Impacts of Climate Change and Land Use/Cover Change on Regional Hydrological Processes: Case of the Guangdong-Hong Kong-Macao Greater Bay Area

Climate change and land use/cover change (LUCC) have been widely recognized as the main driving forces that can affect regional hydrological processes, and quantitative assessment of their impacts is of great importance for the sustainable development of regional ecosystems, land use planning and water resources management. This study investigates the impacts of climate change and LUCC on variables such as streamflow (SF), soil moisture (SM) and evapotranspiration (ET) in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) by using Soil and Water Assessment Tools (SWAT) model under different scenarios during 1979–2018. The results show that the simulation performances were overall good, with Nash-Sutcliffe Efficiency Coefficient (NSE) and coefficient of determination (R2) greater than 0.80 for the monthly-scale SF calibration and validation. According to the results of trend and change point tests of meteorological series, the baseline period (1979–1997) and the interference period (1998–2018) were determined. Interestingly, other land use types were basically converted to urban land, leading to a rapid urbanization in the GBA. Compared with the SF values of the eight estuaries of the Pearl River Basin in the baseline period, both climate change and LUCC has led to the decrease in the SF values in the interference period, and the combined effect of climate change and LUCC was slightly greater than their individual effect. Overall, climate change and LUCC both have important impacts on regional hydrological processes in the GBA.

Improving the Accuracy of Groundwater Storage Estimates Based on Groundwater Weighted Fusion Model

It is an effective measure to estimate groundwater storage anomalies (GWSA) by combining Gravity Recovery and Climate Experiment (GRACE) data and hydrological models. However, GWSA results based on a single hydrological model and GRACE data may have greater uncertainties, and it is difficult to verify in some regions where in situ groundwater-level measurements are limited. First, to solve this problem, a groundwater weighted fusion model (GWFM) is presented, based on the extended triple collocation (ETC) method. Second, the Shiyang River Basin (SYRB) is taken as an example, and in situ groundwater-level measurements are used to evaluate the performance of the GWFM. The comparison indicates that the correlation coefficient (CC) and Nash-Sutcliffe efficiency coefficient (NSE) are increased by 9–40% and 23–657%, respectively, relative to the original results. Moreover, the root mean squared error (RMSE) is reduced by 9–28%, which verifies the superiority of the GWFM. Third, the spatiotemporal distribution and influencing factors of GWSA in the Hexi Corridor (HC) are comprehensively analyzed during the period between 2003 and 2016. The results show that GWSA decline, with a trend of −2.37 ± 0.38 mm/yr from 2003 to 2010, and the downward trend after 2011 (−0.46 ± 1.35 mm/yr) slow down significantly compared to 2003–2010. The spatial distribution obtained by the GWFM is more reliable compared to the arithmetic average results, and GWFM-based GWSA fully retain the advantages of different models, especially in the southeastern part of the SYRB. Additionally, a simple index is used to evaluate the contributions of climatic factors and human factors to groundwater storage (GWS) in the HC and its different subregions. The index indicates that climate factors occupy a dominant position in the SLRB and SYRB, while human factors have a significant impact on GWS in the Heihe River Basin (HRB). This study can provide suggestions for the management and assessments of groundwater resources in some arid regions.

Development and Assessment of Methods for Predicting Rainfall in Unmeasured Watersheds Using the Relation Between Observed and Sensor-Measured Rainfall

Recently, with the development of information and communication technology and the Internet of Things (IoT), observation technology using sensors is being applied in a variety of ways, such as using a sensor to observe rainfall in an unmeasured area. In this study, the relationship between the rainfall sensor signal (S) and the amount of rainfall (R) was developed through an experiment in an artificial rainfall generator, and the applicability was evaluated through outdoor observation. The coefficient of determination of the relational expression developed through the indoor experiment was 0.95, the mean absolute error was 2.66 mm/hr, the root mean square error was 3.87 mm/hr, the efficiency coefficient was 0.89, and the concordance index was 0.97, showing very high reliability. In the outdoor test results, the error rate was 7.96% when comparing the data from the rainfall sensors in vehicles and the precipitation station, which were not observed at the same location. Despite such errors, it is judged that accurate rainfall observation using a rainfall sensor is possible in an area where a precipitation station is not installed.

