CAJ | 학술논문

灌区水文过程对于面源污染物的迁移、转化起到了重要的驱动作用。为揭示东北水稻灌区的水文及面源污染过程，该文在多年试验的基础上，运用修正的SWAT模型对其开展了模拟研究。2009-2011年在吉林省前郭灌区针对水稻生育期及冻融期内的灌区水文过程和农田面源污染物迁移、转化过程开展了系统的监测与试验。水稻生育期内，各级排水系统表现出不同的水文过程：末级排水沟中，由田间通过表层渗流进入排水沟的高浓度的水被灌溉退水所稀释，汇流排水沟的槽蓄量则在很大程度上影响了排水过程及污染物的对流和掺混过程。根据水稻灌区水文特性，以汇流排水沟为子流域，分别采用非稳定渗流公式和马斯京根法描述子流域中稻田向排水沟的渗流排水过程以及向子流域出口的排水汇流过程。试验和模拟结果表明：铵氮（NH4+）、硝氮（NO3-）和化学需氧量（COD）的浓度变化主要取决于排水过程，表层渗流和深层渗流过程决定了排水沟中NH4+和NO3-浓度过程，而排水沟中 COD 浓度还受到灌溉退水的影响。采用溴（Br-）作为示踪剂，通过测定土壤含水率、温度及示踪剂浓度变化，研究了冻结期的水文过程和面源污染物迁移过程，示踪试验结果显示，冻融期土壤中水流运动受到土壤基质势、温度势及重力势的影响，冻土中平衡状态下基质势为土壤温度的函数，土壤中污染物渗出通量与水分渗出通量表现出线性关系。基于水稻灌区下垫面产汇流特性和冻融期土壤对于灌区水文过程以及面源污染物迁移的影响机理，在SWAT模型模块修订的基础上，模拟了东北地区水稻灌区面源污染迁移流失过程，模拟流量、NH4+、NO3-、COD浓度与实测值符合较好，表明改进的模型能够用于东北地区水稻灌区的水文及面源污染过程模拟。灌區水文過程對于麵源汙染物的遷移、轉化起到瞭重要的驅動作用。為揭示東北水稻灌區的水文及麵源汙染過程，該文在多年試驗的基礎上，運用脩正的SWAT模型對其開展瞭模擬研究。2009-2011年在吉林省前郭灌區針對水稻生育期及凍融期內的灌區水文過程和農田麵源汙染物遷移、轉化過程開展瞭繫統的鑑測與試驗。水稻生育期內，各級排水繫統錶現齣不同的水文過程：末級排水溝中，由田間通過錶層滲流進入排水溝的高濃度的水被灌溉退水所稀釋，彙流排水溝的槽蓄量則在很大程度上影響瞭排水過程及汙染物的對流和摻混過程。根據水稻灌區水文特性，以彙流排水溝為子流域，分彆採用非穩定滲流公式和馬斯京根法描述子流域中稻田嚮排水溝的滲流排水過程以及嚮子流域齣口的排水彙流過程。試驗和模擬結果錶明：銨氮（NH4+）、硝氮（NO3-）和化學需氧量（COD）的濃度變化主要取決于排水過程，錶層滲流和深層滲流過程決定瞭排水溝中NH4+和NO3-濃度過程，而排水溝中 COD 濃度還受到灌溉退水的影響。採用溴（Br-）作為示蹤劑，通過測定土壤含水率、溫度及示蹤劑濃度變化，研究瞭凍結期的水文過程和麵源汙染物遷移過程，示蹤試驗結果顯示，凍融期土壤中水流運動受到土壤基質勢、溫度勢及重力勢的影響，凍土中平衡狀態下基質勢為土壤溫度的函數，土壤中汙染物滲齣通量與水分滲齣通量錶現齣線性關繫。基于水稻灌區下墊麵產彙流特性和凍融期土壤對于灌區水文過程以及麵源汙染物遷移的影響機理，在SWAT模型模塊脩訂的基礎上，模擬瞭東北地區水稻灌區麵源汙染遷移流失過程，模擬流量、NH4+、NO3-、COD濃度與實測值符閤較好，錶明改進的模型能夠用于東北地區水稻灌區的水文及麵源汙染過程模擬。
관구수문과정대우면원오염물적천이、전화기도료중요적구동작용。위게시동북수도관구적수문급면원오염과정，해문재다년시험적기출상，운용수정적SWAT모형대기개전료모의연구。2009-2011년재길림성전곽관구침대수도생육기급동융기내적관구수문과정화농전면원오염물천이、전화과정개전료계통적감측여시험。수도생육기내，각급배수계통표현출불동적수문과정：말급배수구중，유전간통과표층삼류진입배수구적고농도적수피관개퇴수소희석，회류배수구적조축량칙재흔대정도상영향료배수과정급오염물적대류화참혼과정。근거수도관구수문특성，이회류배수구위자류역，분별채용비은정삼류공식화마사경근법묘술자류역중도전향배수구적삼류배수과정이급향자류역출구적배수회류과정。시험화모의결과표명：안담（NH4+）、초담（NO3-）화화학수양량（COD）적농도변화주요취결우배수과정，표층삼류화심층삼류과정결정료배수구중NH4+화NO3-농도과정，이배수구중 COD 농도환수도관개퇴수적영향。채용추（Br-）작위시종제，통과측정토양함수솔、온도급시종제농도변화，연구료동결기적수문과정화면원오염물천이과정，시종시험결과현시，동융기토양중수류운동수도토양기질세、온도세급중력세적영향，동토중평형상태하기질세위토양온도적함수，토양중오염물삼출통량여수분삼출통량표현출선성관계。기우수도관구하점면산회류특성화동융기토양대우관구수문과정이급면원오염물천이적영향궤리，재SWAT모형모괴수정적기출상，모의료동북지구수도관구면원오염천이류실과정，모의류량、NH4+、NO3-、COD농도여실측치부합교호，표명개진적모형능구용우동북지구수도관구적수문급면원오염과정모의。
