Watershed protection and landscape enhancement by utilization of river water

Jurnal of Eruiromennal Sriemres Vol. 15.Nn.4.pp.487 - -493 ,2003Artide ID: 101040202030487-07ac pumber: XS2:X703 Document code: AWatershed protection and landscape enhancement by utilizationof river waterZU0 Hua' ，PEI Yuan-sheng'2, HU De-zhi, LUAN Zhao-kun'(1. Research Center lor Eco-Enioumental Seienrer, Chimee Acadeay of Sirnrs. Brijig 10080 Chinu. F-mail: luunk @ mail. ree.ac.cn: 2. Institute of Enironmental Sciences and Eingineering. Lanzhou Jiaotong L'niversily, Lanzhou 730070, China)Ahstract: A schenre far watenthrd pontection and landseape enhanement( WPLE) by uilization of river water was prperd w rovr walerand food risks. The srtheme is brnefieinl tn solv the poblems of wnter resource shorage , goundwaler declines and saltwaler innsion in thewaterbed. The objee o the WPLE scbheme is to arhieve n sainble integrated development of environnenl, ecolgy, eronomy and soriety.rape may exert it syuthetical function on the divrsity f landseape and the enjoymentof inbabiants. Fesibility o[ the xchemne will bhr demonstated bv more experiments and tets. as nell a derrwatins in a lng tem.Keywords: waterbed; landscape; mater resoures: ern.enironmentIntroductionA compon penomenon for waler resources in the wurld is that waler is pleniful during centainseasons, and drought conditions occur in other seasons. Similaly, water demand is also eyelical, with thehighest demand ofen ocuring when the lexsL amount of water is available. Urities therefore faxer aconslant challenge of how lw store water during times of plenly so that adequate resoures are available whenneeded.Storing water involves both walersbhed protection and waler conservation ( Lyle，1994). Naturalwalenshed is responsible for providing waler to the environnent. Sustainable management of the watershed .can enhance the natural habital , conserve waler, and provide long-lerm water slorage and flood prolcction.Water conservation could do with improvements of agriculural， indusrial and municipal waterconsumptions. as well u8 with treatment and uilixation of lower-qualily walers.Aquier storage and rcovery(ASR) is a form of conjunctive use where exess water is slord .undergroundin a suitale aquifer and reowered later as needed( Dlln, 1998). ASR can provide anelective to for sustainable development and management of available waler resoures within a walenshed tobalance the needs of competing water demands( Dodds, 2000) . Drivers for ASR are alsu expanding beyondseasonal stornge to include acting a5 a salinity brrier, aquifer replenishment, and for waler qualityimprovement( Dabbagh, 2001). ASR operaion has been developing in Austalia， the United Siales,Israel, Netherlands, England, Soulh Africa and other countrie today( Eastwod, 2001) .In this paper, we present a scheme of walershed prolection and landeape enhanoement( WPLE) byuilization of river waler in Qingshan City, China， in which the basic principle of ASR is ubopled andfuther extended to eco-environment proection， purticularly to walenhed prolection und landscapeenhancement .1 WPLE schemeBackground* Correponding author中国煤化工MYHCNMHG4882U0 Hua et al.Vol. 15.Qiongshan lies on the Binhai Plain in the north of Hainan Province ，close to the capital city of Haikou(Fig.1). Qiongshan has an area of 2068 km' and a population of 80000. It has a tropical monsoonclimate with an annual average temperature of 23 .8C. Annual rainfall and evaporation avenage 1300 and1900 millimelers, respectively. The rainy season starts in early May and ends in late October. NanduRiver flows through the part of Qiongshan before emptying into the sea. Is length is about 311 km, with 69km in Qiongshan, and average width is 800 m. The whole drainage area of Nandu River is 71.76 km2，and annual avenage waler discharge reaches 6.92 km' . Near 60%- 70% flow of the river happens duringMay to 0ct. The radiant intensity, average temperalure, average rainfall and relative humidity of air inQiongshanin 2001 are shown in Fig.2. The bedrock of Qiongshan has formed over a long geologicalperiod, with a dense network of tidal canals. Typical acid red soils with thickness of 1- I .5 m have beendeveloped under the sub-tropical and tropical climate( Zhu, 1999). The hickness of unconfined aquifer is31 m, below which seven conlined aquifers are situated . Tolal groundwater runoff reaches 0000 m' /d.181 +Radiant inesit16-14Hailkou喜12420.