Plant Interception Research Articles

Analyses of the Effectiveness of Different Media Depths and Plant Treatments on Green Roof Rainfall Retention Capability under Various Rainfall Patterns

Green roofs have been used to reduce rainfall runoff by altering hydrological processes through plant interception and retention as well as detention within the green roof system. Green roof media depth, substrate type, plant type and density, regional climatic conditions, rainfall patterns, and roof slope all impact runoff retention. To better understand the impacts of media depth (10, 15, and 20 cm), plant (planted and non-planted), and rainfall pattern (low, medium, and high) on rainfall retention, we analyzed data collected between September 2005 and June 2008 from 24 green roof models (61 cm × 61 cm) for growing and non-growing seasons. Our results showed that a planted green roof has greater rainfall retention capability than a non-planted green roof for all media depths. Interestingly, a non-planted green roof system with a 10 cm media depth retained greater rainfall than a planted green roof during both growing and non-growing periods. Retention capability decreased with increasing rainfall amounts for both planted and non-planted green roofs and seasons (growing and non-growing). The 15 cm media depth green roof retained significantly greater rainfall depth than the 20 cm models during medium (0.64 to 2.54 cm) and high (>2.54 cm) rainfall events for the growing season but not during the non-growing season. The study provides insight into the interactive effects of media depth, rainfall amount, plant presence, and seasons on green roof performance. The results will be helpful for designing economical and effective green roof systems.

Urban drainage decision model for storm emergency management based on multi-objective optimization

This study proposes a solution to prevent urban waterlogging, a challenging environmental issue, by integrating waterlogging prediction and drainage optimization schemes based on cellular automaton and multi-objective optimization theories. An urban waterlogging model for uncertain flow was constructed considering urban surface fragmentation and space complexity. For dynamic simulation, outputs of water depth and flooded areas were projected with inputs of rainfall, soil infiltration, plant interception, gully discharge, and outflow to its neighbors in each cell at any moment. Using a multi-objective optimization approach, the drainage decision model for optimal solutions calculated the maximal amount of water for pumping from flooded zones to candidate reservoirs with minimal energy cost. This integrated approach was successfully applied to the DongHaoChong catchment, an 11 km2 watershed in Guangzhou, southern China and validated by comparing the simulated flood areas with flooded points from two historical rainstorms (August 15, 2013 and June 23, 2014). The RMSE of the maximum waterlogging depth were 26.89 and 78.48 mm, respectively. Therefore, the proposed model was reliable and capable of simulating uncertain flow at any position and moment with minimal data input and parameters in an urban environment. Water-logged area and depth could be predicted based on the given rainfall assuming 1-, 10-, 50-, and 100-year storm data in the study area, and optimal drainage solutions could be obtained and verified. The proposed urban waterlogging prediction and drainage emergency models could optimize decision-making to improve emergency plans and reduce losses due to urban waterlogging.

CM2Mc-LPJmL v1.0: biophysical coupling of a process-based dynamic vegetation model with managed land to a general circulation model

Abstract. The terrestrial biosphere is exposed to land-use and climate change, which not only affects vegetation dynamics but also changes land–atmosphere feedbacks. Specifically, changes in land cover affect biophysical feedbacks of water and energy, thereby contributing to climate change. In this study, we couple the well-established and comprehensively validated dynamic global vegetation model LPJmL5 (Lund–Potsdam–Jena managed Land) to the coupled climate model CM2Mc, the latter of which is based on the atmosphere model AM2 and the ocean model MOM5 (Modular Ocean Model 5), and name it CM2Mc-LPJmL. In CM2Mc, we replace the simple land-surface model LaD (Land Dynamics; where vegetation is static and prescribed) with LPJmL5, and we fully couple the water and energy cycles using the Geophysical Fluid Dynamics Laboratory (GFDL) Flexible Modeling System (FMS). Several improvements to LPJmL5 were implemented to allow a fully functional biophysical coupling. These include a sub-daily cycle for calculating energy and water fluxes, conductance of the soil evaporation and plant interception, canopy-layer humidity, and the surface energy balance in order to calculate the surface and canopy-layer temperature within LPJmL5. Exchanging LaD with LPJmL5 and, therefore, switching from a static and prescribed vegetation to a dynamic vegetation allows us to model important biospheric processes, including fire, mortality, permafrost, hydrological cycling and the impacts of managed land (crop growth and irrigation). Our results show that CM2Mc-LPJmL has similar temperature and precipitation biases to the original CM2Mc model with LaD. The performance of LPJmL5 in the coupled system compared to Earth observation data and to LPJmL offline simulation results is within acceptable error margins. The historical global mean temperature evolution of our model setup is within the range of CMIP5 (Coupled Model Intercomparison Project Phase 5) models. The comparison of model runs with and without land-use change shows a partially warmer and drier climate state across the global land surface. CM2Mc-LPJmL opens new opportunities to investigate important biophysical vegetation–climate feedbacks with a state-of-the-art and process-based dynamic vegetation model.