Hydrological processes are the driving force of transportation, transformation, and accumulation of agricultural non-point-source pollutants in a paddy irrigation district. The aim of this study was to simulate hydrological processes and non-point source pollution transport processes in a complex irrigation and drainage system in north-east China. Field experiments were conducted to measure quality and quantity of leakage and irrigation return water in field and drainage system in the Qianguo irrigation district (Jilin, China) during the period from 2009 to 2011. The hydrological processes in the various drains were different. In the field canals, the subsurface flow and leakage with high N concentrations were diluted by irrigation return water. The storage process in the lateral drains impacted the drainage process and the convection and mixing processes of the non-point pollutants significantly. In a lateral irrigation canal controlled region, the subsurface flow and the direct seepage flow from paddy fields through the side walls of field drains to the drains were simulated using unsteady flow equation. The water and contaminants in the field drains converged to lateral drains, and finally reached the main drain. A modified Muskingum method was proposed to calculate the processes of water flow and chemical transport in the drainage system. The results from the field experiments and simulations indicated that the fate of ammonium (NH4+), nitrate (NO3-), and chemical oxygen demand (COD) in the system were primarily controlled by the drainage processes. The NH4+and NO3-transport processes were mainly affected by the surface leakage and the deep leakage process, respectively. Besides from irrigation return water, the COD mass discharged from paddy fields to drains was through both subsurface flow and deep leakage. The results clearly showed the contributions of different drainage processes to non-point source pollution in a complex drainage system during the rice-growing period. Bromide (Br-) was used as tracer to investigate water flow and solution transport in the soil during the freezing and thawing periods. The redistributions of soil water, temperature, and Br- tracer were monitored. In the frozen soil, water movement was caused by the temperature gradient, matric potential gradient and gravity. The matric potential of unfrozen water in frozen soil at an equilibrium state was estimated using a temperature-based function. A linear relationship was observed between solution flux and soil water flux. The SWAT was modified and applied successfully to simulate the drainage and contaminants (NH4+, NO3-and COD) transport processes. The methods and results from this study should be useful to characterize non-point source pollutions in paddy irrigation district of north-east China.