Yunqing Xuan
Swansea University, Civil Engineering, Faculty Member
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
The paper investigates compound flooding from waves, sea surge and river flow in northern Jakarta, Indonesia, which is a global hotspot of flooding, by combining process-based coastal and river models. The coastal hydrodynamic modelling... more
The paper investigates compound flooding from waves, sea surge and river flow in northern Jakarta, Indonesia, which is a global hotspot of flooding, by combining process-based coastal and river models. The coastal hydrodynamic modelling of Jakarta Bay in Indonesia shows that coastal storms can lead to a substantial increase in sea water level due to wind and wave setup in the nearshore areas, including Muara Angke river inlet. The compound flood hazard from a range of flood scenarios was simulated and analysed. The results reveal that low-lying areas around the river inlet are prone to flooding even during regular, low-intensity storm events, while rarer storms caused extensive floods. Floods were not caused by direct overwashing of sea defences but by overspill of the banks of the river inlet due to high sea water level caused by wind set up, wave setup, and sea surge obstructing the drainage of the river and elevating its water level during storms. We also found that the sea level...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Complicated model structure and time consuming simulations increase the use of models in decision making process when the stakeholders are not familiar with the tools. Therefore, the user interface (UI) design for decision support system... more
Complicated model structure and time consuming simulations increase the use of models in decision making process when the stakeholders are not familiar with the tools. Therefore, the user interface (UI) design for decision support system (DSS) should not only maintain the scientific model structure but also simplify the interaction with models and the need for easy access. Nowadays, web-based techniques have been developed so fast and Web 2.0 brings the time when web-based systems challenge the desktop applications. This technology also needs to be taken into account in the DSS development for water resource management because the stakeholders are spatial distributed and the internet is the most commonly available resource. In this paper, we developed a WebDSS prototype named VisREACHER that is fully based on Free and Open Source Software (FOSS). It is a stand-alone web page with the decision model running behind which means it offers more than a visualization system of a prepared d...
Research Interests:
Research Interests:
<p><span>This two-year trial aims to bring together academics and industrial partners from UK and China to conduct a pilot study on the use of the active phased array radar to provide early urban flood warnings... more
<p><span>This two-year trial aims to bring together academics and industrial partners from UK and China to conduct a pilot study on the use of the active phased array radar to provide early urban flood warnings for Chinese mega cities, which facing challenging urban flood issues. This is the first in the world of cascade modelling using the cutting-edge active phase array radar (APRA) to provide rainfall monitoring and nowcasting information for a real-time two-dimension urban drainage model. The collaboration built up by this project and the first-hand experiment data will serve well to further catalyse the taking-up of state-of-the-art weather radars for urban flood risk management, and to tackle the innovation in tuning the radar technology to fit the complex urban environment as well as advanced modelling facilities that are designed to link the observations, providing decision making support to the city government. Recommendations for applying high spatial-temporal resolution precipitation data to real-time flood forecasting on an urban catchment are provided and suggestions for further investigation are discussed.</span></p>
Research Interests:
<p> Flooding is widely regarded as one of the most dangerous natural hazards worldwide. It often arises from various sources either individually or combined such as extreme rainfall, storm surge, high sea level,... more
<p> Flooding is widely regarded as one of the most dangerous natural hazards worldwide. It often arises from various sources either individually or combined such as extreme rainfall, storm surge, high sea level, large river discharge or the combination of them. However, the concurrence or close succession of these different source mechanisms can lead to compound flooding, resulting in larger damages and even catastrophic consequences than those from the events caused by the individual mechanism. Here, we present a modelling framework aimed at supporting risk analysis of compound flooding in the context of climate change, where nonstationary joint probability of multiple variables and their interactions need to be quantified.The framework uses the Block Bootstrapping Mann-Kendall test to detect the temporal changes of marginals, and the correlation test associated with the Rolling Window method to estimate whether the correlation structure varies with time; it then evaluates various combinations of marginals and copulas under stationary and nonstationary assumptions. Meanwhile, a Bayesian Markov Chain Monte Carlo method is employed to estimate the time-varying parameters of copulas. </p>
Research Interests:
In this article, we present the use of the coupled land surface model and groundwater flow model SWAT-MODFLOW with the decision support tool WEAP (Water Evaluation and Planning software) to predict future surface water abstraction... more
In this article, we present the use of the coupled land surface model and groundwater flow model SWAT-MODFLOW with the decision support tool WEAP (Water Evaluation and Planning software) to predict future surface water abstraction scenarios in a complex river basin, under conditions of climate change. The modeling framework is applied to the Dee River catchment in Wales, United Kingdom. Regarding hydrology, the coupled model improves overall water balance and low streamflow conditions, compared to a stand-alone SWAT model. The calibrated SWAT-MODFLOW is employed with high resolution climate model data from the UKCP18 project with future scenario of RCP85 from 2020 to 2040. Then, water supply results from SWAT-MODFLOW are fed into WEAP as input for the river reach in the downstream region of the river basin. This system is utilized to create various future scenarios of surface water abstraction of public water supply in the downstream region: maximum licensed withdraw, 50 % authorize...