旨1_3501--- Radinnt目200150-路100f8281JanMarMayJulSopNov“Fig.1 Iocations ot the widon valley and QiongsbanFig.2 Radiant intensity, avenge temperature,ilyaveruge rifll and relative bhumidity in Qiongshanin 2001In order to pronole sustainable development of Qiongshan City, oficils frum the local gowemmenttogether with researchers from Research Center for Eco Environmentul Sciences( RCEES) of the ChineseAcademy of Sciences initiated a campaign of ecological city development. A new city area called theWisdom Valley has thus being constncled by the govenment. The valley is loeated 5 km away from MeilnInlermational Ainport and a sea bridge connets the valley 1o Haikou City . The central tak of the vlleydevelopment is to encourage a kind of economically productive and ecologically fficient industries. a kind .of slemetically responsible and socially harmonious culure, and a kind of physicallyl beauiful andfunctionally vivid landscape .However, the vlly is experiencing rapid population growth and water demnand expanse. Lying on awater supply system, surface water is taken and caried by long distance conduil lo the waterworks inQiongshan City(Li, 2000). Yet finite waler resoures are even now the restrict factor aginst the vlly'sdevelopment. Water use has exceeded groundwaler recharge. On avenge only about 7 percent of the men中国煤化工MYHCNMHGNo.4.W atershed protection and landscape erhancement by utilization of river waler489annual precipitation infiltrates deep enough to rechange thegroundwater. Annual groundwater storage quantity is approximately 日.3 上1.566 bllin m' in Qiongshan Gity, in which only 449 million m'司4could be exploited. It is near 6 m of water table deeline in量-StQiongshan over past 10 yearsdue to overexlotaion ( Fig.3) .Overonsumption of groundwater resources in the area may also resultin saltwater intrusion and may cause a drop in surface water level.1992 1994 1996 1998 20000 2002t,yOn the other hand, during the fooding season, most of the waterproduced from rainstom cannol be uilized due to its swift transpxort Fig.3 Goudvuter tl derines 0p past 10into the sea. Simulaneously， rainstorms produce a plenty of years in Qionghandarmaged waler.I1 is a contradiction of groundwater declines and looding risks. Hainan Island is isolated from themainland, thus its water resources are not related to any other waler systems in China. Local rainfll is theonly original regoure for survival of livings and development of society and econonmy(Gu, 1995; Ma,2001). Most water problems in Qiongshan may arise from four aspecels: seasonal water shortage, sectionalwater shortage, hydrulic scarcity and low efficient water use .1.2 WPLE schemeA common way lo slore water in China is to build dams and the accompanying reservoirs that floodlarge areas. Qionghan ' s flat topography , however. leads to relatively shallow holding ponds that lose a lotof water by evuporation. In view of the high evaporation rales it can be cost eective to stre walerunderground raher than on the ground. By capturing suplus water and rfifcially recharging it, thegroundwater reources would rective additional replenishment thus boosting the amount of waler availablefor laler asretion( Pvelie, 2000 Within the eological city development plan. rsearcberer in RCEESproposed a waler plan for replenishing waler resources. improving ecologead environment und futherensuring sustainable devclopment in the vlley as well as in Qiongshan. The key poimt of the scheme is tostore and utilize the Nandu River' s water in the valley.The Nandu River has been practiced as water resources ofQiongshan City and Haikou City at its upper reaches over decadeyears. Walter qualities at the upriver appopriately satisfy thStandards of River Water Resources( SRWR) in China while those at曾3the lower reaches may not. The upriver water, however, only fts thesecond slandard of SRWR based on a long-term observation inSapy 530 Saopo1 Longlang Dam Monitoring Stain( Fig.4). The upriver waterMar-00Mar-01qualities in 2001 tend to be more stable than those in 1999.Fig.4 lneated index of Nandu Rive' 。Meanwhile, a consumption risk is still presenled since the inlegrateder qualityleraion in Lngtang Dem index of waler quality is around 35. Once the integrated index is overMonioning Station)50，il will be not suilable to be used as a source. Therefore, surfacewaler storage may encounter the problems of both reserves shortage and water quality delerioration.Researchers in RCEFS drew an outline of tasniting river waler lo both suface channels andunderground storoge. The WPLE scheme consits of units, funcions and objects (Fig .5). The besic unite中国煤化工MYHCNMHG4902U0 Hua A al.Vol. 15are the river, the channels, the lakes arnd the unconfined aquifer . The Nandu liver provides water sourcefor the channels by which water is traunsported into the lakcn a a lemporary storage . The channels watermay also parially serve as waler sources for agriculurl and industrial puposes . The lakes act as a cenlralcontrol for redistribution of the waler to agricultural, industrial and cxmmercial purposeg in the valley . Thesorored waler may be injected into the aquifer four long term storage and recovery. It has nol been consideredto injet walter into the confined aquifers due to safely consideralion.FunctiosSourceTransportRecovery--------........