Riparian Buffer Research Articles

Assessing the Impact of Riparian Buffer Systems on Water Quality Improvement and Infiltration Enhancement: Integration of SWAT-MODFLOW and SWAT-REMM

Objectives:This study aims to assess the effect of riparian buffer system on the water quality improvement and infiltration enhancement in the upper Sinduncheon watershed by integrating the SWAT-MODFLOW and SWAT- REMM models.Methods:The study focused on three subbasins in the upper Sinduncheon watershed. Streamflow and groundwater level were simulated and relevant parameters were calibrated using SWAT-MODFLOW. Subsequently, the calibrated parameters were applied to SWAT-REMM to evaluate the effects of riparian buffer systems on the reduction of NO3-N and Suspended Solids (SS) and the enhancement of water infiltration. Riparian buffer scenarios with varying widths (9m, 21m, 27m). Results and Discussion:The results showed that the riparian buffer system led to significant reductions in NO3-N and SS. Specifically, a subbasin with the widest buffer (27m) showed the highest reduction efficiency (82.6% for NO3-N and 99.6% for SS). However, in a subbasin, despite having a wider buffer than other subbasin, the reduction efficiency was lower due to the presence of channelized pollutant inflow areas. Additionally, the riparian buffer increased rainfall infiltration by approximately 13%, contributing to the stabilization of baseflow.Conclusion:This study demonstrates that riparian buffer systems can significantly improve water quality and increase water infiltration in the upper Sinduncheon watershed. Future research should focus on developing tailored riparian buffer strategies that consider regional characteristics such as pollutant inflow patterns, land cover, and topography.

Soil quality assessment and its response to water flow connectivity in different vegetation restoration types, eastern China

Vegetation restoration is the most widely used forest management practice for degraded soils, but the responses of soil quality in different vegetation restoration types may vary. In addition, the relationship between water flow paths connection and soil quality needs to be further explored. In this study, the soil quality index (SQI) and the index of water flow connectivity (IWFC) in the six water flow patterns (PFP, SSB, WSB, CPS, CPW, and CSW) were explored at three forest stands (oak, pine, and bamboo forests) with 50 years for enclosure. The results showed that the bamboo forest stand had the best soil quality as a whole (0.534 ± 0.135), followed by pine (0.530 ± 0.180) and oak forest stands (0.435 ± 0.205). The IWFC in PFP, CPS and CPW water flow patterns decreased gradually with increasing soil depth, while in SSB, WSB and CSB water flow patterns, the IWFC increased at first and then decreased. Finally, the IWFC in the CPW water flow pattern showed the largest positive correlation with the SQI (P < 0.05). The IWFC in the CPW water flow pattern driven by soil physical properties could mainly control the changes in the SQI indirectly (average IE = 0.825) by influencing soil nutrient (average IE = 0.447) and biological (average IE = 0.485) properties, while its direct effects could be ignored (average DE = −0.074), which demonstrated that the joint effects of preferential flow paths and weak stream buffer zones can dramatically reflect the changes in soil quality. The better soil improvement effect of bamboo and pine forest stands compared to the oak forest stand should be given more consideration. This study provided new insights for the assessment of the relationship between soil hydrology and soil quality.

Exploring the scale effect of nonpoint source pollution risk on water quality in Lake Basins of Central Yunnan Plateau using the Minimum Cumulative Resistance model.