A Method for Predicting Efficiency of Perforated Muzzle Brakes

This paper presents a method for predicting a value of a gasdynamic efficiency coefficient for perforated muzzle brakes. The method is based on the interior ballistics modelling for determining gasdynamic flow parameters at the brake inlet and 2D modelling the processes inside the brake with treating vents as circumferential slots. The modelling provides information about the mass flux time changes at the inlet and at the outlet of the brake. Using this information, the mass partition coefficient values and the gasdynamic efficiency coefficient values are calculated. It has been shown that the mass partition coefficient establishes very quickly and it is determined only by the geometry of the brake. The gasdynamic efficiency coefficient establishes after a relatively long time, what demands carrying out calculations for a relatively long time period. However, it has been shown that this problem can be solved by making use of the established ratio of mass fluxes at the outlet and the inlet. So, flow parameters’ values at the inlet are sufficient for determining the gasdynamic efficiency coefficient to the moment of attaining the final value. It has been shown that this value depends on the ballistics and on the vents inclination angle.

Verification and Validation of CFD Modeling for Low-Flow-Coefficient Centrifugal Compressor Stages

In this paper, the numerical model of a centrifugal compressor low-flow stage is verified. The gaps and labyrinth seals were simulated in the numerical model. The task was to determine the optimal settings for high-quality modeling of the low-flow stages. The intergrid interface application issues, turbulence and roughness models are considered. The obtained numerical model settings are used to validate seven model stages for the range of the optimal conditional flow coefficient with Φopt = 0.008–0.018 and the conditional Mach number Mu = 0.785–0.804. The simulation results are compared with the experimental data. The high pressure stage-7 (HPS-7) stage with Φopt = 0.010 and Mu = 0.60 at different inlet pressure of 4, 10 and 40 atm is considered separately. Acceptable validation results are obtained with the recommended numerical model settings; the modeling uncertainty for the polytropic pressure coefficient δη*pol < 4% for the efficiency coefficient δη*pol exceeds the limit of 4% only in the two most low-flow stages, U and V.

Analisis Evaluasi Kinerja Ride Sourcing Dengan Persepsi Pengguna

Transportasi sebagai komponen utama dalam mendukung kelangsungan kehidupan tidak bisa dilepaskan dari aktivitas keseharian manusia. Kedudukan transportasi sebagai penyokong kehidupan manusia mempunyai karakteristik yang berbeda-beda sehingga sangat bersifat spesifik, beberapa faktor yang mempengaruhi hal tersebut antara lain kondisi sosial demografis wilayah. Faktor-faktor tersebut memiliki pengaruh terhadap kinerja transportasi di wilayah tersebut. Tingkat kepadatan penduduk akan memiliki pengaruh signifikan terhadap kemampuan transportasi melayani kebutuhan masyarakat. Seiring dengan perkembangan transportasi, perkembangan teknologi dalam berbagai aspek kehidupan manusia juga semakin berkembang, dan salah satu pengaruh perkembangan teknologi informasi dalam dunia transportasi adalah munculnya platform yang mampu memenuhi kebutuhan sosial masyarakat terhadap transportasi umum, Hal ini tidak lepas dari ketersediaan internet yang luas memberi kita kemampuan untuk berdagang di mana saja dan telah membawa peluang besar di bidang transportasi dan perjalanan. Salah satu moda transportasi publik di Makassar yang saat ini mulai dikelola oleh pihak swasta yang dikenal dengan transportasi berbasis online (Ride Sourcing). Hal inilah yang menarik perhatian peneliti untuk melakukan penelitian terhadap penggunaan transportasi online tersebut dalam hal ini Grab Online dengan menganalisis kinerja transportasi online terhadap persepsi masyarakat dengan menggunakan metode deskriptif kualitatif. Pengolahan data dilakukan dengan metode persentase dan secara statistik dengan regresi linier berganda. Berdasarkan hasil pengolahan data maka diperoleh masing-masing koefisien efektivitas sebesar 0.472 dan koefisien efisiensi sebesar 0.479 yang dianalisa dari beberapa indikator yang paling berpengaruh dalam aspek efektivitas adalah indikator nyaman sebesar 0,485 dan indikator tarif / biaya sebesar 0,562 pada aspek efisiensi. Dimana secara keseluruhan, aspek efektivitas dan efisiensi memberikan pengaruh cukup kuat sebesar 71,3% terhadap persepsi masyarakat dalam penggunaan transportasi online (Grab). The Online Transportation Performance Analysis Of User Perceptions With A Statistical Approach. Transportation as a major component in supporting life cannot be separated from human daily activities. The position of transportation as a supporter of human life has different characteristics so very specifically, several factors that influence this include in the region's social demographic conditions. These factors have an influence on transportation performance in the region. The level of population density will have significance for the ability of transportation to meet the needs of the community. Along with the development of transportation, technological developments in various aspects of human life are also increasingly developing, and one of the developments in information technology in the world of transportation is the improvement of a platform that is able to meet the needs of the public for public transportation. One of the modes of public transportation in Makassar which is currently starting to be managed by private parties is known as online-based transportation. Grab Online by analyzing the performance of online transportation on people's perceptions using descriptive qualitative methods. Data processing is done by the method of contribution and statistics with multiple linear regression. Based on the results of data processing, obtained each acquisition coefficient of 0.472 and efficiency coefficient of 0.479, which was analyzed from some of the most beneficial indicators in the aspect of competence in accordance with comfortable indicators of 0.485 and cost / cost indicators of 0.562 based on efficiency aspects. Where overall, the efficiency and efficiency aspects provide a quite strong amount of 71.3% to the public perception in the use of online transportation (GRAB)

