Hongkai Gao

Hongkai Gao
East China Normal University | ECNU

Professor

About

70
Publications
37,662
Reads
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1,553
Citations
Citations since 2016
55 Research Items
1435 Citations
20162017201820192020202120220100200300
20162017201820192020202120220100200300
20162017201820192020202120220100200300
20162017201820192020202120220100200300
Additional affiliations
September 2011 - present
Delft University of Technology
Position
  • PhD Student
June 2008 - June 2011
Chinese Academy of Sciences
Position
  • Master's Student

Publications

Publications (70)
Article
Full-text available
Although elevation data are globally available and used in many existing hydrological models, their information content is still underexploited. Topography is closely related to geology, soil, climate and land cover. As a result, it may reflect the dominant hydrological processes in a catchment. In this study, we evaluated this hypothesis through...
Article
Full-text available
The root zone moisture storage capacity (SR) of terrestrial ecosystems is a buffer providing vegetation continuous access to water and a critical factor controlling land-atmospheric moisture exchange, hydrological response and biogeochemical processes. However, it is impossible to observe directly at catchment scale. Here, using data from 300 diver...
Article
Full-text available
Understanding how explicit consideration of topographic information influences hydrological model performance and upscaling in glacier dominated catchments remains underexplored. In this study, the Urumqi Glacier No.1 catchment in northwest China, with 52% of the area covered by glaciers, was selected as study site. A conceptual glacier-hydrologica...
Article
Full-text available
Reading landscapes and developing calibration-free runoff generation models that adequately reflect land surface heterogeneities remains the focus of much hydrological research. In this study, we report a novel and simple topography-driven runoff generation parameterization – the HAND-based Storage Capacity curve (HSC), which uses a topographic ind...
Article
Full-text available
Increased attention directed at frozen soil hydrology has been prompted by climate change. In spite of an increasing number of field measurements and modeling studies, the impact of frozen soil on hydrological processes at the catchment scale is still unclear. However, frozen soil hydrology models have mostly been developed based on a bottom-up app...
Article
Full-text available
Background On the front lines of climate change, glacier termini play crucial roles in linking glaciers and downstream ecosystems during glacier retreat. However, we lack a clear understanding of biological processes that occur in surface and basal ice at glacier termini. Methods Here, we studied the bacterial communities in surface ice and basal...
Article
Multi-source merging is an established tool for improving large-scale precipitation estimates. Existing merging frameworks typically use gauge-based precipitation error statistics and neglect the inter-dependence of various precipitation products. However, gauge-observation uncertainties at daily and sub-daily time scales can bias merging weights a...
Article
Full-text available
Glacier hydrology has profound implications for socio-economic development and nature conservation in arid Central Asia. Process-based hydrological models, which are the traditional tools used to simulate glacier melting, have made considerable contributions to advance our understanding of glacio-hydrology. Simultaneously, deep learning (DL) models...
Article
Glaciers are retreating rapidly, exposing extensive new soil habitats in glacier forefields and providing unique areas for studying primary succession. However, understanding the variation patterns and assembly mechanisms of abundant and rare fungi subcommunities along the glacier-retreating chronosequence remains a knowledge gap, especially true f...
Article
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Understanding the role of reservoirs in the terrestrial water cycle is critical to support the sustainable management of water resources especially for China where reservoirs have been extensively built nationwide. However, this has been a scientific challenge due to the limited availability of continuous, long-term reservoir operation records at l...
Preprint
Full-text available
Increased attention directed at frozen-soil hydrology has been prompted by climate change. In spite of an increasing number of field measurements and modeling studies, the impact of frozen-soil on hydrological processes at the catchment scale is still unclear. However, frozen-soil hydrology models have mostly been developed based on a “bottom-up” a...
