Advances in Environmental Biology

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1 AENSI Journls Advnces n Envronmentl Bology ISSN EISSN Journl home pge: Approxmton of Monthly Evpotrnsprton Bsed on Rnfll nd Geogrphcl nformton n Frs Provnce Locted n South of Irn Mehrdd Emd, Hmd Rez Fooldmnd, 3 Ebrhm Aftdoust, 4 Amrpouy Srrf Deprtment of Wter Engneerng, Mrvdsht Brnch, Islmc Azd Unversty, Mrvdsht, Irn Deprtment of Wter Engneerng, Mrvdsht Brnch, Islmc Azd Unversty, Mrvdsht, Irn 3 Deprtment of Wter Engneerng, Mrvdsht Brnch, Islmc Azd Unversty, Mrvdsht, Irn 4 Deprtment of Sol Scences, Roudehen Brnch, Islmc Azd Unversty, Roudehen, Irn A R T I C L E I N F O Artcle hstory: Receved 5 June 04 Receved n revsed form 8 July 04 Accepted 4 September 04 Avlble onlne 0 October 04 Keywords: Evpotrnsprton, Geogrphcl Dt, Thornthwte, Penmn- Monteth, Blney-Crddle, Rnfll, Frs Provnce A B S T R A C T Evporton s ccounted s n mportnt regonl phenomenon, especlly n dry nd semrd res. The estmton of evporton mesure s very mportnt from wter sources mngement vew for ts effects on res wter blnce, rdty nd humdty of wether, drought nd even for regon chnge. The purpose of ths study s nvestgtng the role of rnfll fctors nd geogrphcl nformton on temperture s most mportnt fctors on evporton. Frst by nlyzng dt wth multple regresson, the relton between therml prmeters to rnfll, heght from se level nd lttude determned nd resulted mxmum nd mnmum temperture equtons for months of yer, there for Hrgreves modfed equton of study, the new form of Hrgreves for south of Irn, Thornthwte, Blney - Crddle ccordng to Penmn - Monteth equton clbrted for every month of usng wether dt of three synoptc stton n Frs provnce. Obtned dt from ths study shows rnfll nd geogrphcl governed on concerned re, hve effectve role on evporton. 04 AENSI Publsher All rghts reserved. To Cte Ths Artcle: Mehrdd Emd, Hmd Rez Fooldmnd, Ebrhm Aftdoust, Srrf., Approxmton of Monthly Evpotrnsprton Bsed on Rnfll nd Geogrphcl nformton n Frs Provnce Locted n South of Irn. Adv. Envron. Bol., 8(3), , 04 INTRODUCTION Evporton s one of the mn components of hydrology cycle nd ts correct determnton s very mportnt for mny studes such s hydrologcl blnce of wter, wter desgn nd mngement, smultng grculture crops, nd product ssessng for jungle nd pstures ecosystems, [, ]. [], There s complcted relton between regonl phenomenon. One of the most mportnt reltons s relton between evporton to numerous regonl prmeters. For wter evporton, should be exst level s n evporton level more over enough energy. To contnue evporton process should be exsted trnsfer mechnsm, to trnsfer vlble humdty n nerby tmosphere n evportng level to nother pont untl t ext from sturton condton nd evporton s not stopped more over, regonl prmeters mentoned, other fctors re effectve on evporton such s heght nd lttude. About relton between evporton to lttude nd heght s not presented defnte relton, nd mybe t s becuse of complcted relton between them []. A study whch s done n Znjn re, provde reference evporton usng geogrphcl nformton system, numerl model mps of heght nd obtned reference evporton usng ts relton wth heght nd slope of re, [3]. [5] In study usng wether dt relted to seven synoptc sttons n nsde nd seven synoptc stton n outsde of Frs provnce, clbrted Hrgreves equton ccordng to Penmn- Monteth method for every month of yer nd nnully steps n Irn. Results show tht for every month of yer nd nnully step s used dfferent coeffcent nsted of mn coeffcent n Hrgreves equton, so there s possble for estmte monthly ET o usng clbrton coeffcent of Hrgreves equton for dfferent re of Frs provnce for every month of yer. [3] Consderng to effcent temperture degree nsted of verge temperture degree n ths study obtned new method by clbrted Thornthwte equton ccordng to Penmn- Monteth method s stndrd Correspondng Author: Amrpouy Srrf, Deprtment of Sol Scences, Roudehen Brnch, Islmc Azd Unversty, Roudehen, Irn E-ml: mrpooy.srrf@gml.com

