Trisha L.C. Moore

Ecosystem service provision by stormwater wetlands and ponds — A means for evaluation?

Stormwater control measures (SCMs) such as constructed stormwater ponds and constructed stormwater wetlands (CSWs) are designed to regulate runoff hydrology and quality. However, these created ecosystems also provide a range of other benefits, or ecosystem services, which are often acknowledged but rarely quantified. In this study, additional ecosystem services, including carbon sequestration, biodiversity, and cultural services, were assessed and compared between 20 ponds and 20 CSWs in North Carolina, USA. Carbon sequestration was estimated through the carbon content of pond and wetland sediments across a gradient of system age. Biodiversity was quantified in terms of the richness and Shannon diversity index of vegetative and aquatic macroinvertebrate communities. Cultural services were qualitatively assessed based on the potential for recreational and educational opportunities at each site. Ponds and wetlands were found to support similar levels of macroinvertebrate diversity, though differences community composition arose between the two habitat types. CSWs demonstrated greater potential to provide carbon sequestration, vegetative diversity, and cultural ecosystem services. This assessment provides an initial framework upon which future assessments of ecosystem service provision by SCMs can build.

Critical Review of Technical Questions Facing Low Impact Development and Green Infrastructure: A Perspective from the Great Plains.

Since its inception, Low Impact Development (LID) has become part of urban stormwater management across the United States, marking progress in the gradual transition from centralized to distributed runoff management infrastructure. The ultimate goal of LID is full, cost-effective implementation to maximize watershed-scale ecosystem services and enhance resilience. To reach that goal in the Great Plains, the multi-disciplinary author team presents this critical review based on thirteen technical questions within the context of regional climate and socioeconomics across increasing complexities in scale and function. Although some progress has been made, much remains to be done including continued basic and applied research, development of local LID design specifications, local demonstrations, and identifying funding mechanisms for these solutions. Within the Great Plains and beyond, by addressing these technical questions within a local context, the goal of widespread acceptance of LID can be achieved, resulting in more effective and resilient stormwater management.

Urban Stormwater Characterization, Control, and Treatment.

The following review presents a synthesis of 181 journal articles published during 2015 that represent progress toward better characterizing, controlling, and treating urban stormwater runoff. The review is structured by general topical areas related to (1) stormwater quality and quantity characterization; (2) engineered stormwater control and treatment practices, including erosion and sediment control, stormwater ponds, constructed stormwater wetlands, bioretention, permeable pavement, greenroofs, and rainwater harvesting systems; and (3) watershed-scale modeling and optimization of stormwater control and treatment practices. Common research themes emerging from this collection of studies include potential to enhance hydrologic and pollutant treatment performance of stormwater practices via media amendments and the use of innovative outlet control structures, as well as development of a more mechanistic understanding of hydrologic and water-quality functions to inform modeling and performance predictions. These studies serve to expand the fields knowledge base and will inform future efforts to further improve stormwater control and treatment at various spatial and temporal scales.

Understanding the Relationship between Stormwater Control Measures and Ecosystem Services in an Urban Watershed

AbstractThe dilemma of managing the trade-off between immediate human needs and maintaining the ability of the Earth to provide ecosystem services is considered to be one of the greatest challenges...

Evaluation of factors affecting soil carbon sequestration services of stormwater wet retention ponds in varying climate zones

The carbon sequestration services of stormwater wet retention ponds were investigated in four different climates: U.S., Northern Sweden, Southern Sweden, and Singapore, representing a range of annual mean temperatures, growing season lengths and rainfall depths: geographic factors that were not statistically compared, but have great effect on carbon (C) accumulation. A chronosequence was used to estimate C accumulations rates; C accumulation and decomposition rates were not directly measured. C accumulated significantly over time in vegetated shallow water areas (0-30cm) in the USA (78.4gCm-2yr-1), in vegetated temporary inundation zones in Sweden (75.8gCm-2yr-1), and in all ponds in Singapore (135gCm-2yr-1). Vegetative production appeared to exert a stronger influence on relative C accumulation rates than decomposition. Comparing among the four climatic zones, the effects of increasing rainfall and growing season lengths (vegetative production) outweighed the effects of higher temperature on decomposition rates. Littoral vegetation was a significant source to the soil C pool relative to C sources draining from watersheds. Establishment of vegetation in the shallow water zones of retention ponds is vital to providing a C source to the soil. Thus, the width of littoral shelves containing this vegetation along the perimeter may be increased if C sequestration is a design goal. This assessment establishes that stormwater wet retention ponds can sequester C across different climate zones with generally annual rainfall and lengths of growing season being important general factors for C accumulation.

