The Simulation Research on Agricultural Non-point Source Pollution in Yongding River in Hebei Province

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1 Avalable onlne at Proceda Envronmental Scences 2 (2010) Internatonal Socety for Envronmental Informaton Scences 2010 Annual Conference (ISEIS) The Smulaton Research on Agrcultural Non-pont Source Polluton n Yongdng Rver n Hebe Provnce Dng Xaowen* Research Academy of Energy and Envronmental Studes, North Chna Electrc Power Unversty, Bejng , Chna, Abstract In order to reveal agrcultural non-pont source(nps) polluton n Yongdng rver n Hebe provnce, the resource, loadng and dstrbuton of agrcultural NPS polluton s analyzed n the paper based on remotng sense and geographc nformaton system by export coeffcent model. The result ndcates that, temporal dstrbuton of agrcultural NPS polluton s concentrates on hgh flow seasos/years. As far as the spaceal dstrbuton of agrcultural NPS polluton load s concerned, t concentrates on nfeld (slopng land especally), economc crop plantatons, hgh fertlzer dstrbuton area and vllages. In the concluson, t s suggested that the methods of agrcultural land use, crop plantaton should be mproved and the treatment effcency of waster water and sold waste should be ncreased Publshed by Elsever Ltd. Open access under CC BY-NC-ND lcense. Keywords: Yongdng rver n Hebe provnce; Agrcultural non-pont source polluton; Smulaton research 1. Introducton Non-pont source (NPS) polluton has become an mportant ssue for aquatc envronments and has therefore receved ncreased attenton n recent decades [1]. NPS nputs, especally from agrcultural actvty, have resulted n large amounts of ntrogen (N) and phosphorous (P) beng nput nto aquatc envronments, whch cause a wde range of problems such as toxc algal blooms, oxygen depleton and loss of bodversty. In addton, nutrent enrchment serously degrades aquatc ecosystems and decreases the qualty of water used for drnkng, ndustry, agrculture, recreaton, and other purposes [2]. Many studes have focused on NPS polluton load modelng [3]. In prncple, hydrologcal models provde essental tools for the management of rver catchments because they enable smulaton of potental polluton management * Correspondng author. Tel.: ; fax: E-mal address: bnger2000dxw@163.com Publshed by Elsever Open access under CC BY-NC-ND lcense. do: /j.proenv

