: Design rainfall depth, which is a fundamental index used in river planning, was estimated by rainfall obtained from super-ensemble simulations with bias correction, and the future change under 4 degree warming was projected. The modifications of existing bias correction methods were pro‐ posed to resolve the issue of overfitting and gap in size between reference and super-ensemble simulation data. A bias correction approach considering the bias between the historical experiment, the reference data, and the change between the historical and future experiments separately was defined as two-pass bias correction. The two-pass bias correction was performed with a moving window method that calculated moving average for time period and rank-order statistics. The result indicated that the approach pro‐ posed in this study estimates the design rainfall depth with a small error compared to that calculated without the moving window. The moving window method effectively resolves the issue of overfitting. The projection indicated that the range of projection among sea-surface temperature (SST) patterns is equivalent to 25% of the design rainfall depth for most basins and 60% for certain specific basins. The results indicate the importance of the appropriate bias correction and the consideration of range among the SST patterns for super-ensemble simulation data.
{"title":"Bias correction of d4PDF using a moving window method and their uncertainty analysis in estimation and projection of design rainfall depth","authors":"Satoshi Watanabe, Masafumi Yamada, Shiori Abe, Misako Hatono","doi":"10.3178/hrl.14.117","DOIUrl":"https://doi.org/10.3178/hrl.14.117","url":null,"abstract":": Design rainfall depth, which is a fundamental index used in river planning, was estimated by rainfall obtained from super-ensemble simulations with bias correction, and the future change under 4 degree warming was projected. The modifications of existing bias correction methods were pro‐ posed to resolve the issue of overfitting and gap in size between reference and super-ensemble simulation data. A bias correction approach considering the bias between the historical experiment, the reference data, and the change between the historical and future experiments separately was defined as two-pass bias correction. The two-pass bias correction was performed with a moving window method that calculated moving average for time period and rank-order statistics. The result indicated that the approach pro‐ posed in this study estimates the design rainfall depth with a small error compared to that calculated without the moving window. The moving window method effectively resolves the issue of overfitting. The projection indicated that the range of projection among sea-surface temperature (SST) patterns is equivalent to 25% of the design rainfall depth for most basins and 60% for certain specific basins. The results indicate the importance of the appropriate bias correction and the consideration of range among the SST patterns for super-ensemble simulation data.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69394198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: Motivated by the problem of rainfall duration bias typi‐ cally found in dynamical downscaling, its possible effect on hydrology was evaluated for heavy rainfall events over Kyushu, Japan, during summer. Heavy rainfall in western Kyushu is often related to a persistent Baiu rainband across Kyushu, while in eastern Kyushu it is related to the passage of typhoons near Kyushu. For typical heavy-rainfall peri‐ ods, we ran a tank model for several target rivers to analyze runoff and water-depth sensitivity to the hyetograph by arti‐ ficially extending the rainfall duration to 8 hours while maintaining the same total rainfall. This showed that a spike in peak runoff was suppressed by prolonged weak rainfall as typically found in downscaling outputs. The tim‐ ing of rising runoff and water depth in the tank model was shifted earlier.
