Role of Neighborhood Design in Reducing Impacts of Development and Climate Change, West Sherwood, OR

We used the EPA SWMM-5. 1 model to evaluate the relative impact of neighborhood design and constructed Low Impact Development (LID) features on infiltration, evaporation, and runoff for three future scenarios. In the Current Course (CC) future, current regulations and policies remain in place under lower rates of climate change and population growth. In the Stressed Resources (SR) future, rapid rates of population growth and climate change stress water systems, and conventional development patterns and management actions fail to keep pace with a changing environment. In the Integrated Water (IW) future, with the same rapid rates of climate change and population growth as the SR future, informed water management anticipates and adapts to expected changes. The IW scenario retains public open space, extensive use of constructed LID features, and has the lowest proportion of impervious surface. Neighborhood designs varied in the number of dwelling units, density of development, and spatial extent of nature-based solutions and constructed LID features used for stormwater management. We compared the scenarios using SWMM-5.1 for a set of NRCS Type 1a design storms (2-yr, 25-yr, 20% increase over 25-yr, 30% increase over 25-yr) with precipitation input at 6-min time steps as well as a set of 10-year continuous runs. Results illustrate the importance of neighborhood design in urban hydrology. The design with the highest proportion of impervious surface (SR future) produced runoff of up to 45–50% of precipitation for all variations of the 25-year storm, compared to 34–44 and 23–39% for the CC and IW futures, respectively. Evaporation accounted for only 2–3% of precipitation in the 25-year design storm simulations for any scenario. Results of continuous 10-year simulations were similar to the results of design storms. The proportion of precipitation that became runoff was highest in the SR future (33%), intermediate in the CC (16%), and lowest in the IW future (9%). Evaporation accounted for 6, 11, and 14 of precipitation in the SR, CC, and IW futures with LID, respectively. Infiltration was higher in scenarios with LID than for the same scenario without LID, and varied with the extent of LID employed, accounting for 59, 71, and 74% of precipitation in the SR, CC, and IW scenarios with LID. In addition to differences in performance for stormwater management, the alternative scenarios also provide different sets of co-benefits. The IW and SR future designs both provide more housing than the CC, and the IW future has the lowest cost of development per dwelling unit.

Spatial distribution of severe rainstorms over India and their associated areal raindepthsSpatial distribution of severe rainstorms over India and their associated areal raindepths

Spatial distribution of 97 severe rainstorms of India which occurred during the period 1880 to 1990 was examined, by plotting this data over large-scale base maps of the country , It was found that excepting a few rainstorms, most of these rainstorms, have preferred zones of occurrence. These zones have been demarcated and their boundaries are found to correspond with the orographic boundaries of the region where these zones occur. Also, the isohyetal patterns drawn on the basis of DAD data of these rainstorms for different size areas and durations have shown that within each of the rainstorm zones, there are areas or cells of heavy rainfall which need to be taken care of while transposing rainstorms from one area to another for obtaining design storm estimates.

Devastating rainstorm of June-2013 in Uttarakhand

The state of Uttarakhand is prone to floods and landslides due to its topographic location. The state of Uttarakhand and neighbouring states experienced heavy to very heavy rainfall during 15-18 June, 2013. The analysis of this rainstorm is important because it caused severe floods, landslides, loss of thousands of lives, property etc. During this period, many stations reported very heavy rainfall with a few extremely heavy rainfall (more than 24.5 cm in a day) in Uttarakhand and also in the neighbouring states of Himachal Pradesh, Haryana and Punjab. Most part of the state of Uttarakhand lies in the Greater Himalayan region. For safety from floods, one of the methods is to store water in hydraulic structures. For planning and designing of hydraulic structures, the estimation of design storm is the primary and the basic input for the computation of design flood. In the estimation of design storm, all the heavy rainstorms occurred over or near the area have to be analysed. In this paper, this rainstorm and other heavy rainstorms over a wide area has been analysed for the purpose of computation of Design storm estimates of hydraulic structures in that area. The rainstorm of June 2013 is compared with the earlier historical heaviest rainstorm of 28th to 30th September, 1924 at Lansdowne and it is observed that the rainstorm of June 2013 has contributed more rainfall than the rainstorm of September 1924 rainstorm for an area up to 5000 km2 for 1-day duration, while the DAD estimates for two day and three duration of rainstorm of September 1924 are higher than the rainstorm of June 2013 for area up to 20,000 km2.

