Search

Copyright of Pearl River is the property of Pearl River Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil saturation, coupled with intense rainfall can lead to severe flooding and geological disasters, and understanding the spatiotemporal distribution of hydrological elements within a given region is critical for effective disaster mitigation. The CREST distributed hydrological model, incorporating distributed parameters such as soil water capacity and saturated hydraulic conductivity, was used to simulate runoff processes in Beijiang River Basin from 2019 to 2022. The analysis focused on the spatiotemporal distribution characteristics of precipitation, soil moisture, and runoff before and after the once-in-a-century flood that occurred on June 21, 2022, and further explored the relationship among hydrological elements, landslides, and floods. The results show that the Nash-Sutcliffe efficiency coefficients (NSEs) of the model are 0.84 and 0.82, and Pearson correlation coefficients (CCs) are 0.92 and 0.91, respectively, in the periodic and validation periods. The relative deviation is small, indicating that the CREST model has high simulation accuracy in the Beijiang River Basin. The results find that prior to the once-in-a-century flood event on June 21, 2022, the soil moisture levels across the basin were generally high. As the precipitation continued, the soil approached full saturation, and downstream discharge exceeded 16 000 m3/s. After the flood, as precipitation decreased, both soil moisture and runoff levels dropped. A comparison between the simulated average soil moisture for 2022 and historical landslide locations reveals that areas with high kernel density of historical landslides overlap with regions with high soil moisture in the southeastern part of the basin. Comprehensively, the southeastern region, located downstream, faces a higher risk of combined flood and geological hazards during the flood season.

The distributed hydrological model is the development trend of hydrological models. The model of Nanjing Research Institute of Hydrology (NRIHM) is a lumped hydrological model with a flexible architecture. In order to explore the feasibility and adaptability of using a distributed hydrological model based on NRIHM to carry out hydrological simulation in the humid watershed, the Nandawa-Shahe nested watershed in the humid area was studied. Firstly, based on the construction idea of the NRIHM runoff generation model, a one-layer runoff generation model and a two-layer runoff generation model were constructed. The runoff generation simulation verification at the grid point scale was carried out by using the observation results of the natural experimental watershed. The simulation results were compared, and it was found that the two-layer parabola combination method had a better simulation effect. Based on this runoff generation calculation method, a distributed hydrological model with a two-layer soil structure was constructed. The application was carried out in the catchment area above the Shaheji Reservoir in the Chuhe River system of the Yangtze River. The average deterministic coefficients of the calibration period and the verification period were 0.80 and 0.86, respectively. The relative errors of average flood peak and flood volume were also less than 20 %, indicating that the model could better simulate the actual runoff process, which preliminarily proved that the model had good applicability in humid areas.

Copyright of Pearl River is the property of Pearl River Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Loess Plateau region is seriously affected by soil erosion, water scarcity, and fragile ecosystems, which severely hinder social and economic development in the region. There is currently a lack of quantitative analysis and research on how human activities will affect the changes in water and sediment on the Loess Plateau and how to allocate the areas for reforestation and grassland restoration. This study focuses on the Beiluo River Basin in the Loess Plateau, analyzing the spatiotemporal variations of precipitation, runoff, water resources, sediment yield and normalized difference vegetation index (NDVI) over the past 20 years. The study establishes a distributed hydrological model for the basin, quantitatively evaluates the impact of returning farmland to forests and grassland on water resources and sediment transport, and explores the optimal land retirement plan under different decision-making conditions. The results show that the total water resources, runoff, groundwater resources and sediment yield in the basin are decreasing, and the annual reductions are 7×108 m3, 1×108 m3, 1.2×108 m3, and 1.6×104 tons respectively. While NDVI and precipitation is increasing, and the annual increases are 0.0064 and 65×108 m3 respectively. The continuous increase in NDVI has resulted in a reduction in runoff volume and sediment transport. Returning farmland to forests and grassland or increasing vegetation density can reduce the amount of runoff and sediment transport, with sediment transport being more sensitive. Considering both the impact on runoff and sediment transport, based on multi-objective optimization, an optimal allocation proposal for the area of returning farmland to forest and grass is proposed. The optimal land retirement area is 28.1%. This study provides decision-making support for ecological environment construction, soil and water conservation, and rational utilization of water and sediment resources in the Loess Plateau region.

