Evaluating the effectiveness of management practices on hydrology and water quality at watershed scale with a rainfall-runoff model.

The adverse influence of urban development on hydrology and water quality can be reduced by applying best management practices (BMPs) and low impact development (LID) practices. This study applied green roof, rain barrel/cistern, bioretention system, porous pavement, permeable patio, grass strip, grassed swale, wetland channel, retention pond, detention basin, and wetland basin, on Crooked Creek watershed. The model was calibrated and validated for annual runoff volume. A framework for simulating BMPs and LID practices at watershed scales was created, and the impacts of BMPs and LID practices on water quantity and water quality were evaluated with the Long-Term Hydrologic Impact Assessment-Low Impact Development 2.1 (L-THIA-LID 2.1) model for 16 scenarios. The various levels and combinations of BMPs/LID practices reduced runoff volume by 0 to 26.47%, Total Nitrogen (TN) by 0.30 to 34.20%, Total Phosphorus (TP) by 0.27 to 47.41%, Total Suspended Solids (TSS) by 0.33 to 53.59%, Lead (Pb) by 0.30 to 60.98%, Biochemical Oxygen Demand (BOD) by 0 to 26.70%, and Chemical Oxygen Demand (COD) by 0 to 27.52%. The implementation of grass strips in 25% of the watershed where this practice could be applied was the most cost-efficient scenario, with cost per unit reduction of $1m3/yr for runoff, while cost for reductions of two pollutants of concern was $445 kg/yr for Total Nitrogen (TN) and $4871 kg/yr for Total Phosphorous (TP). The scenario with very high levels of BMP and LID practice adoption (scenario 15) reduced runoff volume and pollutant loads from 26.47% to 60.98%, and provided the greatest reduction in runoff volume and pollutant loads among all scenarios. However, this scenario was not as cost-efficient as most other scenarios. The L-THIA-LID 2.1 model is a valid tool that can be applied to various locations to help identify cost effective BMP/LID practice plans at watershed scales.

Liu Y ，Bralts VF ，Engel BA 《-》

Optimal selection and placement of green infrastructure to reduce impacts of land use change and climate change on hydrology and water quality: An application to the Trail Creek Watershed, Indiana.

The adverse impacts of urbanization and climate change on hydrology and water quality can be mitigated by applying green infrastructure practices. In this study, the impacts of land use change and climate change on hydrology and water quality in the 153.2 km(2) Trail Creek watershed located in northwest Indiana were estimated using the Long-Term Hydrologic Impact Assessment-Low Impact Development 2.1 (L-THIA-LID 2.1) model for the following environmental concerns: runoff volume, Total Suspended Solids (TSS), Total Phosphorous (TP), Total Kjeldahl Nitrogen (TKN), and Nitrate+Nitrite (NOx). Using a recent 2001 land use map and 2050 land use forecasts, we found that land use change resulted in increased runoff volume and pollutant loads (8.0% to 17.9% increase). Climate change reduced runoff and nonpoint source pollutant loads (5.6% to 10.2% reduction). The 2050 forecasted land use with current rainfall resulted in the largest runoff volume and pollutant loads. The optimal selection and placement of green infrastructure practices using L-THIA-LID 2.1 model were conducted. Costs of applying green infrastructure were estimated using the L-THIA-LID 2.1 model considering construction, maintenance, and opportunity costs. To attain the same runoff volume and pollutant loads as in 2001 land uses for 2050 land uses, the runoff volume, TSS, TP, TKN, and NOx for 2050 needed to be reduced by 10.8%, 14.4%, 13.1%, 15.2%, and 9.0%, respectively. The corresponding annual costs of implementing green infrastructure to achieve the goals were $2.1, $0.8, $1.6, $1.9, and $0.8 million, respectively. Annual costs of reducing 2050 runoff volume/pollutant loads were estimated, and results show green infrastructure annual cost greatly increased for larger reductions in runoff volume and pollutant loads. During optimization, the most cost-efficient green infrastructure practices were selected and implementation levels increased for greater reductions of runoff and nonpoint source pollutants.

Liu Y ，Theller LO ，Pijanowski BC ，Engel BA ... -  《-》

Effectiveness of low impact development practices in two urbanized watersheds: retrofitting with rain barrel/cistern and porous pavement.

The impacts of urbanization on hydrology and water quality can be minimized with the use of low impact development (LID) practices in urban areas. This study assessed the performance of rain barrel/cistern and porous pavement as retrofitting technologies in two urbanized watersheds of 70 and 40 km(2) near Indianapolis, Indiana. Six scenarios consisting of the watershed existing condition, 25% and 50% implementation of rain barrel/cistern and porous pavement, and 25% rain barrel/cistern combined with 25% porous pavement were evaluated using a proposed LID modeling framework and the Long-Term Hydrologic Impact Assessment (L-THIA)-LID model. The model was calibrated for annual runoff from 1991 to 2000, and validated from 2001 to 2010 for the two watersheds. For the calibration period, R(2) and NSE values were greater than 0.60 and 0.50 for annual runoff and streamflow. Baseflow was not calibrated in this study. During the validation period, R(2) and NSE values were greater than 0.50 for runoff and streamflow, and 0.30 for baseflow in the two watersheds. The various application levels of barrel/cistern and porous pavement resulted in 2-12% reduction in runoff and pollutant loads for the two watersheds. Baseflow loads slightly increased with increase in baseflow by more than 1%. However, reduction in runoff led to reduction in total streamflow and associated pollutant loads by 1-9% in the watersheds. The results also indicate that the application of 50% rain barrel/cistern, 50% porous pavement and 25% rain barrel/cistern combined with 25% porous pavement are good retrofitting options in these watersheds. The L-THIA-LID model can be used to inform management and decision-making for implementation of LID practices at the watershed scale.

Ahiablame LM ，Engel BA ，Chaubey I 《-》

Field monitoring of a LID-BMP treatment train system in China.

Jia H ，Wang X ，Ti C ，Zhai Y ，Field R ，Tafuri AN ，Cai H ，Yu SL ... -  《-》

Green infrastructure practices simulation of the impacts of land use on surface runoff: Case study in Ecorse River watershed, Michigan.

As an urban fringe district, the Ecorse River watershed is faced with increased impervious area caused by urban expansion. Effects of Green Infrastructure (GI) practice implementation were simulated with the Long-Term Hydrologic Impact Assessment-Low Impact Development 2.1 model (L-THIA-LID 2.1). Suitable locations of each GI practice were identified, based on construction condition requirements and demand on GI practices in the study area. Using the data of 2011, various GI practice combination scenarios were explored according to the cost-efficiency of each GI practice. GI practice implementation scenarios in 2050 were also simulated based on projected land use and rainfall data. Results show that grassed swales, rain barrels (residential areas) and dry ponds were the top three most cost-efficient GI practices, with the cost at $1.5/m³/yr, $3.0/m³/yr and $3.4/m³/yr, respectively. Green roofs with rain cisterns (industrial and commercial area) were the most expensive GI practices, with the cost at $92.9/m³/yr. With the increase of investment in GI practices, the changing curves of the annual runoff volume, Total Nitrogen (TN) load and Total Phosphorus (TP) load reduction ratios match the law of diminishing marginal utility. The scenario with grassed swales, rain barrels, dry ponds and porous pavement would be the most cost-efficient scenario for runoff water quantity reduction. In addition, the scenario with additional wet ponds would be the most cost-efficient one for TN load and TP load reduction. GI practices in each scenario for expected 2050 conditions show better effectiveness on water quantity and quality management.

Li F ，Liu Y ，Engel BA ，Chen J ，Sun H ... -  《-》