Article
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The risk of coastal storm flooding is deteriorating under global warming, especially for the heavily urbanized deltaic cities, like Shanghai. The Nature-Based Flood Defense (NBFD), as an eco-friendly design alternative for hard infrastructure against coastal flooding, is gaining attention. Nevertheless, the vulnerability of saltmarsh due to the bio...
Article
Full-text available
It is important to improve the forecasting performance of rainfall-runoff models due to the high complexity of basin response and frequent data limitations. Recently, many studies have been carried out based on deep learning and have achieved significant performance improvements. However, their intrinsic characteristics remain unclear and have not...
Article
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Glaciers are among the least explored environments on Earth, especially from a perspective of nutrient stoichiometry. Here, we documented and compared the nutrient concentrations and stoichiometric ratios in six distinct habitats of a glacier terminus in the source area of the Yangtze River, including surface ice (SI), basal ice (BI), basal sedimen...
Article
Full-text available
The Storm Water Management Model (SWMM) has been globally used for stormwater management. However, the calibration and evaluation of SWMM for historical rainfall–runoff events in partially separated and combined drainage systems is rarely reported in Norway. In this study, we employed SWMM for the Grefsen catchment in Oslo, Norway. The main problem...
Article
The effects of catchment characteristics and climate variables on water partitioning into evapotranspiration and runoff can be evaluated using the Budyko framework. However, the influence of glaciers on catchment characteristics within the framework has yet been adequately investigated. Here we extend the Budyko framework and apply the elasticity m...
Article
Evaluating the accuracy of precipitation products is essential for many applications. The traditional method for evaluation is to calculate error metrics of products with gauge measurements that are considered as ground-truth. The multiplicative triple collocation (MTC) method has been demonstrated powerful in error quantification of precipitation...
Preprint
Full-text available
Glaciers are among the least explored environments on Earth, especially from a perspective of nutrient stoichiometry. In this study, we documented and compared the nutrient availabilities (concentrations) and composition (stoichiometric ratios) of nutrients (C, N, and P) in six distinct habitats of a glacier terminus in the Yangtze River Source are...
Preprint
Full-text available
Increased attention directed at permafrost hydrology has been prompted by climate change. In spite of an increasing number of field measurements and modeling studies, the impacts of permafrost on hydrological processes at the catchment scale are still unclear. Permafrost hydrology models at the catchment scale were mostly developed based on a “bott...
Article
Full-text available
As one of the key elements of climate change, the temperature changes can affects the energy balance and hydrological cycle. The variations and trend of mean annual maximum temperature (T max ) and minimum temperature (T min ) were analyzed by using linear regress for 44 stations inside and surrounding the Qilian Mountains for period of 1960-2017....
Article
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Global hydrological models (GHMs) are important tools for addressing worldwide change-related water resource problems from a global perspective. However, the development of these models has long been hindered by their low accuracy. In order to improve the streamflow simulation accuracy of GHMs, we developed a GHM—the FLEX-Global—based on the region...
Article
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The paper “Large-scale afforestation significantly increases permanent surface water in China's vegetation restoration regions, Agricultural and Forest Meteorology, Volume 290, 15 August 2020, 108001” by Zeng et al. (2020) finds that northern China is greening up and that “vegetation cover is an important factor in controlling permanent water chang...
Article
Full-text available
Abstract Dielectric techniques are fundamental methods for measuring soil water content, and they commonly rely on the conventional laboratory calibration of the dielectric permittivity models between a dielectric constant and water content. As a non‐negligible factor, porosity has been constructed differently in some models as a calibration consta...
Article
Model realism is of vital importance in science of hydrology, in terms of realistic representation of hydrological processes and reliability of future prediction. Here, we employed a stepwise modeling approach that leverages flexible model structures and multi-source observations for robust streamflow simulation and internal variables validation wi...
Article
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Permafrost extends 40% of the Qinghai-Tibet Plateau (QTP), a region which contains the headwaters of numerous major rivers in Asia. As an aquiclude, permafrost substantially controls surface runoff and its hydraulic connection with groundwater. The freeze–thaw cycle in the active layer significantly impacts soil water movement direction, velocity,...