Stormwater to Base flow? Investigating surface-groundwater interactions for stormwater management and ecosystem enhancement

Minnehaha Creek is among the most valued natural resources within the Minneapolis, MN metro area. However, frequent drought periods – which have left the creek dry in 9 of the last 13 years – impair both the ecological and cultural value of the creek. Rapid rises and falls in streamflow due to stormwater runoff contribute further to flow-related impairments in Minnehaha Creek. We hypothesize that flow in the creek during low-flow periods could be augmented through strategic infiltration and storage of stormwater runoff in the shallow aquifer feeding the creek. Existing hydrogeologic data suggest sustained base flow in Minnehaha Creek is limited due to rapid vertical transmission of recharged groundwater to underlying bedrock aquifers, the vertical travel time of which is on the order of 0.5 years. A streamflow-based systems model applied to infer physical characteristics of the shallow aquifer system indicated that the area of the contributing aquifer system is less than 1% of the creek’s watershed area. O-18 and dueterium isotope signatures likewise indicate limited groundwater inputs to the stream system. However, site-level field measurements of groundwater-surface water interactions – including thermal mapping, streambed seepage rate measurements, and monitoring of piezometric heads throughout the creek’s riparian area – indicate there may be opportunities to augment base flow if infiltration occurs in select regions. The understanding of surface-groundwater exchanges in Minnehaha Creek gained through field measurements will be used to inform stormwater management efforts as to opportunities to capture stormwater for augmentation of base flow.

Can Roadside Vegetation and Soil Act As a Carbon Sink

Stormwater Control Measures (SCMs) have long been understood to clean and treat runoff, but these systems may provide additional ecosystem benefits not currently quantified. The main goal of this project was to determine carbon (C) sequestration potential of common roadside SCMs within the Piedmont and Coastal Plain eco-regions of North Carolina. Along highways vegetated filter strips (VFS) and vegetated swales (VS) or wetland swales (WS) work in conjunction to trap sediment bound pollutants associated with runoff from the roadway. The VFS/VS systems work well in the roadside environment since they are linear and easily border the roadway, additionally they require little maintenance. Roadside VFS/VS systems (ranging in age from 1 to 38 years) within two physiographic regions of NC were sampled to evaluate C accumulation within the soil. Based upon ArcGIS analysis, each site was identified and systematically sampled from May to July 2011. Twenty VFS/VS sites were established in the Piedmont and Coastal Plain region, respectively. An additional 20 wetland swale sites were also sampled in the Coastal Plain region, which allows a comparison between the dry swales and the WSs within the Coastal Plain. Age, regional (i.e. Piedmont versus Coastal Plain), position (sampling distance from roadway), depth, and swale characteristics (i.e. WS versus VS) effects upon C accumulation are being examined in this study.

Stormwater ponds and wetlands: beyond runoff regulation

Stormwater control measures (SCMs) such as ponds and wetlands are designed to regulate runoff hydrology and quality. However, these created ecosystems also provide a range of other benefits, or ecosystem services, that are often acknowledged but rarely quantified. In this study, a range of other ecosystem services, including carbon sequestration, biodiversity, and cultural services, were assessed and compared between 20 stormwater pond and 20 wetlands in North Carolina, USA. Carbon sequestration was estimated through the carbon content of pond and wetland sediments across a gradient of system age. Biodiversity was quantified in terms of the richness and Shannon’s diversity index of vegetative and aquatic macroinvertebrate communities. Cultural services were qualitatively assessed based on the potential for recreational and educational opportunities at each site. Ponds and wetlands were found to support similar levels of macroinvertebrate diversity, though differences community composition arose between the two habitat types. Wetlands outperformed ponds in terms of vegetative diversity, cultural service provision, and carbon sequestration potential. Assessments such as this are needed to quantitatively account for the range of benefits these systems provide.

Potential Carbon Sequestration of Roadside Vegetated Stormwater Control Measures (SCMs)

Stormwater Control Measures (SCMs) are understood to clean and treat runoff, but these systems may provide additional ecosystem benefits not currently quantified. The goal of this project is to determine carbon (C) sequestration potential of 3 common roadside SCMs -vegetated filter strips, swales and wet swales - within the piedmont and coastal plain eco-regions of North Carolina. For the purpose of this study, environmental effects influencing C dynamics are assumed to remain constant within a given eco-region.