2 Dng Xaowen / Proceda Envronmental Scences 2 (2010) strateges, clmate change effects and land use change effects on water qualty and quantty. The results of these smulatons can be used to gude decson makers before plans are mplemented [4]. Smulaton models can be classfed nto physcal-based models and emprcal models. There are varous physcal-based models desgned to smulate hydrologcal processes, nutrent transport through surface runoff, nterflow, and groundwater flow, as well as further n-stream nutrent turnover on a small or large scale. These models nclude ANSWERS [5], SWRRB [6], SWAT [7], HSPF [6], AGNPS [8] and BASINS [9], etc. Although these models can provde accurate results, the values of a large number of parameters can not be obtaned from feld data and must nstead be determned through model calbraton. Thus, the demand for parameters and computaton effcency due to the complexty of the models hnder the applcaton to some extent [10]. In contrast, emprcal models have the advantage of requrng less data and havng fewer parameters. The Export Coeffcent Model (ECM) has been recognzed as relable for modelng NPS polluton [11,12]. The earlest ECM, whch was proposed by Omernk, was used for predctng eutrophcaton n stable water bodes [13]. Specfcally, Omernk collected NPS polluton data from 928 watersheds and establshed the relatonshp between N and P loads and land use types by multple lnear regresson analyss. Based on ths method, Noverll et al. developed a relatvely smpler ECM to predct the effect of N and P nput on eutrophcaton n 33 rvers and lakes n Connectcut [14]. They found that the relatve error between smulatons and observatons was less than 13%. Snce then, the ECM has been contnuously mproved n order to obtan more accurate results. A remarkably advanced ECM was developed by Johnes that s based on the dea that the nutrent loads exported from a watershed s the sum of the losses from ndvdual sources, such as land use, lvestock and rural lvng [15]. Dfferent export coeffcents are adopted for dfferent crops, as well as for dfferent types of lvestock. The export coeffcents for rural lvng are then determned based on the dscharge and treatment effcency of domestc sewage. Ths model also takes nto account the nput from nutrent fxaton by plants and atmospherc deposton. Although the ECM dsregards the complex processes nvolved n NPS polluton and requres less data nput, t has acceptable precson, especally sutable for areas where lttle data are avalable, and can meet the needs of long-term NPS polluton load smulaton. Indeed, the ECM has been used successfully n many studes [16~19]. The Yongdng rver, located n north Chna, covers a dranage area of km 2. It refers to Bejng Cty (captal of Chna), Tanjng Cty and Hebe, Nemeng, Shanx provnce. As far as Hebe provnce s concerned, Because of agrcultural actvtes and ncreasng rural populaton, Agrcultural NPS polluton has become the domnant factor affectng water qualty of the Yongdng rver. Nomenclature NPS N P ECM non-pont source ntrogen phosphorous export coeffcent model 2. Materals and methods 2.1. Research Ste The Yongdng rver, located n Hebe provnce s selected as the research area. whch s km 2. It covers part of Zhangjakou Cty, Baodng Cty, as well as Langfang Cty. The research area s between Nemenggu hgh plateau and North Chna plan,where torrental ran occurs frequently on June, July and August n each year. Angrculture s one of the most mportant ndustres of Hebe provnce, and Angrculture actvtes s the prmary source of NPS polluton.in recent decades, due to ts specal geographc locaton and atmospherc crculaton pattern, torrental ran occurs frequently over the mountanous regons, causng water and sol eroson become a major envronmental problem. In addton, extensve cultvaton and stockbreedng as well as long-term mproper land use also lead to

3 1772 Dng Xaowen / Proceda Envronmental Scences 2 (2010) severe sol loss and NPS polluton. Presently, 70 percents of the Yongdng rver s polluted, the Bad Effects of whch for the local resdents s ncreasng serous Source and Processng of data As Table 1 shows, the study used data ncludes 1: land use map, 1: dgtal elevaton model (DEM) map, 1: admnstratve dvson map, socal as well as economcs nformaton of the study area and so on. Satellte remote sensng mages were nterpreted to acqure the land use data, basn boundary, rver map, watershed map were then obtaned accordng to DEM map through ArcGIS, dstrct bound atlas of the study area based on natonal dstrct bound atlas and basn boundary of the study area was subsequently generated, and under the GIS platform, as well as loadngs and spato-temporal dstrbutons of NPS-N and NPS-P n the study area were smulated, usng mportng basc data and export coeffcents of Table 3.All dgtal maps were projected n Albers concal equal-area. And the dual standard lattude were 25 and 47 degree respectvely, the central longtude was 105 E, the coordnate orgn lattude was zero degree, the spherod was Krassovsky one, and the unt was meter. In result analyss, the boundary of Schuan Provnce and Chongqng Cty, redstrcted n 1997, are defned as present. Table 1. Source and descrpton of basc data Type Scale Descrpton Source Land use Land use n the RS mage dgtalzng and nterpretng, Insttute of Geographcal and Natural Resources Research, CAS Landform Formng basn boundary Natonal Geomatcs Center of Chna Admnstratve Provnces, autonomous regons Natonal Geomatcs dvson and muncpaltes of study area Center of Chna Socal Populaton, lvestock feedng Natonal Bureau of each cty economcs and fertlzer applcaton Statstcs of Chna The export the losses of varous nutrent 30m coeffcent sources Statstcal data and feld montorng 2.3. Export Coeffcent Model (ECM) The ECM, whch s based on the dea that the nutrent loads exported from a watershed equals the sum of the losses from ndvdual sources, has been used n many studes. The ndvdual sources consst of land use, lvestock, rural lvng and atmospherc deposton. The model allows accurate estmaton and analyss of nutrent pollutants [15]. The ECM s outlned as: L n 1 E [ A ( I )] p (1) where L s loss of nutrents (kg), E s export coeffcent for nutrent source (kg/ca yr or kg/km2 yr), A s area of the catchment occuped by land use type (km2), or number of lvestock type, or of people, I s the nput of nutrents to source (kg), and p s the nput of nutrents from precptaton (kg). It should be noted that the land use type should nclude the domnant vegetaton type n an area, whch may mpact runoff n the area.

