Integrity of Local Ecosystems and Storm Water Management in Residential Areas

Journal of Ocean University of China (Occeanic and Coastal Sea Research)ISSN 1672-5182, October 30, 2006, Vol.5, No.4, pp.363-367http: / www. ouc. edu. cn/xbywb/E- mail: xbywb@ ouc. edu. cnIntegrity of Local Ecosystems and Storm WaterManagement in Residential AreasWANG Lin *，WANG Weida, and GONG ZhaoguoCollee of Envirnmental Science and Engineering, Ocean University of China, Qingdao 266003. P. R. China(Received March 21. 2006; accepted September 17, 2006)Abstract The authors designed an ecological storm water system in a residential area to replace the conventional under-ground channels for the collction of storm water so as to reduce the nutrients and sediments discharged. This system con-tains natural sub-creeks as drainage channels discharging overflow to nearby creeks, an open green trench, a storage pond,and natural sub-creeks. The sub-creeks were designed to be integrated into community landscape, which not only increasesthe efficiency of water usage, but also improves the aesthetic qualities of the community residence area as required by Agen-da 21. This research proved the fesibility of an open storm water collection and uilization system for the design of a com.munity water system.Key words storm water management; ecological community; water management; open trench; greenway; pond systemcological integrity， which can be summarized as‘ in-tegrity can only be defined clearly (in terms of evalua-1 Introductiontive criteria) for specific ecosystems, in the context ofPopulation growth has created escalating pressures man being an integral part of the ecosystem.' Sinceon our resources ( natural, human and social) on local,water is a key factor in our ecosystem, the explicit re-regional, and global scales. These pressures negatively lationship between ecosystem integrity and waterimpact the natural environment, our communities andmanagement is our objective. Effective and sustainablethe quality of our lives. In the face of these globalwater usage is not just water-saving， but also its safechallenges, people have more and more concerns for return to our ecosystem. Our case analysis will presentenvironment and sustainability .an idea how to use an ecological instrument to design aThe concept of sustainable development emerged as community for the maximization of its function and al-an effective solution to this thorny problem. Rather so for the fulfllment of requirement of ecological in-than pitting economic growth against environmental tegrity.protection, proponents of sustainability have shiftedthe terms of debate by focusing on development that 2 Relationship Between Runoff and Ecol-meets the needs of the present without compromisingogythe ability of future generations to meet their ownneedsWorld Commission on Environment and Devel-opment, 1987).Adaptation for water balance and conservation helpsBased on the above definition，the authors believe determining a species habitat range. Typically， thethat sustainable community development involves the peak- flow change of pre/ post development is dramat-ability of a local community to utilize its natural, hu- ic; for example, in many intact forest areas, it is onlyman and technological resources to ensure that all 1 % annual runoff under a natural forested condition,members of present and future generations can attain abut it can be 70% annual runoff for an intensive com-high degree of health and well-being, economic securi- munity area. A further impact of deforestation and de-ty, and maintenance of the integrity of the ecological nudement due to over- exploitation and shifting cultiva-systems .tion, biotic and abiatic interferences. has caused con-The concept of integrity in ecosystems traces its siderable degrad中国煤化工such as thatroots to the land ethic defined by Leopold (2004). A shown in Fig.1YHCNMHGrich, though mostly conceptual, literature exists on e-We depend on a heautny ecosystem，Including cleanwater，to survive on this planet. Therefore, effectiveand sustainable water use should be emphasized and* Corresponding author. E mail: lwang@ouc. edu. cnbased on an ecological approach and water management364Journal of Ocean University of ChinaVol. 