Research Interests:
Research Interests:
Availability of water resources is one of the most fundamental factors that affect socio-economic development as well as environment. This is especially true in arid areas of China where this effect has always been highlighted by... more
Availability of water resources is one of the most fundamental factors that affect socio-economic development as well as environment. This is especially true in arid areas of China where this effect has always been highlighted by composition of vegetation and limited biosphere cycle. On the other hand, uncontrolled water utilization often causes desertification and disappearance of oases. Many oases in arid areas nowadays face threats from both changing climate and impacts from human activities such as the ...
Research Interests:
This paper presents an analysis of the annual precipitation observed by a network of 30 rain gauges in Iraq over a 65-year period (1941–2005). The simulated precipitation from 18 climate models in the CMIP5 project is investigated over... more
This paper presents an analysis of the annual precipitation observed by a network of 30 rain gauges in Iraq over a 65-year period (1941–2005). The simulated precipitation from 18 climate models in the CMIP5 project is investigated over the same area and time window. The Mann–Kendall test is used to assess the strength and the significance of the trends (if any) in both the simulations and the observations. Several exploratory techniques are used to identify the similarity (or disagreement) in the probability distributions that are fitted to both datasets. While the results show that large biases exist in the projected rainfall data compared with the observation, a clear agreement is also observed between the observed and modelled annual precipitation time series with respect to the direction of the trends of annual precipitation over the period.
Research Interests:
This paper presents an analysis of the temporary variation of the area-orientated annual maximum daily rainfall (AMDR) with respect to the three spatial properties: location, size and shape of the region-of-interest (ROI) in Great Britain... more
This paper presents an analysis of the temporary variation of the area-orientated annual maximum daily rainfall (AMDR) with respect to the three spatial properties: location, size and shape of the region-of-interest (ROI) in Great Britain and Australia using two century-long datasets. The Maximum Likelihood and Bayesian Markov-Chain-Monte-Carlo methods are employed to quantify the time-varying frequency of AMDR, where a large proportion of the ROIs shows a non-decreasing level of most frequent AMDR. While the most frequent AMDR values generally decrease with larger-sized ROIs, their temporal variation that can be attributed to the climate change impact does not show the same dependency on the size. Climate change impact on ROI-orientated extreme rainfall is seen higher for rounded shapes although the ROI shape is not as significant as the other two spatial properties. Comparison of the AMDR at different return levels shows an underestimation by conventionally used stationary models ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
This paper presents the development and applications of a new, open-source toolbox that aims to provide automatic identification and classification of hydroclimatic patterns by their spatial features, i.e., location, size, orientation,... more
This paper presents the development and applications of a new, open-source toolbox that aims to provide automatic identification and classification of hydroclimatic patterns by their spatial features, i.e., location, size, orientation, and shape, as well as the physical features, i.e., the areal average, total volume, and spatial distribution. The highlights of this toolbox are: (1) incorporating an efficient algorithm for automatically identifying and classifying the spatial features that are linked to hydroclimatic extremes; (2) use as a frontend for supporting AI-based training in tracking and forecasting extremes; and (3) direct support for short-term nowcasting of extreme rainfall via tracking rainstorm centres and movement. The key design and implementation of the toolbox are discussed alongside three case studies demonstrating the application of the toolbox and its potential in helping build machine learning applications in hydroclimatic sciences. Finally, the availability of...
Research Interests:
Research Interests:
Research Interests:
We present a statistical method to quantify the contribution of urbanization to precipitation changes during 1958–2017 across the greater Beijing–Tianjin–Hebei metropolitan region in northern China. We find distinct trends in... more
We present a statistical method to quantify the contribution of urbanization to precipitation changes during 1958–2017 across the greater Beijing–Tianjin–Hebei metropolitan region in northern China. We find distinct trends in precipitation in the past six decades: decreasing in annual and summer while increasing in other seasons. The spatial patterns of precipitation show discernible terrain-induced characteristics with high values in the buffer zones of plain and mountain areas and low values in the northwestern mountainous regions. Our results indicate that although urbanization has limited impacts on the trends and spatial patterns of precipitation, it has a positive contribution to the changes in precipitation for about 80% of the comparisons conducted, especially in autumn (100%), with the negative contribution being dominant in summer (66.67%). In addition, these results are sensitive to the classifications of urban and rural stations, suggesting that how to classify urban/rur...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Abstract The use of weather radars for precipitation forecasting in fast response river basins is very important for early warning systems. Some of the most used techniques, such as radar echo tracking, which is based on patterns and... more
Abstract The use of weather radars for precipitation forecasting in fast response river basins is very important for early warning systems. Some of the most used techniques, such as radar echo tracking, which is based on patterns and correlations, do not contemplate the decay/growth mechanism of rainfall systems. Numerical weather prediction models do consider much more information than radars, but their accuracy is less than the radar forecast; at least for a lead time of up to several hours. In this paper we explore the ...
