Experience

Despite the importance of rainfall and catchment characteristic on urban stormwater quality, there are few studies about role of each urban land use (i.e. residential, commercial, industrial, parks or open space, and transportation) on stormwater quality from urban areas. NURP is still commonly used, even though it was conducted nearly four decades ago (Smullen et al., 1999; USEPA, 1983). The objectives of this study were: (1) to estimate N, P, and sediment loading from six catchments with homogenous land use within urban area; (2) to investigated the role of rainfall characteristics on stormwater quality; (3) to compare the assessed urban runoff quality within each land use with other regions and other land uses ; (4) to develop an estimate of annual TSS, TP, TN loads delivered from urban areas using a simple linear model and incorporating statistical variability by use of a Bootstrap method; and (5) to verify these results by comparing them with those generated by a SWMM model. We calculated EMCs across the 30 events for TSS, TP, and TN as 30, 0.31, and 0.94 mg∙L^-1, respectively. Average pollutant loads within coastal areas for TSS, TP, and TN were calculated as 0.86, 0.03, and 0.01 kg/(ha∙cm), respectively.

The goal of this study was to better understand the behavior of a Coastal Plain retention pond for removal of nitrogen (N), phosphorous (P), and sediment. I selected a rather ordinary pond in the City of Virginia Beach for this study. I monitored water quality at the inlets and the outlet of the retention pond for one year and estimated its treatment efficiency for N, P, and sediment. I found that during cold weather, the pond reduced the level of TSS and P by an average of 75% and 22 %, respectively, while it exported N, increasing it in the pond outflows by an average of 45%. During warm weather, due to biological activities like nitrification/denitrification, the performance of the pond improved, achieving an average TSS reductions of 70% and an average N reduction of 50%, while the level of P was reduced by only 10% on average. Understanding the function of one retention pond in detail and characterizing it with a numerical mode may provide a means of improving treatment across an entire watershed and thus improve the health of downstream ecosystems.

I worked on Comparative Evaluation of HSPF and SWMM Model Applications to Simulate Streamflow Regime for an Urbanized Watershed. While numerous hydrologic models exist, there is limited information about how to select the most appropriate model for a given watershed, and how to evaluate its effectiveness at streamflow simulation. Hydrologic models such as the Storm Water Management Model (SWMM) and the Hydrologic Simulation Program-Fortran (HSPF) are widely used to evaluate the impacts of urban development on watersheds and receiving waters. Thus, I developed SWMM and HSPF model for an urbanized watershed (Fig. 1) and compared the ability of these two models at simulating streamflow, peak flow, and baseflow. The most sensitive hydrologic parameters for HSPF were related to groundwater; for SWMM, it was imperviousness. Both models simulated streamflow adequately; however, HSPF simulated baseflow better than SWMM, while, SWMM simulated peak flow better than HSPF (Nayeb Yazdi et al., 2019a).

I conducted a monitoring program on a nursery for one year. I characterized TSS, TN, and TP, EC, and pH in runoff from a 5.2 ha production portion of a 200 ha commercial container nursery during storm and irrigation events. The objectives of that study were (1) to characterize irrigation and storm runoff quantity and quality at a Mid-Atlantic nursery site; (2) to evaluate the ability of SWMM to simulate hydrology and water quality at the main production areas of that site; (3) to develop an estimate of average annual loading of TSS, TN and TP from a nursery production area, and (4) to generalize these projected annual loads as a function of key variables. as the first study, I modeled runoff quantity and quality at a container nursery. Results showed the average loading of TSS, TN and TP during storm events was approximately 900, 35 and 50 times higher than those of irrigation events, respectively. SWMM was able to characterize runoff quality and quantity reasonably well. Thus, it is suitable for characterizing runoff loadings from agricultural area (Nayeb Yazdi et al., 2019b; Yazdi et al., 2018).

A field sampling campaign was implemented to evaluate the variation in air pollutants levels (PM and CO) near a highway in Tehran, Iran (Hemmat highway). The field measurements were used to estimate road link-based emission factors for average vehicle fleet.