Suspended-sediment responses after strip thinning in headwater catchments

Nam, Seok‐Jin; Hiraoka, M.; Gomi, Takashi; Dung, Bui Xuan; Onda, Yuichi; Kato, Hiroaki

doi:10.1007/s11355-015-0284-0

Cited by 15 publications

(12 citation statements)

References 55 publications

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“…As these authors described for peak flow response, we also found that HC values, spatial patterns, and changes are scaledependent with respect to drainage areas, preferential HC routes, location of the different Geomorphology, DOI: 10.1016/j.geomorph.2017 López-Vicente et al, 2017 -Hydrological connectivity in two Japanese forest catchments vegetation patches, and FMO. Nam et al (2016) also found significant increases in specific sediment yield in K2 in the post-thinning period mainly associated with clearcutting and soilsurface disturbance by skidding trails. At plot scale, Sun et al (2015a and b) demonstrated that thinning altered the interception components, with a significant rise of the throughfall rates and a decrease in the canopy water storage.…”

Section: Validation Of Simulated Scenariosmentioning

confidence: 74%

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Effect of tree thinning and skidding trails on hydrological connectivity in two Japanese forest catchments

et al. 2017

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Land use composition and patterns influence the hydrological response in mountainous and forest catchments. In plantation forest, management operations (FMO) modify the spatial and temporal dynamics of overland flow processes. However, we found a gap in the literature focussed on modelling hydrological connectivity (HC) in plantation forest under different FMO. In this study, we simulated HC in two steep paired forest subcatchments (K2 and K3, 33.2 ha), composed of Japanese cypress (Chamaecyparis obtusa Endl.) and Japanese cedar (Cryptomeria japonica D. Don) plantations (59% of the total area) against a tree thinning intensity of 50% at different time. Additionally, construction of new skidding trails and vegetation recovery was simulated on five thinning-based scenarios that covered a 40-month test period (July 2010-October 2013). As a future scenario, six check-dams located in the main streams were proposed to reduce sediment and radionuclide delivery. An updated version of Borselli's index of runoff and sediment connectivity was run, using the D-infinity flow accumulation algorithm and exploiting three 0.5-m resolution digital elevation models. On the basis of the pre-FMO scenario, HC increased at catchment scale owing to tree thinning and the new skidding trails. This change was more noticeable within the area affected by the FMO, where HC increased by 11.4% and 10.5% in the cypress and cedar plantations in K2 respectively and by 8.8% in the cedar plantation in K3. At hillslope plot and stream scales, the evolution in the values of HC was less evident, except the increment (by 5.4%) observed in the streams at K2 after the FMO. Progressive vegetation recovery after the FMO triggered a slight reduction of connectivity in all compartments of both subcatchments. Forest roads and especially skidding trails presented the highest values of HC, appearing as the most efficient features connecting the different vegetation patches with the stream network. The spatial and temporal evolution of HC over the five past scenarios correlated well with the observed changes in runoff yield, as well as with the available values of rainfall interception and throughfall before, during, and after the FMO. The simulation of the proposed scenario recommends the construction of check-dams as Geomorphology,

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Section: Validation Of Simulated Scenariosmentioning

confidence: 74%

“…et al (2015a and b), Dung et al (2015), Fukushima et al (2015), and Nam et al (2016) obtained in the same study area; and (ii) with unpublished data of runoff yield. We first used the observed changes in the values of rainfall interception and throughfall obtained in the hillslope plots.…”

Section: Validation Of Simulated Scenariosmentioning

confidence: 75%

Effect of tree thinning and skidding trails on hydrological connectivity in two Japanese forest catchments

et al. 2017

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“…Increases in peak flow in K2‐2 and K2‐3 could possibly propagate downstream. Hence, at the catchment outlet in K2‐1, dominant hydrological pathways related to topographic condition and localized soil disturbance alter the changes in peak flow and reduced the significance (Whitaker et al ., ; Shaman et al ., ; Onda et al ., ), although increases in suspended sediment yields in K2‐1 after thinning were significant (Nam et al , ).…”