Article
Patterns of biomass allocation among organs in plants are important because they influence many growth processes. The Yunnan-Guizhou Plateau (YGP) is considered to be one of the most sensitive areas in China to climate changes, but we know little about how current climatic gradients on the plateau influence plant biomass allocation. Gentiana rigesc...
Article
Glacier retreat caused by global warming alters the hydrological regime and poses far-reaching challenges to water resources and nature conservation of the headwater of Yangtze River, and its vast downstream regions with dense population. However, there is still lack of a robust modeling framework of the “climate-glacier-streamflow” in this water t...
Article
Understanding how biophysical processes respond to the surface energy partitioning and water budget is essential for modeling land surface processes. In general, evapotranspiration (ET) associated with vegetation dynamics can function as a vital nexus of the surface energy partitioning and water budget. Here, a dual-source ET model, the GIS-based P...
Chapter
Infrastructures handle high-volume goods and services that require heavily capitalized, large-scale, durable, reliable, shared, interdependent, and specialized systems. Infrastructure facilitates social, economic, and environmental functions by achieving a high degree of efficiency at a low marginal cost to produce, transport, distribute, quality-c...
Article
Full-text available
There has been a surge of interest in the field of urban flooding in recent years. However, current stormwater management models are often too complex to apply on a large scale. To fill this gap, we use a physically based and spatially distributed overland flow model, SIMulated Water Erosion (SIMWE). The SIMWE model requires only rainfall intensity...
Article
Full-text available
Bacterial and fungal communities in biofilms are important components in driving biogeochemical processes in stream ecosystems. Previous studies have well documented the patterns of bacterial alpha diversity in stream biofilms in glacier-fed streams, where, however, beta diversity of the microbial communities has received much less attention especi...
Preprint
Bacterial and fungal communities in biofilms are important components in driving biogeochemical processes in stream ecosystems. Previous studies have well documented the patterns of bacterial alpha diversity in stream biofilms in glacier-fed streams, where, however, beta diversity of the microbial communities has received much less attention especi...
Preprint
Bacterial and fungal communities in biofilms are important components in driving biogeochemical processes in stream ecosystems. Previous studies have well documented the patterns of bacterial alpha diversity in stream biofilms in glacier-fed streams, where, however, beta diversity of the microbial communities has received much less attention especi...
Article
Analyzing the impacts of climate change on hydrology and future projections of water supplies is fundamental for the efficient management and planning of water resources in large river systems on the Tibetan Plateau (TP), which is known as the “water tower of Asia.” However, large uncertainties remain in the projections of streamflow and glaciers i...
Article
Precipitation and air temperature are key drivers of watershed models. Currently there are many open-access gridded precipitation and air temperature datasets at different spatial and temporal resolutions over global or quasi-global scale. Motivated by the scarcity and substantial temporal and spatial gaps in ground measurements in Africa, this stu...
Article
Spatial and temporal patterns of trends in annual and seasonal precipitation over Germany during 1951‐2013 were analyzed using the ensemble empirical mode decomposition (EEMD) method. Three widely used and recognized high‐resolution observation‐based gridded precipitation products, the Climatic Research Unit time‐series data (CRU) and Global Precip...
Article
Full-text available
Introduction Landscapes and water are closely linked. Water shapes landscapes, and landscape heterogeneity in turn determines water storage, partitioning, and movement. Understanding hydrological processes from an ecological perspective is an exciting and fast-growing field of research. Objectives The motivation of this paper is to review advances...
Article
Full-text available
Lake Tana is the largest lake in Ethiopia, and its lake outflowis the source of the BlueNile River that provides vital water resources for many livelihoods and downstream/international stakeholders. Therefore, it is essential to quantify and monitor the water balance of Lake Tana. However, Lake Tana is poorly gauged, with more than 50% of Lake Tana...
