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Generation of a long-term daily gridded precipitation dataset for the rTjSj-Upper Indus Basin(UIB)through temporal Reconstruction,Correction I sag&Informed Regionalization-“ReCIR”

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International Soil and Water Conservation Research 2021年第3期9卷 445-460页

作者： Asim Jahangir Khan Manfred Koch department of Geohydraulics and Engineering hydrology University of Kassel34125KasselGermany

This study attempted to generate a long-term(1961-2010)daily gridded precipitation dataset for the Upper Indus Basin(UIB)with orographic adjustments so as to generate realistic precipitation estimates,enabling hydrological and water resource investigations that can close the water balance,that is difficult,if not impossible to achieve with the currently available precipitation data products for the *** procedure includes temporal reconstruction of precipitation series at points where data were not recorded prior to the mid-nineties,followed by a regionalization of the precipitation series to a smaller scale across the basin(0.125°x 0.125°),while introducing adjustments for the orographic effect and changes in glacier *** reconstruction process involves interpolation of the precipitation at virtual locations of the current(1995-)dense observational network,followed by corrections for frequency and intensity and adjustments for temporal trends at these virtual *** data generated in this way were further validated for temporal and spatial representativeness through evaluation of SWAT-modelled streamflow responses against observed flows across the *** results show that the calibrated SWAT-simulated daily discharge at the basin outlet as well as at different sub-basin outlets,when forcing the model with the reconstructed precipitation of years 1973—1996,is almost identical to that when forcing it with the reference precipitation data(1997-2008).Finally,the spatial distribution pattern of the reconstructed(1961—1996)and reference(1997—2008)precipitation were also found consistent across the UIB,reflecting well the large-scale atmospheric-circulation pattern in the region.

关键词： Precipitation Temporal reconstruction Orographic correction factor(OCF) Soil and water assessment tool(SWAT) Glacier/water mass balance Upper indus basin(UIB)

Hydrogeochemical evaluation and statistical analysis of groundwater of Sylhet, north-eastern Bangladesh

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Acta Geochimica 2019年第3期38卷 440-455页

作者： Nasir Ahmed Md.Bodrud-Doza S.M.Didar-Ul Islam Manzoor Ahmad Choudhry Md.Iftakharul Muhib Anwar Zahid Shahadat Hossain Md.Moniruzzaman Nipa Deb Md.Abdul Quaiyum Bhuiyan Isotope hydrology Division Institute of Nuclear Science and Technology Atomic Energy Research Establishment department of Environmental Sciences Jahangirnagar University Isotope hydrology Section Department of Nuclear Sciences and Applications International Atomic Energy Agency Groundwater hydrology Bangladesh Water Development Board

To investigate the hydrogeochemical characteristics of groundwater 23 shallow, 30 intermediate and 38 deep wells samples were collected from Sylhet district of Bangladesh, and analyzed for temperature, pH, Eh, EC,DO, DOC, Na^+, K^+, Ca^(2+), Mg^(2+), Cl^-, SO_4^(2-), NO_3^-,HCO_3^-, SiO_2^-, Fe, Mn and As. Besides, 12 surface water samples from Surma and Kushiyara Rivers were also collected and analyzed to understand the influence into aquifers. Results revealed that, most of the groundwater samples are acidic in nature, and Na–HCO_3 is the dominant groundwater type. The mean value of temperature, EC,Na^+, K^+, Ca^(2+), Mg^(2+), Cl^-, NO_3^- and SO_4^(2-) were found within the range of permissible limits, while most of the samples exceeds the allowable limits of Fe, Mn and As concentrations. However, relatively higher concentration of Fe and Mn were found in deep water samples and reverse trend was found in case of As. The mean concentrations of As in shallow, intermediate and deep wells were 39.3, 25.3and 21.4 lg/L respectively, which varied from 0.03 to148 lg/L. From spatial distribution, it was found that Fe,Mn and As concentrations are high but patchy in northern,north-western, and south-western part of Sylhet region. The most influential geochemical process in study area were identified as silicate weathering, characterized by active cation exchange process and carbonate weathering, which thereby can enhance the elemental concentrations in groundwater. Pearson's correlation matrix, principal component analysis and cluster analysis were also employed to evaluate the controlling factors, and it was found that, both natural and anthropogenic sources were influencing the groundwater chemistry of the aquifers. However, surface water has no significant role to contaminate the aquifers,rather geogenic factors affecting the trace elemental contamination. Thus it is expected that, outcomes of this study will provide useful insights for future groundwater monitoring and

