Evaluation of seasonal patterns of water quality in the Zambezi River Basin, using Zambezi River Authority (ZRA) data of 2011

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1 Artcle 31 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data 2011 Kabunga NAHIYUNDE Graduate Student Graduate School Internatonal Development ooperaton, Hroshma Unversty, Kagamyama, Hgashhroshma, Hroshma , Japan bungaman@lve.jp hrpn NAMAKANDO Water Resource Engneer Zambez Rver Authorty, Karba House, 32 ha ha ha Road, P.O. Box Lusaka, Zamba. namakoc@yahoo.com Abstract The study reports seasonal varaton qualty, along Lake Karba, Zambez Rver ts trbutares n To evaluate polluton qualty, followng ten parameters were analysed: temperature, ph, Electroconductvty (E, Dsolved Oxygen (DO, Total Dsolved Solds (TDS, Total Suspended Solds (TSS, alkalnty as ao 3, turbdty, Total Phosphorus (TP, ammona-ntrogen (NH 3 -N. The study found that qualty along Zambez Rver ts trbutares was most polluted n Late Ran Season (LRS, that, January to March, wth a Water Polluton Index (WPI The qualty was least polluted durng Late Dry Season (July to September wth a WPI It also made clear that extng Lake Karba generally free any sgnfcant polluton across all seasons. Key words: Zambez Rver, Lake Karba, seasonal varaton qualty, polluton ndex 1. Introducton The Zambez fourth-longest rver n Afrca, largest flowng nto Indan Ocean. The area ts basn 1,570,000 square klometres. The 2,574 klometres-long rver has ts source n Zamba flows through Angola, along border Namba, Botswana, Zamba, Zmbabwe, to Mozambque, t emptes nto Indan Ocean (Zambez Rver, Dangerous levels bactera have been found n backs Zambez Rver, fh have been, recently, found sufferng an unknown apparently fatal dease (Zambez rver polluton warnng, 2007; Magadza, Polluton surface ground resources atmosphere have become major envronmental problems Zambez Rver Basn. The ncrease n polluton dcharges largely attrbuted to urbanaton, ncreased ndustral agrcultural actvtes, mnng sol eroson. The urban centres produce sewage effluent, ndustres emt greenhouse gases or ndustral wastes, agrcultural sector uses fertlers or pestcdes whch all contrbute to polluton surface ground resources. In Zambez Rver Basn, gold pannng prevalent resultng n sol eroson resources polluton. Mne wastes, f not dposed managed properly, result n heavy metal polluton (Tumbare, There an act whch manly deals wth management Zambez Rver economc, ndustral socal development wth partcular emphas on usage energy purposes governed an nter-state Act (wth Zmbabwe called Zambez Rver Authorty Act hapter 467 (Nwasco, n.d.. Much basn s s are used to generate hydroelectrc power (HEP prmarly two largest human-made lakes, Karba, 5,250 km 2 holdng 156 km 3 ; abora Basa, 2,739 km 2 holdng 56 km 3 (Mpe & Tawa, Wth rver flowng through fve countres, re a lkelhood nterstate conflct Journal Internatonal Development ooperaton, Vol.19, No.3, 2013, pp

2 32 Kabunga NAHIYUNDE hrpn NAMAKANDO resultng mmanagement rver. Although polluton resources has not yet created regonal conflcts, lkelhood such conflct exts n future. The sue, however, has potental becomng a regonal problem, partcularly regardng polluton heavy metals, as evdenced extence dchlorodphenyltrchloroethane (DDT heavy metals n Lake Karba (bd. The rparan countres, ree, need to cooperate n mulatng montorng leglaton to prevent such contamnaton. Furrmore, Mpe Tawa (1998 suggest that leglaton should nclude establhment lmts on effluent as well as puntve measures fenders. The world over, four prncple ores or doctrnes have been mantaned rparan states regardng rghts on nternatonal s. 1 The ory absolute terrtoral soveregnty mantans that a course states enjoys exclusve authorty over s an nternatonal course wthn ts terrtory. 