Tiejian Li

• PhD
• Professor (Associate) at Tsinghua University

Floods in mountainous river basins are generally highly destructive, usually causing enormous losses of lives and property. It is important and necessary to develop an effective flood forecast method to prevent people from suffering flood disasters. This paper proposed a general framework for a service-oriented architecture (SOA) for ensemble flood...

This paper introduces the development of a dynamic parallel algorithm for conducting hydrological model simulations. This new algorithm consists of a river network decomposition method and an enhanced mastereslave paradigm. The decomposition method is used to divide a basin river network into a large number of subbasins, and the enhanced masteresla...

A new codification method (named a modified binary tree codification method) is developed for coding drainage networks. To express the inner topological structure of a drainage basin, it is necessary to delineate and code digital drainage networks from digital elevation model datasets. In this study, the established software TOPAZ is used to deline...

In July 2023, an extreme precipitation event (EPE) caused severe damage and nearly 100 fatalities in the Hai River basin, North China. Using a Lagrangian approach, we investigated the moisture transport regime and identified the circulation pattern responsible for the EPE. The primary moisture sources were the northwest Pacific (24%), southeast Chi...

Precipitation enhancement methods are analyzed for comparison and combinations: acoustic treatment in clouds, heat up flow, powder introduction. Artificial air up flows are considered with account of initial overheating 30 – 70 C and heat flow power 2 – 200 MW in area up to 120 m2 on the ground. Proposed and reviewed analytical models describe the...

Numerical weather prediction models often struggle to accurately simulate high-resolution precipitation processes, due to resolution limits and difficulties in representing convection and cloud microphysics. Data-driven methods often offer more accurate approximation of these unresolved processes by learning from high-fidelity referential data. Yet...

This study investigates precipitation observed by a set of collocated ground-based instruments in Zhuhai, a coastal city located at the southern tip of the Pearl River Delta of Guangdong Province in South China. Seven months of ground-based observations from a tipping-bucket rain gauge (RG), two laser disdrometers (PARSIVEL and Present Weather Sens...

A novel clustering method combing the Spearman's rank spatial correlation and the spectral clustering is proposed to investigate the variability in moisture transport. Four moisture transport regimes for the extreme precipitation events (EPEs) over North China are identified through applying the new clustering method to the moisture source distribu...

Problem setting. The paper belongs to precipitation enhancement methods. The new option is proposed inside natural clouds by using low-frequency acoustics, 40–300 Hz, emitted from air sirens near ground. The purpose. The purpose of the article is to determine the necessary acoustic parameters, frequency and power, for effective collision of water d...

Atmospheric rivers (ARs) are an important component of the global water cycle, and AR-related hydrological hazards are across the midlatitudes, including New Zealand. The ability to classify the strength and potential impact of ARs has shown benefits to water resource management in western U.S. regions. In New Zealand, the topography means that the...

Atmospheric rivers (ARs) are elongated channels of enhanced water vapour transport in midlatitudes and contribute significantly to annual rainfall in northern and western New Zealand. Based on data from 529 rain gauge sites and detected landfalling ARs over New Zealand from 1950 to 2020, this study indicates that the presence of ARs generally leads...

Recent studies offer more evidence that the rate of warming is amplified with elevation, indicating thereby that high-elevation ecosystems tend to be exposed to more accelerated changes in temperature than ecosystems at lower elevations. The phenomenon of elevation-dependent warming (EDW), as one of the regional climate-change impacts, has been obs...

With the population projections indicating continued growth during this century, construction of large dams can be considered as one of the best available options to meet the future increases in water, food, and energy demands. While there are reports that thousands of large dams will be built in the near future, a key question is: what are the app...

Problem setting. The paper belongs to methods of precipitation enhancements to solve the problem of fresh water shortage that is known in many regions in a world. In this paper the vertical thermal up flow together with special acoustics are considered in order to enhance precipitation in natural clouds. The purpose The new method is proposed for p...