Research Interests:
First of all, the reader has a hard work (I did) finding in the text the description of how the UK territory is separated in different zones, and the shape of these zones. Why considering only the mainland of UK ? Apparently, the... more
First of all, the reader has a hard work (I did) finding in the text the description of how the UK territory is separated in different zones, and the shape of these zones. Why considering only the mainland of UK ? Apparently, the territory is cut in non-rectangular zones , but why not simply using rectangular zones, since only the very mainland part of UK is studied ? (this is, in my opinion, an important issue with the paper). All the paragraph of the top of page 7 is rather obscure : what does the sentence "the focus is on the impact of location only" mean ? What do the lines 173-174 mean ? Do they mean that the zones have a common shape (that of Figure 1a ? Why this one ?) ? Why considering "randomized locations" ? It is not normal that such crucial description of what the study is about, is so badly described. And the reader can only wonder why a non-negligible part of the UK territory is not covered by the study (the seashores, and all the space between the ...
The use of weather radars for precipitation forecasting in fast response river basins is very important for early warning systems. Some of the most used techniques, such as radar echo tracking, which is based on patterns and correlations,... more
The use of weather radars for precipitation forecasting in fast response river basins is very important for early warning systems. Some of the most used techniques, such as radar echo tracking, which is based on patterns and correlations, do not contemplate the decay/growth mechanism of rainfall systems. Numerical weather prediction models do consider much more information than radars, but their accuracy is less than the radar forecast; at least for a lead time of up to several hours. In this paper we explore the integration of the two forecasting approaches. The MM5 numerical weather prediction model is set up for a region in southeast England. The Nimrod radar data, for the same region, from the British Atmospheric Database Centre (BADC) is adapted and used as reference. The M5 prime regression model tree is used for the integration of both models. The results show that the proposed integration reduced the error of tracking significantly. The results presented here have been evalu...
Research Interests:
Abstract This note provides a concise presentation of the state-of-the-art methods to assess climate change impacts on water systems with reference to the Nile basin. In particular, recent studies dealing with climate change in the Nile... more
Abstract This note provides a concise presentation of the state-of-the-art methods to assess climate change impacts on water systems with reference to the Nile basin. In particular, recent studies dealing with climate change in the Nile basin are summarized and guidelines for dealing with uncertainty in planning water resources in a changing climate are illustrated. The paper also includes potential strategy recommendations to policy and decision makers for planning adaptation measures in the water sector. In particular, the need to better ...
Research Interests:
Research Interests: Geology()
()
Research Interests:
Non-point source pollution from excessive use of fertilizers in agriculture is a major cause of the eutrophication problem in China. Understanding farmers’ decision-making concerning fertilization and identifying the influencing factors... more
Non-point source pollution from excessive use of fertilizers in agriculture is a major cause of the eutrophication problem in China. Understanding farmers’ decision-making concerning fertilization and identifying the influencing factors in this process are key to tackling overfertilization and related pollution issues. This paper reports a study on modelling decisions about fertilizer use based on data collected from 200 farmer households in the Three Gorges Reservoir area of China, using a well-fitted artificial neural network (ANN) with incorporated variance-based sensitivity analysis. The rate of fertilizer use estimated from the model is in good agreement with observed data. The model is further validated and tested by comparing the simulated and observed values. Results show that the model is able to identify the influencing factors and their interactions causing the variation in fertilizer use and to help pinpoint the underlying reasons. It is found that the farmers’ fertiliza...
Research Interests:
This paper presents an improved method of using threshold of peak rainfall intensity for robust flood/flash flood evaluation and warnings in the state of São Paulo, Brazil. The improvements involve the use of two tolerance levels and the... more
This paper presents an improved method of using threshold of peak rainfall intensity for robust flood/flash flood evaluation and warnings in the state of São Paulo, Brazil. The improvements involve the use of two tolerance levels and the delineating of an intermediate threshold by incorporating an exponential curve that relates rainfall intensity and Antecedent Precipitation Index (API). The application of the tolerance levels presents an average increase of 14% in the Probability of Detection (POD) of flood and flash flood occurrences above the upper threshold. Moreover, a considerable exclusion (63%) of non-occurrences of floods and flash floods in between the two thresholds significantly reduce the number of false alarms. The intermediate threshold using the exponential curves also exhibits improvements for almost all time steps of both hydrological hazards, with the best results found for floods correlating 8-h peak intensity and 8 days API, with POD and Positive Predictive Valu...