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Flood in small and medium-sized catchments can be characterized by the short concentration time, high flow velocity, fierce attack, and violent stage change. Mountain torrents also occur frequently in these small and medium-sized catchments. But, it is very difficult to carry out flood forecasting and early warning, due mainly to those located in the ungauged areas. Therefore, it is a high demand to improve the forecast accuracy in the operational hydrology, especially in the areas without enough measured data. In this study, an energy model was proposed to estimate the velocity of overland flow for the high accuracy in the simulation of flow concentration. Firstly, the spatial distribution of the energy was determined for the water particles in the basin. The gravitational potential energy was gradually transformed into kinetic energy using the iterative computation from the upstream to the downstream, according to the flow direction. Secondly, the spatial energy field was constructed considering the energy loss, and then the overland flow velocity was estimated to generate the spatial velocity field. Thirdly, the concentration time was calculated to count the number of grids, when the water particles on each grid reached the outlet of the watershed. Finally, the geomorphic unit hydrograph was generated to determine the relationship between the catchment area and concentration time. The study area was set as the Zhuxipo basin in Yiyang City, Hunan Province, China, located at the source of Yixi, a tributary of the Zishui River. The Zhuxipo basin was divided into 57 sub watersheds using Digital Elevation Model (DEM) data with a resolution of 30 m×30 m. A distributed model was then constructed to simulate 36 floods in the study area from 1984 to 2020. A Xinanjiang model, geomorphic unit hydrograph model, and Muskingum Routing were used to calculate the runoff generation, overland flow concentration, and river network flow concentration, respectively. The geomorphic unit hydrograph was also extracted by the Energy Conversion Method (EC-GUH) and Slope Rain Intensity Method (SR-GUH). At the same time, the EC-GUH and SR-GUH were also used to compute the overland flow concentration for the evaluation. The average flow velocity of the hydrological section was then calculated to estimate the range of energy residual coefficient (the only parameter of EC-GUH), according to the total water volume and kinetic energy of 36 floods. The results show that the EC-GUH method performed better than the SR-GUH method, where the proportion of floods with a peak time error no more than 1 h increased from 30.5% to 83.3%, the number of floods with Nash-Sutcliffe efficiency coefficient no less than 0.9 increased from 9 to 17, and the average Nash-Sutcliffe efficiency coefficient increased from 0.82 to 0.89, indicating a significantly improved simulation accuracy. It was estimated that the range of energy residual coefficient was [0.008, 0.014] under the flow velocity. In this case, the proportion of flood simulation with the Nash-Sutcliffe efficiency coefficient not less than 0.9 was 44%-50%, which was close to the calibration. It infers that the parameter can be estimated indirectly using the average velocity of the outlet section. Consequently, the concentration model presented a clear physical meaning, whose parameters were determined by the calibration or measurement for the cross and vertical section of the channel. As such, the obtained velocity can be used to simulate the flow concentration of overland and river networks. The finding can also provide a reliable idea for the concentration evaluation in the ungauged basins. [ABSTRACT FROM AUTHOR]

The calibration processes of current distributed hydrological model has been a critical issue in data-scared or ungauged regions. In this study, we setup a hydrological model, in which, the variable saturated zone concept originated from the real-time interactive basin simulator is applied for runoff generation and the grid water droplet method for flow concentration. We also proposed a method for parameter estimation based on the characteristics of underlying surface. Based on field infiltration experiments and parameter sensitivity analysis, the quantitative statistical relationships were built between two sensitive parameters (surface saturated hydraulic conductivity K0z, coefficient of attenuation of saturation hydraulic conductivity with depth f) and the topographic parameters and soil types. The overland confluence parameters were determined by field overland flow observation experiments. The proposed parameter estimation method was verified in selected basins. Our results showed that: ① The proposed method for K0z estimation contributes to a better modeling performance for flood simulation in Jiangwan experimental watershed, the average Nash- Sutcliffe efficiency coefficient increased from 0. 82 to 0. 86, and the average absolute values of peak and flood volume errors decreased by 2. 2% and 0. 95%, respectively, but the average absolute value of the peak present time error increased by 4% (still controlled within 2 h). ② Using the measured flood data of 14 basins such as Jiangwan to calibrate the parameter f, we established the quantitative relationship between the calibrated parameter f and the soil type data of different depths was built in 14 basins including Jiangwan, and further tested in other six basins. The parameter f estimated by the soil type data of different depths was very close to that determined by traditional model calibration processes, the average absolute relative error is 2. 8%, the average Nash-Sutcliffe efficiency coefficient of the flood simulation is 0. 83, and the average absolute values of flood peak error and flood volume error were 10. 07% and 6. 86%, respectively, and the average absolute peak present time error was 2. 61 h. Our results indicated that the proposed methods for determining sensitive runoff generation parameters are applicable in data-sparse areas and could provide a better or comparable parameter estimation and flood simulation than that determine by field measurements, model calibration, remote sensing data estimation, and other methods. [ABSTRACT FROM AUTHOR]