2 847 Mehrdd Emd et l, 04 method for estmtng ET o by determnng K coeffcent for every month of yer for seven erology stton n nsde of studed re. Results show n studed re K coeffcent hs mxmum nd mnmum mount n utumn nd wnter. [6], n study by usng clmte dt of fourteen stton n south of Irn compred dfferent knds of Hrgreves equton to estmte monthly ET o by Penmn- Monteth method. Results show mn knd of Hrgreves equton s better thn others n three sttons wth humd clmte nd slow wnd durng the yer. How ever, n seven sttons wth dry nd semrd clmte s new knd of Hrgreves equtons whch s nclude monthly rnfll dt, t hs best condton to estmte ET o whch s mtched wth prevous results, ths equton cn use mnmum nd mxmum mount of wether temperture nd monthly rnfll to estmte monthly ET o usng verge. Purpose : Severl methods hve been presented for estmtng potentl evporton of reference plnt. Mny of these methods need numerous dt of erology but some of these dt re not vlble nd f we suppose they re vlble they hve not dequte precson. Wth consder to ths problem tht Frs provnce fced wth dehydrton problem now. There for dequte plnnng s essentl for rrgton n ths provnce. In numerous studes n Frs provnce evporton estmton s done by temperture dt, but t s provde wth step to forwrd to estmte evporton wthout usng temperture dt n Frs provnce. The mn purpose of ths study s estmtng evporton usng monthly rn full dt nd geogrphcl nformton n Frs provnce. MATERIAL AND METHODS Frs provnce locted n south of Irn nerly. Ths provnce constrned from north to Isfhn from est to Yzd nd Kermn from south to Hormozgn from west to Boushehr nd from west north to Kohkloyeh nd Bouyerhmd provnce. Totl spce of Frs provnce s bout 607 KM/M nd 7.5 percent of totl spce of country. The estmton of populton n provnce ws equl to ccordng to nformton of Irn sttstc center n 009. Ths study s done n Frs provnce boundres, whch nclude 3 synoptc sttons n Abdeh, Lr ctes nd Doroudzn Dm. In tble () presented plce specfctons sttstcl durng the perod n the studed sttons. In fgure (), locton of Frs provnce nd the studed sttons n Irn country s mp s shown. Abdeh stton wth 030 meter heght from se level s hghest nd Lr stton wth 79 heghts from se level s lowest n studed sttons. Fg. : Locton of Frs provnce nd the studed sttons n Irn Country s mp. Tble : The specfctons of the meteorologcl used n the studed regon. Tme perod used Heght from se level Lttude º,' º,' º,4' Longtude 5º,04' 5º,7' 54º,7' Stton nme Abdeh Doroudzn Dm Lr For dong ths study s used mesured dt nd regonl nformton from synoptc sttons of Frs provnce nclude monthly long- term sttstc, mxmum nd mnmum of temperture s n effectve fctor on reference evporton. The reson of usng these prmeters relted to the method of estmtng evporton whch referred to them n followng. Moreover rnfll nd geogrphcl poston of every studed stton nclude lttude nd heght from se level s used for every pont. Then by help of sttstcl nlyss of multple regressons nvestgted correlton of every mentoned temperture prmeters s functon of lttude, heght from se level, whch defned s follow: b H b G b P () Y 3

3 848 Mehrdd Emd et l, 04 Where n ths equton: H: Heght from se level, G: Lttude (degree), P: Rnfll (mm), Y: Every explned regonl prmeters whch nvestgted monthly perods nd seprtely. Regresson coeffcents b, b, b 3 lso determne weght of ndependent vrbles whch llocted to them. Therefore obtned regresson relton for every months of yer tht relted to effectve temperture prmeters (Mx nd Mn Temperture) on evporton to heght of se level, lttude nd stton rnflls nd determned ther precson. By specfyng the sgnfcnt relton between temperture prmeters nd heght of se level, lttude, rnfll n studed stton n Frs provnce provde needed nformton for estmtng reference evporton. Frs usng synoptc erology sttons n Frs provnce