Watershed Restoration Research Articles

Seedling recruitment and cover responses to rock detention structures paired with seed in the Chihuahuan Desert

Drylands are susceptible to erosion by wind and water. Thus, the reestablishment of vegetation is a crucial focus of watershed restoration in order to stabilize soils and improve water infiltration. Currently, limited research exists quantifying vegetation responses to rock detention structures (RDS) in the Chihuahuan Desert, and no studies have quantified the effects of RDS paired with seed introduction. Our study area in the Rincon Arroyo Watershed, in southern New Mexico, tested the hypotheses that two types of RDS, micro‐catchments and stone‐lines paired with seeding, support increases in seedling recruitment and vegetation cover compared to untreated controls. This study also tested whether the application of seed to RDS alters plant communities in comparison to controls. One season after seeded RDS were applied, seedling recruitment, cover, and plant community responses were evaluated at treatment and control areas. Seeded stone‐lines showed significantly greater seedling recruitment (2×) and cover (0.3×) than controls (p < 0.05), whereas seeded micro‐catchments showed significantly greater cover (0.3×) than controls (p < 0.05) but did not exhibit significant differences in seedling recruitment compared to controls (p > 0.05). The lack of a significant difference between plant communities at treatment and control areas (p > 0.05) suggests that the addition of seed had little to no effect on plant communities or positive responses in seedling recruitment and cover. These results suggest that stone‐lines and micro‐catchments, alone, can support vegetation establishment in degraded dryland watersheds without the addition of seed.

Prioritization of Hydrological Restoration Areas Using AHP and GIS in Dulcepamba River Basin in Bolivar–Ecuador

In this study, we performed a preliminary soil analysis and collected environmental data for the Dulcepamba River Basin in Bolivar–Ecuador, before carrying out its hydrological restoration (HR). A geographic information system (GIS) and the multicriterion Analytical Hierarchy Process (AHP) decision-making method were used. The comprehensive evaluation included morphological aspects, soil properties, climatic conditions, vegetation, and land use. The terrain conditions were investigated using indicators such as the flow capacity, topographic moisture, soil resistance, sediment transport, current density, curve number, NDVI, precipitation, and distance to rivers. The results and analysis are presented in a series of maps, which establish a starting point for the HR of the Dulcepamba watershed. The key factors for assessing soil degradation in the watershed include land use, vegetation cover, sedimentation, humidity, and precipitation. Of the studied territory, 10.7 do not require HR, while 20.28% demand HR in the long term. In addition, 30.67% require HR in the short term, and 33.35% require HR immediately. Based on the findings, it is suggested that authorities consider the environmental remediation of the watershed and propose various HR measures. This analytical approach could prove valuable as a tool for the environmental restoration of watersheds in Ecuador.

Restoring freshwater habitat mosaics to promote resilience of vulnerable salmon populations

AbstractPhenotypic diversity and abundance drive salmon resilience in the face of increasing environmental variability. But what happens when human activities fundamentally alter the habitat complexity that drives this diversity? And how can we restore habitats to recover both diversity and abundance to support salmon persistence in a warming climate? Here, we looked at the impact of a large watershed restoration effort on the abundance and climate resilience of the three remaining core natural spring‐run Chinook Salmon populations in the California Central Valley (Butte, Mill, and Deer Creek). Butte Creek fish, which have floodplain access, had higher overall productivity and faster juvenile growth compared with Mill and Deer Creek populations, and the proportion of floodplain inundation was positively correlated with Butte Creek adult abundance two years later. While Butte Creek exhibited significant increases in abundance post‐restoration (~2000%), it generally exhibited lower phenotypic diversity and only a marginal increase in population stability after restoration based on the coefficient of variation (CV). In particular, Butte Creek salmon tended to exhibit larger drops in escapement following dry years (e.g., return years 2010, 2017) compared with Mill and Deer Creek populations, presumably due to limited inundation of its downstream floodplain. The late‐migrating juvenile strategy (i.e., yearling), which disproportionately supported Mill and Deer Creek populations during droughts, was uncommon among Butte Creek adults (averaging 60% of returns for Mill and Deer Creek vs. 0.3% for Butte Creek). Increased spring‐run stock complex stability was found, post‐restoration, when combining the three spring‐run populations (i.e., lower aggregate CV). However, among‐river pairwise correlations also suggested increased synchronization in population abundances post‐restoration, potentially due to increasing frequency and severity of extreme climatic events (e.g., droughts and ocean warming). This study underscores the importance of restoring a connected mosaic of aquatic habitats across modified landscapes, such as cold water refugia and floodplains, to preserve multiple (across‐population) life history pathways for increasing salmon stock complex stability and abundance. These landscape‐scale process‐based habitat restoration efforts are likely to be crucial for the successful long‐term recovery of vulnerable species in a rapidly changing climate.