2 Accordng to ory absolute terrtory ntegrty, a course state has a rght to natural flow nto ts terrtory. 3 The ory lmted terrtory soveregnty a state over ts terrtory lmted oblgaton to use terrtory n a way that does not cause sgnfcant harm to or natons. And lastly 4 accordng to ory communty nterests, physcal unty course creates a communty nterests n (Dombrowsky, It not very apparent as to whch ory gudes management Zambez Rver amongst rparan countres. However, ory communty nterests seems to be at play as evdenced recent reference to shared courses n protocol on Shared Watercourse Systems n Sourn Afrcan Development ommunty (SADD 1995 (bd. It has been stated that upper part Zambez Rver thnly populated pastoralt farmers fhermen that wldlfe sparse; t remarkably free polluton (Zamba Natonal Tourt Board, n.d.. However, wth comng new mnes near source rver n Kabompo, re a possblty new sources polluton. The polluton n Kabompo Rver, whch feeds nto Zambez Rver, would affect hundreds thouss people furr downstream. It purpose th study to provde current nmaton (n 2011 about seasonal varatons qualty along Zambez Rver. Th study ree ntended to analyse dsemnate hydrologcal envronmental data envronmental condtons Zambez Rver, ts trbutares Lake Karba. 2. Method Water qualty data Lake Karba/Zambez Rver ts trbutares were obtaned Zambez Rver Authorty (ZRA- Lusaka. The samples were collected January to December n The samples were collected 17 locatons namely; Vctora Falls, Karba at harara area, Lake Karba at Andora Harbour, Lake Karba Dam-Wall Downstream, Lake Karba Dam-Wall Upstream, Lake Karba at Nyaozda, Lake Karba at Gatche Gatche, Lake Karba at Sanyat Mouth, Lake Karba at Sanyat Mouth-Furr, Lake Karba at B51, Lake Karba at Manchnch Bay, Lake Karba at Ulkrs, Lake Karba at rocodle Farm, Deka Rver, Kalomo Rver, Quay Kanznze Rvers. Fgure 1 shows study area samplng ponts. Dverse methods were used to determne dfferent parameters (actual detals about sample hlng nstruments used can be obtaned ZRA fces n Lusaka. Ten parameters: temperature, ph, electroconductvty (E, dsolved oxygen (DO, total suspended solds (TSS, total dsolved solds (TDS, alkalnty as ao 3, turbdty, total phosphorus (TP NH 3 -N were consdered n th study. The data analys compared varaton qualty over a perod one year. The seasons were categored as follows: October to December-Early Ran Season (ERS; January to March-Late Ran Season (LRS; Aprl to June-Early Dry Season (ERS; July to September-Late Dry Season (LDS. A one-way analys varance (ANOVA was used to analyse season varaton n qualty across four seasons Post-hoc comparons usng Tukey s Honestly Sgnfcant Dfference (HSD were permed to show whch season(s was sgnfcantly dfferent ors. Furrmore, Pearson correlaton (r was permed on parameters to show whch parameters correlated over a perod one year. Attempt to group qualty parameters was done prncpal factor analys (PA. All analyses were done SPSS stattcal package verson 17.0 (SPSS Inc., hcago, III. The qualty map was generated ArcGIS 9.3. Part analys nvolved use Nemerow Sumtomo Water Polluton Index (WPI. In th study, 17 dfferent locales along Lake Karba, Zambez Rver ts trbutares, 10 dfferent parameters were analysed. The WPI was used to evaluate pattern polluton season locaton. The functon th method was to stardze concentraton ranges parameters such that dfferent concentraton ranges each parameter were rescaled equaton to produce a relatve that les wthn a comparable range (Nemerow Sumtomo, The WPI a functon relatve s (, represents concentraton parameter L represents permsble s (PV parameter defned a regulaton. WPI = a functon ( s (1 = f ( 1 1, 2 2, 3 3 n n