Precipitation recycling, defined as that precipitation in a region is partially contributed by evapotranspiration from the same region, is the interaction between terrestrial hydrology and atmospheric processes, and plays a crucial role in forming water resources. For agricultural lands, the evapotranspiration of irrigation water alters local clima...

Extreme precipitation (EP) has significant hydrological and environmental influences on the Chinese Loess Plateau (CLP) during the rainy season (June–September). In this study, we analysed the moisture sources for the EP events over the CLP during the rainy season. Three major moisture source patterns were identified through analysing the moisture...

Anomalous poleward transport of atmospheric energy can lead to sea ice loss during boreal winter over the Arctic, especially in the North Barents–Kara Seas (NBKS), by strengthening downward longwave radiation (DLW). However, compared with the extensive studies of latent energy sources, those of sensible energy sources are currently insufficient. Th...

Self-similarity and plane-filling are intrinsic structure properties of natural river networks. Statistical data indicates that most natural river networks are Tokunaga trees. Researchers have explored to use iterative binary tree networks (IBTNs) to simulate natural river networks. However, the characteristics of natural rivers such as Tokunaga se...

Climate warming has increased grassland productivity on the Qinghai-Tibet Plateau, while intensified grazing has brought increasing direct negative effects. To understand the effects of climate change and make sustainable management decisions, it is crucial to identify the combined effects. Here, we separate the grazing effects with a climate-drive...

Facing irreversible and catastrophic changes on the earth, China has committed to peak the net carbon emission by 2030 and to achieve carbon neutrality by 2060. The pledge requires significant mitigation immediately and sustainably. Considering this background, some perspectives are given in this article based on the comprehensive use of natural re...

In order to verify the accuracy of precipitable water vapor (PWV) in remote sensing and reanalysis datasets under different climatic conditions and ensure the reliability of analysis results, the performances of ERA-5 reanalysis PWV data and the Atmospheric Infrared Sounder (AIRS) remotely-sensed PWV data were tested in the northern Qinghai-Tibet P...

The Qinghai-Tibetan Plateau (QTP) is one of the amplifiers of global climate change. The headwater area of the Yellow River Basin (HYRB) on the QTP is the dominant water source region for the whole Yellow River Basin. However, the sensitive responses of hydrological processes to the intensifying climate change are exerting high uncertainties to the...

Skillful long-lead climate forecast is of great importance in managing large water systems and can be made possible using teleconnections between regional climate and large-scale circulations. Recent innovations in machine learning provide powerful tools in exploring linear/nonlinear associations between climate variables. However, while it is hard...

The Qinghai-Tibetan Plateau (QTP) is one of the amplifiers of global climate change. The headwater area of the Yellow River Basin (HYRB) on the QTP is the dominant water source region for the whole Yellow River Basin (YRB). However, the sensitive responses of hydrological processes to the intensifying climate change are exerting high uncertainties...

Drainage network extraction is essential for different research and applications. However, traditional methods have low efficiency, low accuracy for flat regions, and difficulties in detecting channel heads. Although deep learning techniques have been used to solve these problems, different challenges remain unsolved. Therefore, we introduced distr...

The Qinghai-Tibetan Plateau (QTP) is one of the amplifiers of global climate change. The headwater area of the Yellow River Basin (HYRB) on the QTP is the dominant water source region for the whole Yellow River Basin (YRB). However, the sensitive responses of hydrological processes to the intensifying climate change are exerting high uncertainties...

Atmospheric precipitable water (PW) is the basis of precipitation (P) formation, and the spatial difference between them is one of the focus of water resources research. Based on daily P from 552 meteorological stations and four reanalysis datasets during 1980–2016, the spatial–temporal pattern of PW and precipitation conversion rate (PWCR) in Chin...

A cloud image can provide significant information, such as precipitation and solar irradiation. Predicting short-time cloud motion from images is the primary means of making intra-hour irradiation forecasts for solar-energy production and is also important for precipitation forecasts. However, it is very challenging to predict cloud motion (especia...