Sustainability Assessment of the Upstream Bengawan Solo Watershed in Wonogiri Regency, Central Java Province, Indonesia

The sustainability of watershed management is a key issue that must be considered to ensure the continuation of watershed services such as agriculture, food, and energy. This concern has also been raised in Presidential Regulation No. 2/2015 and No. 18/2020 regarding the National Medium-Term Development plans for the periods of 2015–2019 and 2020–2024, which mandate the restoration of priority watersheds, one of which is the Upstream Bengawan Solo Watershed. The purpose of this study is to fill this knowledge gap by measuring the sustainability of this watershed from a time dynamics perspective. However, several factors can influence the achievement of sustainable development. This paper assesses the sustainability of the watershed over several periods using MDS (Multidimensional Scaling) analysis with the assistance of modified Rapfish (Rapid Appraisal for Fisheries) software (2013 version). The information used in this case study was collected from 20 districts in relation to social, economic, and environmental dimensions. Our result shows that the average index of the social dimension increases from 2007 to 2019 and 2021, while the economic dimension tends to fluctuate. A decrease occurs from 2007 to 2019, and then increases from 2019 to 2021. This differs significantly from the environmental dimension, which decreases from 2007 to 2019 to 2021. The sustainability scores were then compared across regions. The lessons learned in this study can be incorporated into regional policies and actions to overcome challenges in the implementation phase.

Hydrometeorological Trends in a Low-Gradient Forested Watershed on the Southeastern Atlantic Coastal Plain in the USA

Hydrology and meteorological data from relatively undisturbed watersheds aid in identifying effects on ecosystem services, tracking hydroclimatic trends, and reducing model uncertainties. Sustainable forest, water, and infrastructure management depends on assessing the impacts of extreme events and land use change on flooding, droughts, and biogeochemical processes. For example, global climate models predict more frequent high-intensity storms and longer dry periods for the southeastern USA. We summarized 17 years (2005–2021) of hydrometeorological data recorded in the 52 km2, third-order Turkey Creek watershed at the Santee Experimental Forest (SEF), Southeastern Coastal Plain, USA. This is a non-tidal headwater system of the Charleston Harbor estuary. The study period included a wide range of weather conditions; annual precipitation (P) and potential evapotranspiration (PET) ranged from 994 mm and 1212 mm in 2007 to 2243 mm and 1063 in 2015, respectively. The annual runoff coefficient (ROC) varied from 0.09 in 2007 (with water table (WT) as deep as 2.4 m below surface) to 0.52 in 2015 (with frequently ponded WT conditions), with an average of 0.22. Although the average P (1470 mm) was 11% higher than the historic 1964–1976 average (1320 mm), no significant (α= 0.05) trend was found in the annual P (p = 0.11), ROC (p = 0.17) or runoff (p = 0.27). Runoff occurred on 76.4% of all days in the study period, exceeding 20 mm/day for 1.25% of all days, mostly due to intense storms in the summer and lower ET demand in the winter. No-flow conditions were common during most of the summer growing season. WT recharge occurred during water-surplus conditions, and storm-event base flow contributed 23–47% of the total runoff as estimated using a hydrograph separation method. Storm-event peak discharge in the Turkey Creek was dominated by shallow subsurface runoff and was correlated with 48 h precipitation totals. Estimated precipitation intensity–duration–frequency and flood frequency relationships were found to be larger than those found by NOAA for the 1893–2002 period (for durations ≥ 3 h), and by USGS regional frequencies (for ≥10-year return intervals), respectively, for the same location. We recommend an integrated analysis of these data together with available water quality data to (1) assess the impacts of rising tides on the hydroperiod and biogeochemical processes in riparian forests of the estuary headwaters, (2) validate rainfall–runoff models including watershed scale models to assess land use and climate change on hydrology and water quality, and (3) inform watershed restoration goals, strategies, and infrastructure design in coastal watersheds.