3 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data Fgure 1. Samplng stes along Zambez Rver, Lake Karba ts trbutares! Source: Map data 2012 Google (!! /! /!!"!!!"#!(!! /!!"!!"# (!!!"!"#!(!! /!!"!"#!!(!! /!!"!!"# (!! /!!"!!"#!!"# = =!!!!! (2!"# (2!!!!"# =!!!! (2! (= 3,measured n 2, measured concentraton parameter parameter,, L Ljj PV PV parameter parameter determned determned 1, concentraton ( are maxmum average s use j, use j, ( Then, WPI a specfc use j (WPI furr expressed followng equaton: measured concentraton parameter, L PV parameter determned j max j ave j j j use j, (jmax (jave are maxmum average s j use j, respectvely ( are maxmum average s use j, use j, (!! j max j ave j respectvely (!! /!!"!"#!(!! /!!"!"#!"#!!!! (2 WPI== (2 respectvely parameters whch whch hgher hgher presents presents aa hgher hgher level level pollutons, pollutons, such such as as turbdty turbdty parameters! obtaned feld measurements can be drectly ammona-ntrogen, s measured concentraton parameter, L PV parameter determned use j, ( jmax Where parameters whch hgher presents a hgher level pollutons, such as turbdty j j measurements can be drectly ammona-ntrogen, s parameter, Lj PVfeld parameter determned measured concentraton j obtaned calculated usng above equaton, wth a prerequte. The prerequte that f obtaned feld measurements can be drectly ammona-ntrogen, s ( are maxmum average s use j, respectvely. j calculated usng above equaton, wth a prerequte. The prerequte that f j,j ave j average s j use j, jj use (jmax (jave are maxmum must be stardzed applyng obtaned measurement greater greater than 1.0, n a calculated usng above equaton, wth a prerequte. The prerequte that f j j must be stardzed applyng obtaned measurement than 1.0, n parameters whch hgher represents hgher level polluton, such as turbdty ammona-ntrogen, respectvely j followng equaton: obtaned measurement greater than 1.0, n j must be stardzed applyng followng equaton: s parameters j obtaned measurements can be drectlylevel calculated usng such aboveasequaton, whch feld hgher presents a hgher pollutons, turbdtywth a prerequte. followng equaton: = x log ( (3 j must be ( j new = /j ave The prerequte that f obtaned measurement greater than 1.0, n x log ( (3 ( j obtaned feld measurements can be drectly ammona-ntrogen, s j new Lj ave j = x log ( (3 ( jnewusng /equaton, Ljave stardzed applyng followng equaton: calculated above wth a prerequte. The prerequte that f xx aa constant constant (as (as aa stard stard aa relatve relatve comparon, comparon, arbtrary arbtrary employed employed j xx must be stardzed applyng obtaned measurement greater than 1.0, n n applcaton ndex extng polluton j comparon, 5.0 arbtrary employed ( jn xnew x log ( (as = a applcaton constant a (3 stard polluton a relatve x jndex ave extng followng equaton: a applcaton alower ndex extng polluton Where constant (as stard a relatve comparon, 5.0 arbtrary xoxygen n applcaton nxparameters parameters represents hgher level polluton, polluton, suchemployed as dsolved dsolved lower represents aa hgher level such as oxygen ndex extng polluton. = x log ( / (3 ((DO, j new Lj jj s s obtaned feld feld measurements must be stardzed as usng followng followng (DO, parameters avelower represents a hgher must level be stardzed polluton, such dsolved oxygen obtaned measurements usng level polluton, as dsolved oxygen (DO, equaton: obtaned represents feld measurements must be stardzed usng followng (DO, j s equaton: x parameters aconstant (aslower a stard aahgher relatve comparon, 5.0such arbtrary employed x j s equaton: obtaned!!" feld must be stardzed usng followng equaton:!!!measurements n applcaton!!! ndex extng polluton /!!"