This study examined the spatial and temporal patterns of the paleobiome types in the Three-River Headwaters Region (TRHR, Sanjiangyuan) in China from the middle Holocene (i.e. 6000 BP). Existing studies explored the patterns of paleobiome types by identifying the type of biomes in pollen sites, based on the taxonomical assemblage of pollen samples....

Adsorption of a cationic surfactant dodecyl pyridinium chloride (DPC) on silica was studied to show a comparison with the adsorption of an anionic surfactant sodium dodecyl sulfate (SDS), whose carbon chain length is the same and on the same silica. Results provided a better understanding of the adsorption mechanism of cationic and anionic surfacta...

With a new approach based on the ensemble average over particle state transition paths in phase space, a kinetic equation for particles transported in turbulent flows is derived. The probability density function (PDF) for particles is defined as an ensemble average of a special fine-grained PDF, referred to as the local path density operator. The k...

Incising rivers may be confined by low-slope, erodible hillslopes or steep, resistant sidewalls. In the latter case, the system forms a canyon. We present a morphodynamic model that includes the essential elements of a canyon incising into a plateau, including 1) abrasion-driven channel incision, 2) migration of a canyon-head knickpoint, 3) sedimen...

The article subject tends to precipitation enhancement inside natural clouds through acoustical affect. Two models are analyzed and compared to calculate droplet’s amplitudes during their vibrations inside acoustic waves. The optimal regimes are considered for acoustic impact on natural clouds of different types. A neighboring droplet’s distances i...

Acoustic interference of atmosphere has been an attractive research area because of its potential effect on environment, water resources, ecology, agriculture, and other areas. However, it is also a controversial topic because of the difficulty of quantitative assessment and high operating costs. In this study, a novel acoustic interference technol...

China, with its fragile environment and ecosystems, is vulnerable to climate change. Continuous changes in climatic conditions have altered precipitation patterns in most regions of China. Droughts become more frequent and severe in the Xi River basin in South China. It is expected that rapid urbanization and climate change will continue to aggrava...

As the resolution of DEMs is becoming higher, both the efficiency and accuracy of channel head recognition are important for drainage network extraction. In this paper, a D8-compatible high-efficient channel head recognition method is proposed. For each potential channel, this method first calculates a geomorphologic parameter series along the flow...

Following previous studies of the rainfall forecast in Shenzhen owing to landfalling tropical cyclones (TCs), a nonparametric statistical scheme based on the classification of the landfalling TCs is applied to analyze and forecast the rainfall induced by landfalling TCs in the coastal area of Guangdong province, China. All the TCs landfalling with...

Reference evapotranspiration (ETo) is the basic component of the hydrological cycle. This study systematically analyzed the spatiotemporal variations of ETo in the Three-River Headwaters Region (TRHR) by utilizing the FAO Penman–Monteith equation during the period of 1961–2016, and studied the impact of climatic variables on ETo fluctuation based o...

This study develops a new method to estimate spatially distributed rainfall through merging the satellite observation, the raingauge record, and the terrain digital elevation model (DEM) data, including the following four steps: (1) to select a suitable satellite observation dataset, (2) to downscale the selected satellite observation dataset with...

One key issue in the probability density function (PDF) approach for disperse two-phase turbulent flows is to close the diffusion term in the phase space. This study aimed to derive a kinetic equation for particle dispersion in turbulent flows by ensemble averaging over all possible realisations of state transition paths in the phase space. The pro...

Over the past century, vegetation change has been reported at global, national, and regional scales, accompanied by significant climate change and intensified human activities. Among the regions is the rangeland of the Three-River Headwaters Region (TRHR) in China. However, which factor dominates in causing vegetation change in this region is still...

Large-scale reservoirs have played a significant role in meeting various water demands and socio-economic development, while they also lead to undeniable impacts on the environment and ecology. The Longyangxia reservoir located on the Yellow River is the first large-scale reservoir on the upper Yellow River with a control area of 18% of the entire...

