A novel framework for tracking hydrological processes and identifying key factors in mountain-lowland mixed catchments: Implications of forty years of modeling for water management

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2025-03-07 DOI:10.1016/j.watres.2025.123424

Renhua Yan, Lingling Li, Junfeng Gao

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Abstract

Quantitative analysis of runoff, total suspended solids, and total nitrogen dynamics, along with the identification of key factors within catchments, is essential for accurately addressing issues related to turbid and polluted water. Nevertheless, their implementation encounters significant challenges when applied to a mixed catchment containing mountain areas and lowland polder regions, due to the highly heterogeneous hydrological behaviors and consequently the lack of an appropriate approach. Faced with this problem, this study developed a framework by coupling the Soil and Water Assessment Tool (SWAT) and improved Polder Hydrology and Nitrogen modelling System (PHNS), and Random Forest analysis method to track the spatio-temporal changes in runoff, total suspended solids, and total nitrogen loading and identify their environmental determinants in a representative mountain-lowland mixed catchment, southeastern China. The coupled model performed very well for runoff (R²≥0.90) and water quality variables (total suspended solids: R²≥0.88; total nitrogen: R²≥0.73) in both the calibration and validation periods, and showed improvements compared with standalone SWAT model. Forty years’ modelling results indicated that the upstream subbasins 15 (32.86 tonnes/ha/yr), 14 (33.96 tonnes/ha/yr), and 11 (32.32 tonnes/ha/yr) were the critical source areas for total suspended solids and total nitrogen. However, the downstream polder subbasins functioned as a sink for runoff, total suspended solids, and total nitrogen, exporting lower loading intensities. Precipitation and the proportion of slope of 0 to 30° were identified as the critical factors influencing runoff, total suspended solids, and total nitrogen. The proportion of water area also significantly, negatively influenced runoff and total suspended solids. This study provided a feasible method to investigate runoff, total suspended solids, and total nitrogen processes and their environmental factors’ impact, and thus identifying the critical source areas and targeted measures to control the non-point source pollution of mountain-lowland mixed catchments.

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.