Final Exam - SS: Synthetic Biology: Engineering Living Systems - Spring 2006 | BSE 5984, Exams of Engineering

Download Final Exam - SS: Synthetic Biology: Engineering Living Systems - Spring 2006 | BSE 5984 and more Exams Engineering in PDF only on Docsity! Kyle Hall BSE 5984 Advanced Topics in Land and Water Resources Engineering Spring 2006 Final Exam In your post to the EPA NPSInfo list serve you asked “…can man made structures work better than nature??” In short the answer is, no. Unfortunately research has not yet fully revealed the complex relationships between flora, fauna and the hydrologic cycle. In a natural setting these relationships contribute to the dynamic equilibrium of a system. In other words, the system is able to adapt to gradual changes while still supporting ecosystem functions such as flood control, water filtration and wildlife habitat. Research has focused on many components of the hydrologic cycle and techniques have been established to reproduce those functions with varying degrees of success. In addition, research has been conducted to find out how the hydrologic cycle contributes to ecosystem functions while interacting with flora and fauna. The failure of man-made structures is that they can not fully replicate all the necessary interactions between the hydrologic cycle, flora, and fauna. Man made structures are only capable of reproducing a few of the desired ecosystem functions and so man-made structures can not work better than nature. With regards to the forest land being developed, you will likely see impacts in your local streams regardless of the Best Management Practices (BMPs) utilized during construction and after development. Research has shown that no single BMP can address all the possible stormwater concerns created by urbanization (EPA-821-R-99-012, 1999; Tsihrintzis and Hamid, 1997). However, construction of BMPs is mandated in some jurisdictions, indicating there is still significant benefit to incorporating a single BMP (EPA-821-R-99-012, 1999). By combining multiple BMPs, the overall effectiveness will be augmented and stormwater impacts can be moderated. Understanding the limitations of individual BMPs can help choose the appropriate BMP for urban development. There have been numerous studies focused on the impacts urbanization has on local stream hydrology. Some major effects of urbanization include: more precipitation is converted to surface runoff; runoff travels faster through the watershed; the peak flow is increased in local streams; baseflow is reduced in local streams; and water quality is degraded (Rose and Peters, 2001). The intensity of these effects can be moderated by BMPs, but when combined, these effects can produce irreversible results at certain levels of urbanization. The amount of precipitation converted to surface runoff is a function of the infiltration capacity of the soil. As urbanization continues, developments cover the soil with parking lots, buildings (rooftops) and roads. All of these decrease soil infiltration capacity by increasing the The decreased baseflow magnifies the effects of tributary temperature and flow, including overland flow. When stormwater enters the stream as overland flow, heat is transferred from roads and parking lots directly into the stream. Krause et al. (2004) conducted a modeling study in Virginia simulating a change in stream temperature through varying flow, channel width, and shade associated with multiple levels of urban development. Modeling results showed an increase in stream temperature resulting from a decrease in shade and an increase in channel width. A more significant increase in stream temperature was found when the effects of urbanization were combined (Krause et al., 2004). There will be definite impacts on the local streams by developing the forested land. Stream impacts from the urbanization will be manifested in the hydrology as a decrease in the time of concentration, higher peak flow, and lower baseflow. These hydrologic changes will also affect bank stability and aquatic habitat through increased erosion, temperature and degraded water quality. Strategically placed BMPs, such as swales and infiltration trenches, will moderate some of the hydrologic impacts by increasing infiltration and slowing the overland flow. Infiltration will further be enhanced by engineered materials such as porous pavement. BMPs which incorporate vegetation, such as a constructed wetland or riparian buffer, will filter pollutants before the water reaches the stream. In addition to these structural BMPs, non- structural BMPs can have an impact on community behavior. Storm drain stencils can provide a connection to the local stream for the neighborhood residents while education on water management can reduce the amount of water consumed per household. A combination of multiple BMPs will provide the maximum protection to the local stream. However, the increased impervious area and human activity will degrade the quality of runoff compared to the current forested landuse. References Brabec E., S. Schulte and P.L. Richards. 2002. Impervious surfaces and water quality: a review of current literature and its implications for watershed planning. Journal of Planning Literature, 16(4):499-514 USEPA. 1999. Preliminary data summary of urban stormwater best management practices. EPA-821-R-99-012. United States Environmental Protection Agency. Office of Water: Washington, D.C. Galli, J. 1990. Thermal impacts associated with urbanization and stormwater management best management practices. Washington, DC: Sediment and Stormwater Administration of the Maryland Department of the Environment, Metropolitan Washington Council of Governments Krause, C. W., B. Lockard, T. J. Newcomb, D. Kibler, V. Lohani and D. J. Orth. 2004. Predicting influences of urban development on thermal habitat in a warm water stream. Journal of the American Water Resources Association. 40(6):1645-1658. Maxted, J. R. and E. Shaver. 1998. The use of retention basins to mitigate stormwater impacts to aquatic life. Paper presented at the national conference on Urban Retrofit Opportunities for Water Resources Protection in Urban Areas, Chicago, IL. Morse, C. C., A. D. Huryn and C. Cronan. 2003. Impervious surface area as a predictor of the effects of urbanization on stream insect communities in Maine, U.S.A. Environmental Monitoring and Assessment. 89: 95–127. Nelson, E. J. and D. B. Booth. 2002. Sediment sources in an urbanizing, mixed land-use watershed. Journal of Hydrology 264: 51–68. Novotny, V., Olem, H., 1994. Water Quality: Prevention, Identification, and Management of Diffuse Pollution, Van Nostrand Reinhold, New York, p 1054. Pizzuto J. E., W.C. Hession and M. McBride. Geology. January 2000, 28(1): 79-82. Shaw EM. 1994. Hydrology in Practice. 3rd edn. Chapman & Hall: London: 569. Poole, G.C. and C. H. Berman. 2001. An ecological perspective on in-stream temperature: natural heat dynamics and mechanisms of human-caused thermal degradation. Environmental Management. 27(6): 787–802. Rose S. and N. E. Peters. 2001. Effects of urbanization on streamflow in the Atlanta area (Georgia, USA): a comparative hydrological approach. Hydrologic Processes. 15: 1441–1457. Schoonover, J. E., B. G. Lockaby and S. Pan. 2005. Changes in chemical and physical properties of stream water across an urban-rural gradient in western Georgia. Urban Ecosystems. 8: 107–124. Trimble, S.W. 1997. Contribution of stream channel erosion to sediment yield from an urbanizing watershed. Science. 278(21): 1442-1444. Tsihrintzis V. A. and R. Hamid. 1997. Modeling and management of urban stormwater runoff quality: a review. Water Resources Management. 11(2): 136–164.