关键词： Arsenic Groundwater Hydrogeochemistry Multivariate statistics Spatial distribution

Effects of heterogeneity distribution on hillslope stability during rainfalls

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Water Science and Engineering 2016年第2期9卷 134-144页

作者： Jing-sen Cai E-chuan Yan Tian-chyi Jim Yeh Yuan-yuan Zha Faculty of Engineering China University of Geosciences department of hydrology and Water Resources University of Arizona

The objective of this study was to investigate the spatial relationship between the most likely distribution of saturated hydraulic conductivity(Ks) and the observed pressure head(P) distribution within a hillslope. The cross-correlation analysis method was used to investigate the effects of the variance of ln Ks, spatial structure anisotropy of ln Ks, and vertical infiltration flux(q) on P at some selected locations within the hillslope. The cross-correlation analysis shows that, in the unsaturated region with a uniform flux boundary, the dominant correlation between P and Ksis negative and mainly occurs around the observation location of P. A relatively high P value is located in a relatively low Kszone, while a relatively low P value is located in a relatively high Kszone. Generally speaking, P is positively correlated with q/Ksat the same location in the unsaturated region. In the saturated region, the spatial distribution of Kscan significantly affect the position and shape of the phreatic surface. We therefore conclude that heterogeneity can cause some parts of the hillslope to be sensitive to external hydraulic stimuli(e.g., rainfall and reservoir level change), and other parts of the hillslope to be insensitive. This is crucial to explaining why slopes with similar geometries would show different responses to the same hydraulic stimuli, which is significant to hillslope stability analysis.

关键词： Cross-correlation analysis Heterogeneity Hillslope stability Saturated hydraulic conductivity Stochastic conceptualization Pore-water pressure

Determination of the effective utilization coefficient of irrigation water based on geographically weighted regression

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Frontiers of Earth Science 2022年第2期16卷 401-410页

作者： Rui SHI Gaoxu WANG Xuan ZHANG Yi XU Yongxiang WU Wei WU College of hydrology and Water Resource Hohai UniversityNanjing 210098China State Key Laboratory of hydrology-Water Resources and Hydraulic Engineering Nanjing 210029China hydrology and Water Resources department Nanjing Hydraulic Research InstituteNanjing 210029China

This study uses geographically weighted regression to determine the spatial distribution of the effective utilization coefficient of irrigation water in Zhejiang Province,China,owing to the influences of spatial attributes on the irrigation *** sample set of this study comprised 165 agricultural test sites.A multivariate linear regression model and a geographically weighted regression model were established using the effective utilization coefficient of agricultural irrigation water as the dependent variable in addition to a suite of independent variables,including the actual irrigation area,the percentage of farmland using water-saving irrigation,the type of irrigation area,the net water consumption per mu,the water intake method,the terrain slope,and the soil field *** revealed a positive spatial correlation and noticeable agglomeration features in the effective utilization coefficient of irrigation water in Zhejiang *** geographically weighted regression model performed better in terms of fit and prediction accuracy than the multivariate linear regression *** obtained findings confirm the suitability of the geographically weighted regression model for determining the spatial distribution of the effective utilization coefficient of irrigation water in Zhejiang,and offer a new approach on a regional scale.

关键词： effective utilization coefficient of irrigation water spatial autocorrelation multivariate linear regression geographically weighted regression

Identifying soil structure along headwater hillslopes using ground penetrating radar based technique

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Journal of Mountain Science 2016年第3期13卷 405-415页

作者： HAN Xiao-le LIU Jin-tao ZHANG Jun ZHANG Zhi-cai State Key Laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University department of College of hydrology and Water Resources Hohai University Institute of Geochemistry Chinese Academy of Sciences