provded needed nformton nclude rnfll, lttude nd heght of se level. Then by help of obtned regresson reltons, mesured mxmum nd mnmum of temperture tht wth consder to nformton of every stton nd needed prmeters for estmtng evporton by modfed methods of Hrgreves, the new form of Hrgreves for south of Irn, provded Thornthwte nd Blney - Crddle for every month. The reson for choosng these methods hd been needed to mnmum regonl dt, smplcty nd conformty wth Irn regon. Other ppled equtons llustrted n ths reserch. A: Hrgreves modfed model [0] 0.5 ET ChT m 7.8 Tmx Tmn R () Where ET o s evporton terms ml/m n month (Concerned tme perod) Tm: verge of monthly temperture terns centgrde or estmted by tkng verge from mxmum nd mnmum temperture. T mx : Mxmum temperture terms centgrde, whch s used n ths feld from obtned equtons; T mn : Mnmum temperture terms centgrde whch s used n ths feld from obtned equtons; R: Rdton from outsde of erth terms wter mllmeters whch s extrcted from vlble tbles n ths feld wth consder to lttude of stton nd chnged for every month of yer [, 4]; Ch: Clbrton coeffcent for Abdeh, Doroudzn dm nd Lr sttons whch s obtned n dfferent months by fooldmnd nd hghght (007) [5]. B: New form of Hrgreves modfed model for south of Irn 0. ET Tm 46. Tmx Tmn 0.056P R (3) Whch P s totl monthly rnfll terms mllmeter. C: Thornthwte modfed equton (4) 0Teff ET0 6 I T eff 0.5K3T mx T mn (5). (6) 54 I 0.T m n I 7.70 I.790 I (7) Where T eff s monthly effectve temperture terms centgrde, I : Yerly therml ndctor, T m : Dly verge of r temperture terms centgrde degree, : equton coeffcent, K: equton coeffcent. D: Modfed equton of Blney- Crddle ET 0 8.3b m 0.46b mt eff (8) Whch m s relted coeffcent to dy or nnully percentge of sun rdton n month whch s descrbed n dly form (mens the verge of dy hours n concerned month dvde on totl hours of dy multply on 00 number), [7, 8]. And b re clbrton coeffcents whch re obtned from Abdeh, Doroudzn dm, Lr sttons n dfferent months by Fooldmnd (0) [9]. For nvestgtng the estmton precson of equton result s used verge squre root of totl squre errors (RMSE) s followng fgure. RMSE n X Y m Where X : mesured mounts, Y : estmted mounts nd m: equls to number dt mnmum mount of RMSE s equl to zero nd whtever RMSE mount be lower, concerned equton hs better estmton s result s more dequte. Also to determne whch concerned equton estmte more or less thn mesured mounts, t s used from totl remns coeffcent (CRM) s followng fgure. (9)

4 849 Mehrdd Emd et l, 04 CRM n n X X Y CRM mount equls to one t most, f CRM be postve t mens mesured mount s more thn estmted ones, so model estmted low, nd vce vers f CRM be negtve t mens mesured mount s less thn estmted ones, so t s clled model estmted more. Therefore estmted evporton whch s obtned from Hrgreves modfed methods, new form of Hrgreves for south of Irn, Thornthwte nd Blney - Crddle obtned wth evporton nd rel nformton compred wth two comprng method, CRM, RMSE by penmn- method. In every seson of yer one of the months tht hs bgger correlton coeffcent between others choosed becuse of more effectve summrzton nd utlzton. RESULT AND DISCUTION Tble () shows obtned regresson equtons for estmtng regonl prmeters (mxmum nd mnmum monthly temperture) whch s effectve on evporton n dfferent sesons of yer. These prmeters nclude mnmum nd mxmum of temperture whch s selected for four month of yer (for every seson one month) nd s done relted clcultons. R ndcte strong relton between mxmum nd mnmum prmeters of temperture wth lttude, heght from se level nd rnfll one of the other effectve fctors on evporton n Hrgreves modfed methods, new form of Hrgreves for south of Irn, Thornthwte nd Blney - Crddle s temperture whch s used both n verge nd n mnmum nd mxmum temperture dfference n then. In tbles 3 to 5 presented verge squre root mounts nd (RMSE) totl remns coeffcent (CRM) for Hrgreves modfed equtons, new