Assessment of Climate Change Impacts on Wild Animals in Afghanistan

Climate change is an important worldwide environmental issue facing our planet today. Total of (920) vertebrate wild species are living in Afghanistan out of them (764) known species while (160) species are uncertain unknown, almostly protected and proposed protect area in different (9) provinces of Afghanistan were identified by Technology Needs Assessments – Mitigation Report, 2020. Climate change is predicted to be the biggest cause of wildlife habitat change, displacement, and losses of wild animal species in Afghanistan. Reducing the loss of habitats and preventing their collapse by creating protected habitats, constructing forests to stabilize slopes, strengthening soil and regulating water flow, improving agroforestry systems, and sustainable management and restoration of watersheds can decrease climate change effects on wildlife.

Citarum Watershed Restoration through Community Involvement and Tourism Village Development

The Citarum watershed is a source of livelihood for communities in 13 cities and regencies in West Java and Jakarta. However, the Citarum River is considered one of the most polluted rivers in the world, prompting the central and local governments to implement conservation programs. For Tarumajaya Village, the conservation of the Citarum watershed starts from the Situ Cisanti area accompanied by the development of a tourism village to support the Citarum Harum Program. However, the existing participation is only seen from the government side, and there is no significant community participation in terms of communication and others directly in the process of developing this tourism village. Thus, this study aims to identify community involvement in the development of tourism villages to support the restoration of the Citarum watershed in the Upper Citarum Region. This qualitative study was conducted in Tarumajaya Village, Kertasari Sub-district, Bandung Regency. Primary data were obtained through non-participant observation and in-depth interviews, while secondary data were obtained from policy documents. Data analysis included data reduction, presentation, verification, and conclusion drawing. The research findings show that the development of creative tourism villages in Tarumajaya Village is carried out to support environmental preservation and has economic value for the welfare of the community, thus supporting public health. Tarumajaya Village community innovation products have economic value in tourism and show community involvement in supporting sustainable tourism development which is expected to improve public health.

Determining organic nitrogen emission sources and secondary formations in an urban coastal airshed via stable isotope techniques

Organic nitrogen (ON) has been excluded in the majority of atmospheric N studies. However, dissolved organic nitrogen (DON) deposition influences coastal water quality and primary production creating an urgent need for comprehensive atmospheric ON characterization, especially in coastal airsheds. This study measured the concentration and isotopic composition of rainwater DON (δ15N-DON) and applied stable isotope mixing models to determine the ON emission source apportionments in a small-sized coastal city. The DON concentration averaged 10.6 ± 7.6 μM (n = 42), which was 29% of the total dissolved nitrogen in rainwater and produced a deposition flux of 1.5 kg N·ha−1·yr−1. The average rainwater δ15N-DON value was 8.3 ± 5.3‰ and isotope mixing model results suggested vehicles as a dominant source, overall contributing 35 ± 15% of ON emissions, followed by marine emissions (24 ± 16%), organic amines (18 ± 11%), organic nitrates (17 ± 11%), and biomass burning (8 ± 3%). Although secondary ON formations (i.e., organic amines and nitrates) had less contributions than primary emission sources (i.e., vehicles, marine, and biomass burning), it can be significant and rival primary emissions when the fertilizer application started. Our results fill knowledge gaps of ON wet deposition and emission sources in small-sized coastal cities and inform future atmospheric N mitigation strategies and coastal watershed restoration plans in similar regions. We call for further research determining the isotopic composition of ON emission sources and fractionation associated with primary emission and secondary formation in anticipation of creating a similar isotope-based foundation that has been used for decades to investigate inorganic nitrogen emissions.

