Laurent Ahiablame

Effectiveness of Low Impact Development Practices: Literature Review and Suggestions for Future Research

Low impact development (LID) is a land development strategy for managing stormwater at the source with decentralized micro-scale control measures. Since the emergence of LID practices, they have been successfully used to manage stormwater runoff, improve water quality, and protect the environment. However, discussions still surround the effectiveness of many of these practices, resulting in a reluctance to widely adopt them. This paper highlights evidence in the literature regarding the beneficial uses of LID practices. A discussion of how LID practices are represented in hydrologic/water quality models is also provided using illustrative examples of three computational models developed with algorithms and modules to support widespread adoption of LID practices. Finally, the paper suggests directions for future research opportunities.

Enhancing a rainfall-runoff model to assess the impacts of BMPs and LID practices on storm runoff.

Best management practices (BMPs) and low impact development (LID) practices are increasingly being used as stormwater management techniques to reduce the impacts of urban development on hydrology and water quality. To assist planners and decision-makers at various stages of development projects (planning, implementation, and evaluation), user-friendly tools are needed to assess the effectiveness of BMPs and LID practices. This study describes a simple tool, the Long-Term Hydrologic Impact Assessment-LID (L-THIA-LID), which is enhanced with additional BMPs and LID practices, improved approaches to estimate hydrology and water quality, and representation of practices in series (meaning combined implementation). The tool was used to evaluate the performance of BMPs and LID practices individually and in series with 30 years of daily rainfall data in four types of idealized land use units and watersheds (low density residential, high density residential, industrial, and commercial). Simulation results were compared with the results of other published studies. The simulated results showed that reductions in runoff volume and pollutant loads after implementing BMPs and LID practices, both individually and in series, were comparable with the observed impacts of these practices. The L-THIA-LID 2.0 model is capable of assisting decision makers in evaluating environmental impacts of BMPs and LID practices, thereby improving the effectiveness of stormwater management decisions.

Modeling flood reduction effects of low impact development at a watershed scale

Low impact development (LID) is a land development approach that seeks to mimic a sites pre-development hydrology. This study is a case study that assessed flood reduction capabilities of large-scale adoption of LID practices in an urban watershed in central Illinois using the Personal Computer Storm Water Management Model (PCSWMM). Two flood metrics based on runoff discharge were developed to determine action flood (43 m(3)/s) and major flood (95 m(3)/s). Four land use scenarios for urban growth were evaluated to determine the impacts of urbanization on runoff and flooding. Flood attenuation effects of porous pavement, rain barrel, and rain garden at various application levels were also evaluated as retrofitting technologies in the study watershed over a period of 30 years. Simulation results indicated that increase in urban land use from 50 to 94% between 1992 and 2030 increased average annual runoff and flood events by more than 30%, suggesting that urbanization without sound management would increase flood risks. The various implementation levels of the three LID practices resulted in 3-47% runoff reduction in the study watershed. Flood flow events that include action floods and major floods were also reduced by 0-40%, indicating that LID practices can be used to mitigate flood risk in urban watersheds. The study provides an insight into flood management with LID practices in existing urban areas.

Development of two indices for determining hydrologic implications of land use changes in urban areas

Simple metrics are needed by decision makers to quantify hydrologic impacts of land uses as a result of urbanization. Two indices to evaluate hydrologic implications of land use changes were developed and demonstrated in case studies. The first index, pre-development versus post-development index (PPH), compares pre-development to post-development hydrologic conditions for time of concentration, peak runoff for a 2-year 24-hour storm and a 10-year 24-hour storm, and average annual runoff volume. The second, extent of maximum index (EH), compares post-development with potential minimum and maximum hydrologic conditions of a site. The indices were applied in three case studies of residential subdivisions in Lafayette, Indiana. These case studies illustrate how to interpret the resulting index values. The Orchards subdivision, which was designed with conservation principles, scored the best for both indices. Although the two indices can be used separately, it is advised to use them together.