5, No. 4, 20062.graveled areas, sidewalks, and paved recreation areas.To satisfy population needs, we have more and morepaved areas - for example, new housing or industrialust- Post-Dev-3 ac. imperviousdevelopments，urban infills， driveways, patios， new言1roads, etc. So the amount of runoff increases rapidly .享0.-Pre-DevIt has been estimated that the amount of urban runoffSac.forest...from paved areas in Qingdao， China has increased2.5about ten folds over the last 100 years due to develop-Rainfall/ in. 24 h eventment. In addition, the level and range of pollutants inFig.1 Pre/Post development comparison (Source: SBUHrunoff has increased.method, perv. Cn 70/imp.Cn 99, 5 acre site.).should be coupled with ecological environment- com-3.2 Management of Stormwatermunity development .Stormwater from the roof is piped down to theground, and discharged into the drain, then into a big3 Current Situation of Storm Water Man-pipe, and eventually into the sea. Sometimes the wa-ter is discharged directly into a stormwater pipe. Oth-agement in Communityer times the water is sent into a stream, or a large3.1 Increasing Runoffconcrete channel. Traditional stormwater design isRunof is created to a certain extent when humanaimed at letting the stormwater flow as fast as possibleactivities alter the natural water balance. As trees,to the sea - through big pipes or big channels. Figs.2vegetation and soils are replaced with roads and build-and 3 indicate a layout of runoff collection and dis-ings, less rainfall infiltrates into the ground, less getscharge pipeline system in Shinan District, Qingdao,taken up by vegetation and more becomes storm waterChina，which explicitly ilustrates a conventional wayrunoff. The follow equations show runoff increaseto discharge runoff and a network using large-sizedwith impervious cover area in an urban area.runoff collection pipeline with a diameter of 2m is un-der construction. The higher the impervious area, theAnnual runoff is calculated by:●R=PXP1X Rv,larger the discharge pipeline and the higher the dis-R = annual runoff (in. ),charge speed. Fig.4 shows the runoff pollutants im-P= annual rainfall (in.),pacting on the seawater quality of Qingdao Bay; theP1 = fraction of annual rainfall events that pro-detail of pollutants contained in the runoff is shown induce runoff (usually 0.9),Table 1，which presents pollution assessment of the●Rv= runoff coefficient.stormwater collection system at Loushan outlet inThe runoff coefficient is calculated by:Qingdao (Wang et al, 2004). As shown in Table 1,●Rv=0.5+ 0.9la,the pollutants tended to increase with time. The in-●la = impervious fraction.creased pollutants in runoff seriously impact the re-This cofficient is based on the percentage of imper- ceiving water body quality and its ecology.vious cover of the watershed area. Impervious surfaces‘Therefore, conventional approaches to flooding con-are limited to two main features of human develop- trol obviously results in frequent flooding and draughtment: building rooftops and transportation systems.in the drainage area and the quality of the storm waterImpervious surfaces are man-made areas that do not will be influenced. And, no doubt, non-point pollu-readily absorb or retain water, including, but not lim- tion is related to stormwater. The unsustainability ofited to, building roofs, parking and driveway areas,these approaches is evident in many communities a-, Zhongshan Road CcGuangzhou Road CCGuancheng Road CCShandong Road CcZiyang Road ccJiangsu Road CCYanan Road CL了i士TuandaoAnhui Road CCNanhai oCYunxi中国煤化工iRoad cCWWTPDonghaiRoad ccfHCNMH GTaipingjiaooCCC- Cover channelOpen channelFig.2 Location of storm water outlets to coastal waters of Shinan District, Qingdao, China.WANG L.. et al: Integrity of Local Ecosystems and Storm Water ManagementTable 1 Pollution asessment of stormwater collection system at Loushan outlet ( Estuary) in QingdaoTSSCODBODsNH3-NTotal HgCad_OiLTotal PTime1997249244616.60.260.00216.71998861402212.20.054.40.431999387401823.80.0821.83.222000193253:15.10.2012.95.492001782055215.50.510. 