↓UaitsRiverChannelsLakes ix-) AquiferObjoctsWatershedprotection and landscape enhancementig.s Scheor of WPLE bhy uiliatiouo of river walerUtilization of river water to WPLE presents an integral technology as well as a dynamic prorcess. Fromthe river to the aquifer , surface water translates into gnoundwalter, which involves physical ，chemical andbiological purification processes. On the exlended flow paths, it may be a natural process for the channelsto lransmit waler to Landscape and also to infiltrate water into the upper unsaluralcd aquifer. Both lakes andchannels provide water for wetland， woodland and grassplot based on ecological conservation anddevelupment. Rased on the units and their functions, objeets of the scheme are to proteet watershed, toenhance landscape, and then to improve ecolongical environment .2 Discussions2.1 Development of WPLEIn 2000, one channel was construcled to store and transmil water on its utility. A dam was built,separaling the channel from the river. In the sunmer of 2001, surplus waler in the river was transportedinto the channel. A single well was independently aplied to cycle Lsting as well as to demine initialwater chemistry and storage capabilities of the aquifer. Dala， recorded eletronically at the extensometerand the piezometers, are being collected periodically, enlered into a database, and checked. Water lablesare measured peidically in wells. lnjetion 0low rates are monitored etrorically. Al present, it isdificult to analyze the iregular data and further detemine the related panumelers due to an unstable shor(-term operation on the single well. Work continues on the development and optimization of a two-dimensional groundwater model. An automatie control system for regulating the waler transmission processesis being designed locally.Furhemore, long term pumping recorls and extended monitoring uctivities are necessary in order to .fully charaterive aquifer systems in the area. Da clletion on the number of permited aquifer storgeand recovery facilities is proposed . More geological dala may be collected to further evaluate the possibilityof the WPLE scheme. At present, a technical board, organized by RCEES and the local govemment, isexamining the science of this process and determine what types of tests are needed and safe in the WPLE中国煤化工MYHCNMHGNo.4w atershed protertion and landscape enhancement by utilization of river walter491prjct。2.2 w atershed protectionImprovermen! of waler use efciencyg is an essential function of the WPLE syslem. First ，the syslem isexpected to meet consumptive demands and t0 reduce the pressure: on natural groundwater resoures.Annual water supply of Qionghan was 2.3 bilion m' in 2000, in which about 243 million m' was exploitedfrom groundwater. I1 was estimated that annual water demand from groundwater in 2005 would reach 300million m'. The system has the potential to store up 15 lo 30 million m' of water into the unconfinedaquifer. which largely alleviale the pressure of goundwater supply and satisfy the demand of the valley .Second. the syslem may also inprove water quality lesides enhancernent of waler supply capacity.The river waler can be purified physically ，chermically and biolgially. Improvements of water qualityilly lake place by slf-purifying mechanism going with the transmitting prresses. Natural treatmentsprimarily happen duing surface water infiltrating into the soil.'Thind, it is pssible that both lood risk and drought risk may be relieved. During the foodingseasons, channels may Bcatter surplus waler into the lakes and the aquifer so that waler is redistributed onthe ground and underground . Water producced from rainslom could calch more dispersed and stationedspace ralher than the limited walercure of the Nandu River. Consequently. the WPLE syslem washesaway stormwater, preventing it from replenishing the valley . During droughl seasons, on the other hand,the stored surface water may ltend to lhe urgent consumption. and goundwater may be pumped andrecovered for the same expendiure. The WPLE system, as an emergeney storage, also prevents groundsubsidence and saline intrusion .Protecting the walershed is the highest prionity in sustainable waler managenent. Often rferred to aslandform engineering. is primary gua! is to mamipulate and enhance the nalural flow onf waler to improve thesite' s ability to catch, hold, and absorb water. The vlly' B lopography can be used to guide walerthrough the construeted channels and lakes , which ate efecive methods of clleting water tn slorage areasas well as dstributing the watler back to the site. Moreover, the WPLE sytem could be viewed as astomwaler relention syslcm that pnvides a mre environmental and ashetie alermative to conventionaldrainage system . Relention system stores runof waler to be reased slow!y and/or absorbed into theground, and prorides lood protection. In addition, groundwaler sourves are the cleanest and most energy-eficient soure . The WPLE scheme can improve waler use eficieney and provide sffcicnt groundwaler forthe valley.2.3 Landscape enhancementI is plainly evident from all the previous pinciles and guidelines that site design und landrapingare inerenly linked wih walcr. Suficiont waler spply, terefr, has an enomous ipession onlandsuape. The WPLE scheme involves both walersbed prlection and landscape enhancement. It is a maindiference from ASR that the WPLE sylem emphasizes eological improvements. The channels may befavorable l" rlistribution and ruilty of water resoures duing the Inusmiting proessese.s Channels andlakes al first represent themseves as landscape upearanre. 