Nutrients Runoff from a Forested Catchment during an Extreme Storm Event: A Case Study of the Headwaters of the Shimanto River in the Western Part of Kochi Prefecture, Japan in July, 2011
{"title":"Nutrients Runoff from a Forested Catchment during an Extreme Storm Event: A Case Study of the Headwaters of the Shimanto River in the Western Part of Kochi Prefecture, Japan in July, 2011","authors":"Yoshiki Shinomiya, Yuichi Yokoyama","doi":"10.2965/jswe.42.219","DOIUrl":null,"url":null,"abstract":"We investigated the loads of suspended solids ( SS ) , total ( TN ) and dissolved ( DN ) nitrogen during an extreme storm event ( total rainfall, 742 mm ) on 18 and 19 July 2011 in a forested mountain headwater catchment of the Shimanto River in the western part of Kochi Prefecture, Japan. We compared the extreme storm event with the normal event ( total rainfall, below 100 mm ) and the storm event ( total rainfall, 100 – 300 mm ) . The experimental catchment ( 73 ha ) has an underlayer of sandstone and is mainly covered with a secondary forest that comprises evergreen trees. Samples of streamwater were collected every two hours using an automatic water sampler during six events ( total rainfall, 44 – 742 mm ) . The load of TN during the extreme storm event was about 5 kg ha -1 event -1 , which is similar to the domestic average annual TN load ( 4.9 kg ha -1 yr -1 ) . The proportion of DN to TN in the specific cumulative load decreased sharply from 97% – 99% in the normal event and 77% – 97% in the storm event to 5% in the extreme storm event phase. The results clearly show that the load of particulate nitrogen was markedly greater than the load of DN during the extreme storm event.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":"31 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Japan Society on Water Environment","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.2965/jswe.42.219","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 1
Abstract
We investigated the loads of suspended solids ( SS ) , total ( TN ) and dissolved ( DN ) nitrogen during an extreme storm event ( total rainfall, 742 mm ) on 18 and 19 July 2011 in a forested mountain headwater catchment of the Shimanto River in the western part of Kochi Prefecture, Japan. We compared the extreme storm event with the normal event ( total rainfall, below 100 mm ) and the storm event ( total rainfall, 100 – 300 mm ) . The experimental catchment ( 73 ha ) has an underlayer of sandstone and is mainly covered with a secondary forest that comprises evergreen trees. Samples of streamwater were collected every two hours using an automatic water sampler during six events ( total rainfall, 44 – 742 mm ) . The load of TN during the extreme storm event was about 5 kg ha -1 event -1 , which is similar to the domestic average annual TN load ( 4.9 kg ha -1 yr -1 ) . The proportion of DN to TN in the specific cumulative load decreased sharply from 97% – 99% in the normal event and 77% – 97% in the storm event to 5% in the extreme storm event phase. The results clearly show that the load of particulate nitrogen was markedly greater than the load of DN during the extreme storm event.
研究了2011年7月18日和19日在日本高知县西部岛曼托河森林山源集水区发生的一次极端暴雨事件(总降雨量为742 mm)中悬浮固体(SS)、总氮(TN)和溶解氮(DN)的负荷。我们将极端风暴事件与正常事件(总降雨量,低于100毫米)和风暴事件(总降雨量,100 - 300毫米)进行了比较。实验集水区(73公顷)有砂岩的下层,主要覆盖着由常绿树木组成的次生林。在6个事件(总降雨量44 - 742毫米)中,使用自动水采样器每两小时采集一次溪水样本。极端风暴期间全氮负荷约为5 kg ha -1 event -1,与国内年均全氮负荷(4.9 kg ha -1 yr -1)相近。DN / TN在比累积负荷中的比例从正常期的97% ~ 99%和风暴期的77% ~ 97%急剧下降到极端风暴期的5%。结果清楚地表明,在极端风暴事件中,颗粒氮的负荷明显大于DN的负荷。