0063.00.58482768(34.00.350.0141.0.7020032674768114.80.130.012 .1.01.0520046074652:19.40.110.76evaporation, occur simultaneously. Infiltration occurswhen precipitation seeps into the ground. This de-pends heavily on the permeability of the ground andland surface characteristics.Land cover can affect both the degree of infiltrationand the runoff following the precipitation events. Thedegree of vegetation and the albedo (degree of absorp-tion/ reflection of sun's rays) of the surface influencerates of evaporation, humidity levels and cloud forma-tion. In the undeveloped area of the study site ofHuayang Community (Wang et al, 2004)， filtration .accounts for 51% of the total precipitation, runoff2.2% and evaporation 46.7%，as shown in Fig.5 .Fig.3 Construction of storm collection pipeline at TanchengNatural land cover has various properties that helpRoad，Qingdao, China.to regulate water flows both above and below theground. Forest canopy and leaf accumulation， for ex-ample，help to attenuate the impact of raindrops onthe earth' s surface， thereby reducing soil erosion.Roots hold the soil in place， especially on steeperslopes, and also absorb water. Openings in leaf accu-mulation and soil pores permit the infiltration of wa-ter, which is carried through the soil into the ground-water. Where ground cover is insufficient, sheet, rilland/ or gully erosion may result.| 0 FiltrationRunoff0 EvaporationFig.4 Pollutants plume in Qingdao Bay.round the world and in Qingdao as well. Our new ideaFig.5 Water distribution fllwing precipitation underon stormwater management might solve many of the :natural condition at study area.world' s water problems, such as flooding or droughtand non- point pollution.4.2 Water Concept: Retain the Natural Water Bal-4 Ecologiy Oriented Storm Water Manage-ance Befo中国煤化工mentTo minimizefYHC N M H Gentional ap-proach to flooding control, a seml-natural storm water4.1 Natural processmanagement system was proposed for most recovery ofRainall comes in the formsof snow, rain, hail, etc. the natural water cycle, matching the natural situationThe next three stages, i. e., infiltration， runoff， and before development.366Journal of Ocean University of ChinaVol. 5, No. 4, 2006The conventional underground pipeline system was rainwater harvest in the community is:replaced by open trench for storm water management,Q=CIAwhich is a combination of infiltration， retention andcontrolled release. An ecological pond and wetland where: Q = maximum rate of runoff (m3 s 1);system should be employed as the polish and final stor- C = runoff cofficient representing the ratio of run-age tanks of the collected stormwater. The naturalap- off to rainfall, C= 0.7;proach has to be site specific and design -oriented, suchI = average rainfall intensity for a duration equal toas theconstruction of riparian wetland and forest the time of concentration (mmb~ |);buffering zone coupling the pond system to integrateA = drainage area contributing to the design locationthe water quality management with ecological remedi-(m2).ation together (Cook, 1991).Planning objectives: retain the natural water bal-The benefits of natural approaches are the follow-ance before development， which requires: filtrationing:accounts for 51% of the total precipitation， runoff1) Filtering runoff: rain that runs off the land can2.2 % and evaporation 46.7%; a master design of thebe slowed and infiltrate in the forest, settling out sedi-Community is shown in Fig.6. Storm water will be .ments, nutrients and pesticides before they reachcollected by the open trench and flows into the land-streams.Infiltration rates 10 - 15 times higher thanscaping pond located in the center of the communitygrass turf and 40 times higher than a plowed field areshown in Fig.6. The pond will be used for both watercommon in forested areas (Hedberg，1999).2) Taking up nutrients: pollutants are taken up bystorage and final polishing. The retention time of thewater in ponds is three weeks for further purificationtree- roots and plants in the swale and wetland. Nutri-to meet the water quality standards for landscaping,ents are stored in leaves， limbs， and roots instead ofgarden watering, car cleaning and other uses. Rainreaching the stream (Mitsch, 1992).water harvest in the three- week period during summer3) Providing shade: leaf canopy ’s shade keeps theis about 283 m'，and the design volume of the polishwater cool, allowing it to retain more dissolved oxy-pond is 300 m'.gen, and encouraging growth of plants and aquatic in-sects, which in turn provides food for fish ( KauffmanWulonghe Creeket al., 1997) .treatment plant4) Contributing leaf food: leaves flling into thepond provide food and habitat for organisms critical tothe aquatic food chain.5) Saving water: large amounts of fresh water isexhausted for landscaping aims; the natural approach-Openes of storm water management reduce the water re-trench -quirement by about 30% of the total water consump-tion in the community for each person each day (De-Huayang residential areasign Manual, 1997)There are many other natural processes in additionLandscape garden andpond systemto the water cycles that are around us in the built en-vironment. Humans will always need to maintain ade-Fig.6 Master design for Huayang community.quate space for plants to capture solar energy andtransform it into human foods. This space must notThe open green trench was used to replace the un-only accommodate cropland, but also consider stormderground channel for the collection of storm water,water management and community habits.and the reduction of nutrients and sediments. Thenatural sub-creeks were used as the drainage channel5 A Case Study - Storm Water Manage-discharging the overflow to the region creek， Wu-ment in Huayang Communitylonghe Creek. The open green trench, storage pond,Huayang community, Beizhai of Laoshan District,natural sub-creeks have been integrated into the urbanlandscape .has a population of 1516 and an area of 21.83 ha; theThe two sub-creeks are. ecologicallv characterized byconstruction area is 0.017km’, about 40% of the totalsoft embankme中国煤化工restrial zone,area. The area of roads and squares is 0.008 57 km?,which are integ|YHCNMHGTheecologi-that of green belts is 0.0256km2, and that for public cal creeks will promnote ture rising ol underground wa-parking lots is 0.028 km2. The rainwater harvested in ter table and improve the ecological environment of thethe community is 283 m’in three weeks in summer community .(Wang et al, 2004). The equation used to calculateThe integrity ecology of community and stormwaterWANG L. et al: Integrity of Local Ecosystems and Storm Water Managementmanagement has abandoned the conventional water ing car, and landscaping components. Each year aboutmanagement method of adopting underground channel30% of fresh water will be saved by using stormwa-systems for the discharge of sewerage out of the urban ter, and it will conserve resources, improve the eco-area. Instead it has employed the ecological concept logical environment and establish a better- balancedthat open green trenches and natural creeks should bewater cycle in the region studied.used to collect, transport and retain urban runoffs,which realizes the optimization of sustainable socio-e-conomical development and environmental protection.ReferencesCook,E. A., 1991. Urban landscape networks: an ecologi-6 Conclusionscal planning framework. Landsc. Res.,. 16(3): 7-15.Hedberg， T, 1999. Attitudes to traditional and alternativeA model of sustainable community was developedsustainable sanitary systems. Water Sci. Tech.. 39: 9-16.for the geographic scope sustainable community by Kauffman, J. B.. R. L. Beschta, N. Oting, and D. Lyt-synchronously considering the natural， buman andjen, 1997. The lethal decline riparian and stream restora-technological aspects of the problem to realize the in-tion in the western united states. Fisheries, 22: 12 -24.tegrity of community ecology; stormwater was for theLeopold, A. C，2004. Living with the land ethic. Bio-first time designed to be integrated into landscapingMishra, A. K., and U. C. Sharma, 2001. Traditional wis-Science, 54(2): 1design to realize community ecological improvement.dom in range management for resource and environmentThe conventional stormwater management approachconservation in north eastern region of India. Himalayanwith an underground pipeline system was replaced byEcol. Dev, 9(1): 20 -34.an open trench system, which, in combination of ri- Mitsch, W. J.1992. Landscape design and the role of cre-parian zone，soft embankment and aqua-plant pond,ated, restored, and natural riparian wetlands in control-forms an ecological system， capable of transportingling nonpoint source pollution. Ecol. Eng., 1: 27-47Wang, L., z. Gstormwater，removing pollutants and presenting astudy of water conservation and management. Proceed-enjoyable landscape.ings of the 4th Interational Conference on Watershed Man-Overlow of the system was stored in the polishagement and Urban Waler Supply, Dec. 13 - 15. Shen-pond for other uses, including watering garden, clean-zhen, China, A-20.中国煤化工MYHCNMH G