Temporal variability of throughfall as a function of the canopy development stage: from seasonal to intra-event scale

ABSTRACT The interception process impacts rainfall magnitude and intensity under the canopy. In this study, the effect of plant interception on throughfall characteristics was assessed in the deciduous Caatinga vegetation, at different canopy development stages and for temporal scales ranging from seasonal to the intra-event scale. Throughfall and stemflow percentages were slightly higher at the onset of the rainy season, when leaf area density is low, with resulting lower interception losses. However, there was no statistical difference among the variables at the seasonal scale. At the intra-event scale, average and maximum throughfall intensity at different time intervals showed statistical difference between the stages of canopy development. Regardless of leaf area density and rainfall depth, vegetation is able to retain all the water up to 2 min in the beginning of each rainfall event with accumulated rainfall smaller than 0.6 mm. Furthermore, the Caatinga vegetation attenuates the rainfall intensity by 30–40%.

Changes in Land Use Affect Dependable Discharge in the Miu River Basin

Land use changes in a watershed will affect to net rainfall and have an impact to river discharge. Evaluation of plant interception due to land use changes would had better view of net rainfall. The descriptive research is aims to determine changes in land use that affect net rainfall and reliable discharge using the Nreca calculation model. The area of the Miu watershed was 654. 55 km2 and the changes in land use was considered the years of 2005, 2010 and 2016 which is observed by using ArcGIS software to evaluate the catchments area. The land use changes show the forest area decrease from 82. 10% in 2005 to 78. 65 and 89. 67% for 2010 and 2016, but there has been a lot of increase in open area from 1. 71% in 2005 to 8. 19% in 2016. Net rainfall was applied in calculation of dependable discharge and the results obtained show the flow consistency. The input parameter for initial SMS is 200 mm, PSUB is 0. 85 and GWF is 0. 25. The average discharge obtained is 9. 15 m3/sec. The graph shows very close relationship between net rainfall that influencing to dependable discharge.

Microtopographic modification conserves urban wetland water quality by increasing the dissolved oxygen in the wet season

Microtopography affects hydrological processes and forms different microhabitats. Our previous study uncovered that riparian zone microtopography created various microhabitats with different soil environments and runoff-infiltration patterns. However, how riparian microtopography and microtopography within the water area (waterfall and tributary) affects downstream water quality remains unclear. Therefore, water samples were taken almost monthly in both the main stream and the tributary, before and after waterfalls, and near the bottom of three microtopographic types from June 2016 to March 2017. Compared with the dry season, the fact that water quality worsened in the wet season and that there were positive correlations for nitrate (NO3−) between water and the corresponding soil samples suggested that the riparian-soil environment affected the adjacent water quality mainly in the wet season. Nevertheless, riparian microtopography did not influence water quality downstream because of the low rainfall frequency and the weak leaching process due to plant interception. In the wet season, both the tributary and the waterfall increased the dissolved oxygen in the water body and, therefore, lowered the risk of eutrophication. The tributary has two pathways for improving the water quality, by increased disturbance and flow velocity, while the waterfall only has the former. However, such effects were not significant in the dry season. We conclude that the application of microtopographic modification is useful in maintaining urban wetland water quality in wet seasons.

Formation of banded vegetation patterns resulted from interactions between sediment deposition and vegetation growth

This research investigates the formation of banded vegetation patterns on hillslopes affected by interactions between sediment deposition and vegetation growth. The following two perspectives in the formation of these patterns are taken into consideration: (a) increased sediment deposition from plant interception, and (b) reduced plant biomass caused by sediment accumulation. A spatial model is proposed to describe how the interactions between sediment deposition and vegetation growth promote self-organization of banded vegetation patterns. Based on theoretical and numerical analyses of the proposed spatial model, vegetation bands can result from a Turing instability mechanism. The banded vegetation patterns obtained in this research resemble patterns reported in the literature. Moreover, measured by sediment dynamics, the variation of hillslope landform can be described. The model predicts how treads on hillslopes evolve with the banded patterns. Thus, we provide a quantitative interpretation for coevolution of vegetation patterns and landforms under effects of sediment redistribution.

