Mechanism of nutrient dynamics and water quality formation driven by subsurface water flow of sand bar in sandy river

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14729
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Hydraulic engineering
• Research Institution: Nagoya University
• Principal Investigator: OBANA Makiko 名古屋大学, 工学研究科, 講師 (10447831)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 砂州 / 伏流水 / 窒素動態 / 脱窒能 / 河道植生域

Outline of Final Research Achievements

The conservation and adjustment of sandbar landscape is pointed out as the goal of river environmental management. This study is focused on the denitrification of sand bar driven by subsurface water flow in aim to the quantification of water purification function in a river. This research is consisted of 3 parts as 1) monitoring of subsurface water flow and water quality in sandbars, 2) mechanism analysis of nutrient dynamic based on water flume experiment, and 3) development of nutrient dynamics model. In the result, the new method for quantify the denitrification potential based on the field observation result which include morphological and hydronic parameters was proposed. An empirical formula which quantifies the potential according to landscape elements in sand bar was created by using the field data. Furthermore, it has become possible to compare the denitrification potential of each river by using our new method.

Free Research Field

水工水理学

Academic Significance and Societal Importance of the Research Achievements

本研究によって，今まで個別事象として捉えられてきた①表流水流れ・土砂輸送と伏流水流動，および②砂州内窒素循環過程の統合的な取り扱いが可能となり，砂州の伏流水を通した窒素循環過程の代表プロセスである脱窒についての基礎的な現象が明らかとなったことに大きな意義がある．その現象の把握とモデリングにより植生種や比高などが考慮された場所に応じた砂州の栄養状態が把握されることは，河道の植生成長や生物生息場などの知見に，学術的基礎を提供するものとして位置づけられるほか，洪水時の流れ・土砂輸送と関連づけられていることから，河川がインパクトを受けた際の窒素動態の予測の議論に繋がるものでもある．