchment scale.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatio-temporal patterns of the effects of precipitation variability and land use/cover changes on long-term changes in sediment yield in the Loess Plateau, China

Gao

Zhang

Liu

et al. 2017

Hydrol. Earth Syst. Sci.

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“…The results ( cf . Table ) showed a 33% increase of the overall average unit‐area runoff from the raindrop splash erosion (1 m 2 ) to runoff sheet erosion (10 m 2 ), supporting findings from numerous documented studies (Chaplot and Le Bissonnais, ; Chaplot and Poesen, ; Mutema et al, ). This increase in runoff with increasing plot area could be attributed to the variation of soil surface characteristics.…”

Section: Discussionmentioning

confidence: 65%

“…Several recent studies do take cognisance of the negative impact of sheet erosion, considering the process is a major cause of top‐soil loss in the region (Dlamini et al, ; Müller‐Nedebock and Chaplot, ), with about 12 ton/ha/year soil loss from sheet erosion for the province (Le Roux et al ., 2011). Recent field studies in KwaZulu‐Natal (Dlamini et al, ; Mchunu et al, ; Chaplot et al, ; Mchunu and Chaplot, ; Mutema et al, ) have focused on sheet erosion in natural grasslands and pastures.…”

Section: Introductionmentioning

confidence: 99%

Assessment of soil erosion under rainfed sugarcane in KwaZulu‐Natal, South Africa

Abdalla

Dickey

Hill

et al. 2019

Natural Resources Forum

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Soil erosion from agricultural land use runoff is a major threat to the sustainability of soil composition and water resource integrity. Sugarcane is an important cash and food security crop in South Africa, subjected to an intensive soil erosion, and consequently, severe land degradation. This study aimed to investigate soil erosion and associated soil and cover factors under rainfed sugarcane, in a small catchment, KwaZulu‐Natal, South Africa. Three replicated runoff plots were installed at different slope positions (down, mid and upslope) within cultivated sugarcane fields to monitor soil erosion during the 2016–2017 rainy season. On average, annual runoff (RF) was significantly greater from 10 m2 plots with 1163.77 ± 2.63 l/m/year compared to 1 m2 plots. However, sediment concentration (SC) was significantly lower in 10 m2 (0.34 ± 0.04 g/l) compared to 1 m2 (6.94 ± 0.24 g/l) plots. The annual soil losses (SL) calculated from 12 rainfall events was 58.36 ± 0.77 and 8.84 ± 0.20 t/ha from 1 m2 and 10 m2 plots, respectively. The 1 m2 plot, SL (2.4 ± 1.41 ton/ha/year) in the upslope experienced 33% more loss than the midslope and 50% more loss than the downslope position. SL was relatively lower from the 10 m2 plots than the 1 m2 plots, which is explained by high sediment deposition at the greater plot scale. SL was negatively correlated with the soil organic carbon stocks (r = −0.82) and soil surface cover (r = −0.55). RF decreased with the increase of slope gradient (r = −0.88) and soil infiltration rate (r = −0.87). There were considerable soil losses from cultivated sugarcane fields with low organic matter. These findings suggest that to mitigate soil erosion, soil organic carbon stocks and vegetation cover needs to be increased through appropriate land management practices, particularly in cultivated areas with steep gradients.

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Land use change impacts on floods at the catchment scale: Challenges and opportunities for future research

Rogger

Agnoletti

Alaoui

et al. 2017

Water Resources Research

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320

232

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Research gaps in understanding flood changes at the catchment scale caused by changes in forest management, agricultural practices, artificial drainage, and terracing are identified. Potential strategies in addressing these gaps are proposed, such as complex systems approaches to link processes across time scales, long‐term experiments on physical‐chemical‐biological process interactions, and a focus on connectivity and patterns across spatial scales. It is suggested that these strategies will stimulate new research that coherently addresses the issues across hydrology, soil and agricultural sciences, forest engineering, forest ecology, and geomorphology.

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Annual water, sediment, nutrient, and organic carbon fluxes in river basins: A global meta‐analysis as a function of scale

Abstract: International audienc

Cited by 50 publications

References 166 publications

Spatio-temporal patterns of the effects of precipitation variability and land use/cover changes on long-term changes in sediment yield in the Loess Plateau, China

Spatio-temporal patterns of the effects of precipitation variability and land use/cover changes on long-term changes in sediment yield in the Loess Plateau, China

Assessment of soil erosion under rainfed sugarcane in KwaZulu‐Natal, South Africa

Land use change impacts on floods at the catchment scale: Challenges and opportunities for future research

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