Influence of wetlands on nutrients in headwaters of agricultural catchments

Stempvoort, Dale R. Van; MacKay, D. Ross; Collins, Pamela V.; Brown, Susan J.; Koehler, Geoff

doi:10.1002/hyp.14866

Cited by 3 publications

(1 citation statement)

References 92 publications

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“…The impact of wetlands on hydrological extremes and nutrient export has been studied using different hydrological models [13,[18][19][20][21][22], including the Soil Water Assessment Tool (SWAT) model [23], and observational studies [12,24,25]. Impacts seem to vary with location [26] and wetland type but the consensus is that wetlands reduce peak flows [27,28] and nutrient loading [29,30].…”

Section: Introductionmentioning

confidence: 99%

Micro-Catchments, Macro Effects: Natural Water Retention Measures in the Kylldal Catchment, Germany

Nauta,

Waterloo,

Gevaert

et al. 2024

Water

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Floods are among the most devastating and financially burdensome natural disasters in Europe. The combined impact of climate change and land use change is expected to exacerbate and intensify the destructive consequences of river floods. In this study, we analysed the effects of wetland restoration on peak and base flows and on water quality in the Kylldal catchment of the Kyll River in the German Middle Mountains using the Soil and Water Assessment Tool+ (SWAT+). Monthly median daily discharge increases varied between 3% and 33% in the studied (micro)catchments. The higher median flow rates show that discharge peaks were attenuated and distributed over a longer period, making both extreme peak flows and low flows less common. Peak flows tended to decrease, with the largest effects between late fall and early spring when peak flow values decreased by up to 18%. The annual maximum peak flows in each of the three micro-catchments decreased by 12–24% on average. The occurrence of daily average flow rates larger than 1 m3 s−1 was up to 45% lower after wetland restoration. Low flows increased by up to 21% and 13% in the summer and fall, respectively, which suggests that drought risk also decreases after wetland restoration. Average nitrogen exports decreased by 38–50% in the project areas and by 20% at the catchment level. Average phosphorus exports decreased by 52–67% in the project areas and by 25% at the catchment level. The study highlights the potential of wetland restoration for improving hydrological services, mitigating flood risks, and enhancing water quality. Restoring and maintaining freshwater ecosystems and their natural sponge functions is crucial for effectively managing water resources and addressing the challenges posed by climate change and land use changes.

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Section: Introductionmentioning

confidence: 99%

Micro-Catchments, Macro Effects: Natural Water Retention Measures in the Kylldal Catchment, Germany

Nauta,

Waterloo,

Gevaert

et al. 2024

Water

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Nutrient delivery by groundwater discharge to headwater streams in agricultural catchments

Stempvoort

MacKay

Collins

et al. 2022

Hydrological Processes

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Nutrient concentrations in riparian groundwater are variable from site to site, making it challenging to use these data to quantify nutrient fluxes contributed by groundwater discharge to headwater streams. Instead, we define event‐excluded baseflow (BFEE), and use stream discharge data and stream samples collected during BFEE to estimate groundwater discharge and loading of nutrients to the streams. Based on this method, in two study catchments (Thames River basin, Ontario, Canada) groundwater discharge during BFEE contributed about 30% of the total streamflow and 20%–30% of the total loading of soluble reactive phosphorus (SRP) and nitrate. Previous estimates of baseflow using hydrographic separation techniques indicate that groundwater discharge likely contributes even larger fractions, ~50%–60% of flow in these catchments. We infer that groundwater likely contributes ~40% of the annual SRP load and ~ 50%–60% of the nitrate‐N load. These results indicate that groundwater discharge plays an important role in the nutrient loading to headwater streams. This reinforces the findings of earlier studies that have inferred a dominant influence of legacy reservoirs of nutrients in the subsurface of similar agricultural catchments on the loads of these nutrients in headwater streams.

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Agricultural intensification in Lake Naivasha Catchment in Kenya and associated nutrients and pesticides pollution

Onyango,

Kitaka,

van Bruggen

et al. 2024

Sci Rep

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Investments in agricultural intensification in sub-Saharan Africa aim to fulfill food and economic demands. However, the increased use of fertilizers and pesticides poses ecological risks to water bodies in agricultural catchments. This study focused on assessing the impact of agricultural intensification on nutrient and pesticide pollution in the L. Naivasha catchment in Kenya. The research revealed significant changes in the catchment’s agricultural landscape between 1989 and 2019, driven by intensified agricultural expansion. As a result, nutrient and pesticide emissions have worsened the lake’s trophic status, shifting it towards hypereutrophic conditions. The study found a weak relationship between total nitrogen (TN) and sum dichlorodiphenyltrichloroethane (∑DDT), indicating that an increase in TN slightly predicted a reduction in ∑DDT. Analysis also showed potential phosphorus (P) limitation in the lake. Additionally, the observed ratio between dichlorodiphenyldichloroethane and dichlorodiphenyldichloroethylene (DDD:DDE) and (DDE + DDD):DDT ratios suggest recent use of banned DDT in the catchment. The study concludes that the transformation of L. Naivasha landscape shows unsustainable agricultural expansion with reduced forest cover, increased croplands, and increased pesticide contamination. This reflects a common issue in sub-Saharan Africa, that sustainable catchment management must address, specifically for combined pollutants, to support water quality and achieve the SDGs in agriculture.

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Influence of wetlands on nutrients in headwaters of agricultural catchments

Cited by 3 publications

References 92 publications

Micro-Catchments, Macro Effects: Natural Water Retention Measures in the Kylldal Catchment, Germany

Micro-Catchments, Macro Effects: Natural Water Retention Measures in the Kylldal Catchment, Germany

Nutrient delivery by groundwater discharge to headwater streams in agricultural catchments

Agricultural intensification in Lake Naivasha Catchment in Kenya and associated nutrients and pesticides pollution

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