# =!!" (4 (!! /!!" (4 (!!!!"!!!!"!"# =!!"!!!"!!!!"!" /! = (4 (! parameters lower represents a hgher level polluton, such as dsolved oxygen (4!!"!"#!!"!!!" Where saturaton any parameter at room temperature m s obtaned feld measurements must be stardzed usng followng (DO, Where m j saturaton any parameter at room temperature saturaton any parameter at room temperature. Where m Where equaton: m saturaton any parameter at room temperature parameters parameters whch whch PV (L (Ljj defned defned aa range range numbers, numbers, such such as as ph, ph, PV PV parameters PVPV(L a rangewhch numbers, such as ph, PV ranges 6 to 9, a j defned!to!!whch requred, calculated followng equaton: ranges 6 9, a stardzed!"!whch parameters PV (L defned a range numbers, such as ph, PV j j =6 to 9, a stardzed j requred, whch calculated followng equaton: (4 (!ranges! /!!"!"# stardzed requred, whch calculated followng equaton:!!! j!" 9,!" ranges 6 to If average average L a stardzed j requred, whch calculated followng equaton: If If average LL jjj Where any parameter at room temperature m saturaton If average Lj!!!(!!"!"# (! /!!"!"# = =!!!(!!"!"# (5!! /! (! (5 PV (5 (!!"!!!"#!"!"#!(!!(! parameters whch PV (Lj defned a range numbers, such as ph,!"!"#!"!"# (!! /!!"!"# = (!!"!"#!(!!"!"# (5 ranges 6 to 9, j requred, whch calculated followng equaton: (! a stardzed!(! > average averagell L jjj!"!"#!"!"# If average If >> If If >average averageljlj!!!(!!"!"# (! /!!"!"# = =!!!(!!"!"# (6 (6 (! (6 (!!!"!(!!! /!!"!"#!!"#!"#!"!"#!!(!!"!(!!"#!!(!!" (!!"!"#!"!"# (!(! /! = (5 /! = (6!!!"!"!"#!"# (!!(! (!!"#!(!!"#respectvely, maxmum mnmum s L (e.g., ph: mn = 6, max = 9. The (L!"!"!"#!"!"!"# (L are, Where (L jmn jmax j j ave average L (e.g., ph: (6 + 9/2 = 7.5. L If Where > average j (L jjj max are, respectvely, respectvely, maxmum maxmum mnmum mnmum s s L Ljj (e.g., (e.g., ph: ph: mn mn = = 6, 6, (L mn max are, (L Where (Ljjmn Based on chemcal loadngs relatve to r +results!!(! average L (e.g.,pvs, ph: (6 9/2 = 7.5. samples are classfed nto 4 categores. The max = 9. The (L!!"!"# = (Ljmax are, respectvely, maxmum =mnmum s Lj (e.g., ph:(6 mn = 6, (LjThe ave mn average Ljj (e.g., ph: (6 + 9/ max 9. (Ljjave (!Where! /!!"=!"# (!(L!(!!"!"#!" j!"# L max = 9. The ave average j (e.g., ph: (6 + 9/2 = 7.5. Based on on chemcal chemcal loadngs loadngs relatve relatve to to r r PVs, PVs, results results samples samples are are classfed classfed nto nto 44 Based categores. The classfcaton classfcaton used n ntoth th study reflects sutablty eventual human Based on chemcal loadngs relatve rstudy PVs,reflects results samples are eventual classfedhuman nto 4 categores. The used sutablty consumpton (after low cost respectvely, treatment e.g. fltraton, bolng or chlornaton. chlornaton. The PVs effluent categores. classfcaton used n th study reflects mnmum sutablty eventual consumpton (after cost treatment e.g. fltraton, bolng or The (Ljlow max are, maxmum s Lj PVs (e.g., ph:effluent mnhuman = 6, Where (LjmnThe drnkng were used ntreatment th study. study. example PVs PVs used E, E, The alkalnty as effluent ao33 consumpton (after low cost e.g. fltraton, bolng or chlornaton. PVs drnkng were used n th example used alkalnty as ao average L (e.g., ph: (6 + 9/2 = 7.5. max = 9. The (L j ave j Ammona ntrogen were drnkng stards as shown n table 5. In addton, WPI n th drnkng were used n th study. example PVs used E, alkalnty as ao Ammona ntrogen were drnkng stards as shown n table 5. In addton, WPI n3 th Based chemcal loadngs relatve to contamnaton r results areclassfed nto 4 studyon does take nto nto account dueasto toshown bologcal actvtes. So f f meets Ammona ntrogen were drnkng PVs, stards n table 5.samples In addton, WPI n th study does take account contamnaton due bologcal actvtes. So meets