Nonpoint source (NPS) pollution has emerged as the predominant water environment issue confronting plateau lakes in central Yunnan. Quantitative analysis of the impact of NPS pollution on water quality constitutes the key to preventing and controlling water pollution. However, currently, there is a dearth of research on identifying NPS pollution risks and exploring their relationship with water quality based on the Minimum Cumulative Resistance (MCR) model in the plateau lake basins of central Yunnan. Particularly, studies on the spatial heterogeneity of the impact of NPS pollution on water quality from a multi-scale perspective are scarce. Therefore, this study focuses on three typical lake basins in the Central Yunnan Plateau-Fuxian Lake, Xingyun Lake, and Qilu Lake (the Three Lakes). Utilizing the MCR model to identify NPS pollution risks, the study analyzes seven different scales, including sub-basins, riparian buffer zones (100 m, 300 m, 500 m, 700 m, and 1,000m) and lakeshore zones, to reveal the multi-scale effects of NPS pollution on water quality through correlation analysis. The results indicate that: (1) Over 60% of the areas in the Three Lakes Basin are at high or extremely high risk, mainly concentrated in flat terrain and around inflow rivers; (2) The area of NPS pollution from paddy field source landscape (PFSL) is greater than that from construction land source landscape (CLSL), and the high-risk areas of NPS pollution are also larger for PFSL compared to CLSL; (3) The mean resistance values of PFSL and CLSL show a significant negative correlation with monthly mean values of water quality indexes (NH3-N, TP, CODCr), with the 1,000 m riparian buffer zone scale showing the greatest correlation with most water quality indexes, especially NH3-N; (4) The correlation between the mean resistance value of CLSL and the monthly mean values of water quality indexes is significantly higher than that of PFSL, indicating a greater impact of CLSL on water quality compared to PFSL. In summary, PFSL and CLSL are the primary sources of NPS pollution in the Three Lakes Basins. The 1,000 m riparian buffer zone scale is the most sensitive to the impact of NPS pollution on water quality. This study provides scientific references for landscape pattern optimization and precise control of NPS pollution risks in the Central Yunnan Plateau lake basins and offers a new research perspective for exploring multi-scale effects of NPS pollution on water quality.

Influence of Typical Regional Land Use/Landscape Pattern on Water TN of the Upper Yellow River

This study aimed to explore the relationship between land use landscape pattern and water quality in the upstream of the Gansu water conservation, water and soil erosion, and ecological fragile areas. Based on the land use data and water quality monitoring section in 2020 in the 200 m, 500 m, 1 km, 2 km, 50 km, and 10 km riparian buffer area, the single-factor index evaluation method, random forest regression model, and BP neural network were used to quantify the response relationship between land use and landscape pattern of the upper Yellow River in Gansu province and water quality index and to carry out the basin water quality prediction based on land use landscape index data. The results showed that： ① through the single-factor index method, the major indicators of the total nitrogen （TN） in July and September, dissolved oxygen （DO）, permanganate index, ammonia nitrogen （NH4+ -N）, total phosphorus （TP）, and other surface indexes met the surface water environment class Ⅲ water quality standard. ② The random forest regression model was used to analyze the influence of land use and landscape index on TN, and the difference in TN in different typical areas was obtained. The land use types with the highest influence on the TN index in water conservation areas, soil and soil erosion areas, and ecological fragile areas were cultivated land, grassland, and construction land, respectively. ③ The BP neural network was used to predict the water quality index based on different typical areas of land use landscape index. The result of water conservation areas was good, the error rate between the predicted value and the actual value was below 10%, and the prediction accuracy was high. The study showed that water quality prediction based on land use and landscape index/water quality quantitative relationship model had a good water quality prediction effect.

Biodiversity and Soil Reinforcement Effect of Vegetation Buffer Zones: A Case Study of the Tongnan Section of the Fujiang River Basin

The riparian vegetation buffer zone is an important component of riverbank ecosystems, playing a crucial role in soil consolidation and slope protection. In this study, the riparian vegetation buffer zones in the Tongnan section of the Fujiang River Basin were selected as the research object. Surveys and experiments were conducted to assess the species composition and the soil and water conservation effectiveness of the riparian vegetation buffer zone. There are a total of 35 species, mainly comprising angiosperms and ferns. The dominant species include Cynodon dactylon, Setaria viridis, Phragmites australis, Erigeron canadensis, and Melilotus officinalis. The Patrick richness index (R) and Shannon–Wiener diversity index (H) are more significantly influenced by the types of land use in the surrounding area, whereas the impact on the Simpson diversity index (D) and Pielou uniformity index (E) is comparatively less pronounced. When the root diameter is less than 0.2 mm, the tensile strength of Cynodon dactylon roots is the highest. For root diameters larger than 0.2 mm, Melilotus officinalis roots exhibit the highest tensile strength. The presence of plant root systems significantly reduces erosion, delaying the time to reach maximum erosion depth by 1–4 min, decreasing erosion depth by 9–38 mm, and reducing the total amount of erosion by 20.17–58.90%. The anti-scouribility effect of Cynodon dactylon is significantly better than that of Setaria viridis. The root system notably enhances soil shear strength, delaying the shear peak by 0.26–4.8 cm, increasing the shear peak by 4.76–11.37 kPa, and raising energy consumption by 23.76–46.11%. Phragmites australis has the best resistance to shear, followed by Erigeron canadensis, with Melilotus officinalis being the least resistant. Therefore, to balance the anti-scouribility effect and shear resistance of plant roots, it is recommended to use a combination of Cynodon dactylon and Phragmites australis for shallow-rooted and deep-rooted planting. This approach enhances the water and soil conservation capacity of riverbanks.