Spatial and Temporal Evaluation of Hydrological Response to Climate and Land Use Change in Three South Dakota Watersheds

This study analyzed changes in hydrology between two recent decades (1980s and 2010s) with the Soil and Water Assessment Tool (SWAT) in three representative watersheds in South Dakota: Bad River, Skunk Creek, and Upper Big Sioux River watersheds. Two SWAT models were created over two discrete time periods (1981-1990 and 2005-2014) for each watershed. National Land Cover Datasets 1992 and 2011 were, respectively, ingested into 1981-1990 and 2005-2014 models, along with corresponding weather data, to enable comparison of annual and seasonal runoff, soil water content, evapotranspiration (ET), water yield, and percolation between these two decades. Simulation results based on the calibrated models showed that surface runoff, soil water content, water yield, and percolation increased in all three watersheds. Elevated ET was also apparent, except in Skunk Creek watershed. Differences in annual water balance components appeared to follow changes in land use more closely than variation in precipitation amounts, although seasonal variation in precipitation was reflected in seasonal surface runoff. Subbasin-scale spatial analyses revealed noticeable increases in water balance components mostly in downstream parts of Bad River and Skunk Creek watersheds, and the western part of Upper Big Sioux River watershed. Results presented in this study provide some insight into recent changes in hydrological processes in South Dakota watersheds. Editors note: This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.

Spatial Translation and Scaling Up of Low Impact Development Designs in an Urban Watershed

The downstream impacts of best management practices designed to manage stormwater at the source are not well documented. This study investigated two aspects of…

Comparative Analysis of METRIC Model and Atmometer Methods for Estimating Actual Evapotranspiration

Accurate estimation of crop evapotranspiration (ET) is a key factor in agricultural water management including irrigated agriculture. The objective of this study was to compare ET estimated from the satellite-based remote sensing METRIC model to in situ atmometer readings. Atmometer readings were recorded from three sites in eastern South Dakota every morning between 8:15 and 8:30 AM for the duration of the 2016 growing season. Seven corresponding clear sky images from Landsat 7 and Landsat 8 (Path 29, Row 29) were processed and used for comparison. Three corn fields in three sites were used to compare actual evapotranspiration ( ). The results showed a good relationship between estimated by the METRIC model ( -METRIC) and estimated with atmometer ( -atm) ( = 0.87, index of agreement of 0.84, and RMSE = 0.65 mm day−1). However, -atm values were consistently lower than -METRIC values. The differences in daily between the two methods increase with high wind speed values (>4 m s−1). Results from this study are useful for improving irrigation water management at local and field scales.

Modeling low impact development in two Chicago communities

Sustainable practices that will aid in reducing runoff volume and nutrient loading during storm events are needed in many urban areas. Continued assessment of the hydrologic impact of low impact development (LID) practices in urban communities is needed to support development and re-development of residential areas. An evaluation using the L-THIA LID model of two south-side Chicago communities with hypothetical implementation levels of LID features is presented in this study. The results revealed that incorporating LID practices such as porous pavement, and rain barrels, could have a noticeable impact on average annual runoff and the nonpoint source (NPS) pollutants carried in the runoff. Porous pavement on 50% of current parking lot space could result in an estimated 24% decrease in runoff volume. Additionally, the runoff reduction for all scenarios ranged from 2–24%. Hence, these results indicate that implementation of LID features in urban communities could provide substantial benefits.

Estimation of Crop Evapotranspiration Using Satellite Remote Sensing-Based Vegetation Index

Irrigation water is limited and scarce in many areas of the world, including Comarca Lagunera, Mexico. Thus better estimations of irrigation water requirements are essential to conserve water. The general objective was to estimate crop water demands or crop evapotranspiration ( ) at different scales using satellite remote sensing-based vegetation index. The study was carried out in northern Mexico (Comarca Lagunera) during four growing seasons. Six, eleven, three, and seven clear Landsat images were acquired for 2013, 2014, 2015, and 2016, respectively, for the analysis. The results showed that was low at initial and early development stages, while was high during mid-season and harvest stages. These results are not new but give us confidence in the rest of our results. Daily maps helped to explain the variability of crop water use during the growing season. Based on the results we can conclude that maps developed from remotely sensed multispectral vegetation indices are a useful tool for quantifying crop water consumption at regional and field scales. Using maps at the field scale, farmers can supply appropriate amounts of irrigation water corresponding to each growth stage, leading to water conservation.

Effectiveness of roadside vegetated filter strips and swales at treating roadway runoff: a tutorial review

Water leaving roadside ditches has the potential to affect the quality of downstream waters. Vegetated filter strips (VFSs) and grassed swales (GSs) are often used to manage roadside ditches for water quality protection. This paper summarized field data from relevant studies to determine the efficiency of these two best management practices (BMPs) in removing nutrients and trace metals from roadside ditches, and discussed implications for downstream water quality, as well as driving factors that influence the performance of roadside VFSs and GSs. The literature examined shows that roadside VFSs and GSs are quite effective at reducing total suspended solids (TSS), while a mixed performance was reported for metal and nutrient removal. Based on the data, VFSs and GSs appear to be more effective at removing particulate-bound than dissolved pollutants.