In order to study the runoff changes in the arid oasis irrigation area,this paper constructs a distributed hydrological model of Yanqi Basin based on SWAT model with the Chinese meteorological assimilation driving datasets (CMADS) from 1955 to 2017,traditional hydrometeorological station data,land use data,soil data,digital elevation data,analyzes the sensitivity of parameters by SUFI-2 (Sequential Uncertainty Fitting) algorithm,calibrates several important parameters influencing runoff simulation results through SWAT-CUP (SWAT Calibration Uncertainty Procedures) software,and verifies the model by the measured runoff from 1991 to 2017.The results show that:the simulated runoff of Yanqi Basin in Xinjiang for a long time scales coincides with the measured runoff.During the calibration period and verification period,the Nash coefficient (NES) is above 0.82,the Pearson correlation coefficient (R2) is 0.86 and 0.90 respectively,and the relative error (Re) is less than 10.Therefore,SWAT model is well applicable to the runoff simulation of Yanqi Basin.Based on this,runoff changes from 2016 to 2100 in Yanqi Basin under the scenarios of RCP4.5 and RCP8.5 are simulated.It can be found that precipitation changes in Kaidu River basin have a significant impact on runoff in Yanqi Basin,that is,when precipitation increases by 20% and temperature increases by 2°C,the runoff increases by 26.53% compared with the current year.

Temporal-spatial discretization parallel computing is a parallel method with high efficiency. However, previous researches are mainly based on the MPI framework and multi-tree coding rules. In order to realize temporal-spatial parallel computation in distributed hydrological model by widely used Pfafstetter, this paper adopted the OpenMP programming model, the layered simulation unit method and temporal-spatial discretization method based on Pfafstetter coding were designed for the flow routing process of WEP-L distributed hydrological model. The layered simulation unit method established the sub-watershed topology table according to the Pfafstetter coding rules. The sub-basin was stratified according to the order of the upstream to the downstream. Then, on this basis, the time factor was taken into account to re-stratify to realize temporal-spatial discretization. Finally, the sub-watershed simulation tasks which were independent of each other in time and space of the same layer were assigned to different threads to realize parallel computing. The Yellow River basin was selected as the research area and the parallel effect was tested with a different number of threads. The experimental results show that the flow routing parallelization improves the simulation efficiency of the model. Based on a CPU with 20 cores，when only the layered simulation unit algorithm is considered, the maximum acceleration ratio is 4.14. However, the acceleration ratio can reach to 8.17 when temporal-spatial discretization is considered. [ABSTRACT FROM AUTHOR]

Robust calibration of physically based hydrological models is essential for the quantification of runoff components in snow and glacier melt runoff fed basins. This study evaluates a hydrograph partitioning curve (HPC) based calibration technique utilizing seasonality of precipitation and temperature in the Yarlung Tsangpo River basin. The HPC indicate the separating periods when various runoff components,including baseflow,snowmelt and glacier melt runoff,and rainfall direct runoff,dominate the basin hydrograph. Parameters of the THREW distributed hydrological model are grouped into four categories according to their controls on the runoff processes,and subsequently calibrated in a stepwise procedure using extracted HPC. The HPC-based calibration method is evaluated against traditional methods on the basis of robustness,performance of discharge simulations in sub-basins,and estimates of snow water equivalent (SWE) across the whole basin. Results show that:① The HPC-based calibration method provides results comparable to traditional methods in the calibration period while improving the discharge simulation for the evaluation period relative to single objective calibration methods;② The HPC-based calibration method shows superiority in producing robust sub-basin discharge and tends to estimate smaller bias for the basin SWE;③ The HPC-based calibration method estimates the contributions of snowmelt,glacier-melt,and rainfall direct runoff to discharge during 2001—2015 as 20%,14% and 66%,respectively,while the traditional calibration methods yield a higher contribution for glacier-melt runoff and lower contribution for snowmelt runoff. Our findings indicate the potential of the HPC-based calibration method as a tool to quantify the contribution of runoff components,thus improving the modeling of hydrological behaviors under changing climate conditions for similar basins. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Research of Environmental Sciences is the property of Research of Environmental Sciences Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Research of Environmental Sciences is the property of Research of Environmental Sciences Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Evapotranspiration (ET) is an important parameter of agriculture, meteorology and hydrology research, and also an important part of the global hydrological cycle. This paper applied the improved DHSVM distributed hydrological model to estimate daily ET of Tahe area in 2007 using leaf area index and other surface data extracted TM remote sensing data, and slope, aspect and other topographic indices obtained by using the digital elevation model. The relationship between daily ET and daily watershed outlet flow was built by the BP neural network, and a water balance equation was established for the studied watershed, together to test the accuracy of the estimation. The results showed that the model could be applied in the study area. The annual total ET of Tahe watershed was 234. 01 mm. ET had a significant seasonal variation. The ET had the highest value in summer and the average daily ET value was 1. 56 mm. The average daily ET in autumn and spring were 0. 30, 0. 29 mm, respectively, and winter had the lowest ET value. Land cover type had a great effect on ET value, and the broadleaf forest had a higher ET ability than the mixed forest, followed by the needle leaf forest. [ABSTRACT FROM AUTHOR]