Research Oriented Papers Summary (Summer 2009)

Article # 1:
Evan Shane Williams and William R. Wise, Hydrologic Impacts of Alternative Approaches to Storm Water Management and Land Development, April 2006, Journal of the American Water Resource Association
Summary:
The paper discusses of the hydrologic impacts caused by different alternatives of storm management and land development options. The study is carried out based on the alternatives considering the traditional and clustered development along with LID technique and with the LID technique. Along with these alternatives they studied how the hydrology is affected with connected (runoff from impervious cover being discharged into the conveyance system directly without any infiltration i.e. implying no vertical storage) and disconnected impervious cover (allowing infiltration i.e. rooftop runoff discharged into lawns and roads draining to swales). These alternatives were compared with the existing conditions i.e. without any land development. They have used different metrics to compare the effects of runoff – peak flow, flow duration, time to peak, and runoff volume. The paper focuses on the possible areas of hydrologic concerns with different land developments and storm management practices.

Article # 2:
E. Downey Brill, JR. John M. Flach, Lewis D. Hopkins, S. Ranjithan, MGA: A Decision Support System for Complex Incompletely Defined Problems, August 1990
Summary:
The paper focuses on how the infiltration types effect could be different depending on the type of land development. The study carried out evaluates combinations of different infiltration practices (i.e spread roof to lawn, rain garden, reduction on street width, green swales etc) and they have even carried out comparative analysis of different soil groups with these mentioned infiltration practices. The research proves that the land development which leaves most of the land unaltered i.e. leaving it in natural condition are the ones which have less effects on the urban runoff. With the strategic combinations of land development and corresponding infiltration practices it would be possible to deal with the hydrologic impacts caused due to the increased runoff.

Article # 3:
David J Sample, James P Heaney, Integrated Management of Irrigation and Urban Storm Water Infiltration, October 2006, Journal of Water Resource Planning and Management
Summary:
The paper focuses on integrating the water conservation, irrigation management planning and storm management for a study area of a subdivision in Boulder, Colorado. Paper illustrates different studies carried out in integrating the storm water and usage of LID techniques which has received recent attention in the research community. According to the studies carried out LID is considered to be better mimic of the pre development conditions and LID relies in managing the runoff at the site thereby reducing the directly connected impervious area (DCIA) thereby reducing the storm runoff produced. DCIA runoff as is collected by the storm conveyance system which have the potential of being transported away from the irrigation users, therefore for in-site storm management we need concentrate on the non-DCIA and pervious areas. They have carried out different options of irrigation management plans and studied the water budget of the area. Cost comparison was carried out between these options. They have carried out study to find out the optimal rain water storage volume to result in highest net benefits, it was found to be for the capacity of 10000L that results in highest net benefit. Author concludes about how the most benefited (Net benefit) option is associated with conserving the water (storing in cisterns) for the irrigation options.

Article # 4:
Kristin L Gilroy, Richard H McCuen, Spatio-temporal effects of low impact development practices, 2009, Journal of hydrology
Summary:
The paper focuses the importance of the factors like optimal location, quantity of BMP and land use types which needs to be investigated to achieve the optimal effectiveness of the LID’s being used for the storm water management. The paper covers the study carried out on a spatio-temporal micro watershed which is used to study the effectiveness of BMP with respect to the location and the volume. In the study they have considered bio retention and cisterns to deal with the increased peak discharge and runoff volume. Bio retention was used majorly as the infiltration where as cisterns was above surface storage which is used to manage the runoff from the rooftop. The authors have carried out the study considering different land use patterns and modeled using 2 different storm events 1 yr and 2 yr. They have studied the effectiveness of each of the BMP used with respect to these scenarios. For the comparison of the results they have considered two metrics i.e. peak flow and runoff volume to measure the effectiveness of the scenarios and BMP used.

Article # 5:
Q. Xiao, E G McPherson, J R Simpson and S L Ustin, Hydrologic processes at the urban residential scale, October 2006
Summary:
The paper focuses on building up a physical numerical model to understand hydrologic processes in the urban scale and its interaction with different BMP’s. The model was applied to a single family residential lot in Los Angeles, CA. Model was calibrated and validated by the data collected for over 2 yrs. They have modeled rain gutters, driveway interceptors and lawn retention basin. It was observed that there was about 65% reduction in storm water by using driveway interceptor. But using the rainwater gutters the annual irrigation demand was provided by 9%. It was observed that all the BMP’s installed in the treatment site were effective in reducing the storm runoff and reducing the irrigation demand from the municipal water demand. Using these strategies enabled the improvement of urban eco system. BMP has reduced the maximum runoff flow to the streets and the maximum annual evaporation and increased the deep percolation. Increased percolation increases the downstream base flow and groundwater recharge. For runoff reduction driveway interceptor and drywell combination was the best but this BMP carries the risk of carrying pollutants from the surface runoff into the ground water. Cistern provided additional irrigation demand supply but for more effective use of cistern it should be appropriately designed for the catchment areas. Few of the sites will not follow the sub surface balance which focuses on the importance of more detailed model with such kind of topographic situations.

Article # 6:
Wolfram Schluter, Chris Jefferies, Modeling the outflow from a porous pavement, October 2001
Summary:
This paper focuses on modeling a 20 month old porous pavement in Edinburgh which was calibrated using 15 storm events. Storm water software package Erwin is used to simulate the outflow from these porous pavements. 16 events were recorded out of which one was recorded using the flow logger where as the rest were recorded with the V notch weir located at the outlet of the monitoring manhole. The porous pavement does not drain total inflow but it retains a certain amount which would be evaporated unless a future precipitation occurs. From the conclusion which they observed after running the simulation model for both single event and long term simulation is that the wetness of the porous pavement prior to the event will increase the outflow of the following event. Therefore studying the simulation for long term would be more advisable as it takes into consideration the wetness of the porous pavement. The study observed that Porosity of the filling material under the porous pavement has a little influence on the volume of the runoff but has an impact on the peak flow rate.

Article # 7:
James. W, James W.R.C, Von Langsdorff H, Computer Aided design of permeable concrete block pavement for reducing stressors and contaminants in an urban environment, October 2003
Summary:
This paper focuses on illustrating the new component which is linked up to EPA SWMM which is used to model the permeable pavements called as PCSWMM. The paper gives illustration of all the different components in the PCSWMM. Permeable pavement depends on design of storage capacity (which can store the storm water) and surface infiltration rate. PCSWMM addresses hydraulic and hydrologic aspects of permeable pavement. Two main concerns addressed by the software is the maximum depth of water that can be stored for the designed storm and the time taken to drain from the base layer of the pavement. This interface calculates the flow of runoff through different layers of the pavements i.e. pavers, base layer, and subgrade. The paper did not cover any examples of using this software. The authors mentioned about the groundwater and infiltration calculations need to be tested or verified.