Attribution of climate change and human activities to streamflow variations with a posterior distribution of hydrological simulations

Hydrological simulations are a main method of quantifying the contribution rate (CR) of climate change (CC) and human activities (HAs) to watershed streamflow changes. However, the uncertainty of hydrological simulations is rarely considered in current research. To fill this research gap, based on the Soil and Water Assessment Tool (SWAT) model, in this study, we propose a new framework to quantify the contribution rate of climate change and human activities based on the posterior histogram distribution of hydrological simulations. In our new quantitative framework, the uncertainty of hydrological simulations is first considered to avoid the phenomenon of "equifinality for different parameters", which is common in hydrological simulations. The Lancang River (LR) Basin in China, which has been greatly affected by human activities in the past two decades, is then selected as the study area. The global gridded monthly sectoral water use data set (GMSWU), coupled with the dead capacity data of the large reservoirs within the LR basin and the Budyko hypothesis framework, are used to compare the calculation result of the novel framework. The results show that (1) the annual streamflow at Yunjinghong station in the Lancang River Basin changed abruptly in 2005, which was mainly due to the construction of the Xiaowan hydropower station that started in October 2004. The annual streamflow and annual mean temperature time series from 1961 to 2015 in the LR Basin showed a significant decreasing and increasing trend at the α = 0.01 significance level, respectively. The annual precipitation showed an insignificant decreasing trend. (2) The results of quantitative analysis using the new framework showed that the reason for the decrease in the streamflow at Yunjinghong station was 42.6 % due to climate change, and the remaining 57.4 % was due to human activities, such as the construction of hydropower stations within the study area. (3) The comparison with the other two methods showed that the contribution rate of climate change calculated by the Budyko framework and the GMSWU data were 37.2 % and 42.5 %, respectively, and the errors of the calculations of the new framework proposed in this study were within 5 %. Therefore, the newly proposed framework, which considers the uncertainty of hydrological simulations, can accurately quantify the contribution rate of climate change and human activities to streamflow changes. (4) The quantitative results calculated by using the simulation results with the largest Nash-Sutcliffe efficiency coefficient (NSE) indicated that climate change was the dominant factor for streamflow reduction, which was in opposition to the calculation results of our new framework. In other words, our novel framework could effectively solve the calculation errors caused by the “equifinality for different parameters” of hydrological simulations. (5) The results of this case study also showed that the reduction in the streamflow in June and November was mainly caused by decreased precipitation and increased evapotranspiration, while the changes in the streamflow in other months were mainly due to human activities such as the regulation of the constructed reservoirs. In general, the novel quantitative framework that considers the uncertainty of hydrological simulations presented in this study has validated an efficient alternative for quantifying the contribution rate of climate change and human activities to streamflow changes.

PERFORMANCE OF LINEAR MODELS IN PREDICTING CATION EXCHANGE CAPACITY OF CALCAREOUS SOILS

Determination of soil cation exchange capacity (CEC) in lab is cumbersome, time consuming, and costly. Accordingly, this article attempted to formulate pedotransfer functions for predicting it using some soil physical and chemical properties e.g., sand (SA), silt (SI), clay (CL), organic matter (OM) and calcium carbonate (CC). This research included four steps: preparing soil database; selecting independent variables which are related to CEC value; formulating models using NCSS 12.0.2 software, and the last step is to achieve specific objective of the research which is the comparsion among models by a series of efficiency criteria: root mean square error (RMSE), Nash-Sutcliffe model efficiency coefficient (EF), average absolute percent error (AAPE), and percentage of improving model efficiency (PIME). The statistical results of the research indicated that CEC of calcareous soils could be predicted from models that have one variable (CL), two variables (CL and OM), and three variables (CL, OM, and CC) with slight decrease in the RMSE (2.95402, 2.81180, and 2.79268) respectively, and slight increase in the EF (0.887360, 0.898448, and 0.90023) respectively. While the reliable models to predict soil CEC are formulated from the fewer number of independent variables with having the lowest points of the standardized residual of CEC that greater than +2 cmolc kg-1).

