Land Cover and Water Quality Patterns in an Urban River: A Case Study of River Medlock, Greater Manchester, UK

Abstract

Urban river catchments face multiple water quality challenges that threaten the biodiversity of riverine habitats and the flow of ecosystem services. We examined two water quality challenges, runoff from increasingly impervious land covers and effluent from combined sewer overflows within a temperate zone river catchment in Greater Manchester, North-West UK. Sub-catchment areas of the River Medlock were delineated from digital elevation models using a Geographical Information System. By combining flow accumulation and high-resolution land cover data within each sub-catchment and water quality measurements at five sampling points along the river, we identified which land cover(s) are key drivers of water quality. Impervious land covers increased downstream and were associated with higher runoff and poorer water quality. Of the impervious covers, transportation networks have the highest runoff ratios and therefore the greatest potential to convey contaminants to the river. We suggest more integrated management of imperviousness to address water quality, flood risk and, urban wellbeing could be achieved with greater catchment partnership working.

Land Cover Effects on Selected Nutrient Compounds in Small Lowland Agricultural Catchments

“…Nevertheless, this fact points to the need to search for new predictors, which could explain nutrients variability during growing season, and such additional variables could include macrophytes density, as well as soil properties metrics [42]. Moreover, from scaling (weighting) methods presented in the literature [47,98,99], the use of buffer zones and/or Euclidean distance scaling seems to be the optimal solution for modelling purposes in lowland landscapes. Flow accumulation scaling could be difficult to apply due to blind drainage, similar to slope scaling in terms of small differences in elevation and low steeper slopes.…”

“…Most of the work in this area, however, concerned catchments of over a hundred square kilometers, including upland or highland relief and steeper slopes of the terrain, where high hydrological connectivity and intensive erosion result in increased ion migration [43][44][45]. Meanwhile, few studies used widely available land cover datasets [39], while in most cases land cover metrics were computed with the use of government or self-classification-based land cover maps [46,47], making the results not comparable at the European scale. Finally, the results and conclusions of such investigations were not consistent and the effects of particular land cover metrics on nutrients ranged from negative to even positive [48,49].…”

Exploring the Interactions of Physical, Chemical and Biological Variables of an Urban River Using Network Analysis

“…The upstream section of the river had higher counts of benthic invertebrates when compared to the lower sections of the river. The distribution of the functional feeding groups (FFGs) ( Tables 2 and 4) showed the dominance of the collector-filterers (40%), which suggested the role of discharge in transporting drift that served as food to the groups [1], indicating the absence of non-forest covers and increased urban cover [14], especially at the more urban sections of the river. Windsor et al [54] noted that contaminated rivers found in the highly urban sites of South Wales, U.K., were characterised by their reduced taxonomic and functional diversity and simplified food web structure.…”

“…However, increasing human population growth and the associated agricultural and urban demands put large amounts of pressure on freshwater resources in terms of both the quality and quantity needed to satisfy human needs [5][6][7][8][9][10][11][12]. These pressures on rivers modify and sometimes limit the biodiversity abundance, which consequently impacts on the ecosystem system services provided by these rivers [10,13,14]. The impact of point and non-point source pollution on rivers' biodiversity, richness and abundance have been widely studied [15][16][17][18][19].…”

“…Other challenges include channel modifications, canalisation, urban runoff, leakages and agricultural effluent, which impact the river's diversity and abundance [39]. Further studies on the land cover for this case study can be found in [14].…”