Journal Article

Assessment of river water quality during snowmelt and base flow periods in two catchment areas with different land use

Hayakawa, Atsushi, Woli, Krishna Prasad, Kuramochi, Kanta, Hatano, Ryusuke

2008

Overview

River water quality was evaluated with respect to eutrophication and land use during spring snowmelt and summer base flow periods in Abashiri (mixed cropland-livestock farming) and Okoppe (grassland-based dairy cattle farming), eastern Hokkaido, Japan. Water from rivers and tributaries was sampled during snowmelt and summer base flow periods in 2005, and river flow was measured. Total N (TN), NO 3 -N, and Si concentrations were determined using standard methods. Total catchment and upland areas for each sampling site were determined with ArcGIS hydrology modeling software and 1:25,000-scale digital topographic maps. Specific discharge was significantly higher during snowmelt than during base flow. In both areas, TN concentrations increased, whereas Si concentrations decreased, with increased specific discharge, and were significantly higher during snowmelt. The Si:TN mole ratio decreased to below or close to the threshold value for eutrophication (2.7) in one-third of sites during snowmelt. River NO 3 -N concentrations during base flow were significantly and positively correlated with the proportion of upland fields in the catchment in both the Abashiri ( r =0.88, P <0.001) and Okoppe ( r =0.43, P <0.01) areas. However, the regression slope, defined as the impact factor (IF) of water quality, was much higher in Abashiri (0.025) than in Okoppe (0.0094). The correlations were also significantly positive during snowmelt in both areas, but IF was four to eight times higher during snowmelt than during base flow. Higher discharge of N from upland fields and grasslands during snowmelt and the resulting eutrophication in estuaries suggest that nutrient discharge during snowmelt should be taken into account when assessing and monitoring the annual loss of nutrients from agricultural fields.

• Publisher: Springer Netherlands,Springer,Springer Nature B.V
• Subject: Agricultural land / Agriculture / Applied sciences / Assessments / Base flow / Catchment areas / Catchments / computer software / Continental surface waters / correlation / Dairy cattle / Dairy farms / Discharge / Drainage / Earth and Environmental Science / Earth sciences / Earth, ocean, space / Ecology / Ecotoxicology / Engineering and environment geology. Geothermics / Environment / Environmental Management / Environmental Monitoring / Estuaries / Eutrophication / Exact sciences and technology / Farming / farming systems / Flow velocity / Forest soils / Freshwater / geographic information systems / Grasslands / highlands / Hydrology / Impact factors / Japan / Laboratories / Land use / Livestock / Livestock farming / monitoring / Monitoring/Environmental Analysis / Natural water pollution / nitrate nitrogen / Nitrogen - analysis / Nutrients / Pollution / Pollution, environment geology / River flow / river water / Rivers / Rivers - chemistry / silicon / Silicon Dioxide - analysis / Snow / Snowmelt / Soil - analysis / Soil sciences / spring / Studies / Summer / Topographic mapping / Water - standards / Water quality / Water treatment and pollution / watersheds