Soil structure plays an important role in understanding soil attributes as well as hydrological processes. Effective method to obtain high quality soil map is therefore important for both soil science research and soil work ability improvement. However,traditional method such as digging soil pits is destructive and time-consuming. In this study, the structure of headwater hillslopes from Hemuqiao catchment(Taihu Basin, China) have been analyzed both by indirect(ground penetrating radar, GPR) and direct(excavation or soil auger) methods. Four transects at different locations of hillslopes in the catchment were selected for GPR survey. Three of them(#1, #2, and #3) were excavated to obtain fullscale soil information for interpreting radar *** found that the most distinct boundary that can be detected by GPR is the boundary between soil and underlain bedrock. In some cases(e.g., 8-17 m in transect #2), in which the in situ soil was scarcely affected by colluvial process, different soil layers can be identified. This identification process utilized the sensitive of GPR to capture abrupt changes of soil characteristics in layer boundaries, e.g., surface organic layer(layer #1) and bamboo roots layer(layer#2, contain stone fragments), illuvial deposits layer(layer #3) and regolith layer(layer #4). However, in areas where stone fragments were irregularly distributed in the soil profile(highly affected bycolluvial and/or fluvial process), it was possible to distinguish which part contains more stone fragments in soil profile on the basis of reflection density(transect #3). Transect #4(unexcavated) was used to justify the GPR method for soil survey based on experiences from former transects. After that, O horizon thickness was compared by a hand *** work has demonstrated that GPR images can be of a potential data source for hydrological predictions.

关键词： Ground Penetrating Radar(GPR) Hillslope Soil structure

Transferability and Scalability of Soil Total Carbon Prediction Models in Florida, USA

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Pedosphere 2018年第6期28卷 856-872页

作者： Sabine GRUNWALD Congrong YU Xiong XIONG department of Soil and Water Sciences University of Florida State Key Laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University College of hydrology and Water Resource Hohai University Agricultural and Biological Engineering department University of Florida

The applicability, transferability, and scalability of visible/near-infrared(VNIR)-derived soil total carbon(TC) models are still poorly understood. The objectives of this study were to: i) compare models of three multivariate statistical methods, partial least squares regression(PLSR), support vector machine(SVM), and random forest methods, to predict soil logarithm-transformed TC(logTC) using five fields(local scale) and a pooled(regional-scale) VNIR spectral dataset(a total of 560 TC spectral datasets), ii)assess the model transferability among fields, and iii) evaluate their up-and downscaling behaviors in Florida, USA. The transferability and up-and downscaling of the models were limited by the following factors: i) the spectral data domain, ii) soil attribute domain,iii) methods that describe the internal model structure of VNIR-TC relationships, and iv) environmental domain space of attributes that control soil carbon dynamics. All soil logTC models showed excellent performance based on all three methods with R^2> 0.86,bias 2.70%, and ratio of prediction error to interquartile range(RPIQ) > 4.54. The PLSR method performed substantially better than the SVM method to scale and transfer the TC models. This could be attributed to the tendency of SVM to overfit models, while the asset of the PLSR method was its robustness when the models were validated with independent datasets, transferred, and/or scaled. The upscaled soil TC models performed somewhat better in terms of model fit(R2), RPD, and RPIQ, whereas the downscaled models showed less bias and smaller RMSE based on PLSR. We found no universal trend indicating which of the four limiting factors mentioned above had the most impact that constrained the transferability and scalability of the models. Given that several factors can impinge on the empirically derived soil spectral prediction models, as demonstrated by this study,

关键词： attribute domain multivariate statistical methods partial least squares regression random forest support vector machine soil carbon dynamics visible-near infrared spectroscopy

Laplace-Transform Finite Element Solution of Nonlocal and Localized Stochastic Moment Equations of Transport

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Communications in Computational Physics 2009年第6期6卷 131-161页

作者： Eric Morales-Casique Shlomo P.Neuman department of hydrology and Water Resources University of ArizonaTucsonArizona 85721USA

Morales-Casique et al.(*** Res.,29(2006),pp.1238-1255)developed exact first and second nonlocal moment equations for advective-dispersive transport in finite,randomly heterogeneous geologic *** velocity and concentration in these equations are generally nonstationary due to trends in heterogeneity,conditioning on site data and the influence of forcing ***-Casique et al.(*** Res.,29(2006),pp.1399-1418)solved the Laplace transformed versions of these equations recursively to second order in the standard deviationσY of(natural)log hydraulic conductivity,and iteratively to higher-order,by finite elements followed by numerical inversion of the Laplace *** did the same for a space-localized version of the mean transport *** we recount briefly their theory and algorithms;compare the numerical performance of the Laplace-transform finite element scheme with that of a high-accuracy ULTIMATE-QUICKEST algorithm coupled with an alternating split operator approach;and review some computational results due to Morales-Casique et al.(*** Res.,29(2006),pp.1399-1418)to shed light on the accuracy and computational efficiency of their recursive and iterative solutions in comparison to conditional Monte Carlo simulations in two spatial dimensions.