4 34 Kabunga NAHIYUNDE hrpn NAMAKANDO classfcaton used n th study reflects sutablty human consumpton (after low cost treatment e.g. fltraton, bolng or chlornaton. The PVs effluent drnkng were used n th study. example PVs used E, alkalnty as ao 3 ammona-ntrogen were drnkng stards as shown n Table 1 Table 5. In addton, WPI n th study does take nto account contamnaton due to bologcal actvtes. So f meets clean crtera, t may stll need some m treatment (e.g. chlornaton but at a far lower cost. Utlzng PVs obtaned Envronmental ouncl Zamba (EZ /Zamba Bureau Stards (ZBS WHO as shown n Table 1, WPI was classfed nto four categores expressng Zambez Rver polluton levels as lted below. 0.0 WPI 1.0 = clean (meets PV crtera 1.0 < WPI 5.0 = slghtly polluted 5.0 < WPI 10.0 = moderately polluted WPI > 10.0 = hghly polluted Table 1. Water Parameters r orrespondng Permsble Values used Zambez Rver Permsble No Parameter Unt Drnkng Water Qualty (ZBS EZ Waste nto Aquatc Envronment, 1993 Physcal 1 Temperature nd 40 at entry pont 2 Electroconductvty µs/cm Total Suspended Solds mg nd Total Dsolved Solds mg nd Turbdty NTU hemcal 6 Dsolved Oxygen mg nd after mxng > 5 7 ph nd Alkalnty as ao 3 mg 120** nd 9 Total Phosphorus mg nd Ammona mg 1.5* 10.0 ZBS - Zamba Bureau Stards, NTU.-Nephelometrc Turbduty Unts nd: not determned *Based on WHO (1993, Levels lkely to gve re to consumer complants ** Based on Lehr (1980 ** Ammona [mg] was converted to ammona-ntrogen [mg] all calculatons 3. Data Analys 3.1 Analys Boxplots Nne Parameters The ndvdual parameters were analysed usng descrptve stattcs, boxplots were used as a convenent way graphcally depctng parameters seasonal numercal data through fve-number summares: smallest observaton (sample mnmum, lower quartle (Q1, medan (Q2, upper quartle (Q3, largest observaton (sample maxmum. The boxplots were used to ndcate whch parameter n a gven season, f any, mght be consdered outlers Zambez Rver data. The boxplots dplay dfferences between populatons wthout makng any assumptons underlyng stattcal dtrbuton as y are non-parametrc. The spacng between dfferent parts box help to ndcate degree dperson (spread skewness n data, dentfy outlers.

5 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data Fgure 2. Boxplot ph Fgure 3. Boxplot Electroconductvty Fgure 4. Boxplot Dsolved Oxygen Fgure 5. Boxplot Total Suspended Solds Fgure 6. Boxplot Total Dsolved Solds Fgure 7. Boxplot Alkalnty as ao 3

6 36 Kabunga NAHIYUNDE hrpn NAMAKANDO Fgure 8. Boxplot Turbdty Fgure 9. Boxplot Total Phosphorus Fgure 10. Boxplot Ammona-Ntrogen Boxplots ndvdual parameters n four seasons were examned. Fgure 2 to Fgure 10 show an example boxplots some meanngful varables related to qualty Zambez Rver, Lake Karba ts trbutares such as ammonantrogen, DO, total phosphorus. The lne across box represents medan, as bottom top box show locatons frst thrd quartles (Q1 Q3. The whkers are lnes that extend bottom top box to lowest hghest observatons nsde regon defned Q1-1.5(Q3-Q1 Q3+1.5(Q3-Q1, ndvdual ponts wth s outsde se lmts (outlers are plotted wth asterks (Vega et al., Boxplots provde a vual mpresson shape underlyng dtrbutons. example, boxplots (such as that turbdty ndcate that underlyng dtrbuton skewed towards hgher levels. Boxplots wth large spread ndcate large seasonal varatons compostons (see ph boxplots. By nspectng se plots t was possble to perceve dfferences among four seasons. example, ph hgher n ERS (exceedng effluent stards ph 9 n some locatons lowest n EDS. The hgh ph n ERS probably an ndcator stormy wth hgh levels organc materal norganc nutrents whch tend to ncrease ph.