Agricultural Contribution of Chloride to a Saturated Riparian Buffer System: A Case Study in Central Illinois

ABSTRACT Increases in chloride concentrations in surface water and groundwater from anthropogenic sources is a growing concern throughout the world. In the midwestern United States, the agriculture contribution of chloride may elevate concentrations in surface and groundwater systems. A saturated riparian buffer (SRB), installed to reduce nutrient input into an adjacent stream, and the groundwater water upgradient were investigated to identify sources of chloride and to quantify the agricultural contribution. During a 7-year period, over 2,200 water samples collected from 35 wells, a diversion box, and a stream were analyzed for major anions. Additionally, the waters from four quarterly (seasonal) samplings (n = 155) during the seventh year were analyzed for cations. A cumulative probability curve identified three populations of chloride: (1) upgradient shallow groundwater; (2) diversion box (waters drained from an agricultural field), downgradient shallow groundwater (representing the SRB), diamicton groundwater (waters collected deeper from within the unweathered parent material); and (3) stream water. A background chloride concentration was established at 3.9 mg/L. Elevated concentrations above the background level coupled with principal component analysis suggest agricultural contribution from the diverted tile-drainage waters was a source of chloride. In winter and spring, chloride concentrations were highest in the diversion box, while up-gradient wells were the lowest. Waters downgradient of the diversion tiles had chloride concentrations lower than the tile but higher than the upgradient waters due to mixing of the diverted tile water and the upgradient groundwater. For the specific site, agriculture contributes chloride, but at concentrations below the chronic threshold of 230 mg/L.

Windthrow in riparian buffers affects the water quality of freshwater ecosystems in the eastern Canadian boreal forest

Despite the wide application of riparian buffers in the managed boreal forest, their long-term effectiveness as freshwater protection tools remains unknown. Here, we evaluate windthrow incidence in riparian buffers in the eastern Canadian boreal forest and determine the effect of windthrow on the water quality index of the adjacent freshwater ecosystems. We studied 40 sites—20 riparian buffers, aged 10 to 20 years after harvesting and 20 control sites within intact riparian environments—distributed among clay and sandy (esker) soils and black spruce (Picea mariana) and jack pine (Pinus banksiana) stands. We observed more windthrow in the harvested stands (36%) relative to the control sites (16%), regardless of substrate and species. We determined that the most important factors explaining windthrow were exposition, harvesting, aquatic environment size, and stand characteristics. These factors drive wind exposure, speed, and force, which determine post-harvest windthrow risk. Furthermore, windthrow negatively affected the water quality index of the adjacent aquatic systems, i.e., greater windthrow decreased the protective effect of the riparian buffer. We recommend increasing the use of partial harvest near riparian environments and adapting riparian buffers to site conditions to ensure the long-term protection of adjacent freshwater ecosystems.

Temporal Analysis of Riparian Buffer Zones and Demographic Trends in the Coastal Districts of Kastamonu

Aim of study: This study investigates the temporal changes of forest areas within and outside the Riparian Buffer Zones (RBZs) and examines their correlation with demographic trends in the coastal districts of Kastamonu from 1987, 2000, and 2016 to assess how population dynamics influence forest cover. Area of study: The study was conducted in four coastal districts in northern Kastamonu province, Türkiye, covering approximately 1000 square kilometers and focusing on 153 forest villages. Material and methods: Geographic Information Systems and remote sensing data delineated and analyzed land cover and population changes. The study used Landsat imagery and population data to explore spatial and temporal dynamics within the RBZs Main results: The study found a significant increase in forest area from 1987 to 2000 and a subsequent decrease from 2000 to 2016, with these changes showing a weak but significant negative correlation with the declining local population. Research highlihts: The findings suggest that declining rural populations may reduce anthropogenic pressures on forests and pose challenges to effective forest management and conservation. The research highlights the need for sustainable strategies integrating demographic change with forest conservation efforts to maintain ecosystem services and biodiversity.