Evaporation of perennial semi‐arid woodland in southeastern Australia is adapted for irregular but common dry periods

AbstractMeasurements of water vapour flux from semi‐arid perennial woodland (mallee) were made for 3 years using eddy covariance instrumentation. There have been no previous long‐term, detailed measures of water use in this ecosystem. Latent energy flux (LE) on a half hourly basis was the measure of the combined soil and plant evaporation, ‘evapotranspiration’ (ELE) of the site. Aggregation over 3 years of the site measured rain (1136 mm) and the estimated evaporation (794 mm) suggests that 342 mm or 30% of rain had moved into or past the root zone of the vegetation. Above average rainfall during 2011 and the first quarter of 2012 (633 mm, 15 months) would likely have been the period during which significant groundwater recharge occurred. At times immediately after rainfall, ELE rates were the same or exceeded estimates of potential E calculated from a suitably parameterized Penman–Monteith (EPMo) equation. Apparent free water E from plant interception and soil evaporation was about 2.3 mm and lasted for 1.3 days following rainfall in summer, while in autumn, E was 5.1 mm that lasted over 5.4 days. The leaf area index (LAI) needed to adjust a wind function calibrated Penman equation (EPMe) to match the ELE values could be back calculated to generate seasonal change in LAI from 0.12 to 0.46 and compared well with normalized difference vegetation index; r = 0.38 and p = 0.0213* and LAI calculated from digital cover photography. The apparently conservative response of perennial vegetation evaporation to available water in these semi‐arid environments reinforces the conclusion that these ecosystems use this mechanism to survive the reasonably common dry periods. Plant response to soil water availability is primarily through gradual changes in leaf area. Copyright © 2015 John Wiley & Sons, Ltd.

Green Roofs in the Mediterranean Area: Interaction between Native Plant Species and Sub-Surface Runoff

Green roofs (GRs) may represent a solution for minimizing the impact of urbanization on the hydrological cycle and for sustainably managing water resources in urban environment. Several studies have shown that GRs effectively control the surface runoff conveyed into the combined sewer systems, by reducing overall volumes and peak flow rates. The hydrological/hydraulic performance of a GR is strongly dependent upon vegetation species used. In this study the influence of plants on the sub-surface runoff is investigated by monitoring two experimental GRs in wet weather conditions. It is hypothesized that although plants reduce sub-surface runoff, they may also boost the formation of preferential flow paths. The results showed that the sub-surface runoff is strongly influenced by vegetation. While for smaller storm events the GR highly retains stormwater due to the plant interception, for larger storm events the GR’s performance decreases due to the increase of sub-surface runoff. This may be due to the presence of the plant root which produces preferential macropores flow through the substrate.

Application of the SUSTAIN Model to a Watershed-Scale Case for Water Quality Management

Low impact development (LID) is a relatively new concept in land use management that aims to maintain hydrological conditions at a predevelopment level without deteriorating water quality during land development. The United States Environmental Protection Agency (USEPA) developed the System for Urban Stormwater Treatment and Analysis Integration model (SUSTAIN) to evaluate the performance of LID practices at different spatial scales; however, the application of this model has been limited relative to LID modeling. In this study, the SUSTAIN model was applied to a Taiwanese watershed. Model calibration and verification were performed, and different types of LID facilities were evaluated. The model simulation process and the verified model parameters could be used in other cases. Four LID scenarios combining bioretention ponds, grass swales, and pervious pavements were designed based on the land characteristics. For the SUSTAIN model simulation, the results showed that pollution reduction was mainly due to water quantity reduction, infiltration was the dominant mechanism and plant interception had a minor effect on the treatment. The simulation results were used to rank the primary areas for nonpoint source pollution and identify effective LID practices. In addition to the case study, a sensitivity analysis of the model parameters was performed, showing that the soil infiltration rate was the most sensitive parameter affecting the LID performance. The objectives of the study are to confirm the applicability of the SUSTAIN model and to assess the effectiveness of LID practices in the studied watershed.