7 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data Prncpal omponent Analys (PA Prncpal omponent Analys (PA dd not fnd any ambguty n component matrx (Table 2. After analysng rotated matrx, t was even clearer that four components emerged. As shown n Table 2, component 1 (F1 was compred Turbdty, TSS, TP NH 3 -N. omponent 2 (F2 consttuted E, TDS Alkalnty as ao 3 thrd component (F3 was made up DO ph as shown n Table 2. Temperature consttuted last component (F4. Table 3 shows that four parameters explaned 81.37% varance. Table 2. Pattern Structure Matrx Pattern Matrx Structure Matrx omponent omponent Turbdty.958 Turbdty.954 TSS.918 TSS.915 TP.813 TP.813 Ammona-Ntrogen.550 Ammona-Ntrogen.557 E.963 TDS.966 TDS.963 E.966 Alkalnty as ao Alkalnty as ao DO.918 DO.888 ph.788 ph.841 T.965 T.962 Table 3. Total Varance Explaned Intal Egens Extracton sums squared loadngs Rotaton Sums Squared Loadngs omponent Total % Varance umulatve % Total % Varance umulatve % Total

8 38 Kabunga NAHIYUNDE hrpn NAMAKANDO Table 4. Pearson orrelaton T ph E DO TSS TDS Alkalnty as ao 3 Turbdty TP Ammona Ntrogen Season Locaton T 1 PH.337** 1 E -.143**.050** 1 DO -.071**.577**.172** 1 TSS.060**.043**.024**.167** 1 TDS -.143**.050** 1.000**.172**.025** 1 Alkalnty as ao 3.144**.214**.635**.184**.091**.635** 1 Turbdty.060**.016**.014**.140**.930**.015**.077** 1 TP.089**.068**.045**.190**.618**.045**.094**.710** 1 Ammona-Ntrogen -.074** -.146**.063** -.101**.343**.063**.064**.390**.298** 1 Season -.571** -.414**.142** -.180** -.180**.142**.032** -.179** -.216**.220** 1 Locaton.037**.172**.497**.198**.202**.497**.345**.232**.242**.139** ** orrelaton sgnfcant at 0.01 level (2-taled * orrelaton sgnfcant at 0.05 level (2-taled 3.3 Pearson orrelaton orrelatons were observed between several parameters among m sgnfcant ones were between: TDS E (r = 1.0; between turbdty TSS (r =.93; between total phosphorus turbdty (r =.71 between alkalnty as ao 3 both E TDS (r =.635. In addton, locaton [ste] was correlated postvely wth almost all parameters except ammonantrogen temperature. The turbdty TSS lkely made up phosphorus contanng consttuents as re was a strong correlaton between se parameters. Equally, re was a strong correlaton between TDS E. The fndngs suggest that hgh TDS brngs onset hgh E n specfc locatons. The fndngs furr suggest that changes n season brng about turbdty hgh TSS as re was a very strong correlaton between m Multple omparon Water Parameters One-way analys varance was used to compare mean scores (M ten polluton parameters. The study was ntended to uncover mpact season ( ndependent varable on qualty parameters (dependent varables. ANOVA only uncovered nmaton on wher qualty across seasons dffered sgnfcantly, but dd not reveal any sgnfcant dfference. An F (degrees freedom between groups, degrees freedom wthn groups rato was also calculated, whch represented varance between groups, dvded varance wthn groups. A large F rato ndcates that re more varablty between groups (caused ndependent varable or season than re wthn each group (referred to as error term. A sgnfcant F test ndcates that we can reject null hypos, whch states that populaton means are equal. It does not, however, tell us whch groups dffer. To uncover dfference was, a post-hoc test was conducted to determne whch groups were sgnfcantly dfferent one anor. Furrmore, eta squared stattcs have been reported n th study. Eta squared can range 0 to 1 represents proporton varance n dependent varable that explaned ndependent (group varable. Effect sze stattcs provde an ndcaton magntude dfferences between groups (not just wher dfference could have occurred chance (Pallant, In th study, f Sg. /or probablty (p less than or equal to.05, t meant re was a sgnfcant dfference some among mean scores on polluton parameter four seasons. The ten parameters were compared aganst season results are reported n subsequent sectons Temperature A one-way between-groups analys varance was conducted to explore mpact season on temperature, as measured over a perod twelve months. The seasons were dvded nto four (season 1: Oct to Nov-ERS; season 2: Jan to Mar-LRS; season 3: Apr to Jun-EDS; season 4: Jul to Sep-LDS. There was a stattcally sgnfcant dfference at p <.05 level n temperature four seasons: F (3, 182 = 36.10, p =.00. Despte reachng stattcal sgnfcance, actual dfference n mean scores between