Scales of Connectivity within Stream Temperature Networks of the Clackamas River Basin, Oregon

Water quality varies along the stream network; thus, considering the directional, dendritic nature of stream networks with surrounding landscape variables is essential in explaining spatial variations of water quality. Using a spatially extensive stream temperature monitoring effort in the Clackamas River Basin in the United States, we first compare spatial scales of analysis of atmospheric, landscape, and in-stream explanatory variables through their correlation with summer stream temperatures. We then derive a predictive stream temperature model with factors representing the spatial variation of local climate, recent wildfire effects, and discharge. Finally, we compare nonspatial multiple linear regression to a spatial stream network (SSN) model to assess the combined importance of the spatial scale of analysis and flow-connected stream distance in explaining total variation in stream temperatures. Most explanatory variables show the most highly significant relationships to stream temperature when derived as a percentage of the total upstream area above observation sites. Elevation and vegetation cover, however, were most significantly correlated to stream temperature at the riparian buffer area scale and the local reach contributing area scale, respectively. Multiple regression analysis using total upstream burned area, total upstream area with underlying High Cascades geology, and the elevation within the 100-m-wide riparian area explained 81 percent of variation in stream temperature. SSN outperformed this nonspatial statistical model, however, in explaining the total variation in stream temperature. These comparisons of scaled data sets demonstrate both the local and cumulative upstream effects on stream temperature, providing a spatial network-informed framework to those prioritizing watershed restoration and wildfire recovery activities.

Research on the Application of NbS in Watershed Ecological Restoration: A Case Study of Jiulong River Watershed Shan-Shui Initiative

Nature-based solutions (NbS) rapidly develop globally to address societal challenges and provide human well-being and biodiversity. Watershed restoration plays an essential role in enhancing the ecological and socio-economic benefits of the region. The design and implementation of watershed restoration projects are crucial to their effectiveness, and NbS has been applied as a concept in ecosystem-related projects. This paper proposes an evaluation method to assess the implementation of the Shan-Shui Initiative in the Jiulong River Watershed restoration projects based on the eight criteria proposed by the International Union for the Conservation of Nature (IUCN) Global Standard for Nature-Based Solutions. The aim is to standardize the implementation process of watershed restoration projects to achieve more significant benefits and practically apply the concept of NbS in watershed restoration. The implementation scheme of the Shan-Shui Initiative in the Jiulong River Watershed is designed to evaluate and improve the design and implementation scheme of ecological restoration projects in the actual basin. According to the assessment results, the degree of matching based on NbS for the implementation scheme of the Jiulong River Watershed Shan-Shui Initiative is 73%, which meets the criteria of NbS but needs to be improved in terms of monitoring and assessment, synergistic management, and benefit trade-offs.

Military in Watershed Restoration: A Multistakeholder Study on the Involvement the Indonesian Military in Citarum River Conservation

The Citarum watershed, Indonesia, was notorious for being the most polluted and destroyed in Indonesia. In 2018, the Indonesian Government created a new policy to restore this watershed, named Citarum Harum, by putting together multiple actors to combat watershed degradation, including one unique actor, namely the Indonesian military. This anomaly had created a new pattern and dynamics in watershed restoration. Historically, Indonesia had a peculiar civil-military relationship with the past military government. This creates a unique framework for how actors currently react to military involvement. This article examines these phenomena and elucidates the effectiveness of military involvement in watershed restoration. The study was conducted by the Citarum Harum watershed restoration programme in West Java, Indonesia. This study used in-depth interviews and multi-level stakeholder influence mapping on multiple informants involved in the restoration. The findings indicate a good shift in actor relations that creates improvements in watershed restoration. However, several other conditions also arise from the military's involvement, such as overlapping authorities, incompetency on some technicalities, desynchronization, and a shift in public perception. These problems require some adjustment in the roles of both civil and military personnel in the restoration programme to optimise the military's involvement further.

