ABSTRACT

The greater River Derwent catchment is one of the largest river basins in Tasmania, Australia, and is the main supply of drinking water to the state’s capital, Hobart. Recently, summer-time occurrence of blue-green and filamentous algal blooms, combined with taste and odour problems at the drinking water intake, have raised concerns regarding the river’s water quality. In order to develop nutrient management strategies, it is crucial to understand nutrient sources and loads. This article therefore determines nutrient production loads using point source effluent data combined with estimates for diffuse sources using land-use data. Overall, we found that aquaculture is the main point source of total nitrogen (TN) and total phosphorus (TP) compared to sewage treatment plants, while agriculture is the main diffuse source of TP and forestry the main diffuse source of TN in the catchment overall. These estimates are compared to river mass loads derived from a two-year monitoring program, revealing some discrepancies between estimated and measured loads for some of the sub-catchments. Our findings identify priority areas for improved nutrient management and highlight the need for more frequent and continuous water quality monitoring to help reduce uncertainties for estimating nutrient loads in the River Derwent catchment.

摘要

大德文特河流域是澳大利亚塔斯马尼亚州最大的河流流域之一，也是该州首府霍巴特的主要饮用水供应。最近，夏季出现的蓝绿色和丝状藻华，加上饮用水取水口的味道和气味问题，引发了人们对河流水质的担忧。为了制定养分管理策略，了解养分来源和负荷至关重要。因此，本文使用点源流出物数据结合使用土地利用数据对扩散源的估计来确定养分生产负荷。总体而言，我们发现与污水处理厂相比，水产养殖是总氮（TN）和总磷（TP）的主要点源，总体而言，农业是 TP 的主要扩散来源，而林业是 TN 的主要扩散来源。将这些估计值与两年监测计划得出的河流质量负荷进行比较，揭示了一些子集水区的估计和测量负荷之间的一些差异。我们的研究结果确定了改善养分管理的优先领域，并强调需要更频繁和持续的水质监测，以帮助减少估算德文特河流域养分负荷的不确定性。