title: Hydrology and phosphorus transport simulation in a lowland polder by a coupled modeling system.
abstract: Modeling the rain-runoff processes and phosphorus transport processes in lowland polders is critical in finding reasonable measures to alleviate the eutrophication problem of downstream rivers and lakes. This study develops a lowland Polder Hydrology and Phosphorus modeling System (PHPS) by coupling the WALRUS-paddy model and an improved phosphorus module of a Phosphorus Dynamic model for lowland Polder systems (PDP). It considers some important hydrological characteristics, such as groundwater-unsaturated zone coupling, groundwater-surface water feedback, human-controlled irrigation and discharge, and detailed physical and biochemical cycles of phosphorus in surface water. The application of the model in the Jianwei polder shows that the simulated phosphorus matches well with the measured values. The high precision of this model combined with its low input data requirement and efficient computation make it practical and easy to the water resources management of Chinese polders. Parameter sensitivity analysis demonstrates that Kuptake, cQ2, cW1, and cQ1exert a significant effect on the modeled results, whereas KresuspensionMax, Ksettling, and Kmineralizationhave little effect on the modeled total phosphorus. Among the three types of uncertainties (i.e., parameter, initial condition, and forcing uncertainties), forcing uncertainty produces the strongest effect on the simulated phosphorus. Based on the analysis result of annual phosphorus balance when considering the high import from irrigation and fertilization, lowland polder is capable of retaining phosphorus and reducing phosphorus export to surrounding aquatic ecosystems because of their special hydrological regulation regime.
authors.affiliation: Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; School of Geographical Sciences, Southwest University, Chongqing 400715, PR China; Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing 400715, PR China. Electronic address: yrh036@163.com.
authors.forename: Renhua
authors.initials: R
authors.lastname: Yan
authors.affiliation: Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China.
authors.forename: Jiacong
authors.initials: J
authors.lastname: Huang
authors.affiliation: Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: gaojunf@niglas.ac.cn.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Gao
mesh_terms: D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D005068:Eutrophication; D060587:Groundwater / Q000032:analysis / Q000737:chemistry; D062070:Hydrology; D060106:Lakes; D008956:Models, Chemical; D010758:Phosphorus / Q000032:analysis*; D011891:Rain; D045483:Rivers; D014867:Water / Q000032:analysis; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*; D062066:Water Resources
chemical_list: D014874:Water Pollutants, Chemical; D014867:Water; D010758:Phosphorus
keywords: Coupling; Lowland polder; Paddy field; Phosphorus dynamics; Pumping station