What controls home range relocations by estuarine fishes downstream from watersheds with altered freshwater flow?

We tracked locations of three fish species in two bays with differing hydrology in SW Florida in 2018–2020 to test the hypotheses about fish residency, movements, and environmental variables. Due to extensive watershed modification, one bay receives less freshwater and the other receives more relative to natural conditions. Home range duration differed for gray snapper (54 ± 6 days), red drum (132 ± 39), and goliath grouper (226 ± 63). Distances between relocation movements were similar for gray snapper and red drum (~ 1.2 km), but farther for goliath grouper (2.3 ± 0.3 km). Relocations were primarily seaward for gray snapper (83%) but varied for the other species. Home range duration related to age for goliath grouper (< 100 days for 1–1.5-year-olds, 300–425 days for 4–4.5-year-olds). Generalized additive models marginally related probability of gray snapper relocating to salinity and temperature whereas relocations of the other species occurred during all environmental conditions. Movement simulations lacking environmental cues produced similar emigration patterns as observed in tagged fish. Overall, results suggest that movements here are not strongly linked to environmental conditions, will be resilient to watershed restoration that should moderate salinity, and have implications for understanding the impacts of localized depletion due to recreational fishing.

Comparing Drivers of Spatial Variability in U.S. Lake and Stream Phosphorus Concentrations.

Decision makers need to know the drivers of surface water phosphorus (P) concentrations, the environmental factors that mediate P loading in freshwater systems, and where pollution sources and mediating factors are co-located to inform water quality restoration efforts. To provide this information, publicly available spatial data sets of P pollution sources and relevant environmental variables, like temperature, precipitation, and agricultural soil erodibility, were matched with >7,000 stream and lake total P observations throughout the conterminous United States. Using three statistical approaches, consisting of (a) correlation, (b) regression, and (c) machine learning techniques, we identified likely drivers of P concentrations. Surface water concentrations in streams were more strongly correlated and effectively predicted by annual fertilizer and manure input rates and agricultural legacy sources compared to that of lakes. This observation suggests that streams may be more immediately responsive to improvements in agricultural nutrient management. In contrast, lake concentrations, though still positively associated with agricultural input and surplus variables, may be more influenced by historic erosional inputs, internal lake recycling, and other environmental factors. Thus, lake TP concentrations may not be as immediately responsive as streams to improvements in phosphorus management. Both stream and lake P concentrations will potentially increase because of warming temperatures and forest recovering from past acidification, putting even further pressure on existing water quality restoration efforts to meet nutrient loading reduction targets. The identified spatial data sets and relationships elucidated in this effort can inform the placement and development of watershed restoration strategies to reduce excess P in aquatic systems.

Enduring tensions between scientific outputs and science learning in citizen science

Citizen science has been lauded for its promise and potential to simultaneously advance both the scientific enterprise as well as science education. Oftentimes, however, citizen science projects struggle to balance these dual goals and negotiate the tensions that arise between them. Many of these enduring tensions center on the tradeoffs involved between producing high quality data while also maintaining engaging learning experiences for volunteers. In this article, we present a case study of how a community-based organization navigated these tensions in the context of a multi-stakeholder, collaborative monitoring program that featured citizen science as part of a broader watershed restoration effort. Specifically, we describe how project organizers responded to tensions in their citizen science initiative by creating a tiered system for volunteer participation. This system aimed to produce high-quality data to inform watershed management as well as a suite of science learning opportunities for volunteers in ways aligned with their respective interests and goals. Ultimately, we suggest that such a system can support multiple pathways for building healthy and resilient social-ecological systems by potentially broadening the knowledge sources and perspectives from which conservation decisions are made.