Article
This study highlights the features of vine copula for examining compound events involving underlying conditions that amply the compounding effects. To illustrate, we study compound floods in Texas (TX), U.S. These compound floods consist of combinations of precipitation and surface runoff with the El Niño–Southern Oscillation (ENSO) and rising temp...
Article
Full-text available
Reading landscapes and developing calibration-free runoff generation models that adequately reflect land surface heterogeneities remains the focus of much hydrological research. In this study, we report a novel and simple topography-driven runoff generation parameterization – the HAND-based Storage Capacity curve (HSC), that uses a topographic inde...
Article
Full-text available
High-altitude inland-drainage lakes on the Tibetan Plateau (TP), the earth's third pole, are very sensitive to climate change. Tibetan lakes are important natural resources with important religious, historical, and cultural significance. However, the spatial patterns and processes controlling the impacts of climate and associated changes on Tibetan...
Article
Full-text available
Hydrological models often require calibration. Multi-objective calibration has been more widely used than single-objective calibration. However, it has not been fully ascertained that multi-objective calibration will necessarily guarantee better model accuracy. To test whether multi-calibration was effective in comparison to single-calibration in t...
Article
Full-text available
Benthic biofilms in glacier-fed streams harbor diverse microorganisms driving biogeochemical cycles and, consequently, influencing ecosystem-level processes. Benthic biofilms are vulnerable to glacial retreat induced by climate change. To investigate microbial functions of benthic biofilms in glacier-fed streams, we predicted metagenomes from 16s r...
Article
Full-text available
In various conceptual models, the shape parameter (β) of the storage capacity curve, representing the non-linear relationship between relative soil moisture and runoff, determines runoff yield given certain circumstances of rainfall and antecedent soil moisture. In practice, β is typically calibrated for individual catchments and for different purp...
Article
Full-text available
Glacier-fed streams are highly dynamic environments that integrate upstream catchment processes and are prominent geomorphological and ecological components of alpine landscapes. In these systems, hydrological and physicochemical factors change significantly with location downstream of the glacier. Variation in microbial communities in benthic biof...
Article
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Whether coupling auxiliary information (except for conventional rainfall–runoff and temperature data) into hydrological models can improve model performance and transferability is still an open question. In this study, we chose a glacier catchment to test the effect of auxiliary information, i.e., distributed forcing input, topography, snow-ice acc...
Article
Understanding which catchment characteristics dominate hydrologic response and how to take them into account remains a challenge in hydrological modeling, particularly in ungaged basins. This is even more so in non-temperate and non-humid catchments, where - due to the combination of seasonality and the occurrence of dry spells - threshold processe...
Article
Full-text available
With remote sensing we can readily observe the Earth's surface, but direct observation of the sub-surface remains a challenge. In hydrology, but also in related disciplines such as agricultural and atmospheric sciences, knowledge of the dynamics of soil moisture in the root zone of vegetation is essential, as this part of the vadose zone is the cor...
Article
Full-text available
This study presents an "Earth observation-based" method for estimating root zone storage capacity – a critical, yet uncertain parameter in hydrological and land surface modelling. By assuming that vegetation optimises its root zone storage capacity to bridge critical dry periods, we were able to use state-of-the-art satellite-based evaporation data...
Conference Paper
Full-text available
The Height Above the Nearest Drainage (HAND), a digital elevation model normalized using the nearest drainage is used for hydrological and more general purpose applications, such as hazard mapping, landform classification, and remote sensing. One of the essential characteristics of HAND is its ability to capture heterogeneities in local environment...
Article
Full-text available
With remote sensing we can readily observe the Earth's surface, but looking under the surface into the root zone of vegetation is still a major challenge. Yet knowledge on the dynamics of soil moisture in the root zone is essential for agriculture, land–atmosphere interaction and hydrological modelling, alike. In this paper we develop a novel appro...