Riparian proper functioning condition assessment to improve watershed management for water quality

Abstract

Pollutants can be reduced, ameliorated, or assimilated when riparian ecosystems have the vegetation, water, and soil/landform needed for riparian functions. Loss of physical form and ecological function unravels assimilation processes, increasing supply and transport of pollutants. Water quality and aquatic organisms are response measures of accumulated upstream discharges, and ultimately of changes in riparian functions. Thus, water quality monitoring often fails to identify or lags behind many causes of pollution or remediation from riparian degradation. This paper reviews the interagency riparian proper functioning condition (PFC) assessment for lotic (running water) riparian ecosystems and outlines connections between PFC and water quality attributes (sediment, nutrients, temperature, and dissolved oxygen [DO]). The PFC interaction of hydrology, vegetation, and soils/landforms influences water quality by dissipating energy associated with high waterflow, thereby reducing vertical instability and lateral erosion while developing floodplains with captured sediment and nutrients. Slowing flood water enables aquifer recharge, deposition, and plant nutrient uptake. Water-loving, densely rooted streambank stabilizing vegetation and/or wood helps integrate riparian functions to maintain channel pattern, profile, and dimension with characteristics for a diversity of habitats. A complex food web helps slow the nutrient spiral with uptake and storage. Temperature fluctuations are dampened by delayed discharges, narrower and deeper active channels, coarser substrates that enhance hyporheic interchange, and shade from riparian vegetation. After assessment and implementation, monitoring recovery of impaired riparian function attributes (e.g., streambank plant species) naturally focuses on persistent drivers of water quality and aquatic habitat. This provides timely environmental indicators of stream ecological health and water quality remediation projects or land management. Key words: environmental indicators-function-nutrients-rivers and streamssediment-temperatureWater quality standards are based on needs for beneficial uses, whereas opportunities for remediation are often based on need(s) for riparian functions. Water quality or biological community assessments (USEPA 2009a(USEPA , 2009b cannot predict if an ecosystem is crossing geomorphic or ecological thresholds causing devastating changes to the riparian and aquatic ecosystems (Hall et al. 2014;Kozlowski et al. 2013). For nonpoint source issues, water quality data are lagging indicators (response indicators) and do not inform riparian resource managers or riparian restoration monitors in a timeframe relevant for adaptive management. Water quality and many other terrestrial and aquatic ecosystem goods and services depend on riparian functions. One of the goals of many federal, state, and tribal environmental and natural resource programs is to maintain and restore functionality of stream and wetland riparian areas. This impacts sediment and nutrient loa...

Delineating and mapping riparian areas for ecosystem service assessment

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Importance of Geology and Geomorphology in Watershed Health Assessment

“…Geology includes elements such as lithology and structural settings (Wilson and Droste, 2000). Whereas, geomorphology processes incorporate the climate or hydrology sectors with parent materials, sediment, and vegetation cover to form a landform (Swanson et al, 2017). Geomorphology indeed comprises both quantitative and qualitative explanations of landscapes and landforms, as well as processes investigations and process interactions creating these forms in temporal and spatial scales (Renschler and Harbor, 2002).…”

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