International Journal of Advancements in Research & Technology, Volume 3, Issue 12, December ISSN

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1 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - ain waer harvesing; a pahway o achieving sufficiency in waer supply and flood miigaion, Benin Ciy perspecive, Nigeria. Onu Pascal u.,* uan xie,ling Xu Key laboraory of indusrial Ecology and Environmenal Engineering (Minisry of Educaion, china), school of Environmenal science and Technology, Dalian universiy of echnology, ling gong road, Dalian, china Corresponding auhor: Onu Pascal U. address: ukapas@yahoo.com Absrac: ain waer harvesing is recognized as a key player in alleviaing waer problems, and i has proven effecive especially for new projecs when he rain waer harvesing sysems are opimized. This sudy emphasized he dual role of rainwaer harvesing, such as waer supply and flood reducion (using green roof as an eco-friendly harvesing measure for flood conrol). Annual rainwaer harvesing poenial deermined for Benin Ciy was m. oof cachmen area of m and sorage ank size of m were obained as appropriae for he high demand scenario of.m monhly demand. % reliabiliy for his sorage ank size was also obained, while over % flow frequency reducion was obained for he green roof applied as he measure for flood reducion. Green roof Sensiiviy analysis indicaed a less seep roof wih shrub vegeaion ype is preferred for flow frequency reducion in conrolling flooding. A green roof slope of wih shrub vegeaion reduced flow frequency by over % Key words: rain waer harvesing poenial, Benin, WWHM, rainfall, green roofs, flood conrol. Inroducion Waer is scarce goods, his is a globally acknowledged fac, hence he curren paradigm shif on demand managemen as a measure for waer conservaion. Like mos African counries Nigeria is posed wih enormous challenges in meeing he waer requiremen and demands of is eeming populace even hough i is highly endowed wih abundan waer resources. A key resource in abundance in Benin Ciy, Edo sae of Nigeria is waer, rainwaer precisely. This sae records and has high and long amoun of rainfall, consisenly above mm annually and a rainy season spanning over six monhs. Predominan environmenal problems wihin he sae include, poor access o clean adequae public waer supply, flooding and erosion Copyrigh SciesPub.

2 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - which leads o polluion of waer sreams. Sansrom, assered ha i is no longer feasible in a long erm, cos effecive and environmenal friendly manner o increase waer supply by building addiional dams, conveyance sysem, sinking new wells, consrucing desalinaion plans, soluions mus be found a he user end of he pipe i.e. increasing waer use produciviy,reducing conveyance losses, re-using waer and opimizing allocaion. While adequae waer supply remains a big challenge in he counry, incidence of flooding has persised, [] repored ha saes would experience devasaing flooding wih wors scenarios expeced in Kogi, Edo, Dela and Anambra (This day live April ). amous Obedi in his repor (poin blank news.com) highlighed he many incidence of flood experienced in he counry ha has caused serious damages o lives and properies, and mos of which are direc consequence of river overflows due o high rainfall evens. A.E Olajuyigbe, O.O. oowa, E. Durojaye() assessed flood hazards in Nigeria, and also observed similar rends, Boh sudies indicaed high rainfall evens as major cause of floods. Eroksuz and ahman () invesigaed waer saving poenial of rain waer anks in mulisoried residenial buildings for ciies in easern Ausralia, and concluded ha appropriae sized ain waer anks can provide significan waer savings even in dry years. S.I Oni e al () in heir sudy idenified he pracice of WH o be predominan in rural areas and he insufficiency of ank size uilized for harvesing, [] ascerained ha irrespecive of rainfall amoun and duraion, roof area, design and slope are key deerminans of harvesable rain waer, seeper slopes and design wih harvesing possible from all sides of roof harves more waer.imeaze e al () used a daily waer balance model o opimize ank size for large scale roof cachmen in Melbourne Ausralia, [] repored ha W harvesed and sored in he rainy season can supplemen waer demand in dry season, [] showed ha only % of sampled populaion in he norhern Nigeria harves rain waer, [] used a daily waer balance model o design an opimal sorage ank size for souh wes Nigeria, and obained % reliabiliy for a ank size of L and L for low and high demand scenarios respecively for oile flushing and combined oile and laundry use. David J. Sample and Jia Liu() opimized rainwaer harvesing sysems for he dual purpose of waer supply and runoff capure in irginia US, and obained % reliabiliy arge for commercial, office and high densiy residenial cases which also had he lowes runoff uni cos, using ASP model. Chidozie and Nnennaya () assessed WH wih focus on flood miigaion and domesic waer supply in Nigeria. This paper aims o emphasize he relevance of he dual funcion of WH (waer supply for high densiy residenial buildings and flood miigaion), bringing ino perspecive is flood conrol role, and seeks o add o he sparse knowledge exising in his regard. WH in recen imes has gained populariy and is emphasis among he several sraegies for miigaing urban waer crisis has proven effecive especially when i is opimized. WH if well praciced and implemened ino waer supply schemes has he poenial of miigaing waer problem, saving or reducing waer cos as well as conrolling sorm waer or flooding. This is rue in view of he fac ha all waer originae from rainwaer, and more so, because mos cases of flood especially in Nigeria are Copyrigh SciesPub.