PASTA: Programming and Automation Support for Scalable Task-Parallel HLS Programs on Modern Multi-Die FPGAs

In recent years, the adoption of FPGAs in datacenters has increased, with a growing number of users choosing High-Level Synthesis (HLS) as their preferred programming method. While HLS simplifies FPGA programming, one notable challenge arises when scaling up designs for modern datacenter FPGAs that comprise multiple dies. The extra delays introduced due to die crossings and routing congestion can significantly degrade the frequency of large designs on these FPGA boards. Due to the gap between HLS design and physical design, it is challenging for HLS programmers to analyze and identify the root causes, and fix their HLS design to achieve better timing closure. Recent efforts have aimed to address these issues by employing coarse-grained floorplanning and pipelining strategies on task-parallel HLS designs where multiple tasks run concurrently and communicate through FIFO stream channels. However, many applications are not streaming friendly and many existing accelerator designs heavily rely on buffer channel based communication between tasks. In this work, we take a step further to support a task-parallel programming model where tasks can communicate via both FIFO stream channels and buffer channels. To achieve this goal, we design and implement the PASTA framework, which takes a large task-parallel HLS design as input and automatically generates a high-frequency FPGA accelerator via HLS and physical design co-optimization. Our framework introduces a latency-insensitive buffer channel design, which supports memory partitioning and ping-pong buffering while remaining compatible with vendor HLS tools. On the frontend, we provide an easy-to-use programming model for utilizing the proposed buffer channel; while on the backend, we implement efficient placement and pipelining strategies for the proposed buffer channel. To validate the effectiveness of our framework, we test it on four widely used Rodinia HLS benchmarks and two real-world accelerator designs and show an average frequency improvement of 25%, with peak improvements of up to 89% on AMD/Xilinx Alveo U280 boards compared to Vitis HLS baselines.

The Relationship between Erosion and Precipitation and the Effects of Different Riparian Practices on Soil and Total-P Losses via Streambank Erosion in Small Streams in Iowa, USA

Streambank erosion in agricultural landscapes contributes high amounts of sediment and total-P to surface water, resulting in the degradation of stream habitats and reduction in ecological services. Moreover, the implication of future climate change on bank erosion is also a growing concern. Streambank erosion rates from riparian forest buffers (RFo), grass filters (GFi), row-crops (RCr) and pastures, including fenced pastures (FPa), rotationally grazed pastures (RPa), intensive rotationally grazed pastures (IPa), and continuously grazed pastures (CPa), in three landform regions of Iowa, were measured over seven years. Bank erosion pins were measured seasonally (spring, summer and fall) in the first five years (2002–2006) and yearly for two more years (2007–2008). It was found that summer and spring seasons are the important ones since the relationships between erosion and precipitation were significantly “strong” in almost all the riparian practices, and precipitation was found to be the main factor driving streambank erosion. Streambank mean soil losses and soil total-P losses from RFo (23.3 tons km−1 yr−1 and 9.8 kg km−1 yr−1, respectively), GFi (31.1 and 9.9) and FPa (44.0 and 23.7) practices were all significantly lower than the grazing pasture practices, including RPa (142.3 and 58), CPa (255 and 105.1), IPa (234.6 and 122.7) and RCr fields (352.9 and 118.9). Also, RPa had significantly lower total-P loss than CPa, IPa and RCr practices (RFo, GFi, FPa &lt; RPa &lt; CPa, IPa, RCr). RCr practices had the highest streambank soil losses among all other riparian practices (RFo, GFi, FPa &lt; RPa &lt; IPa, CPa &lt; RCr). The study showed that riparian conservation practices (RFo, GFi and FPa) showcased significant benefits in mitigating streambank soil loss and associated soil total-P load to streams. However, their effectiveness is highly sensitive to changing climatic conditions and the extent of spatiotemporal variations.