Purely alluvial rivers cannot sustain knickpoints along their long profiles, as they would be obliterated by diffusional morphodynamics. Bedrock streams with a partial alluvial cover, however, form and sustain slope breaks over long periods of time. Here we consider the case of an initial profile of a bedrock-alluvial stream with a sharp slope brea...

Multiyear and multipurpose reservoirs generally need to adjust operational functions for different storage levels; most existing reservoir schemes lack the pertinence to model the complex behaviors of such reservoirs. This pa- per proposes an improved operation-based reservoir scheme to simulate the storage and out ow variations for multiyear and m...

Drainage network extraction plays an important role in geomorphologic analyses, hydrologic modeling, and non-point source pollutant simulation, among others. Flow enforcement, by imposing information of known river maps to digital elevation models (DEMs), leads to improved drainage network extraction. However, the existing flow enforcement methods...

Since the 21st century, the natural runoff from the headwater region of the Yellow River has generally been decreasing, resulting in a particularly prominent contradiction in utilization of water resources. In this study, key components were identified from the perspective of water-energy-food (WEF) nexus, and a WEF nexus model was established for...

The Three River Headwaters Region (TRHR) has great uncertainty on drought conditions under climate change. The aim of this study is to compare the drought conditions detected by multiple drought indices across the TRHR. We applied four single drought indices, i.e., Precipitation Condition Index (PCI), Temperature Condition Index (TCI), Soil Moistur...

The analysis of spatio-temporal signals plays an important role in various fields including sociology, climatology, and environmental studies, etc. Due to the abrupt breakdown of the sensors in the sensor network, there always are missing entries in the observed spatio-temporal signals. In this paper, we study the problem of recovering spatio-tempo...

Presented in this paper is an introduction to the study on sky rivers, especially the concept, theory, and implications. A sky river is in essence a generalization for a rich variety of meteorological systems including tropical cyclones, extratropical frontal cyclones, shear lines and others from the viewpoint of fluid mechanics. All these meteorol...

Mountain rivers subject to earthquakes and intense precipitation have highly variable sediment supply rates. Here we consider the morphodynamics of 1-D mixed bedrock-alluvial rivers with temporally varying sediment supply rates. We use a periodic sedimentograph, characterized by short periods of high sediment feed rate and longer periods of low sed...

Numerical weather predictions (NWPs) are very useful in hydrological modeling, including for river flow forecasting and flood warning in river basins. However, uncertainties in NWPs also significantly impact the accuracy of streamflow forecasting. Therefore, evaluating the accuracy of NWPs is crucial to achieve reliable streamflow forecasts. In thi...

River discharge, which represents the accumulation of surface water flowing into rivers and ultimately into the ocean or other water bodies, may have great impacts on water quality and the living organisms in rivers. However, the global knowledge of river discharge is still poor and worth exploring. This study proposes an efficient method for mappi...

The Fokker-Planck equation is widely adopted in studies of Markov processes found in a variety of disciplines. It can be found that the evolution of probability density function in the state-space is completely determined by the jump moments of state transition of a stochastic system. Usually, the jump moments are only a function of starting and en...

The Yellow River headwaters region (YRHR) contributes nearly 40% of total flow in the Yellow River Basin (YRB), which is suffering from a serious water shortage problem. Investigation of the relationship between runoff and climate variables is important for understanding the variation trend of runoff in the YRHR under global climate change. Global...

Rainfall stations of a certain number and spatial distribution supply sampling records of rainfall processes in a river basin. Uncertainty may be introduced when the station records are spatially interpolated for the purpose of hydrological simulations. This study adopts a bootstrap method to quantitatively estimate the uncertainty of areal rainfal...

The hydropower system in the Upper Yellow River (UYR), one of the largest hydropower bases in China, plays a vital role in the energy structure of the Qinghai Power Grid. Due to management difficulties, there is still considerable room for improvement in the joint operation of this system. This paper presents a general LINGO-based integrated framew...