Interceptação vegetal e precipitação interna em área de caatinga arbustiva e arbórea, Coreaú (Ceará)

This research analyzes the relationship between vegetation interception and internal precipitation in Caatinga area, in the county of Coreaú, State of Ceara. The research was based on the selection of two areas of 100sq meters, with strata and different stages of regeneration of the vegetation layer, where fifteen rain gauges made of plastic bottles were installed in each area. It was found that the greater the external rainfall is, the smaller the plant interception in both environments becomes. Besides, there was an interception in bush plot in relation to bush-tree, reaching a ratio of 4:1. Key-words: Bush Caatinga. Bush-tree Caatinga; Vegetation interception; Internal precipitation.

Arbuscular mycorrhizas enhance plant interception of leached nutrients

Arbuscular mycorrhizal fungi (AMF) can increase plant growth and nutrition. However, their capacity to reduce the leaching of nutrients through the soil profile is less well understood. Here we present results of an experiment in which the effects of forming arbuscular mycorrhizas (AM) on plant growth and nutrition, nutrient depletion from soil, and nutrient leaching, were investigated in microcosms containing the grass Phalaris aquatica L. Mycorrhizal and non-mycorrhizal plants were grown in a mixture of riparian soil and sand under glasshouse conditions. The formation of AM by P. aquatica significantly increased plant growth and nutrient uptake. Lower levels of NO3-, NH4+ and plant available P in both soil and leachate were observed in columns containing mycorrhizal root systems. These differences in nutrient interception were proportionally greater than the increase in root biomass of the mycorrhizal plants, compared with their non-mycorrhizal counterparts. Taken together, these data indicate that mycorrhizal root systems have an important, but previously little considered, role to play reducing the net loss of nutrients via leaching.

An environmental indicator to drive sustainable pest management practices

The indicator EPRIP (Environmental Potential Risk Indicator for Pesticide) was released in 1997 with the aim of providing farmers with advice in selecting the most suitable pesticide with the least environmental impact. EPRIP 2, the newly developed, standalone version includes several improvements in the description of driving forces, in particular plant interception, drift and runoff and new database functionalities. EPRIP 2 is based upon the Exposure Toxicity Ratio (ETR) of the predicted environmental concentration (PEC) with toxicological parameters. When several applications of different active ingredients are used within the same pest control strategy, EPRIP 2 calculates a score for each active ingredient and for the overall pest control strategy. The latter evaluation is based on the probability of the EPRIP value exceeding two fixed risk thresholds. The probability of exceeding each threshold is calculated using the risk points of every application in the strategy and taking into account the risk points for surface water, groundwater, soil and air.

Vegetation controls on soil moisture distribution in the Valles Caldera, New Mexico, during the North American monsoon

AbstractSoil moisture distributions are expected to be closely tied to ecosystem processes in water‐limited environments of the southwest United States. Nevertheless, few studies have addressed how soil moisture varies across grassland to forest transitions frequently observed in semiarid mountain settings. In this study, we quantify the vegetation controls on surface soil moisture by sampling a range of different ecosystems present in the Valles Caldera, New Mexico. Soil and atmospheric variables were measured during a 2‐week field campaign conducted in late July to early August 2005 during the North American monsoon. Field observations were supplemented by a network of continuous instruments used to assess conditions prior to and after the sampling campaign. Results reveal that soil moisture responds directly to summer precipitation events and is mediated by plant interception, which differs across the grassland–forest continuum. The nature of the spatial and temporal variations in soil moisture changes across the different sampled ecosystems: wetlands, riparian forests, grasslands, ponderosa, deciduous and mixed conifer forests. In particular, statistical analyses of soil moisture distributions indicate that distinct regimes (e.g. probability density functions) exist along the semiarid vegetation gradient, which may not be revealed through simple metrics such as the ecosystem average. Ecosystem differences are further elucidated through comparison of the spatial variations in each vegetation type, indicating higher variability in wetland and grassland sites. Copyright © 2008 John Wiley & Sons, Ltd.