How Are Man-Made Changes in Freshwater Flow Related to the Abundance of Juvenile Estuarine Fishes?

Changes in freshwater flow to estuaries can cause a suite of ecosystem impacts including eutrophication and alterations to plant communities, zooplankton populations, and other biota. In southwest Florida, historical manipulation of freshwater flow due to development, canals, and drainage ditches is pervasive. Because there are estuaries with reduced, increased, and relatively natural freshwater flow, this region presents an ideal system to study how these changes relate to downstream fish abundances. We used a 20-year trawl dataset focused on juvenile and small-bodied fish from three mangrove-lined sub-estuaries with contrasting flow conditions in southwest Florida’s Ten Thousand Islands to identify important environmental and temporal variables influencing fish populations. We used generalized additive models to investigate total fish abundance, species richness, diversity, and the abundances of 23 ecologically, recreationally, or commercially important species and describe their relationships with important environmental and temporal variables. While salinity and temperature had species-specific relationships with fish abundances, seasonality, interannual variability, and sub-estuary were more closely related to fish than salinity and temperature in most cases. Only 8 of 23 species responded most strongly to temperature, and only 1 species responded most strongly to salinity. This suggests that for most species in our study, temporal factors such as timing of spawning and recruitment variability had stronger relationships with the structure of fish populations than changes in freshwater flow. This work quantified how changes in freshwater flow, using salinity as a proxy, may relate to downstream fish abundances and therefore the potential implications of planned watershed restoration that is part of the Comprehensive Everglades Restoration Plan.

Species Distributions in a Changing Estuary: Predictions Under Future Climate Change, Sea-Level Rise, and Watershed Restoration

Species Distributions in a Changing Estuary: Predictions Under Future Climate Change, Sea-Level Rise, and Watershed Restoration

The Grande Ronde Model Watershed: Integrating Science into Restoration Implementation and Adaptive Management.

Watershed conservation groups throughout the Pacific Northwest coordinate and implement watershed and habitat restoration to recover Pacific salmon Oncorhynchus spp. Many watershed organizations struggle with implementing an adaptive management process that integrates monitoring data and the latest science into their restoration programs. We describe the evolution and lessons learned from the Grande Ronde Model Watershed (GRMW), one of the longest running watershed organizations coordinating fish habitat restoration projects. Since 1992, the GRMW has initiated nearly 300 habitat restoration projects and their partners more than 600 projects. These projects have evolved from an opportunistic approach, focusing on small-scale riparian fencing and instream structures to a data driven, collaborative processes for identifying, ranking, and implementing large process-based floodplain projects using the latest science. The GRMW recently developed an adaptive management process to assess restoration goals and priorities, and a multi-scale monitoring program that leverages the extensive data collected by partners, and periodic collection of LiDAR to evaluate past, current, and future restoration projects. These recently developed components, which are based on the collective history of the GRMW, provide important lessons for other watershed restoration organizations. These include partnering with local organizations to collect monitoring data; use of a transparent multi-scale process for prioritizing restoration; development of a stepwise process for design and implementation of priority projects; a formal adaptive management process with a designated lead to use the latest science to modify goals, priorities, project selection, and design; and use of remotely sensed data to assist with multi-scale monitoring of project success.

Recovering the lost potential of meadows to help mitigate challenges facing California’s forests and water supply