Riparian buffer strips promote biomass, species richness and abundance of flying insects in agricultural landscapes

Agricultural intensification is debated as one of the major drivers for the decline of insect biodiversity. Agri-environmental schemes (AES) are a common measure to promote biodiversity in agriculture by granting compensational payments to farmers for environmentally friendly practices. In this study we examined the effect of buffer strips of at least 5 m width, adjacent to small watercourses and drainage ditches, on insect biomass and insect species richness in agricultural landscapes. We selected ten arable fields in each of four regions in lower and upper Bavaria, Southern Germany. 25 out of 40 sites had a buffer strip between arable crops and watercourse. Insects were sampled at three time periods (May/June, June/July and August/September) for two weeks each. In each period two samples were collected (one per week). On each site Malaise traps were set up in 5 and 80 m distance to the embankment of the watercourse. Half of the samples was then subjected to metabarcoding and the other half was classified into different insect groups by morphological identification and the number of the individuals for each group was counted. For hoverflies (Syrphidae), individuals were identified at species-level. Data on vegetation structure (cover of grasses and herbs) in the studied riparian buffer strips was collected and correlated with number of species, abundances and biomass of flying insects. The five taxonomic orders with the highest species richness and individual numbers were: Diptera, Hymenoptera, Coleoptera, Lepidoptera and Hemiptera. Diptera dominated hereby with 34% of all species and 81% of all individuals. On average, mixed models indicated 31% higher insect biomass, 15% higher species richness and 29% higher individual numbers of flying insects in buffer strips at 5 m distance to the watercourse compared to sites with no buffer strip. The effect was even stronger for butterflies (32% higher species species richness, 70% more individuals) and hoverflies (24% higher species richness, 51% more individuals). In the presence of a buffer strip significantly higher numbers were found for total individuals, Diptera, Hymenoptera and Coleoptera. In 80 m distance to the watercourse, the samples of flying insects were not significantly influenced by a riparian buffer strip. This study highlights the importance of buffer strips in agricultural regions and their multifunctional potential in fostering biodiversity additionally to their acknowledged use for water protection. Ideally, buffer strips are rich in herbs and inflorescences and are therefore beneficial for the insect fauna by serving as valuable habitat with high potential connectivity at landscape level.

Integrative Review of Riparian Buffers Benefits in Urbanized Watersheds

Riparian buffers or riparian corridors are areas of vegetation in the floodplains and areas surrounding a stream. By the early 2000s, numerous national reports and studies of riparian buffer benefits established that vegetation near streams is helpful in protecting the stream from increasing urban runoff, minimizing bank erosion, reducing flooding, and improving overall water quality. However, influential studies concluded that buffer benefits dwindle as urbanization increases, eventually becoming ineffective. This study evaluates more recent research that suggests riparian buffers are more effective at countering urbanization impacts than previously understood, and considers the extent to which we can quantify these benefits and identify the factors that maximize their effectiveness (i.e. greater efficiency based on buffer distance from the stream, extent of stream setbacks, and percentage of impervious cover in the area). Much of the research has been conducted in the Kansas City area in the Blue River Watershed, which begins in Kansas and flows into Missouri River east of downtown Kansas City, Missouri. About 800,000 residents live in the watershed, which includes some of the region’s fastest growing areas. It is critical to protect this major resource, and other regional rivers and streams, for residents of the Kansas City Metropolitan area and the ecosystems that depend on them. It is also critical to provide the latest and best information to the community-of-practice currently updating regional stormwater management planning and design guidance.

Land Use and Soil Carbon Sequestration in the Kou Watershed, Burkina Faso

Background: Soil organic carbon is an indicator that must be considered when assessing the sustainability of agroecosystems. Aim: The aim of the study is to assess the impact of different land use patterns on soil organic carbon stock and the contribution of this component to climate change mitigation. Methodology: soil samples were taken from depths of 0-15 cm and 15-30 cm along diagonal transects of study plots, with seventy-two composite samples collected in total. Results: Soils in the riparian zone (23.77%) and irrigated crops (25.73%) were found to be the richest in clay. Only clay content was positively correlated with soil depth (r=0.104). The Kruskal-Wallis test shows that the amount of carbon varies significantly (p-values between 2.510-4 and 7.910-4) across land use/land cover classes (LULC). Wetland (28.91 ± 2.83 t/ha) and woody savannah (28.53 ± 4.24 t/ha) had the highest carbon stock, and shrub savannah had the lowest (12.77 ± 0.82 t/ha). The carbon stock at a depth of 0-15 cm exceeds that found at 15-30 cm. Over the 1,330.80 ha of the Kou River riparian buffer zone, the total atmospheric carbon sequestered in the soil was 119,833.27 metric tons of CO2. Conclusion: The carbon sequestration capacity of the Kou River’s riparian zone is significant in the context of climate change mitigation.