3 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - consequen of high rainfall sorm evens. A proper harnessing of he high rainfall poenial of his region would in he long run save mains waer cos for various waer uilizaion processes and purposes, while also reducing pressure on public waer supply sysems. The wesern Washingon hydrology model (WWHM) is used in assessing he impac of green roof as conribuory measures for sorm waer conrol). Oher forms of harvesing ha are ecofriendly include green roofs, permeable pavers, rain gardens, swales, ec., among hese forms, Green roof has an addiional aesheic value advanage and i is relaively cheaper and no common in his par of he world. Mos previous sudies have focused exclusively on waer supply.. Modes of eco-friendly rainwaer harvesing. Two specific modes of eco-friendly rain waer harvesing are idenified, namely acive and passive modes.. acive modes This mode of harvesings is applicable for boh residenial and commercial srucures, and mosly involves mechanical means for capuring, cleaning and soring rain waer. I also reduces load on municipal sewer and sorm waer sysems whils reducing impac on he environmen. The essence is o capure sore and reuse waer and involves he use of anks, ciserns, rain barrels, ec.. passive modes The passive mode serves basically o conrol waer unil hey can naurally be absorbed or infilraed back ino he land. I usually doesn involve he use of mechanical mehods for collecing, cleaning or soring waer. There essence is o capure, sore, slow, infilrae run off while enhancing exising elemens of your environmen. They include permeable pavemen, rain gardens, green roofs, compos and mulch, ec... Permeable paving Permeable paving is a surface layer ha allows rainfall o percolae ino an underlying reservoir base where rainfall eiher infilraes underlying soil or removed by a subsurface drain. I is used on walk ways, paios, or drive ways and no only adds aesheic value bu also improves waer qualiy by slowing runoff, and breaking down polluans, as hey conain void spaces ha allow he sorm waer o flow from pavemen surface o he sub base and ino underlying soil... ain gardens A rain garden is simply a shallow depression using soils and plans o manage runoff from impervious areas like roof, drive way. They are highly aesheic and can hold several inches of rain waer, while allowing sorm waer o slowly seep ino he ground.i can also hold firs flush Copyrigh SciesPub.

4 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - rains which usually conains high level polluans. ain gardens collecs, absorbs, and filer sorm waer runoff... Green roofs This are echniques for capuring rain waer which generally consis of a membrane and drainage layer opped wih a soil like growing medium and hardy plans, in simple erms hey are buildings whose roofs are parially or compleely covered by plans. Besides he aesheic appealing naure of green roofs, he also improve air qualiy while capuring and slowing runoff. esidenial scale version usually has a shallow soil profile and planed wih sedums, and oher low growing succulens. esidenial scale version usually has a shallow soil profile... Swales A swale is like a dich ha is shallow, wih wide condui sloped genly basically o mimic convenional sorm waer conveyance and piping sysem. They are ypically lined wih landscaping maerials like urf grass or naive vegeaion o help reduce peak flow rae of rainfall and are usually sied around parking los, amongs ohers places.. Maerials and Mehod or his case sudy we proceeded firs by deermining he minimum appropriae roof size capable of harvesing enough waer o mee he demand scenario. We considered a range beween (m -m ) which is consisen wih he sudy conduced by [] and ypical of wha is obainable in he sudy area. Monhly rainfall daa for a year period (-) was uilized, obained from Nigeria meeorological saion Benin and a runoff coefficien of for hard roofs in humid ropics. Thereafer simulaions wih various ank sizes in he range of -m where embarked on o make for opimized resuls. And hen reliabiliy curves were obained for he sysem. Opimal values make for economic harvesing which is imperaive especially when considering implemenaion of WH on new projecs. We assumed a persons house hold size based on a sudy survey by [], a l/c/d waer consumpion considering waer use for basic hygiene purpose only. This yielded a oal monhly demand of.m obained by applying equaion, evenually a spread shee was simulaed for he year rainfall daa for various roof and ank sizes, (m ank and roof size shown in able ) assuming zero iniial ank sorage from he monh of January, over flow was allowed as negaive value was no allowed for ank sorage hence volume of waer in ank canno be greaer han ank size, monhs wih zero ank volume i.e. = were regarded as failure monhs. Applying equaions he reliabiliy curves for various roof and ank sizes of he sysem were obained The demand, supply, harvesing poenial and he performance of WHS mahemaical models are generally based on mass balance equaions, he following equaions usually apply: Copyrigh SciesPub.