Regularity of transportation for cohesive bank-collapsed materials

The transportation of bank-collapsed materials is a key issue among river evolution processes. In this study, a series of flume experiments were conducted to monitor riverbank collapse processes and to explore the regularity of transportation for cohesive collapsed materials. The collapsed materials, both the bed and suspended loads, that transformed from collapsed materials were intensively evaluated under experimental conditions. The results showed that the collapsed materials contributed to 12～20 % sedimentation in situ, 8～14 % suspended loads and 70～80 % bed loads. In addition, the bed load motion efficiency coefficient (eb), suspended load motion efficiency coefficient (es) and sediment carrying capacity factor (U3/gRω) were introduced to describe the transportation of collapsed materials in terms of energy dissipation. This research provides theoretical and practical benefits for predicting channel evolution processes.

Economic and energy evaluation of sainfoin growing technology elements for green feed

One of the main directions of fodder production intensification is the cultivation of fodder crops and fodder harvesting from them at the lowest cost of energy and labor resources, the maximum yield of fodder products per unit area, and 1 UAH of production costs. To successfully perform this task, it is necessary, first of all, to increase the productivity of forage crops, the use of cost-effective and energy-saving technologies and increase the efficiency of fertilizer application. One of the most valuable perennial legumes is sainfoin, which is characterized by high fodder value, unpretentiousness to growing conditions and has great agronomic value. At the same time, the existing technologies for growing sainfoin for fodder purposes remain energy- and resource intensive. The aim of the research was to determine the influence of mineral fertilizers and seed inoculation on the economic and energy efficiency of the sainfoin growing technology on green fodder. Experimental studies were conducted during 2016-2018 on the research field of the Department of Forage Production, Land Reclamation and Meteorology, located in the NULES of Ukraine "Agronomic Research Station" on typical low-humus chernozem. Experimental research was conducted during 2016-2018 on the research field of the Department of Forage Production, Land Reclamation and Meteorology, located in the NULES of Ukraine "Agronomic Research Station". The scheme of the experiment included the following factors: factor A - varieties of sainfoin: Amethyst Donetskyi, Adam, Smaragd; factor B - fertilizer, inoculation: 1) without fertilizers, 2) N45R60K90 + seeds inoculation, 3) P60K90 + seeds inoculation. As nitrogen fertilizer was used ammonium nitrate 34%, phosphorus - simple superphosphate 19%, potassium - potassium salt 56%. Method of sowing - row, spring, coverless. Inoculation was performed by Rhizotorphin. Economic evaluation of the results of field experiments was carried out in accordance with generally accepted methods developed by the Institute of Cereals NAAS, the Institute of Feed and Agriculture of Podillya NAAS, NSC "Institute of Agrarian Economics" and other research institutions. Calculations of energy efficiency of growing sainfoin for green fodder were calculated according to the "Methodology of bioenergy assessment of technologies for the production of livestock products and feed." According to the economic assessment, the calculations of monetary and material costs are performed taking into account the full mechanization of works. The costs for them are calculated according to the technological maps developed in the process of research. The cost of seeds, fertilizers and fuel was taken at wholesale prices as of January 1. 2019, 1 ton of fodder units of sainfoin was equated to the cost of 1 ton of feed grain. According to the results of research, it was found that when setting up an experiment with different varieties of sainfoin, both with the introduction of mineral fertilizers and without them, the costs were the same. Economic indicators differed significantly at the end of the growing season, as the productivity of different varieties of sainfoin differed significantly not only due to the biological characteristics of varieties, but also as a result of their different reactions to mineral fertilizers. According to the obtained results of the calculation, among the studied varieties of sainfoin the highest conditionally net profit (13354-16504 UAH/ha) and the level of profitability (129-176%), as well as the lowest cost of 1 ton of feed units (1431-1627 UAH per 1 ton) and crude protein (UAH 8393–7291 per 1 ton) were observed on crops of sainfoin Amethyst Donetskyi. In general, the most economically feasible in terms of profitability (176%) was the cultivation of this variety in the absence of fertilizer. The highest indicators of EEC (energy efficiency coefficient) (4.6-6.3) were observed for the cultivation of sainfoin variety Amethyst Donetskyi in the absence of mineral fertilizer or application of phosphorus-potassium fertilizers only.