{"title":"Possible hydrological effect of rainfall duration bias in dynamical downscaling","authors":"Yuta Tamaki, M. Inatsu, T. Yamada","doi":"10.3178/hrl.13.55","DOIUrl":"https://doi.org/10.3178/hrl.13.55","url":null,"abstract":": Motivated by the problem of rainfall duration bias typi‐ cally found in dynamical downscaling, its possible effect on hydrology was evaluated for heavy rainfall events over Kyushu, Japan, during summer. Heavy rainfall in western Kyushu is often related to a persistent Baiu rainband across Kyushu, while in eastern Kyushu it is related to the passage of typhoons near Kyushu. For typical heavy-rainfall peri‐ ods, we ran a tank model for several target rivers to analyze runoff and water-depth sensitivity to the hyetograph by arti‐ ficially extending the rainfall duration to 8 hours while maintaining the same total rainfall. This showed that a spike in peak runoff was suppressed by prolonged weak rainfall as typically found in downscaling outputs. The tim‐ ing of rising runoff and water depth in the tank model was shifted earlier.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3178/hrl.13.55","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42949828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: This study demonstrated groundwater flow simulations to investigate a vertical trend of equivalent hydraulic conductivity of alluvial fan gravel deposits in Sapporo, Japan, considering open void connectivity. Equivalent hydraulic conductivity was defined according to Darcy’s Law for a cube of 10 m in size, consisting of one million cells assigned among fully packed (without open voids), loosely packed (with less-connected voids) or very loosely packed (with well-connected voids) deposits. The stochastic generation was performed under each configuration in terms of target depth sections for vertical trend analysis, and horizontal variogram ranges (random, high, and low connectivity, and no open voids) for open void connectivity. The logarithmic average of 100 equivalent hydraulic conductivities was calculated in each configuration, and the vertical trends were determined. The simulation results showed that the equivalent hydraulic conductivity increased when the open void frequency was large in the shallow zone and the connectivity of the open voids was assumed. In particular, the high connectivity assumption was needed to match the in situ trend with a decay exponent of 0.05 m –1 . Modeling the vertical trend with such a large decay exponent was essen-tial to obtain realistic solutions of the groundwater flow and transport system in the alluvial fan.
{"title":"Vertical trend analysis of equivalent hydraulic conductivity in alluvial fan gravel deposits considering open void connectivity","authors":"Yoshitaka Sakata","doi":"10.3178/HRL.13.7","DOIUrl":"https://doi.org/10.3178/HRL.13.7","url":null,"abstract":": This study demonstrated groundwater flow simulations to investigate a vertical trend of equivalent hydraulic conductivity of alluvial fan gravel deposits in Sapporo, Japan, considering open void connectivity. Equivalent hydraulic conductivity was defined according to Darcy’s Law for a cube of 10 m in size, consisting of one million cells assigned among fully packed (without open voids), loosely packed (with less-connected voids) or very loosely packed (with well-connected voids) deposits. The stochastic generation was performed under each configuration in terms of target depth sections for vertical trend analysis, and horizontal variogram ranges (random, high, and low connectivity, and no open voids) for open void connectivity. The logarithmic average of 100 equivalent hydraulic conductivities was calculated in each configuration, and the vertical trends were determined. The simulation results showed that the equivalent hydraulic conductivity increased when the open void frequency was large in the shallow zone and the connectivity of the open voids was assumed. In particular, the high connectivity assumption was needed to match the in situ trend with a decay exponent of 0.05 m –1 . Modeling the vertical trend with such a large decay exponent was essen-tial to obtain realistic solutions of the groundwater flow and transport system in the alluvial fan.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49483465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fereshteh Ghiami-Shomami, Kohzo Kawasaki, Leonardo, S. Shinoda, Yan Fan
Estimation of reference evapotranspiration (ET0) is important in hydrological studies. As climate change is pre‐ dicted to cause changes in water resources and agriculture sectors, the possible implications of changes in different climate variables on ET0 need to be understood. Sensitivity analysis was employed to illustrate the effects of perturba‐ tion in meteorological parameters (maximum and minimum air temperature (Tmax and Tmin), sunshine hours (n), maxi‐ mum and minimum relative humidity (RHmax and RHmin)) and wind speed (uz) on ET0. ET0 was calculated by The Food and Agriculture Organization of the United Nations (FAO) 56 Penman-Monteith approach using climate data from 1979–2017 for the Enbara and Futatsumori water‐ sheds in forested mountain areas in Japan. We quantified the contributions of climatic factors to ET0 at daily, monthly, seasonal and annual time scales. Daily results showed large fluctuations. According to the monthly and seasonal analysis, during warm seasons, Tmax and n had more influence on ET0, especially in May, while for the cold seasons, RH effect was dominant, especially in December. Based on the annual results, the factors most influencing ET0 were Tmax followed by n, uz, RH and Tmin. We also found that the response of ET0 to changes in cli‐ matic parameters differs for sites with different topographic and geographic characteristics.