Result comparisons between LINGO and GAMS. (DOCX)

Small and medium river basins may frequently suffer from the destructive hydrological extremes (e.g., floods). However, the common problem in such regions is a lack of long-term historical observations. Meteorological and hydrological station networks in some river basins in China were newly-built only a few years ago, and it is infeasible to estim...

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Potential evaporation (PE) is the basic component of the global hydrological cycle and energy balance. This study detected the temporal and spatial variations of PE and related driving factors in Tibet, China, for the period 1961–2001, based on observed data recorded at 22 meteorological stations. The results showed that (1) Tibet experienced a sta...

Rainfall stations with a certain number and spatial distribution supply sampling records of rainfall processes in a river basin. Uncertainty may be introduced when the station records are spatially interpolated for the purpose of hydrological simulations. This study adopts a bootstrap method to quantitatively estimate the uncertainty of areal rainf...

This study evaluated the performance of the gridded CRU TS precipitation dataset in describing the spatial and temporal characteristics of precipitation over the Three-River Headwaters Region (TRHR) during 1961-2014, and the results were compared with those derived from the point raingauge records (RGR) at 29 meteorological stations. It indicated t...

Accurate mid- and long-term runoff forecasting is of great significance for rational development and utilization of water resources in “Yellow River Headwater” region, where runoff in the headwater region contributes to nearly 35% of the total amount of the Yellow River basin. In this paper, the monthly runoff data of Tangnaihai station in “Yellow...

In the global carbon cycle, terrestrial biomass plays an important role in both as a sink and source. To evaluate biomass variation due to various natural hazards, it is necessary to detect the location, extent and duration of vegetation disturbance at a large spatial scale with an efficient method. This study contributes to develop such a method,...

Signal processing on graphs is an emerging field studying signals in irregular domains, and has been applied to many applications such as sensor networks and recommendation systems. In this paper, a novel method for the recovery of time-varying spatial signal based on graph is proposed. A graph is established according to the spatial position of th...

Study region Three-River Headwaters (TRH) region, China. Study Focus Precipitation is regarded as the basic component of the global hydrological cycle. This study investigated the spatial and temporal characteristics of precipitation over the TRH region during 1961-2014, based on the observed data of 29 meteorological stations. New Hydrological Ins...

Large-scale problems that demand high precision have remarkably increased the computational time of numerical simulation models. Therefore, the parallelization of models has been widely implemented in recent years. However, computing time remains a major challenge when a large model is calibrated using optimization techniques. To overcome this diff...

Based on the theory of characteristics, this research elaborates on the numerical treatment of two types of seaward boundary conditions for modelling long-wave dynamics in truncated estuarine and coastal domains. These seaward boundary conditions are devised for the solution of the fully non-linear shallow water equations in the time domain. The fi...

As a result of climate change/variation and its aggravation by human activities over the past several decades, the hydrological conditions in the middle Yellow River in China have dramatically changed, which has led to a sharp decrease of streamflow and the drying up of certain tributaries. This paper simulated and analysed the impact of sediment-t...

A vertical two-dimensional numerical model is employed to study the scour beneath a vibrating pipe exposed to steady currents. The ability of the model is first validated against previous scour experiments concerning both fixed and vibrating pipes. Both the development of scour depth and the final bed profile are generally well reproduced by the mo...

Soil erosion is the root cause of environmental and ecological degradation in the Loess Plateau of the Yellow River. Watershed sediment dynamics was fully analyzed here, and a physically based, distributed, and continuous erosion model at the watershed scale, named the Digital Yellow River Integrated Model (DYRIM), was developed. The framework, the...

Severe soil erosion in the Loess Plateau region and associated large sediment discharge downstream in China have been of great concern for years. A physically based distributed model, the Digital Yellow River model (DYRIM), was developed in 2007 for land management at the basin scale in this region. In DYRIM, an explicit sediment yield equation was...

This paper develops an algorithm for computing spatially distributed monthly potential evaporation (PE) over a mountainous region, the Lhasa River basin in China. To develop the algorithm, first, correlation analysis of different meteorological variables was conducted. It is observed that PE is significantly correlated with vapor pressure and tempe...