'They alo enable moisure tn not only spredinto air, but alko penetrnte more widely int sil and further culivate plunts thal enrich the landseape.Consequenuly, channels flow as well as lakes may be more tuhully fiting for municipal green gcenes.The WPLE syslem may improve the ecological enirnment of the vlly. Since groundwater levels in中国煤化工MYHCNMHG92ZU0Hutetol.Val. 15depleled aquifers are rsiored and groundwater discharge is mainained. udequate waler could be loxaled1o prote waer dependent cologe systems. A kind of phsically beauiful and fnelinally vivid landscapemay exent is sythetical function on the diversity of landscape and the enjoyment of inabitats. The key ofthe WPLE scheme is the ecological integration. It is aimed al improving is stnuctural coupling. metabolismprocess and funetional susainabilily through culivating an eclogially virid landscape，ltall functioningproduction and syteneatically responsible culure( Wang，199). I is also significant to protect biologicaldiversity and futher lo provide for equity within arnd belween generations .2.4 Arguments of the WPLE schemeEnvironmental impacts from water sourcse developments may arise from the impact of the proposeddevelpment itself on the environment( Xiao, 2000) . Though il has been planned to constnudt the WPLEsystem in the valley, opponents argue that many important questions remain unanswered in trmm of thefeasibility of the WPLE scheme . The counteriews involved with the fart that:Water in the channels and the lakes may be likely plluted by the developed industy andagriculture in the valley, which is seriously harmnful lo human health;. Construcled channels may change the local land pattem, which may damage the inerent ecologicalsystem;Recovery mechanisms are not clear, thus it is not absolutely，physically available in the fuure . Thestored waler have migrated downgradient from potential users;●Compatibility of the injected water with the aquifer water, recovery eficiency, and the efets of therecovered waler on the environment are unknown ;●It is not clear, even cannot predicted, that the complicaled interactions from the WPLE systemmight be surely beneficial to its development of the valley .There are sill many concems related to the WPLE scheme . However ，the scheme provides a chanceofa backup water source for walershed prolection and landscape enhancement. In onler to extend theapplications of the WPLE system， feasibility of the WPIE scheme will be demonstrated by moreexperiments and tests, 8 well明observations in the long run .3 ConclusionsUilizaion of river water to watershed protection and landscape enhancement may beneft lto thedevelopment of Qiongshan City, which provides a sounds framework for future planning, investigations,and research and development of water sources to meet the vlley ’5 increasing demands. The provision ofadequate water to protect ecological systems dependent on waler resources will be a fundamnental concem inthe scherme. The Bystem may not only alleviale the pressure of groundwater supply but handle with theproblems of groundwater declines and salwaler intrusion in the watershed 明well. Channels and lakesrepresent themselves as landscape appearances, perfectly ftting for municipal green scenes. A kind ofpbysically beautiful and functionally vivid landscape may exert its synthetical funetions on the diversity oflandscape and the enjoyment of inhabitants .References :DabbaghT A.2001. The mangement of deslinated water[J]. Desalination., 135(1- -3); 7- -23.DillonP」, Parelic P, 1998. Envionnental guideline for aquifer stornge and recovery: Australia experience[ C].3rd int ymp arifcial中国煤化工MYHCNMHGNo.4W atershed protection and landscape enhancement by uriliation of river water93rechargc, Ameterdam. Sept 1998.IDoddsJ F.2000. Small sealr aquifer storngr nnd reoery- A ease study from England and implications for wider developmen[ ci.30thIAH cungrets on groundwater: Past arhievements and future chailenges .26 November-- 1 December 2000. South Africa: Capr Town .Easthodl JC, Sanfreld P I. 2001. Key surcess factors in an ASR schemre[ J]. Quarerly Jounal of Eugineering Grology and Hydrogrlogy, 34(4): 399-409.iu w B.1995. 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