{"title":"Sensitivity of potential evapotranspiration to climate factors in forested mountainous watersheds","authors":"Fereshteh Ghiami-Shomami, Kohzo Kawasaki, Leonardo, S. Shinoda, Yan Fan","doi":"10.3178/HRL.13.41","DOIUrl":"https://doi.org/10.3178/HRL.13.41","url":null,"abstract":"Estimation of reference evapotranspiration (ET0) is important in hydrological studies. As climate change is pre‐ dicted to cause changes in water resources and agriculture sectors, the possible implications of changes in different climate variables on ET0 need to be understood. Sensitivity analysis was employed to illustrate the effects of perturba‐ tion in meteorological parameters (maximum and minimum air temperature (Tmax and Tmin), sunshine hours (n), maxi‐ mum and minimum relative humidity (RHmax and RHmin)) and wind speed (uz) on ET0. ET0 was calculated by The Food and Agriculture Organization of the United Nations (FAO) 56 Penman-Monteith approach using climate data from 1979–2017 for the Enbara and Futatsumori water‐ sheds in forested mountain areas in Japan. We quantified the contributions of climatic factors to ET0 at daily, monthly, seasonal and annual time scales. Daily results showed large fluctuations. According to the monthly and seasonal analysis, during warm seasons, Tmax and n had more influence on ET0, especially in May, while for the cold seasons, RH effect was dominant, especially in December. Based on the annual results, the factors most influencing ET0 were Tmax followed by n, uz, RH and Tmin. We also found that the response of ET0 to changes in cli‐ matic parameters differs for sites with different topographic and geographic characteristics.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69394096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Tsuruta, Hiroyuki Yamamoto, M. Katsuyama, Y. Kosugi, M. Okumura, N. Matsuo
: Cryogenic vacuum distillation (CVD) methods have been widely used to extract water from unsaturated soil materials. However, recent studies have reported that extraction conditions (e.g. extraction time) and soil type can influence the stable isotope ratios of soil water extracted by CVD. We examined (i) the effects of extraction time on the stable isotope ratios of soil water extracted by CVD, and (ii) how the stable isotope ratios differed from those of soil water extracted by other methods. We first examined extraction times of 1–6 h, and observed no significant differences in the δ 2 H or δ 18 O values of extracted soil water for extraction times >2 h. However, extraction for 1 h collected only 48% of soil water, and the δ 2 H and δ 18 O values were significantly lower than those for extraction times >2 h. We then compared the stable isotope ratios of soil water extracted by CVD and centrifugation. Although the stable isotope ratios for both extraction methods were within the range of that of rainwater, the stable isotope ratios for water extracted by CVD were lower than those for water extracted by centrifugation. Our results highlight questions surrounding the use of CVD for stable isotope analysis of soil water.