form of Hrgreves equton for south of Irn, Thornthwte nd Blney - Crddle n ll month of yer for ll sttons. Tble : Obtned regresson equtons for estmtng effectve therml prmeters on evporton n dfferent sesons of yer. R Regresson equtons Temperture Seson T mx = (-0.09 H) + ( G) (0.80 P) Mxmum Sprng 0.98 T mn = ( H) + (49.83 G) (0.64 P) Mnmum T mx = ( H) + ( G) (0.94 P) Mxmum Summer T mn = ( H) + (65.7 G) (0.36 P) Mnmum T mx = (-0.00 H) + (78.7 G) (0.05 P) Mxmum Autumn 0.94 T mn= ( H) + (3.379 G) ( P) Mnmum T mx = ( H) + ( G) (0.096 P) Mxmum Wnter 0.79 T mn = ( H) + (.403 G) ( P) Mnmum *G, H, P Respectvely ndctes heght from se level (Meter) lttude (Degree) rnfll (Mllmeter) In order locton comprson nd justfy obtned results ndfferent plce of Frs provnce, consderng to envronmentl condton nd physogrphy whch s governed on provnce s necessry. Wth these nterprettons cn found t tht equton consstency of evporton n dfferent sesons of yer nd objectve evdence ndcte rel evporton n dfferent plce of Frs provnce. One of ts resons cn be relted to consder physogrphcl fctor such s rnfll, lttude nd heght of se level n ET o estmton. Ths fctor re effectve controllng on evporton n ny plce whch s used drectly or ndrectly s well n Hrgreves modfed methods, new form of Hrgreves for south of Irn, Thornthwte nd Blney - Crddle. Tble 3: Averge squre root mounts (RMSE) nd totl remns coeffcent (CRM) estmted n Abdeh stton. Blney - Crddle Thornthwte Hrgreves for south of Irn Hrgreves CRM RMSE CRM RMSE CRM RMSE CRM RMSE Tble 4: Averge squre root mounts (RMSE) nd totl remns coeffcent (CRM) estmted n Doroudzn Dm stton. Blney - Crddle Thornthwte Hrgreves for south of Irn Hrgreves CRM RMSE CRM RMSE CRM RMSE CRM RMSE (0) Tble 5: Averge squre root mounts (RMSE) nd totl remns coeffcent (CRM) estmted n Lr stton. Blney - Crddle Thornthwte Hrgreves for south of Irn CRM RMSE CRM RMSE CRM RMSE Hrgreves CRM RMSE Abdeh stton: Mnmum verge mount (RMSE) of ll month of yer relted to modfed equton of Blney - Crddle s 0.4 nd CRM mount s negtve modfed Hrgreves equton n four month (33 percent of yer) hs mnmum mount of RMSE n monthly scle nd new form of modfed Hrgreves equton for south of Irn n four month (33 percent of yer) hs mnmum mount of RMSE, modfed

5 850 Mehrdd Emd et l, 04 Thornthwte equton n two month (7 percent of yer) hs mnmum mount of RMSE nd modfed Blney - Crddle equton n two month (7 percent of yer) hs mnmum mount of RMSE lso modfed Hrgreves equtons, modfed Thornthwte nd modfed Blney - Crddle n four month hve postve CRM nd n eght month hve negtve CRM, so these equton n totl mount of evporton estmted more thn Penmn - Monteth equton. New form of modfed Hrgreves equton for south of Irn n two month hs postve CRM nd n ten month hs negtve CRM, so these equtons n totl mount of evporton estmted more thn Penmn - Monteth equton. Doroudzn Dm stton: mnmum verge mount of yer (RMSE) relted to modfed Hrgreves equton s 0.47 mounts nd negtve CRM, whch nnully rnge of percentge of mnmum mount RMSE of every month for every equton nd postve mount of CRM of every equton n every month s s follow: In monthly scle, modfed Hrgreves equton n three month (5 percent of yer) hs mnmum mount of RMSE, new form of modfed Hrgreves equton for south of Irn n fve month (4 percent of yer) hs mnmum mount of RMSE, modfed Thornthwte equton n one month (8 percent of yer) hs mnmum mount of RMSE nd Blney - Crddle equton n three month (5percent of yer) hs mnmum mount of RMSE. Also modfed Hrgreves equton nd modfed Blney - Crddle n four month hs postve CRM nd n eght month hs negtve CRM. So these equtons n totl mount of evporton estmted more thn Penmn - Monteth equton. New form of modfed Hrgreves equton for south of Irn n two month hs postve CRM nd n ten month hs negtve CRM. So these equtons n totl mount of evporton estmted more thn Penmn - Monteth equton. Lr stton: Mnmum verge mount of yer (RMSE) relted