Lifeng Yuan | Environmental Scientist & Hydrologic Modeler

Exploring the Statistical Characteristics of Coastal Winter Precipitation Measured using a Parsivel2 Disdrometer: A Case Study in North Carolina

Mon, 01 Jan 0001 00:00:00 +0000

Objective

The study investigates the microphysical characteristics of coastal winter precipitation in North Carolina using high-resolution data from a Parsivel2 disdrometer, with a focus on understanding particle size distribution (DSD), precipitation types, and statistical variability under different winter conditions.

Using SWMM for Emergency Response Planning: A Case Study Evaluating Biological Agent Transport Under Various Rainfall Scenarios and Urban Surfaces

Mon, 01 Jan 0001 00:00:00 +0000

Objective

This study aims to assess how biological agents, specifically surrogates for hazardous pathogens like Bacillus anthracis, could be transported through urban stormwater systems under different rainfall intensities and land surface types. The research supports emergency preparedness and homeland security response using hydrological modeling.

Evaluating Monthly Flow Prediction with SWAT, Support Vector Regression, and Discrete Wavelet Transform

Mon, 01 Jan 0001 00:00:00 +0000

Research Question

Can discrete wavelet decomposition improve a hybrid SWAT–support vector regression framework for monthly streamflow prediction across multiple monitoring sites in a watershed with limited observations?

Why It Matters

Reliable monthly streamflow estimates support water-resources planning, drought and flood assessment, reservoir management, and agricultural water management. Process-based watershed models can be difficult to calibrate at multiple locations, while observed hydrologic series are nonlinear and nonstationary. A hybrid approach can retain SWAT’s watershed representation while using machine learning to correct remaining prediction errors.

Simulating the potential effects of elevated CO2 concentration and temperature coupled with storm intensification on crop yield, surface runoff, and soil loss based on 25 GCMs ensemble: A site-specific case study in Oklahoma

Mon, 01 Jan 0001 00:00:00 +0000

Objective

This study evaluates the long-term impacts of climate change stressors—specifically elevated CO₂, increased temperature, and storm intensification—on agricultural productivity and environmental degradation in Oklahoma. The goal is to inform future land and water management practices under projected climate scenarios.

Enhanced streamflow prediction with SWAT using support vector regression for spatial calibration: A case study in the Illinois River watershed, U.S.

Mon, 01 Jan 0001 00:00:00 +0000

Summary

This study presents a hybrid modeling approach combining the Soil and Water Assessment Tool (SWAT) with Support Vector Regression (SVR) to improve monthly streamflow prediction in the Illinois River Watershed (IRW), USA. Traditional SWAT calibration using SWAT-CUP is time-consuming and often inaccurate in dry seasons or ungauged watersheds. The new SWAT-SVR model uses SWAT outputs and drainage area as SVR inputs, bypassing heavy calibration and enabling more accurate spatial predictions. The model showed better performance in the wet season and for medium streamflows (5–30 m³/s), with applicability for watersheds ranging from 500 to 3000 km². This article can be accessed from https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0248489.

Review Paper: Review of Watershed-Scale Water Quality and Nonpoint Source Pollution Models

Mon, 01 Jan 0001 00:00:00 +0000

Original post date: Jan 10, 2020 4:58:1 PM

Purpose

Offers a comprehensive review of existing watershed and water quality models/tools relevant to nutrient loading, namely nitrogen, phosphorus, TSS, and their environmental fate and transport. The goal is to assist watershed managers in selecting appropriate tools for hydrologic assessment, nutrient management, policy development, and TMDL (Total Maximum Daily Load) analysis.

EPA Report: A Review of Watershed and Water Quality Tools for Nutrient Fate and Transport

Mon, 01 Jan 0001 00:00:00 +0000

Original post date: Mar 12, 2020 1:58:23 AM

Purpose

The report provides a comprehensive review of tools used to model the fate and transport of nutrients (mainly nitrogen, phosphorus, TSS) within watersheds. Its primary goal is to guide decision-makers, researchers, and watershed managers in selecting and applying models appropriate to their data, objectives, and watershed conditions.

