Detection and attribution of urbanization effect on flood extremes using nonstationary flood-frequency models.

Urbanization is found to have an impact on high flows in a urbanized catchmentThe use of point processes is advocated for trend detection and attributionThe use of process-related covariates gives a better representation of change.

Occurrence of contaminants of emerging concern in the Eerste River, South Africa: Towards the optimisation of an urban water profiling approach for public- and ecological health risk characterisation.

The study evaluated the presence and fate of various contaminants of emerging concern (CECs) from a South African wastewater treatment works (WWTW) and surface waters located around an urban setting. A total of 45 CECs were quantified from nine sampling locations over an 11-month period. Daily loads (g/day) of the target analytes in the WWTW showed persistence of some CECs, along with population-normalised daily loads (mg/day/1000inh) of pharmaceuticals and drugs of abuse (DOA) that were estimated for the first time in the study area. Multiple chemical markers were recorded in river water located upstream of the WWTW discharge throughout the study period, suggesting a high degree of diffuse pollution from urban communities in the study area that are not connected to sewage networks or where sanitation services are limited. The potential of using defined surface water locations to perform community-wide substance use profiling for non-sewered communities was also explored. Environmental risk characterisation for the WWTW effluent and surface waters throughout the study period provided multiple risk quotients (RQ) for the target list of CECs spanning over various sentinel trophic levels. High risk profiles (RQ > 1.0) with a frequency of exceedance (FoE) larger than 75 % were recorded for several CECs in both WWTW effluent and surface water locations that suggest potential long-term ecological health risk impacts of pollution hotspot areas in the river catchment situated around the urban area. We present challenges in surface water quality within the study area that is relatable, or may even present more challenging, in other low- or middle-income country (LMICs) settings. The study also highlighted some challenges and limitations associated with the much-needed application of wastewater-based epidemiology (WBE) intervention in non-sewered communities that can inform on public health and communal substance use profiles of the entire urban setting.

An empirical investigation of climate and land-use effects on water quantity and quality in two urbanising catchments in the southern United Kingdom.

Using historical data of climate, land-use, hydrology and water quality from four catchments located in the south of England, this study identifies the impact of climate and land-use change on selected water quantity and water quality indicators. The study utilises a paired catchment approach, with two catchments that have experienced a high degree of urbanisation over the past five decades and two nearby, hydrologically similar, but undeveloped catchments. Multivariate regression models were used to assess the influence of rainfall and urbanisation on runoff (annual and seasonal), dissolved oxygen levels and temperature. Results indicate: (i) no trend in annual or seasonal rainfall totals, (ii) upward trend in runoff totals in the two urban catchments but not in the rural catchments, (iii) upward trend in dissolved oxygen and temperature in the urban catchments, but not in the rural catchments, and (iv) changes in temperature and dissolved oxygen in the urban catchments are not driven by climatic variables.