to new form of modfed Hrgreves equton for south of Irn s 0.6 mount nd negtve CRM, tht nnully rnge of percentge of mnmum mount RNSE of every month for every equton nd postve mount of CRM of every equton nd n every month s s follow. In monthly scles modfed Hrgreves equton n no month (zero percent of yer mnmum mount of RMSE, new form of modfed Hrgreves equton for south of Irn n eght month (67 percent of yer) hs mnmum mount of RMSE, modfed Thornthwte equton n one month (8 percent of yer) hs mnmum mount of RMSE nd Blney - Crddle equton n three month (5 percent of yer) hs mnmum mount of RMSE. Also modfed Hrgreves equton nd new form of modfed Hrgreves equton for south of Irn nd modfed Blney - Crddle n sx month hs postve CRM nd n other sx month hs negtve CRM. So ths equton n totl mount of evporton estmted less thn Penmn - Monteth equton. Concluson: Generl concluson of ths study shows tht the results of ths study refer to consstency of controllng regonl fctors for evporton nd physogrphcl fctors. Wth consder to ths problem tht modfed Hrgreves methods for south of Irn, Thornthwte nd Blney - Crddle nclude combnton of regonl fctors (Mnmum nd mxmum of envronment temperture) physogrphcl fctors (heght from se level, Lttude, rnfll) n estmtng evporton, therefore t s very useful n estmtng ET o. Consderng to hgh correlton between temperture (mnmum nd mxmum) wth heght from se level, lttude nd rnfll fctors (In dfferent month of yer R n tolerted between 0.79 to ) suggested tht usng from used method f we re fced wth lck or shortge condton of mesurng stton nd regsterng regonl prmeters. Fndng locl reltons (wth hgh correlton) between constnt nd vrble prmeters such s heght from se level, lttude, rnfll nd mportnt regonl fctors ( cover mny shortges of dt n these condtons. It s needed to sy for wde re fndng dequte relton between regonl prmeters, rnfll, lttude nd heght from se level s possble rrely. Accordng to obtned results from CRM nd RMSE comprson n stton form nd monthly suggested tht use modfed equton of Blney - Crddle n Abdeh stton, modfed Hrgreves equton for Doroudzn dm stton nd new form of modfed Hrgreves model for south of Irn. REFERENCES [] Allen, R.G., L.S. Perer, D. Res nd M. Smth, 998. Crop Evpotrnsprton Gudelnes for computng crop wter requrements, FAO Irrgton nd Drnge Pper 56, FAO, ISBN [] Alzdeh, A.A., 003. Wter, sol nd plnt journl, Fourth edton. [3] Ahmd, S.H. nd H.R. Fooldmnd, 008. Sptlly dstrbuted monthly reference evpotrnsprton derved from the clbrton of Thornthwte equton: cse study, South of Irn. Irrgton Scences, 6: [4] Byte Movhed, F., 006. Estmton of evpotrnsprton usng GIS n Znjnrud ctchment. Ntonl Conference of Mngement of Irrgton nd Drnge, 7. [5] Fooldmnd, H.R. nd M. Hghght, 007. Sptl nd temporl clbrton of Hrgreves equton for clcultng monthly ET o bsed on Penmn - Monteth method. Irrg. Drn, 56:

6 85 Mehrdd Emd et l, 04 [6] Fooldmnd, H.R., H. Zndlk nd M.H. Rvnn, 008. Comprson of dfferent types of Hrgreves equton for estmtng monthly evpotrnsprton n the south of Irn. Arch. Agron. Sol Sc. 54: [7] Fooldmnd, H.R. nd S.H. Ahmd, 009. Monthly sptl clbrton of Blney - Crddle equton for clcultng monthly ET o n south of Irn. Irrg. Drn, 58: [8] Fooldmnd, H.R., R. Torb nd A. Amndn, 009. Sttstc pplcton n sol nd wter. Mrvdsht, Islmc Azd Unvercty pubctons, Frst edton, [9] Fooldmnd, H.R., 0. A clbrton of Blney - Crddle equton for clcultng monthly ET o n south of Irn. Irrg. Drn, 58: [0] Fooldmnd, H.R., 0. Evluton of Blney - crddle equtons for estmtng evpotrnsprton n south of Irn. Agrculturl Reserch, 6(3): [] French, M.N., W.F. Kryewsk nd R.R. Cuykendll., 99. Rnfll forecstng n spce nd tme usng neurl networks, J. Hydrol, 37: -37. [] Poormohmmd, S., H. Mleknejd nd M.H. Rhmyn, 00. Investgtng the role of physogrphcl fctors on effectve therml prmeters on evporton (cse study: Yzd Provnce) Khosh boom reserch nd scentfc journl, (): 9-9.