5 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - D = n N d... () Where D is he oal monhly demand or consumpion, N is he number of house hold (flas), n is he number person per household, and d is average daily waer demand Harvesing poenial = A C r () f Where A is conribuing roof area (m ), C r is coefficien of run-off, and f is rainfall ime series, daily, monhly or annual v = ( v + D ) < v....() r s n eliabiliy = (- failure monhs/ monhs ) x % () Or e = (-n/n) *%..... () C = S_/X...() Where v is presen waer ank volume, v - is waer ank volume remaining from a previous ime sep, D is oal monhly consumpion or demand, is capured or harvesed waer a curren ime, and s is volume or ank capaciy. e is reliabiliy, n = number of failure monhs and N is oal number of simulaed monhs.c is coefficien of variaion, S_ sandard deviaion of monhly or annual rainfall in mm, and X is mean monhly or annual rainfall. We invesigaed furher he performance of green roof as a measure for sorm waer miigaion and conrol using he Wesern Washingon hydrology model (WWHM). WWHM is similar o he EPA SWMM (sorm waer managemen model) which has been widely used for flood miigaion, [].WWHM is simply anoher version developed and used for he Washingon region, wih basically similar modules and characerisics as he SWMM which is applied for single or long erm simulaions of runoff quaniy and qualiy for primary urban areas. I racks he quaniy and qualiy of runoff made wihin each sub-cachmen, flow rae, deph and qualiy of waer in each pipe channel during a simulaion period, which is made of muliple ime seps. WWHM compares predeveloped and pos developed roued runoff saisics wih flow frequency for a year - year sorm evens. I also idenifies waer qualiy, flow rae and volume. The gray river hachery in wesern Washingon has same rainfall daa and paern as he sudy area, and falls under he Wahkiakum Couny hence is choice for use in running he model. A series of rials where conduced using he model for he purpose of obaining a passable design. Copyrigh SciesPub.

6 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - Table I. Model inpus Predeveloped pervious land la pasure A.B acre Miigaed impervious land Lawn acre oof area Pond acre acre Green roof Slope oof lengh Green area Deph of maerial f acre in. egeaion ype Shrubs. esuls, analysis and discussion ecognized key facors for deermining rain waer harvesing poenial o saisfy any demand scenario are rainfall, cachmen area, coefficien of variaion, sorage faciliy/ capaciy and demand level. ainfall considered probably he mos paramoun facor, is however somewha unpredicable as man has lile influence or conrol over is inensiy, duraion or amoun. Cachmen ype, area and sorage faciliy are fundamenal facors ha can be adjused and managed, hence we explore heir maximizaion and deermine reliabiliies of he simulaed sorage ank sizes for his case sudy. The reliabiliy of any rain waer harvesing sysem (WHS) sysem is a measure of he probabiliy of he sysem no failing or he sufficiency o supply he necessary amoun of waer []. I is he fracion of ime in a ypical simulaion period ha a ank hasn run dry. oof areas of m -m all gave negaive values for his demand scenario and clearly indicaes ha he minimum roof area capable of harvesing enough waer o saisfy his demand case is m. The negaive values (on m -m ) indicae deficis in supply, and degree of deficis, able also shows he number of failure monhs during he course of he year. The roof area range beween -m harvesed rain waer inadequae o mee demand as here were a lo of failure monhs due basically o high waer demand of his building. The oal annual demand for his case is m. m roof area annually harves m rain Copyrigh SciesPub.