Groundwater systems in snow-dominated drainage areas supply cool baseflows that support instream and downstream users late into the dry season. Yet, these catchments are becoming rarer with climate change and anthropogenic pressures that threaten groundwater systems. Restoration of low-gradient meadows and streams can recover a catchment’s natural storage potential, especially in Mediterranean biomes such as the Sierra Nevada of California where summer groundwater recharge is scarce. The degradation of meadows due to intense human modification has decreased groundwater elevations and shifted wet meadow plant communities toward more xeric forest and shrub communities. We applied machine learning tools to find potential “lost meadows” that may no longer support high groundwater elevations or meadow vegetation but do exhibit basic geomorphic and climatic characteristics similar to existing meadows. The model reveals potential meadow habitat in the Sierra Nevada of nearly three times its current extent. We offer two conceptual applications of the model for incorporating meadows in watershed restoration planning. The first application focuses on strategically expanding wet meadows already associated with fuel breaks for increasing wildfire resistance. The second shows how meadow restoration in post-wildfire landscapes could increase capture of sediment from burned hillslopes where increased sediment storage would benefit water storage. Meadows are important habitats that have become degraded due to long-term overuse. Re-envisioning their potential extent shows that, with restoration, meadows could also serve as components of California’s multi-tiered efforts to manage pressing threats to its forests and water supply.

On‐ and off‐site erosion impacts of restoration measures in a tropical karst watershed

AbstractKarst areas are vulnerable landscapes which, if unprotected, could be permanently degraded. To bridge the gap existing in the reduction of on‐ and off‐site impact of restored tropical karst areas, this study was carried out in a 3.5 ha karst watershed of the Brazilian savanna (Cerrado). Precipitation, surface runoff, and soil loss were measured in representative runoff plots (22.1 × 1.84 m), used to assess the watershed erosion and sediment yield to a downstream sinkhole. The study was carried out during three hydrologic years, between September 2018 and May 2020. The predominant soils in the watershed were Lithic entisol and Quartzsamment, and the original land covers were natural savanna, seasonal forest, and degraded pastureland (Andropogon gayanus). The latter was restored with native savanna species, in the lower part of the watershed, and with a reformed pastureland, in the upper part. The USLE rainfall erosivity (R), soil erodibility (K), and soil cover (C) factors, runoff, soil loss, and the original soil and sediment textures were obtained from the runoff plots. The watershed soil loss and sediment yield were obtained by the USLE and GIS. Precipitation and rainfall erosivity ranged from 936 to 1223 mm, and from 6694 to 7746 MJ mm ha−1 h−1, in the period, respectively. Although the ecological watershed restoration reduced mean soil loss from 11.6 to 5.8 Mg ha−1 year−1, and sediment yield from 29.2 to 14.6 Mg year−1, on‐ and off‐site soil loss tolerances were still exceeded in 29 and 61% of the basin area, respectively. Ecological restoration also reduced the sand and clay content of the sediment entering the underground caves and river downstream, contributing to their hydrologic sustainability.

The effect of piping stream channels on dissolved oxygen concentration and ecological health.

Sunlight plays a key role in the nutrient cycle within streams. Streams are often piped to accommodate urban residential or commercial development for buildings, roads, and parking. This results in altered exposure to sunlight, air, and soil, subsequently affecting the growth of aquatic vegetation, reducing reaeration, and thus impairing the water quality and ecological health of streams. While the effects of urbanization on urban streams, including changing flow regimes, stream bank and bed erosion, and degraded water quality, are well understood, the effects of piping streams on dissolved oxygen (DO) concentrations, fish habitats, reaeration, photosynthesis, and respiration rates are not. We addressed this research gap by assessing the effects of stream piping on DO concentrations before and after a 565-m piped section of Stroubles Creek in Blacksburg, VA, for several days during the summer of 2021. Results indicate that the DO level decreased by approximately 18.5% during daylight hours as water flowed through the piped section of the creek. Given the optimum DO level (9.0mg·L-1) for brook trout (Salvelinus sp.), which are native and present in a portion of Stroubles Creek, the resulting DO deficits were - 0.49 and - 1.24mg·L-1, for the inlet and outlet, respectively, indicating a possible adverse impact from piping the stream on trout habitat. Photosynthesis and respiration rates were reduced through the piped section, primarily due to the reduced solar radiation and the resultant reduction in oxygen production from aquatic vegetation; however, the reaeration rate increased. This study can inform watershed restoration efforts, particularly decisions regarding stream daylighting with respect to potential water quality and aquatic habitat benefits.