Cutthroat trout responses to increased light via conventional and alternative riparian buffers

Forested headwaters, particularly in the Pacific Northwest, USA, are typically heavily shaded by dense stands of riparian vegetation. Reduced riparian cover can occur from natural or anthropogenic events, resulting in increased light which can increase fish biomass by promoting in-stream food resources. We conducted a 5 y before-after-control-impact (BACI) study on 10 small streams in the Oregon Coast Range, USA, and investigated how changes to the magnitude of stream light, mediated by conventional and alternative riparian buffer configurations adjacent to upland timber harvest, changed Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) abundance, biomass, bioenergetics, diet composition, and the availability of aquatic food resources. Riparian buffer treatments reduced canopy cover as much as 34 % cover (98–99 % pre; 64–98 % post-treatment) and enhanced total available sunlight reaching the stream surface by 8–31 % relative to unharvested references that only changed by 3–4 %. In the first year following the treatments, young-of-year trout (YOY, age 0) densities changed by between +0.1 and +0.78 #/m2 in treatment streams while densities changed by –0.001 and +0.02 #/m2 at reference streams. Although change in YOY densities was positively correlated with change in stream light (rs=0.81, p=0.02), changes in basal resources (periphyton and macroinvertebrates) were both positive and negative and did not increase with change in stream light. Adult (age 1+) trout responses were mixed in the first year post-treatment, but changed by –0.14 to +0.24 #/m2 at treatment sites (–0.02 to –0.05 at reference sites) in the second year post-treatment, likely due to increased recruitment from the strong cohort of YOY in the first year. Bioenergetics analysis in one post-treatment year showed that adult trout did not experience greater summer growth (–0.003 to +0.0005 g g−1 d−1) or proportions of maximum consumption (0.18–0.25) in streams with more light than at reference streams (–0.001 and +0.001 g g−1 d−1, 0.19 and 0.23). Overall, while standing stock assessments suggest that fish showed some increases after experimental treatments that increased light, our data did not provide the clear mechanistic evidence for bottom-up drivers that was expected. The relationship between canopy removal and fish production is not always predictable in small headwater streams, and even though fish populations were generally resilient to riparian manipulation, evaluations of terrestrial food resources, the dynamic between canopy cover and light reaching the stream, and changes to temperature may lend valuable insight on the impacts to fish populations.

Identifying factors influencing reservoir eutrophication using interpretable machine learning combined with shoreline morphology and landscape hydrological features: A case study of Danjiangkou Reservoir, China

Reservoir nearshore areas are influenced by both terrestrial and aquatic ecosystems, making them sensitive regions to water quality changes. The analysis of basin landscape hydrological features provides limited insight into the spatial heterogeneity of eutrophication in these areas. The complex characteristics of shoreline morphology and their impact on eutrophication are often overlooked. To comprehensively analyze the complex relationships between shoreline morphology and landscape hydrological features, with eutrophication, this study uses Danjiangkou Reservoir as a case study. Utilizing Landsat 8 OLI remote sensing data from 2013 to 2022, combined with a semi-analytical approach, the spatial distribution of the Trophic State Index (TSI) during flood discharge periods (FDPs) and water storage periods (WSPs) was obtained. Using Extreme Gradient Boosting (XGBoost) and SHapley Additive exPlanations (SHAP), explained the relationships between landscape composition, landscape configuration, hydrological topography, shoreline morphology, and TSI, identified key factors at different spatial scales and validated their reliability. The results showed that: (1) There is significant spatial heterogeneity in the TSI distribution of Danjiangkou Reservoir. The eutrophication levels are significant in the shoreline and bay areas, with a tendency to extend inward only during the WSPs. (2) The importance of landscape composition, landscape configuration, hydrological topography, and shoreline morphology to TSI variations during the FDPs are 25.12 %, 29.6 %, 23.09 %, and 22.19 % respectively. Besides shoreline distance, the Landscape Shape Index (LSI) and Hypsometric Integral (HI) are the two most significant environmental variables overall during the FDPs. Forest and grassland areas become the most influential factors during the WSPs. The influence of landscape patterns and hydrological topography on TSI varies at different spatial scales. At the 200 m riparian buffer zone, the increase in cropland and impervious areas significantly elevates eutrophication levels. (3) Morphology complexity, shows a noticeable threshold effect on TSI, with complex shoreline morphology increasing the risk of eutrophication.