7 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - waer, m, harves.m, and m harvess.m rain waer respecively. A m roof area, failure monhs is highly reduced as more waer is harvesed, when compared o he -m roof area range. urher sill, wih his roof area, a lo more waer is harvesed, especially in he monhs of July, Sepember, and Ocober, which allows for adequae savings if an appropriae sorage sized faciliy is insalled. This would enable and make for available waer in shorfall monhs i.e. in he dry seasons around November down o ebruary. This is possible due o he low rainfall coefficien of variaion of his region (), which implies a close or uniform disribuion of rainfall. This reduces difference in monhly waer harvesable.i.e. here is minimal shorage in monhly supply hus wih an appropriae sorage ank size, waer in he rainy season especially in July, Sepember, Ocober can be sored and used o augmen for he shorfall monhs. Alhough roof areas above m harves rainwaer which supersede he demand case, proposing heir use would ranslae o increase cos, and unnecessary wase via overflows which may also conribue o floods. Again, idenified roof cachmen areas for high densiy residenial sorey buildings in he counry usually fall wihin he m o m range (A.O Eruola e.al ). Working wih his range, ank sizes beween m o m were simulaed for he years rainfall ime series resuling in a oal of simulaion monhs. rom able, for he m roof area, m, m, m, m, and m ank sizes resuled in, and failure monhs respecively, declining seadily and linearly. The reliabiliy values for his anks sizes correspond o %,.% and % respecively. I is observed ha only a marginal increase in reliabiliy is obained beween he ank size of m and m (%), and.% from m o m, however beyond m sorage ank size reliabiliy remains consan irrespecive of increase in ank size. This is anoher indicaion ha he m roof area is limied in is capaciy o harves adequae waer for his demand scenario, hus any furher increase in sorage capaciy would be insignifican and meaningless and off course cos ineffecive. However wih he m roof cachmen area, failure monhs dropped reasonably o even wih a ank size of m, resuling in a reliabiliy of % an increase of.% for a m lower ank size. There is an increase of.%( beween he m and m roof cachmen area from.% o %) reliabiliy a same m sorage ank size. rom he able i is also eviden ha increasing furher sorage ank size under his roof cachmen, reliabiliy would ye increase as failure monhs would reduce. m sorage ank has he highes reliabiliy of % a failure monhs and m sorage ank has a reliabiliy of % a failure monhs. Worhy of noe also is he fac ha his roof cachmen area, i.e. m affords no only increased harvesing poenial bu also a wider range of sorage size implemenable, for increased demand scenarios. urhermore i is clear from able II and III ha he sorage ank size of m could save reasonable quaniy of waer enough o balance and susain forh coming monhs which are usually he criical monhs of January down o April. The m roof cachmen and m sorage ank was only able o save or conain waer in he ank for % of he simulaed period, while he monhs of ebruary and March all ran dry hroughou he simulaed period. Waer savings in he ank resumed from April a %, o % in May and increasing gradually and Copyrigh SciesPub.

8 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - seadily for he years simulaed period unil Sepember a %, before gradually declining again o % in December. This is he reverse for he m roof cachmen wih he m and m sorage ank sizes. Table II. Summary of waer volume calculaions for a roof area of m and ank size of m a he demand scenario of.m Monhly consumpion M on h J Y e ar M A M *. *.... Copyrigh SciesPub.

9 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - Copyrigh SciesPub. J J A S O N D is rainfall in mm, ( m ), ( m )

10 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - Table III. Summary of reliabiliy values for varied roof and sorage ank sizes Sorage ank m roof area m roof area size(m ) ailure monhs eliabiliy (%) Toal simulaion monhs ailure monhs eliabiliy (%) Table I: harvesing poenial for roof size of m Monhs Monhly harvesable rainwaer(m ) Cumulaive harvesed rainwaer(m ) Monhly waer demand (m ) Cumulaive demand (m ) mean monhly rainfall (m ) Difference beween and (excess /defici) January ebruary March.. -. April May.. -. June July... - Augus.. -. Sepember Ocober..... November.... December Copyrigh SciesPub.

11 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - m roof area m roof area realibiliy (%) ank size (m) ig.reliabily curves for varied roof and ank sizes a he demand of.m ig. Mean monhly ainfall ime series (mm) from (-). green roof and flood conrol Green roofs are echniques for capuring rain waer which generally consis of a membrane and drainage layer opped wih a soil like growing medium and hardy plans. Amongs he numerous benefis obained from is applicaion, is abiliy and relevance in reducing significanly runoff peak of he mos rain fall evens is recognized, his i achieves by delaying he iniial ime of runoff due o waer absorpion in he roof sysem, reducing oal runoff by reaining par of he rainfall, and disribuing he runoff over a long ime period via a relaive slow release of excess waer sored in he pores of he subsrae emporarily, i.e. reducing he frequency of flow. educing frequency flow of rainfall evens especially high inensiy rainfall evens conribues Copyrigh SciesPub.