Section: Resultsmentioning

confidence: 99%

Peak flow responses to strip thinning in a nested, forested headwater catchment

Dung

Hiraoka

Gomi

et al. 2015

Hydrological Processes

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Abstract:We evaluated the effects of 50% strip thinning on peak flow responses in 17-ha and 9-ha nested catchments. We observed 117 storm events from April 2010 to December 2013, including 32 events in the pre-thinning period, 15 events during the thinning operation, and 70 events in the post-thinning period. Paired-catchment analysis with multiple pairs of nested gauging stations revealed that changes in peak flow responses varied depending on the location of the nested observation stations. Increases in peak flow during the operation period were significant in gauging stations located at the outlet and the middle of a catchment. Increases in peak flow during the post-treatment period became significant in all nested catchments, but not in the catchment outlet. Rates of increase in peak flow ranged from 17.7% to 44.4%, which is within the range of previous studies. Different responses for changes in peak flow among nested pairs were associated with changes in internal hydrological flow pathways due to removal of timber and hydrological connectivity via overland flow generated by newly installed and reactivated skid trails. Our findings suggest that the effects of timber harvesting on peak flow are scale-dependent with respect to drainage areas, hydrological links, and management practices. Selection of gauging locations and process-based observations within catchments are essential for testing hypotheses related to the effects of timber harvesting with robust hydrological monitoring.

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“…Nanko et al (2016) also detected an increase in the throughfall fraction (from 58% to 79%) in a mature Japanese cypress forest in southern Japan after thinning. Nam et al (2016) examined changes in suspended-sediment yields (SSY) after a 50% strip thinning in a Japanese cedar and cypress plantation forest in central Japan Tochigi revealing that SSY increased 17.0-fold compared with the pre-thinning period. Recently, López-Vicente et al 2017observed an increase of hydrological connectivity at hillslope and stream scales owing to tree thinning and new skidding trails in a forest plantation in central Japan, whereas progressive vegetation recovery one year after forest management operations triggered a reduction of hydrological connectivity in all compartments.…”

Section: Discussionmentioning

confidence: 99%

Radiocesium concentrations in soil and leaf after decontamination practices in a forest plantation highly polluted by the Fukushima accident

López‐Vicente

Onda

Takahashi

et al. 2018

Environmental Pollution

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Owing to the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident a vast amount of radiocesium was released polluting the land. Afterwards, a variety of decontamination practices has been done, reducing the ambient dose rates. In this study we evaluated the effectiveness of eight forest decontamination practices by means of monitoring the radiocesium (Cs) concentration in soil and leaf samples, and the daily discharge rates in ten plots during 27 months (May 2013-July 2015). A forest plantation located 16 km southwest to the FDNPP and within the exclusion area was selected. Radiocesium concentrations were analysed using a germanium gamma ray detector. The differences in radiocesium activities between the different plots were statistically significant (p < 0.05) and four homogeneous groups were distinguished. Tree thinning and litter removal greatly reduced the radioactivity and the two plots devoted to these practices presented the highest discharge rates of Cs (Th + LR; 350-380 Bq/m day), followed by the two Th plots (163-174 Bq/m day). The clearcutting with LR and the LR plots (104 and 92 Bq/m day) also had higher rates than those rates in the control plots (51 Bq/m day). We only observed low rates in the two plots with matting (19-25 Bq/m day). The temporal variability was explained by (i) the different rainfall depths registered during the measurement intervals (accumulated precipitation from 14 to 361 mm); and (ii) the fluctuations of the total surface coverage. The decrease trend in radiocesium concentration was high in 2013, moderate in 2014 and low in 2015 owing to the vegetation recovery after the countermeasures, thus reducing the possibility of the second pollution of the neighbouring areas. The average proportions of contribution of Cs discharge by soil and leaf fraction were 96.6% and 3.4%.

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Suspended-sediment responses after strip thinning in headwater catchments

Cited by 15 publications

References 55 publications

Effect of tree thinning and skidding trails on hydrological connectivity in two Japanese forest catchments

Effect of tree thinning and skidding trails on hydrological connectivity in two Japanese forest catchments

Peak flow responses to strip thinning in a nested, forested headwater catchment

Radiocesium concentrations in soil and leaf after decontamination practices in a forest plantation highly polluted by the Fukushima accident

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