Assessment of the impact of land use in an agricultural catchment area on water quality of lowland rivers

Abstract

In several countries around the world, agricultural land area exceeds 70% (Uruguay 82.6%, Kazakhstan 80.4%, Turkmenistan 72.0%, Great Britain 71.7%, Ukraine 71.6% and others). This poses a serious risk of dissipating nitrates into the aquatic environment in agricultural catchments. The aim of this study was to assess the impact of land use on water quality parameters in an agricultural catchment area. It was decided to select for analysis the catchment of the Orla River (river length of 88 km, catchment area of 1,546 km2). The catchment area is predominantly agricultural in character and its entire area has been declared as an agricultural nitrate vulnerable zone (NVZ). A total of 27 survey sites were selected on the main watercourse and its tributaries. Analyses were conducted in the years 2010–2012 to determine physical and chemical parameters of water (pH reaction, conductivity, dissolved oxygen, total nitrogen, organic nitrogen, ammonia nitrogen, nitrates, total and reactive phosphorus) as well as six macrophyte metrics of ecological status assessment (MIR, IBMR, RMNI, MTR, TIM, RI). The average values of most physico-chemical parameters of water quality repeatedly exceeded limits of good ecological status, both in the Orla River and its tributaries. As many as 18 survey sites were classified as moderate ecological status, five sites as poor and only four as good ecological status. The results indicate the impact of land use in the catchment on water conductivity. Differences were observed in the concentrations of biotic components in the main watercourse and its tributaries, and in water quality in the southern part of the catchment in relation to the rest of the study area. This is probably connected with a greater share of forests and surface waters in that area.

The concept for innovative Comprehensive Assessment of Lowland Rivers

“…Rivers are a complex ecosystem, sensitive to the pressure of many factors and dependent on the use of the catchment area [86]. Therefore their assessment requires considering many parameters, both natural, and hydraulic, and including anthropopressure.…”

“…The final index values are then calculated using specific formulas. The score obtained from the calculation (0-100) is compared to the five-point NSFWQI rating scale excellent (91-100), good (71)(72)(73)(74)(75)(76)(77)(78)(79)(80)(81)(82)(83)(84)(85)(86)(87)(88)(89)(90), moderate (51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66)(67)(68)(69)(70), low and bad (0-25), [93,94]. Another index commonly used in river assessment is the Water Pollution Index (WPI).…”

Spatio-temporal evolution of eutrophication and water quality in the Turawa dam reservoir, Poland

“…Since surface water bodies can perform a number of functions, the water accumulated in reservoirs is of particular importance, e.g., flood protection, hydropower use, bathing areas, fishing, recreation, natural habitat, source of drinking water, and use for other purposes (e.g., agricultural, economic) 9 – 11 . However, these functions may be disturbed by various unfavorable processes, such as eutrophication, which is caused by the influx of large amounts of organic substances, particularly those rich in phosphorus and nitrogen compounds, and most often has an agricultural origin 12 – 14 . Eutrophication increases the fertility of the reservoir, which in turn cause the development of undesirable cyanobacteria, diatoms, and green algae, which manifest themselves in the form of the water bloom 15 , 16 .…”

Impact of anthropogenic infrastructure on aquatic and avian predator–prey interactions in a modified lowland river

“…Globally, lowland rivers provide essential foraging resources and refuge habitats for freshwater communities including aquatic and avian predators and their prey but are becoming increasingly vulnerable to negative impacts from anthropogenic modifications (Oglęcki et al., 2021). Previous work in lowland systems has identified negative ecosystem impacts associated with anthropogenic modifications to ecohydrological processes, including increased nutrient run off (Kupiec et al., 2021), water quality pollution (Dos Reis Oliveira et al., 2019), and creation of unnatural hydrological conditions (Davis et al., 2015). River maintenance measures required for operating anthropogenic structures may also be ecologically inconsiderate; channelisation and dredging homogenise river structure (Harrison et al., 2004), and the seasonal removal of riparian vegetation and natural in‐stream features (e.g., fallen trees) can exacerbate winter die‐off of habitat (Singh et al., 2021).…”