12 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - significanly o flood reducion. The ables below reflecs he effec of green roof on frequency flow. or his case, m (~ acre) roof area represens % of oal cachmen area usually recommended for green roof applicaion.i is clear from he able ha flow frequency from predeveloped o miigaed scenario for he simulaed years show a seady reducion from he firs years down o he h year having approximaely % and % minimum and maximum reducions respecively, Plus (+ or blue) in he figure represens flow a predeveloped phase and (x or red) flow a miigaed phase. educing he frequency of flow a his rae, doubless slows down sorm waer flow ino drainage sysems, which when capured and direced o a sorage faciliy could serve for oher domesic purpose. I is also clear from he ables of annual peaks, ha here is a gradual and seady frequency flow reducion from he mid down o early, mos of which have a miigaed flow falling below cfs. Abou % of he simulaed years had flow reduced o less han cfs (cubic fee/sec), achieving his degree of reduced flow speed enables conrol over sorm runoff, hence conribuing o flood reducion. Table. Summary of flow frequency reducion for green roof low (cfs) Predeveloped Miigaed % reducion years..% years. % years...% years..% years...% years...%. sensiiviy analysis Green roofs conribue o flood conrol by slowing down or reducing he frequency of sorm runoff. The response of green roof ( acre) under shrubs and ground cover vegeaion ypes, a various slopes (-) are refleced on he following figures below. A slighly improved flow frequency reducion from he predeveloped o he miigaed is observable on he shrub vegeaion ype over he ground cover ype vegeaion, his is however marginal (% on he firs years) while he range for he enire simulaed period is abou (-%). urher sill, i is clear from he figures of a o i ha he seeper he green roof slope, he lesser he reduced frequency flow i.e. he faser he flow hence creaing a vulnerable flooding siuaion, hus implying an inverse Copyrigh SciesPub.

13 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - relaionship. The green roof slope of gives he highes flow frequency reducion of approx. % while he slope of is %.These resuls are consisen wih [] who repored seeper roofs as harvesing more waer. Thus a less seep green roof is preferred, in his case slope for flood conrol. Again, i is also clear ha a gradual and seady increase in frequency flow reducion is observed from he beginning down o he end of he simulaion period for all slope range examined on boh shrub and ground cover vegeaion ypes. Abou -.% on he slope for he ground cover vegeaion, and -% on he shrub vegeaion and slope. rom he figures, is ye clear ha above a slope of he miigaed flow begins o bypass he predeveloped flow, indicaing he commencemen of a possible conribuion o flooding or logging, raher han conrolling i (i.e. miigaed flow approaching or closing up on predeveloped flow. Noe, enire purpose on flow frequency reducion o conrol flooding is for he miigaed peaks o be as far away or lower from predeveloped as possible). Cumulaive Probabiliy Cumulaive Probabiliy.... C C C C C C.. (a)ground cover a slope (b)shrub a slope.. Cumulaive Probabiliy Cumulaive Probabiliy.... C C C C C C.... (c)shrub a slope (d)shrub a slope Copyrigh SciesPub.

14 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - Cumulaive Probabiliy Cumulaive Probabiliy.... C C C C C C.... (e) Shrub a slope (f)shrub a slope Cumulaive Probabiliy Cumulaive Probabiliy.... C C C C C C (g) shrub a slope (h)shrub a slope.... Cumulaive Probabiliy.. C C C.. (i)shrub a slope igures (a-i) green roof response o varied slopes and vegeaion ypes. y-axis is flow frequency in cfs and x-axis is ime in years. Conclusion This sudy examined and emphasized is dual role for waer supply and flood (using green roof) conrol, for Benin Ciy Nigeria as case sudy. Green roof is an eco-friendly mode of harvesing rain waer having an addiional aesheic value and cos advanage over oher ecofriendly Copyrigh SciesPub.