Drainage water management, woodchip bioreactor, and saturated riparian buffer as stacked conservation practices for improving crop yields and water quality

Stacking edge-of-field practices may improve nutrient removal from crops. To examine the effects of stacking edge-of-field conservation practices, a woodchip bioreactor (WBR) and saturated riparian buffer (SRB) were installed in series by intercepting tile flow from a field having a drainage water management system. Nutrient monitoring from 5 years evaluated nutrient export annually and based on the precipitation intensity. Drainage water was monitored for total suspended solids (TSS), nitrate-N, total-P, total-N, and ortho-P at the inlet and outlet of WBR and control structure of SRB. Nutrient export reductions of WBR and SRB were determined for precipitation events that were categorized as low <12.7 mm, mid 12.7–25.4 mm, high 25.4–50.8 mm, and very high >50.8 mm. Over the five seasons, nitrate-N export was reduced 88 % at the WBR outlet and 78 % at SRB outlet when used in a stacked series configuration. The efficacy of edge-of-field practices was affected by the intensity of precipitation events. The low and mid-intensity precipitation events generated 67 % of the total discharge from the subsurface drainage system which accounted for 74 % of the influent nitrate-N. During low and mid-intensity precipitation events, discharge was reduced by 58–65 %, nitrate-N was reduced by 49–88 % and total-P was reduced by 65–73 % by using stacked practice of WBR and SRB. During high and very high-intensity precipitation events only nitrate-N export was reduced by 61–66 %. This indicates that when designing stacked edge-of-the-field practices the cumulative effect of the practices and their performance during different precipitation events should be taken into account when managing conservation practice-based cropping systems.

Modeling of water level trends and characterizing potential influencing factors in Lake Baringo in Kenya

Water plays a significant role in every sector of the ecosystem. The fluctuation of the water levels in lakes is influenced by natural and man-made factors within the water catchment. Lake Baringo, which has no visible outlet, has been rising drastically, causing panic among native communities and businesses on the shores of the lake. Using GIS and Remote Sensing, this study intends to analyze the changes in water lakes using the Automatic water extraction index (AWEI), determine the causes of the fluctuation using Land use Land cover, land surface temperature, soil erosion, and siltation in the lake basin and the lake respectively, precipitation, and later predict of the water level for the year 2030 using the MOLUSCE tool. The tool utilizes an artificial neural network and cellular automata to analyze land use and land cover conveniently. It was found that the lake’s water level has been increasing drastically over the years, and the leading causes of the fluctuations were increased rainfall and human activities within the water basin. There are visible increased human activities within the water basin, such as agriculture, deforestation, settlement, and urbanization. It was also found that there will be a further increase in water level in 2030. With all the above results, it is recommended that better policies be made to conserve the water basin effectively, and a plan should be drawn to re-delineate the new riparian buffer.

Combining ecosystem service value and landscape ecological risk to subdivide the riparian buffer zone of the Weihe River in Shaanxi