Comparative ecological risks of pesticides used in plantation production of papaya: Application of the SYNOPS indicator

Pesticides are used intensively for crop protection in tropical fruit plantations. Assessments of the relative risks posed by pesticides are needed to assist in the development of management plans that minimize ecological impacts. In this study, the risk indicator SYNOPS_2 was used to compare risks to aquatic ecosystems by pesticides commonly used in papaya plantations. Plant interception and spray drift were measured during six applications of three pesticides (chlorothalonil, chloropyrifos, and malathion) using a turbo fan driven sprayer. Plant interception was estimated to be higher (42.6+/-12.7%; p=0.04) in late (8-14 months old) than in early (4 months old) trees (20.1+/-25.3%). Chlorothalonil concentrations of up to 11.0 microg L(-1) were found in water from an adjacent ditch after field application. Concentrations of this pesticide (7.4+/-4.1 microg L(-1)) in runoff water were also significantly (p<0.01) higher than those of malathion (2.4+/-1.9 microg L(-1)) and chlorpyrifos (0.8+/-0.5 microg L(-1)). Good correlation between measured and predicted values (r2=0.56-0.85, p<0.01) showed that SYNOPS_2 is able to describe trends in runoff pollution in papaya plantations. Linear equations were obtained in order to correct numerical disagreement between measured and calculated runoff concentrations. An independent test showed a reasonable agreement between measured chlorothalonil concentrations and the predicted values using the proposed equations. Fifteen pesticides used in papaya cultivation were ranked according to their calculated chronic biological risk index. Pesticides with the highest risk index for non-target organisms were: chlorothalonil for algae, lambda cyahalotrin for Daphnia and fish, and malathion for earthworms. Chlorothalonil was the pesticide with the highest exposure level in water and therefore represents a high risk for aquatic life. Results show that SYNOPS_2 can be used as a pesticide risk indicator on papaya and possibly other tropical fruit plantations.

Scenario-based simulation of runoff-related pesticide entries into small streams on a landscape level

The prediction of runoff-related pesticide entry into surface waters on a landscape level usually requires considerable efforts with regard to input data, time, and personnel. Therefore, the need for an easy to use simulation tool with easily accessible input data, for example from already existing public sources, is obvious. In this paper, we present a simulation tool for the simulation of pesticide entry from arable land into adjacent streams. Our aim was to develop a tool applicable on the landscape level using “real world data” from numerous sites and for the simulation of parameter case studies concerning particular parameters at single sites. We used the ratio of exposure to toxicity (REXTOX) model proposed by the OECD, which had been successfully validated in the study area as part of a previous study and which was extended to calculate pesticide concentrations in adjacent streams. We simulated the pesticide entry on the landscape level at 737 sites in small streams situated in the central lowland of Germany with winter wheat, barley, and sugar beat as the main agricultural crops. A sensitivity analysis indicated that the most significant model parameters were the width of the no-application zone and the degree of plant interception. The simulation was carried out for the 15 most frequently detected substances found in the study area using eight different environmental scenarios, covering variation of the width of the no-application zone, climate, and seasonal scenarios. The highest in-stream concentrations were predicted for a scenario using no (0 m) buffer zone in conjunction with increased precipitation. According to the predicted concentrations, the risk for the aquatic communities was estimated based on standard toxicity tests and the application of a safety factor. The simulation results are presented both by means of risk maps for the study area showing the simulated pesticide concentration and the resulting ecological risk for numerous sites under varying scenarios and by case study diagrams with focus on the model behavior under the influence of single parameters. Risk maps confirmed the importance of no-application (buffer) zones for the levels of pesticide input. They also indicated the importance of the existing no-application zones for certain compounds and in some cases the need for a further evaluation of these regulations. The simulation tool was implemented as a standard PC software combining the REXTOX model with a geographical information system and can be used on any current personal computer. All input data was taken from public sources of German authorities. With little effort the tool should be applicable for other areas with similar data quality.

The interrelationships among plant biomass, plant surface area and the interception of particulate deposition by grasses.

The interrelationships among plant biomass, plant surface area and interception fraction were determined for the interception by corn of 238Pu-bearing particles released to the atmosphere from the H-Area nuclear fuels chemical separations facility on the U.S. Department of Energy's Savannah River Plant in Barnwell County, South Carolina. The relationship between interception fraction and corn biomass was accurately approximated by a filtration model with an absorption coefficient of 3.60 m2 kg-1. A filtration model with an absorption coefficient of 2.91 m2 kg-1 accurately approximated the relationship between biomass and interception fraction for data compiled from the literature for a variety of grass species. A linear regression model accurately approximated the relationship between interception fraction and surface area, but was not a better predictor of interception fraction than the filtration model for biomass.