15 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - mehods. A green roof cachmen area and sorage ank size of m and m were deermined respecively as appropriae for he high demand scenario (high buildings).a reliabiliy of % was aained for his sorage ank size, as his ensured less failure monhs of harvesed waer for waer supply. Benin Ciy has a high annual harvesing poenial of m, and green roof wih shrub vegeaion ype could reduce he flow frequency on a acre land basin by over %, which is significan in flood conrol. Sensiiviy analysis indicae a less seep green roof wih shrub vegeaion conribues significanly o flow frequency reducion hence flood reducion. Generally, he pracice of green roofs in Nigeria is rare. This paper herefore would find usefulness for policy makers, urban planners, engineers, and he public waer consumers and also help o add o he body of knowledge exising in his field. Acknowledgemen: The suppor from he naional naural science foundaion of china (NSC-JST ) and naional science and echnology major projec waer polluion conrol and reamen (No.zxo-) is highly appreciaed. eference. [] Adelia, B., S.Joao,.Semira. improving access o waer resources hrough rainwaer harvesing as a miigaion measure: he case of he Brazilian semi-arid region. Miigaion and adapaion sraegies for global change ():- [] Chidozie Charles Nnaji, Nnennaya cordelia Mama preliminary assessmen of rain waer harvesing poenial in Nigeria: focus on flood miigaion and domesic waer supply, waer resources managemen (): - DOI/s--- [] David J. Sample, Jia Liu, opimizing rainwaer harvesing sysems for he dual purpose of waer supply and runoff capure, journal of cleaner producion xxx ()- [] Duru Pa.N, Chibo Chrisian N, flooding in Imo sae Nigeria; he socio-economic implicaions for susainable developmen humaniies and social science leer,();- [] Eruola A.O e.al quaniaive and qualiaive assessmen of rainwaer harvesing for roofop cachmen case sudy of oke-lanoro communiy in Abeokua, souh wes Nigeria, European waer :-, Copyrigh SciesPub.

16 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - [] Erokuz, ahman A. rainwaer anks in muli-uni buildings: a case sudy for Ausralian ciies, resource conservaion and recycling ::- [] amous Obedi amous, devasaing floods in Nigeria [] Ghisi E,Monibeller A, Schmid W () poenial for porable waer savings by using rainwaer, an analysis of over ciies in souhern Brazil, build environ ():- [] Hua Peng in, Zhuo-XiLi, Gong Tao u () he effecs of low impac developmen on urban flooding under differen rainfall characerisics Journal of Environmenal Managemen () - [] Imeaze e.al,, opimizaion of rainwaer ank design for large roofs: case sudy in Melbourne, Ausralia, resource conservaion and recycling a:.- [] Ishiaku H.T,afee Majid.M, oziah Johar, rain waer harvesing an alernaive o safe waer supply in Nigeria rural communiy, waer resources managemen [] Kuczera G() regional impacs of roof waer harvesing supplemenary public waer supply. Paper presened a he rainwaer colloquium in kuala lumpur Malaysia. [] Oni S.I e al. rainwaer harvesing poenial for domesic waer supply in Edo sae. Indusrial journal of managemen and social sciences ol. No.:- [] Monzur Alam imeaz e al. rain waer harvesing poenial for souh wesern Nigeria using daily waer balance model, resources conservaion and recycling () - [] Oi vicor, economic advanage of rain waer harvesing over waer borehole: susainable developmen a he exension sie of federal polyechnic oko,inl.journal of waer resources and environmenal engineering vol.().pp-,may [] Olanike Olowoiya Aladenola, Omoayo B.Adeboye, assessing he poenial of rainwaer harvesing, waer resources managemen ():-, DOI/S-- - [] Olajuyigbe A.E,oowa O.O, Durojaye.E, assessmen of flood hazard in Nigeria, he case of mile,lagos, Medierranean journal of social science vol.() may [] Preksedis Marco Ndomba, rank Joseph Wambura, reliabiliy of rainwaer harvesing sysems in suburbs. A case sudy of changanyikeni in dares salaam, Tanzania Nile basin waer science and engineering journal.ol,issue, [] uslan.h, rainwaer reliabiliy, analyses for large buildings: facory, governmen, commercial complex, universiytecknologi MAA shah Alam, malaysia Copyrigh SciesPub.

17 Inernaional Journal of Advancemens in esearch & Technology, olume, Issue, December - ISSN - [] ahman, M.M and Yusuf,.M.S, rainwaer and he reliabiliy concep. h ASCE specialy concep on probabiliies mechanic and srucural reliabiliy,pp [] Sandsorm, K.: ephemeral rivers in he ropics. Linkoping Universiy, Sweden [] ivan Ezra lekwor e al, evaluaing he poenial of rain waer harvesing as a supplemenary source of waer supply in Kanai(Mali) disric of zangon-kaaf local gov. kaduna Nigeria, global advances research journal of env sci and oxicology, vol.()pp-, June [] Yemi Akinsuji and Tunde Sanni, saes o experience devasaing flooding in Nigeria in, his day live Copyrigh SciesPub.