关键词： Geologic media porous media random heterogeneity conditioning stochastic transport moment equations nonlocality localization Laplace transform finite elements ultimatequickest

Hydrological impacts of afforestation-A review of research in India

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Journal of Forestry Research 2014年第1期25卷 37-42页

作者： B.Venkatesh N.Lakshman B.K.Purandara Regional Centre National Institute of Hydrology department of Applied Mechanics National Institute of Technology Karnataka

We review the current status of experimental studies in India to understand the linkages between afforestation and hydrology. This discipline deals with the use and management of water, social awareness of environmental problems, and ecosystem limitations on provision of watershed services by river basins in the mountain regions of India. Our review begins with examination of experimental works in tropical countries and proceeds to discussion of initiatives of Indian research institutes and Government organizations towards establishing experimental watersheds to understand the impacts of land cover changes on hydrologic regimes in the Indian sub-continent. This is followed by the review of the experimental work carried out by various authors to assess the impact of land cover changes on major water balance components such as, runoff, groundwater, evapotranspiration and sediment yield. The spatial scales of these experiments have been limited to small watersheds or field plots. This paper also describes impacts of human interventions （such as planta- tions of exotic forest species to restore degraded landscapes） on the water balance components in diverse hydro-geo-environmental conditions in the Indian sub-continent. We focus on identifying the research areas which require immediate attention to develop tools to assist planners and policy makers in assessing and managing the water resources in these complex environments. The review is largely based on research results reported during the last 20 to 30 years.

关键词： afforestation Western Ghats experimental watersheds land-use/cover changes humid tropics

Xin'anjiang Nested Experimental Watershed(XAJ-NEW)for Understanding Multiscale Water Cycle:Scientific Objectives and Experimental Design

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Engineering 2022年第11期18卷 207-217页

作者： Ke Zhang Yunping Li Zhongbo Yu Tao Yang Junzeng Xu Lijun Chao Jin Ni Liutong Wang Yun Gao Yuzhong Hu Zuoding Lin State Key Laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China Yangtze Institute for Conservation and Development Hohai UniversityNanjing 210098China College of hydrology and Water Resources Hohai UniversityNanjing210098China Bureau of hydrology(Information Center)of Taihu Basin Authority Shanghai 200434China Bureau of hydrology of Anhui Province Hefei 230022China department of hydrology Chinese Ministry of Water ResourcesBeijing 100053China

This paper presents the background,scientific objectives,experimental design,and preliminary achievements of the Xin’anjiang nested experimental watershed(XAJ-NEW),implemented in 2017 in eastern China,which has a subtropical humid monsoon climate and a total area of 2674 *** scientific objectives of the XAJ-NEW include building a comprehensive,multiscale,and nested hydrometeorological monitoring and experimental program,strengthening the observation of the water cycle,discovering the spatiotemporal scaling effects of hydrological processes,and revealing the mechanisms controlling runoff generation and partitioning in a typical humid,hilly *** two years of operation,preliminary results indicated scale-dependent variability in key hydrometeorological processes and variables such as precipitation,runoff,groundwater,and soil *** effects of canopy interception and runoff partitioning between the surface and subsurface were also *** operation of this program can further reveal the mechanisms controlling runoff generation and partitioning,discover the spatiotemporal scaling effects of hydrological processes,and understand the impacts of climate change on hydrological *** findings provide new insights into understanding multi scale hydrological processes and their responses to meteorological forcings,improving model parameterization schemes,and enhancing weather and climate forecast skills.

关键词： Water cycle Runoff generation Hydrological processes Hydrological scaling Soil moisture Groundwater Canopy interception