Bamboo Fences as a Nature-Based Measure for Coastal Wetland Protection in Vietnam

Climate change has induced sea-level rise and a high intensity of storms, which create high nearshore waves. These caused severe mangrove degradation and erosion along the coastal wetland areas in the Mekong Delta in Vietnam. Mangroves in the coastal wetland foreshore can withstand only some certain design storm waves and grow under several certain submerged conditions. Therefore, reducing waves and shallowing wetland elevation for recovering mangroves and protecting them in an early birth state is important. Bamboo or melaleuca fences have been used as a nature-based solution to reduce waves and currents approaching the shore for these above purposes along Vietnamese Mekong deltaic coasts. This paper investigates wave transmission through the bamboo fence system and assesses its effectiveness in protecting the mangroves. Waves were simultaneously measured at two locations for comparison: in front of and behind the fences. The result shows that the wave reduction by the fences is considerable, and sedimentation occurs rapidly in the shelter areas behind the fences, which is highly favorable for the recovery and growth of mangroves. Next, the empirical formulae have been proposed for relationships between the wave transmission coefficient of the fence and the dimensionless wave-structures parameters, such as the relative water depth, the wave steepness, and the fence freeboard. The findings create a basic technical reference for designing a naturally friendly-based solution by using bamboo and/or wooden fences in coastal protection generally and protecting mangroves specifically. The outcome of the research contributes to narrowing an existing gap in Vietnamese design guidelines for coastal wetland protection and also facilitates the use of locally available eco-friendly materials for coastal management along the Vietnamese Mekong delta coasts.

Estimation of the G2P Design Storm from a Rainfall Convectivity Index

The two-parameter gamma function (G2P) design storm is a recent methodology used to obtain synthetic hyetographs especially developed for urban hydrology applications. Further analytical developments on the G2P design storm are presented herein, linking the rainfall convectivity n-index with the shape parameter of the design storm. This step can provide a useful basis for future easy-to-handle rainfall inputs in the context of regional urban drainage studies. A practical application is presented herein for the case of Valencia (Spain), based on high-resolution time series of rainfall intensity. The resulting design storm captures certain internal statistics and features observed in the fine-scale rainfall intensity historical records. On the other hand, a direct, simple method is formulated to derivate the design storm from the intensity–duration–frequency (IDF) curves, making use of the analytical relationship with the n-index.

Enhancing the usability of weather radar data for the statistical analysis of extreme precipitation events

Spatially explicit quantification on design storms are essential for flood risk assessment and planning. Since the limited temporal data availability from weather radar data, design storms are usually estimated on the basis of rainfall records of a few precipitation stations having a substantially long time coverage. To achieve a regional picture these station based estimates are spatially interpolated, incorporating a large source of uncertainty due to the typical low station density, in particular for short event durations. In this study we present a method to estimate spatially explicit design storms with a return period of up to 100 years on the basis of statistically extended weather radar precipitation estimates based on the ideas of regional frequency analyses and subsequent bias correction. Associated uncertainties are quantified using an ensemble-sampling approach and event-based bootstrapping. With the resulting dataset, we compile spatially explicit design storms for various return periods and event durations for the federal state of Baden Württemberg, Germany. We compare our findings with two reference datasets based on interpolated station estimates. We find that the transition in the spatial patterns from short duration (15 minute) to long duration (2 days) events seems to be much more realistic in the weather radar based design storm product. However, the absolute magnitude of the design storms, although bias-corrected, is still generally lower in the weather radar product, which should be addressed in future studies in more detail.