Riparian buffer zones are transitional and ecological intersections between land and water. These areas play a major role in advancing ecosystem protection and restoration. Here, we investigated the spatial and temporal evolution of land use, ecosystem service value (ESV), and landscape ecological risk (LER) in riparian buffer zones between 1990 and 2020 using the Shaanxi section of the Weihe River as a case study using a GIS grid, the unit-area-equivalent-factor method, the landscape ecological risk index, and the natural breakpoint method. We also established four ecological zones using standardized Z-scores. The predominant land categories in the study area comprised cultivated, construction, and grassland, which together accounted for more than 80 % of the total area. The construction land demonstrated the most significant increase of 4,062.33 hm2 area, and cultivated land showed most significant decrease of 13,048.56 hm2 area, between 1990 and 2020. Next, study-site ESV increased from 28.30 × 108 CNY in 1990 to 28.94 × 108 CNY in 2020, reflecting 2.26 % growth. High-value areas were principally bodies of water and primarily situated along the Weihe River, extending from west to east along the main channel. The LER of the study area was dominated by the lowest ecological risk, low ecological risk, and medium ecological risk classes, which collectively accounted for more than 70 % of the total area. The main land types in the areas with high ecological risk were forest land and cultivated land. The study area’s LER demonstrated a decreasing trend from 1990 to 2020, and the area with the lowest ecological risk and low ecological risk zones increased by 9.97 %. The riparian buffer zone was divided into ecological restoration, reconstruction, conservation, and protection zones based on two factors, namely, ESV and LER. The most dominant of these was the ecological reconstruction zone, which showed a 13.75 % decrease in area share between 1990 and 2020. The ecological restoration zone occupied the smallest area with the largest increase of 56.63 % during this period. In conclusion, this study contributes to ecological zoning and management of the riparian buffer zone along the main channel of the Weihe River. Appropriate zoning is integral to protecting this valuable ecosystem and achieving sustainable development of surrounding human communities.

Planting trees in buffer strips for attenuating phosphorus runoff in Jiangsu Province, China

AbstractIn the last four decades, the Jiangsu province, like the rest of China, has undergone rapid economic development coupled with a rapid increase in environmental pollution. Freshwater ecosystems have been particularly affected. In Lake Tai, China's third‐largest freshwater lake by volume, water quality has been severely reduced. There is a renewed interest in establishing riparian buffer strips in China as a conservation practice for mitigating agricultural non‐point source pollution. To study the effect of riparian buffers on phosphorus attenuation, eight 50 m × 20 m plots were established between a rice farm and the shore of Lake Tai in China, with the 20 m width facing the lake shore. They were planted with hybrid poplar (Populus deltoides × euramericana), hybrid cypress (Taxodium ascendens × mucronatum), or a mixture of both at densities of 2 m × 3 m, 2 m × 5 m, or 5 m × 5 m, while one plot was left as a control. Samples collected from soil, tree leaves, and groundwater during 2014–2018 were analyzed for multiple forms of phosphorus. Results indicated that riparian buffer width and time (year) were the most significant factors of phosphorus attenuation on all plots. Tree density had a minor effect, with medium density being the most effective, and we found negligible differences among hybrid tree species on attenuating phosphorus. Farmers should use densely vegetated buffer strips at least 15 m wide to ensure a significant reduction in nutrient runoff. Species selection should be based on market value and ecological benefits.

Interactive impact of landscape composition and configuration on river water quality under different spatial and seasonal scales

Currently, the comprehensive effect of the landscape pattern on river water quality has been widely studied. However, the interactive influences of landscape type, namely composition (COM) and configuration (CON) on water quality variations, as well as the specific landscape driving types affecting water quality variations under different spatial and seasonal scales remain unclear. To further improve the effectiveness of landscape planning and water quality protection, this study collected monthly water samples from the Fengyu River Watershed in southwestern China from 2018 to 2021, the Biota-Environment Matching Analysis (Bioenv) was used to identify key metrics representing landscape COM and CON, respectively. Then, the multiple regression (MLR) and redundancy analysis (RDA) were used to explore the relationship between these landscape metrics and water quality. In addition, this study used a variation partitioning analysis (VPA) to quantify the interactive and independent influence of landscape COM and CON on water quality. Results revealed that construction land and the Shannon's diversity index (SHDI) were the key metrics of landscape COM and CON, respectively, for predicting water pollution concentrations. The interactive contribution was particularly sensitive to seasonal changes in riparian buffer areas (27.66 % to 48.73 %), while it remained relatively stable at the sub-watershed scale (38.22 % to 40.51 %). Moreover, landscape CON had a higher independent contribution to variations on water quality across most spatio-temporal scales. Overall, identifying and managing key landscape type and consequential metrics, matching with the spatio-temporal scale, holds promise for enhancing water quality conservation. Furthermore, this study provides valuable insights into the identification and selection of core landscape metrics.