{"title":"Effects of cryogenic vacuum distillation on the stable isotope ratios of soil water","authors":"K. Tsuruta, Hiroyuki Yamamoto, M. Katsuyama, Y. Kosugi, M. Okumura, N. Matsuo","doi":"10.3178/HRL.13.1","DOIUrl":"https://doi.org/10.3178/HRL.13.1","url":null,"abstract":": Cryogenic vacuum distillation (CVD) methods have been widely used to extract water from unsaturated soil materials. However, recent studies have reported that extraction conditions (e.g. extraction time) and soil type can influence the stable isotope ratios of soil water extracted by CVD. We examined (i) the effects of extraction time on the stable isotope ratios of soil water extracted by CVD, and (ii) how the stable isotope ratios differed from those of soil water extracted by other methods. We first examined extraction times of 1–6 h, and observed no significant differences in the δ 2 H or δ 18 O values of extracted soil water for extraction times >2 h. However, extraction for 1 h collected only 48% of soil water, and the δ 2 H and δ 18 O values were significantly lower than those for extraction times >2 h. We then compared the stable isotope ratios of soil water extracted by CVD and centrifugation. Although the stable isotope ratios for both extraction methods were within the range of that of rainwater, the stable isotope ratios for water extracted by CVD were lower than those for water extracted by centrifugation. Our results highlight questions surrounding the use of CVD for stable isotope analysis of soil water.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3178/HRL.13.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69394090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The authors proposed a methodology for estimating flow duration curves (FDC) for perennial and ephemeral catch‐ ments in islands using a disaggregated approach. The pro‐ posed method is approached statistically and uses no complex parameters in order to reduce uncertainty and retain simplicity. Firstly, the FDC was disaggregated into three parts (high, middle and low) and, for the purpose of this study, it focusses on the low flow section. Initially, the mean monthly flow was used for estimating runoff in both types of catchments. The results show the mean monthly flow provided proper estimates in the perennial catchments, but for the ephemeral catchments the estimates were sub‐ standard. Therefore, a different approach using climate indices such as aridity and a precipitation index was used in a generalized regression equation. The results show the majority of the ephemeral catchments responded properly to the climate indices indicating climate as a major control‐ ling factor at the lower end of the FDC.
{"title":"Estimating flow duration curves in perennial and ephemeral catchments using a disaggregated approach","authors":"C. Leong, Y. Yokoo","doi":"10.3178/hrl.13.14","DOIUrl":"https://doi.org/10.3178/hrl.13.14","url":null,"abstract":"The authors proposed a methodology for estimating flow duration curves (FDC) for perennial and ephemeral catch‐ ments in islands using a disaggregated approach. The pro‐ posed method is approached statistically and uses no complex parameters in order to reduce uncertainty and retain simplicity. Firstly, the FDC was disaggregated into three parts (high, middle and low) and, for the purpose of this study, it focusses on the low flow section. Initially, the mean monthly flow was used for estimating runoff in both types of catchments. The results show the mean monthly flow provided proper estimates in the perennial catchments, but for the ephemeral catchments the estimates were sub‐ standard. Therefore, a different approach using climate indices such as aridity and a precipitation index was used in a generalized regression equation. The results show the majority of the ephemeral catchments responded properly to the climate indices indicating climate as a major control‐ ling factor at the lower end of the FDC.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3178/hrl.13.14","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69394128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tomohiro Tanaka, H. Yoshioka, Sokly Siev, H. Fujii, S. Ly, C. Yoshimura
: Hydrological-hydraulic modeling is a core technique in assessing surface water dynamics of rivers, lakes, and floodplains. The local inertial model (LIM) as a physically simplified model of the shallow water equations is essential for efficient numerical simulator of surface water dynam‐ ics. In this paper, we point out that the conventional semi-implicit finite difference scheme for the friction slope terms, despite being convenient, is not consistent in the sense that it may lead to incorrect numerical solutions if the temporal resolution is not high. We propose an alternative discretization to resolve this issue, which is more accurate and stable, and has comparable computational efficiency. The new numerical scheme is implemented into a modern hydrological-hydraulic model, demonstrating reasonable accuracy. The new scheme is also compared with a recently-proposed implicit scheme, demonstrating compa‐ rable theoretical and computational performances. The results indicate that the proposed scheme potentially serves as a new central core for numerical simulation with the LIM.