Analyses Of The Hydrologic Performance Of Bioretention Facilities

Due to urbanization, and replacing natural pervious lands by impermeable surfaces, the patterns of rainfall-runoff are altered and thus, negatively influence natural water systems regarding both water quantity and water quality. Bioretention as an efficient LID practice has received significant interest in the recent years. Bioretention practice due to its advantages can be considered as one of the most promising LID practices that maintains the fundamental hydrologic functions in a natural environment and can be integrated into neighborhood landscaping. The primary objective of the current study is analyzing the effects of inflow and outflow characteristics on right-of-way (roadside) bioretention facilities. Inlet and outlet flow hydrographs under several design storm conditions were examined. After the formulation of a SWMM model (node and link plus LID), numerical experiments including sensitive analysis will be designed to simulate and investigate the runoff control performance of a right-of-way bioretention facility. The effective length of the bioretention was found by FLOW3D software (finite element). The performance of the bioretention cell with the effective lengths (12 &16m) reinvestigated and results compared to original bioretention cell

Evaluation Of Etobicoke Exfiltration System Applications In The City Of Barrie

These days engineers reduce the adverse effects of urbanizations using Low Impact Developments (LID) on their municipal design. Etobicoke Exfiltration System (EES) as a LID Best Management Practice (BMP) was demonstrated in 1993 and is being implemented at a hospital rehabilitation project in Toronto. To evaluate EES through modeling, a methodology was used to implement EES in SWMM 5.1.012, and the outcome was applied for a case study in Barrie. The primary components of EES include inlets, void space storage of granular material laid beneath the main sewer system. These components were modeled by orifices and a storage unit to simulate the exfiltration of water from the stone trench into the surrounding native soil. The model was applied in a case study in Barrie regarding hydrologic performance analysis. The results indicated a significant reduction of runoff volume and peak flow reduction for a single design storm. However, some challenges revealed by these results regarding the case study

Analyses Of The Hydrologic Performance Of Bioretention Facilities

Due to urbanization, and replacing natural pervious lands by impermeable surfaces, the patterns of rainfall-runoff are altered and thus, negatively influence natural water systems regarding both water quantity and water quality. Bioretention as an efficient LID practice has received significant interest in the recent years. Bioretention practice due to its advantages can be considered as one of the most promising LID practices that maintains the fundamental hydrologic functions in a natural environment and can be integrated into neighborhood landscaping. The primary objective of the current study is analyzing the effects of inflow and outflow characteristics on right-of-way (roadside) bioretention facilities. Inlet and outlet flow hydrographs under several design storm conditions were examined. After the formulation of a SWMM model (node and link plus LID), numerical experiments including sensitive analysis will be designed to simulate and investigate the runoff control performance of a right-of-way bioretention facility. The effective length of the bioretention was found by FLOW3D software (finite element). The performance of the bioretention cell with the effective lengths (12 &16m) reinvestigated and results compared to original bioretention cell

Using Sensors (IoT) to Monitor and Improve the Efficiency of Living Green Infrastructure in Urban Development (Literature Review)

The use of information and communication technology for environmental purposes in urban development can help establish a smart city. Creating a network of sensors that monitor the various parameters of living structure would allow industry professionals to better manage, plan and design storm water mitigation practices. By using IoT, the data from the sensors is stored in the cloud where it can be retrieved and analyzed as needed. There are currently monitoring systems that focus on one particular aspect of the urban environment such as storm water, air pollution or green roofs but this literature review focuses on how these individual approaches can be combined into one to monitor various aspects of living infrastructure including hydrological, atmospheric, soil based and ecological. Based on the literature available, several limitations are identified that need to be addressed before such a monitoring system is possible and can be incorporated into mainstream practice.