Using SWAT to Evaluate Streamflow and Lake Sediment Loading in the Xinjiang River Basin with Limited Data

Mon, 01 Jan 0001 00:00:00 +0000

Original post date: Sep 24, 2019 10:40:44 PM

Abstract

Soil erosion and lake sediment loading are primary concerns of watershed managers around the world. In the Xinjiang River Basin of China, severe soil erosion occurs primarily during monsoon periods, resulting in sediment flow into Poyang Lake and subsequently causing lake water quality deterioration. Here, we identified high-risk soil erosion areas and conditions that drive sediment yield in a watershed system with limited available data to guide localized soil erosion control measures intended to support reduced sediment load into Poyang Lake. We used the Soil and Water Assessment Tool (SWAT) model to simulate monthly and annual sediment yield based on a calibrated SWAT streamflow model, identified where sediment originated and determined what geographic factors drove the loading within the watershed. We applied monthly and daily streamflow discharge (1985–2009) and monthly suspended sediment load data (1985–2001) to Meigang station to conduct parameter sensitivity analysis, calibration, validation, and uncertainty analysis of the model. The coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE), percent bias (PBIAS), and RMSE -observation’s standard deviation ratio (RSR) values of the monthly sediment load were 0.63, 0.62, 3.8%, and 0.61 during calibration, respectively. Spatially, the annual sediment yield rate ranged from 3 ton ha−1year−1 on riparian lowlands of the Xinjiang main channel to 33 ton ha−1year−1 on mountain highlands, with a basin-wide mean of 19 ton ha−1year−1. The study showed that 99.9% of the total land area suffered soil loss (greater than 5 ton ha−1year−1). More sediment originated from the southern mountain highlands than from the northern mountain highlands of the Xinjiang river channel. These results suggest that specific land-use types and geographic conditions can be identified as hotspots of sediment source with relatively scarce data; in this case, orchards, barren lands, and mountain highlands with slopes greater than 25° were the primary sediment source areas. This study developed a reliable, physically-based streamflow model and illustrates critical source areas and conditions that influence sediment yield.

Spatio-Temporal Variation Analysis of Precipitation during 1960-2008 in the Poyang Lake Basin, China.

Mon, 01 Jan 0001 00:00:00 +0000

Original post date: Oct 15, 2009 6:16:57 AM

Abstract

Long-term monthly precipitation data from 1960 to 2008 at 17 rain stations are analyzed to explore spatio-temporal variation of the seasonal and annual precipitation in the Poyang Lake basin, China, using anomaly analysis, simple linear regressive technique, Mann-Kendall trend test and Continuous Wavelet Transform. The results indicate that: (1) increasing precipitation trend is observed in summer and winter, while decreasing precipitation trend is identified in spring and autumn, and the above mentioned precipitation trends are not statistically significant; (2) changing trend of the areal average annual precipitation is non-significantly increasing, and increasing trend happens in almost the whole basin except in western and south-eastern small parts; (3) the spatial distribution of the seasonal and annual precipitation anomalies between 1991-2008 and 1960-2008 is similar to that of seasonal and annual precipitation trend during 1960-2008; (4) three main time-frequency distributions are observed in annual precipitation series during 1960- 2008, and they are 18 - 26 years, 8 - 14 years and 2 - 8 years, respectively; accordingly, there are three main periods in annual precipitation series, and they are 11-year, 22-year and 5-year respectively. This result will be helpful for further research on availability, scientific management and assessment of the water resources of the Poyang Lake basin.

About

Mon, 01 Jan 0001 00:00:00 +0000

Professional profile

I am an Environmental Scientist and Hydrologic & Watershed Modeler with more than 20 years of experience in watershed hydrology, soil erosion, climate-impact assessment, urban stormwater, and environmental data science.

Contact

Mon, 01 Jan 0001 00:00:00 +0000

Projects

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Selected projects

Urban Stormwater

U.S. EPA · U.S. Coast Guard · DHS 2021–2024

Stormwater Fate & Transport of Biological Contaminants

Led high-resolution SWMM development to simulate Bacillus anthracis transport across urban surfaces under multiple storm scenarios, integrating custom Python automation and field observations for decontamination-strategy evaluation.

Publications

Mon, 01 Jan 0001 00:00:00 +0000

Research

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Overview

I am an environmental modeling scientist specializing in watershed hydrology, soil erosion, and hydro-climatic processes. My research integrates process-based models—including SWAT/SWAT+, WEPP, and SWMM—geospatial analysis (GIS and remote sensing), and data-driven approaches (machine learning) to understand and predict watershed responses under environmental change.

Teaching & Mentoring

Mon, 01 Jan 0001 00:00:00 +0000

7+ Years of Teaching

4 Graduate Students Mentored

3 Registered Educational Software Systems

Teaching philosophy

I am a dedicated educator and researcher with a Ph.D. in Physical Geography from the Chengdu Institute of Mountain Hazards and Environment, Chinese Academy of Sciences (CAS). My teaching philosophy is centered on cultivating intellectual curiosity, encouraging innovation, and fostering collaboration to prepare students for dynamic, real-world career environments.