{"title":"A consistent finite difference local inertial model for shallow water simulation","authors":"Tomohiro Tanaka, H. Yoshioka, Sokly Siev, H. Fujii, S. Ly, C. Yoshimura","doi":"10.3178/HRL.13.28","DOIUrl":"https://doi.org/10.3178/HRL.13.28","url":null,"abstract":": Hydrological-hydraulic modeling is a core technique in assessing surface water dynamics of rivers, lakes, and floodplains. The local inertial model (LIM) as a physically simplified model of the shallow water equations is essential for efficient numerical simulator of surface water dynam‐ ics. In this paper, we point out that the conventional semi-implicit finite difference scheme for the friction slope terms, despite being convenient, is not consistent in the sense that it may lead to incorrect numerical solutions if the temporal resolution is not high. We propose an alternative discretization to resolve this issue, which is more accurate and stable, and has comparable computational efficiency. The new numerical scheme is implemented into a modern hydrological-hydraulic model, demonstrating reasonable accuracy. The new scheme is also compared with a recently-proposed implicit scheme, demonstrating compa‐ rable theoretical and computational performances. The results indicate that the proposed scheme potentially serves as a new central core for numerical simulation with the LIM.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69394137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many recent studies have argued that tropical cyclones will become severer in future warming climate and may cause various catastrophic damages to human life and econ‐ omy. This study explores the impact of climate change on Typhoon Chanthu (2016) by performing a high-resolution (1 km) simulation for current and future climate. We focused on the typhoon intensity, size, heat fluxes, associ‐ ated precipitation and wind speed over northern Japan under global warming with different initial times at 6-hour interval. We find that the typhoon tracks in the present and future climates remained similar, however with stronger intensity and heat fluxes in warming climate condition. In the landfall region of Hokkaido in future climate, the maxi‐ mum wind speed and precipitation amount associated with the typhoon is significantly increased. The results imply that the damages associated with Typhoon Chanthu in future climate over northern Japan would be enhanced through strong wind, heavy rainfall and flooding.
{"title":"Quantitative estimations of hazards resulting from Typhoon Chanthu (2016) for assessing the impact in current and future climate","authors":"S. Nayak, T. Takemi","doi":"10.3178/HRL.13.20","DOIUrl":"https://doi.org/10.3178/HRL.13.20","url":null,"abstract":"Many recent studies have argued that tropical cyclones will become severer in future warming climate and may cause various catastrophic damages to human life and econ‐ omy. This study explores the impact of climate change on Typhoon Chanthu (2016) by performing a high-resolution (1 km) simulation for current and future climate. We focused on the typhoon intensity, size, heat fluxes, associ‐ ated precipitation and wind speed over northern Japan under global warming with different initial times at 6-hour interval. We find that the typhoon tracks in the present and future climates remained similar, however with stronger intensity and heat fluxes in warming climate condition. In the landfall region of Hokkaido in future climate, the maxi‐ mum wind speed and precipitation amount associated with the typhoon is significantly increased. The results imply that the damages associated with Typhoon Chanthu in future climate over northern Japan would be enhanced through strong wind, heavy rainfall and flooding.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3178/HRL.13.20","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69394131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A hydrological model, XAJMISO is adopted from the XinAnJiang (XAJ) model and modified by transforming the parametric routing system into a non-parametric system to reduce parameters and improve performance. The pro‐ posed model replaces routing components of the XAJ model with two linear systems: surface flow and subsurface flow, including interflow and baseflow. The discharge at the basin outlet is then calculated using response functions of surface and subsurface flow, which are derived by means of a multiple input single output (MISO) system. In con‐ trast to other MISO studies, the present study defines the finite length for calculating response function coordinates based on time scales of all runoff components. The model is applied to six river basins of different data aridity indices in the United States and compared with our modified XAJ (mXAJ) model. The results reveal that the proposed model sufficiently represents the relationship between rainfall and runoff of relatively large basins and provides better and more stable performance. The proposed model also makes calibration much easier by reducing four sensitive parame‐ ters out of seven in mXAJ.