4 Dng Xaowen / Proceda Envronmental Scences 2 (2010) Results and dscusson 3.1. The tme Dstrbuton of Agrcultural NPS polluton n Yongdng rver n Hebe provnce In terms of the hydrologcal year scale, agrcultural NPS polluton loads vary evdently n dfferent year Polluton occurs under the condton of stormwater runoff, whch changes wdely n dfferent hydrologc year Agrcultural NPS polluton of the wet year s serous and n contrast, loadng of dry year s small. In terms of the hydrologcal term scale, 80 percents of the agrcultural NPS polluton concentrated n wet pero (June, July and August), because annual ranfall s also concentrated on ths tme. In all, the loss of agrcultural NP polluton s postve correlaton wth the ranfall, whch ndcates that agrcultural NPS polluton accumulates n t dry season, and occurs n wet one wth ranfall and sol eroson The space dstrbuton of Agrcultural NPS polluton n Yongdng rver n Hebe provnce As far as the space dstrbutons of Agrcultural NPS polluton n study area s concerned, major source agrcultural NPS polluton s land use, followed by hoggery and rural vllages. Among varous land use types, cultvated land, slopng land especally, contrbuted the most. Conventonal tlla s just the prmary tllage pattern n thestudy area. Moreover, n the vast mountanous area of the study area, dow slope cultvaton has been a common practce for years. Although down slope cultvaton s consdered to be eas for plowng felds, t also facltates the downward movement of water durng cultvaton. Addtonally, down slop cultvaton promotes sol eroson n response to every ranfall event durng the growng season. In dfferent cultvated lands, wheat cultvated area s the domnant Agrcultural NPS. For the economc yeld fro ths crop, the use of fertlzers may have rased envronmental contamnaton. Furthermore, crop resdue, whch not systematcally managed, s a N-rch polluton source. It has been documented that regardless of the resdual lev conventonal tllage s less effectve at reducng N n water and sedments than no-tll systems. Besdes land use, another mprotant angrcultural NPS s hoggery, where varous types of lvestock are bred. Meantme, rural lvng s also one cann t be gnored for ts domestc sewage and sold waster wth scarcely effcen treatment. 4. Conclusons In ths study, angrcultural NPS polluton n Yongdng rver n Hebe provnce s smulaton by ECM based o remotng sense and geographc nformaton system. The result ndcates that polluton s concentrates on hgh flo seasos/year. As far as the spaceal dstrbuton of the load s concerned, t concentrates on plan, nfeld (slopng lan especally), wheat cultvated area, hoggery and vllages. In the concluson, t s suggested that the methods agrcultural land use, crop plantaton should be mproved and the treatment effcency of waster water and sol waste should be ncreased. Acknowledgements Ths research work was funded by the Natural Scence Foundaton of Hebe Provnce(D ) and t Doctoral Faculty Research Foundaton of North Chna Electrc Power Unversty ( ). The RS an geography data were suppled by natonal satellte meteorologcal center (NSMC), Insttute of Geographcal an Natural Resources Research, Chnese Academy of Scences (CAS), and Natonal fundamental geograph nformaton center (NFGIC). The authors gratefully acknowledge the valuable datum provded by the agences.

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