CSIRO Land and Water, PO Box 5, Wembley, WA 6913, Australia.
Sci Total Environ. 2013 Jan 15;443:491-504. doi: 10.1016/j.scitotenv.2012.10.085. Epub 2012 Dec 5.
Surface water quality in catchments undergoing urbanisation may be affected by the release of pre-existing (or legacy) solutes, such as nutrients, as well as new sources associated with urban land use. This paper examines both for a number of urbanisation scenarios and adopting the modelling capability developed for the analysis of urbanisation effects on catchment water balance. The flat relief of the study catchment and its sandy soils, in combination with a Mediterranean-type climate, lead to large rates of diffuse gross recharge and diffuse (evaporative) discharge with low overall runoff from the catchment (<1mm per unit area). Under these conditions solutes stored in shallow groundwater have long residence times (longer than 100 years). Urbanisation of such a catchment leads to significant changes in water regime, leading to a reduction in groundwater residence time and 'flushing' of legacy solutes towards the surface water network. Concurrently, urban development introduces new sources of solutes. It was found that the modelled concentrations of legacy solutes in the urban drains are greater than the water quality standards in the region; though, legacy solute concentrations reduce by 50% within the first 2-3 years and become less than 5% within 10 years for all urban scenarios. The full effect of new urban landscape on water quality was estimated to be longer than 5 years. Urban density and groundwater abstraction for irrigation of public open space and domestic garden have an effect on the surface water quality, as they influence the rate of legacy solute replacement and accumulation of the solute associated with the new urban forms. It was shown that water quality control measures in new urban developments should be directed to legacy nutrients during the first 2-3 years but measures reducing nutrient leachate from soil, such as soil amendments, should be considered for long-term solutions.
受城市化影响的汇水区域地表水质可能会受到先前（或遗留）溶质（如营养物）释放的影响，以及与城市土地利用相关的新污染源的影响。本文针对多种城市化情景进行了研究，并采用了为分析城市化对汇水盆地水量平衡的影响而开发的建模能力。研究汇水区域的平坦地形及其沙质土壤，加上地中海式气候，导致了大量的弥散总补给和弥散（蒸发）排泄，汇水区的总径流量很小（每单位面积小于 1 毫米）。在这些条件下，浅层地下水中储存的溶质具有很长的停留时间（超过 100 年）。这种汇水区域的城市化会导致水情发生重大变化，导致地下水停留时间缩短，并将遗留溶质“冲洗”到地表水网络中。同时，城市发展引入了新的溶质源。研究发现，模型模拟的城市排水中遗留溶质的浓度高于该地区的水质标准；尽管如此，所有城市化情景下，遗留溶质的浓度在最初的 2-3 年内减少了 50%，在 10 年内减少到 5%以下。新的城市景观对水质的全部影响预计将持续超过 5 年。城市密度和地下水抽取用于灌溉公共开放空间和私人花园，会对地表水质产生影响，因为它们会影响遗留溶质的替代速度以及与新城市形态相关的溶质的积累。研究表明，新城市发展中的水质控制措施应在最初的 2-3 年内针对遗留营养物，但应考虑采用土壤改良等减少土壤养分淋失的措施来解决长期问题。