{"title":"Development of XAJMISO hydrological model for rainfall-runoff analysis","authors":"Khin Htay Kyi, Minjiao Lu","doi":"10.3178/hrl.13.34","DOIUrl":"https://doi.org/10.3178/hrl.13.34","url":null,"abstract":"A hydrological model, XAJMISO is adopted from the XinAnJiang (XAJ) model and modified by transforming the parametric routing system into a non-parametric system to reduce parameters and improve performance. The pro‐ posed model replaces routing components of the XAJ model with two linear systems: surface flow and subsurface flow, including interflow and baseflow. The discharge at the basin outlet is then calculated using response functions of surface and subsurface flow, which are derived by means of a multiple input single output (MISO) system. In con‐ trast to other MISO studies, the present study defines the finite length for calculating response function coordinates based on time scales of all runoff components. The model is applied to six river basins of different data aridity indices in the United States and compared with our modified XAJ (mXAJ) model. The results reveal that the proposed model sufficiently represents the relationship between rainfall and runoff of relatively large basins and provides better and more stable performance. The proposed model also makes calibration much easier by reducing four sensitive parame‐ ters out of seven in mXAJ.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3178/hrl.13.34","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69394176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Changes in runoff caused by forest management prac‐ tices such as thinning need to be better understood for effective water resource management. We established matched (20° slope) 62%-thinning treatment and grassland control lysimeter plots in a 22-year-old cypress plantation in the Inuyama Research Forest of the Ecohydrology Research Institute, Japan. Runoff (surface and subsurface) was directed into a collection tank with a 90° v-notch weir outlet. Measurements were made before and after the thin‐ ning treatment and were compared with grassland control. Monthly manual measurements of subsurface runoff (March 2011–December 2014) performed via a measuring cylinder and stopwatch yielded 18 pre-thinning and 24 post-thinning observations. In addition, 26 pre-thinning and 24 post-thinning sets of storm-event measurements were continuously recorded via a water level data logger. Fol‐ lowing thinning, subsurface runoff and peak storm-runoff changed by up to +133% and –80% respectively. By con‐ trolling the geology, soil characteristics and hydrological pathways, we were able to attribute these outcomes to reduced transpiration and increased ground resistance from felled logs respectively, suggesting that well-managed high-intensity thinning may be beneficial for increasing water supply and controlling floods. However, this is only achievable if felled logs are aligned along contour lines on the hillslopes.
{"title":"Thinning of cypress forest increases subsurface runoff but reduces peak storm-runoff: a lysimeter observation","authors":"K. Kuraji, Mie Gomyo, A. Nainar","doi":"10.3178/hrl.13.49","DOIUrl":"https://doi.org/10.3178/hrl.13.49","url":null,"abstract":"Changes in runoff caused by forest management prac‐ tices such as thinning need to be better understood for effective water resource management. We established matched (20° slope) 62%-thinning treatment and grassland control lysimeter plots in a 22-year-old cypress plantation in the Inuyama Research Forest of the Ecohydrology Research Institute, Japan. Runoff (surface and subsurface) was directed into a collection tank with a 90° v-notch weir outlet. Measurements were made before and after the thin‐ ning treatment and were compared with grassland control. Monthly manual measurements of subsurface runoff (March 2011–December 2014) performed via a measuring cylinder and stopwatch yielded 18 pre-thinning and 24 post-thinning observations. In addition, 26 pre-thinning and 24 post-thinning sets of storm-event measurements were continuously recorded via a water level data logger. Fol‐ lowing thinning, subsurface runoff and peak storm-runoff changed by up to +133% and –80% respectively. By con‐ trolling the geology, soil characteristics and hydrological pathways, we were able to attribute these outcomes to reduced transpiration and increased ground resistance from felled logs respectively, suggesting that well-managed high-intensity thinning may be beneficial for increasing water supply and controlling floods. However, this is only achievable if felled logs are aligned along contour lines on the hillslopes.","PeriodicalId":13111,"journal":{"name":"Hydrological Research Letters","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3178/hrl.13.49","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69394108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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