9 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data groups was qute small. The effect sze, calculated usng eta squared, was.37. Post-hoc comparons usng Tukey HSD test ndcated that mean score ERS (M = 27.40, SD = 1.90 LRS (M = 27.30, SD = 2.20 was sgnfcantly dfferent EDS (M = 25.60, SD = 2.80 LDS (M = 23.00, SD = In addton EDS dffered sgnfcantly LDS. Thermal polluton occurs when humans change temperature a body. The most common pont source rmal polluton coolng, whch used to cool machnes. Thermal polluton may also be caused storm runf warm surfaces such as streets parkng lots. Sol eroson anor cause, snce t can cause cloudy condtons n a body. loudy absorbs sun s rays, resultng n a re n temperature. Thermal polluton may even be caused removal trees vegetaton whch normally shade body. Novotny (2002 also argues that temperature turbdty are specal cases physcal pollutants that affect or pollutants mpar aquatc lfe. The most mportant mpact rmal polluton a decrease n dsolved oxygen. Less oxygen n envronment may affect aquatc organms overall health ecosystem. Thermal polluton can result n sgnfcant changes to aquatc envronment. Most aquatc organms are adapted to survve wthn a specfc temperature range. Thermal polluton may also ncrease extent to whch fh are vulnerable to toxc compounds, parastes, dease. If temperatures reach extremes heat or cold, few organms wll survve. Judgng effluent stards ZBS, all samples were wthn permsble range although re were sgnfcant seasonal temperature dfferences. Th expected because natural seasonal fluctuatons whch brng about varatons n temperature ph A one-way between-groups analys varance was conducted to explore mpact season on ph, as measured over a perod twelve months. The seasons were dvded nto four (season 1: Oct to Nov-ERS; season 2: Jan to Mar-LRS; season 3: Apr to Jun-EDS; season 4: Jul to Sep-LDS. There was a stattcally sgnfcant dfference at p <.05 level n ph four seasons: F (3, 182 = 21.40, p =.00. Notwthstng reachng stattcal sgnfcance, actual dfference n mean scores between groups was relatvely small. The effect sze, calculated usng eta squared, was.26. Post-hoc comparons usng Tukey HSD test ndcated that mean score ERS (M = 8.30, SD =.49 was sgnfcantly dfferent LRS (M = 7.90, SD =.42, EDS (M = 7.60, SD =.42 LDS (M = 7.80, SD =.49. In addton, LRS dffered sgnfcantly EDS. The ph natural depends on several factors, whch nclude bcarbonate bufferng system, types rocks, types sol, nature dcharged pollutants. The concentraton carbonates carbon doxde man nfluence on ph clean. Hgh concentratons bcarbonate produce alkalne s (hgh ph, whle low concentratons usually produce acdc s (low ph. Acdc alkalne compounds can be weared nto stream dfferent types rock present. When lmestone (ao 3 present, carbonates can be released, affectng alkalnty. The types sol n dranage area also affect ph. Dranage ests marshes ten slghtly acdc, due to presence humc acds produced decayng vegetaton (hou et al., Ntrogen oxdes (NO, NO 2 sulphur doxde (SO 2 mnng actvtes (Hll, 2010, automoble exhaust ( machnes powered fossls fuels are converted nto ntrc acd (HNO 3 sulphurc acd (H 2 SO 4 n atmosphere. These acds can affect ph streams combnng wth moture n ar fallng to earth as acd ran. Surface s can sometmes act as weak buffer solutons dependng on concentratons carbonates bcarbonates (Explorng Envronmental Water Qualty, The ph s natural surface s usually range 5.5 to 8.5. Extremely hgh ( 9.6 or low ( 4.5 s are unsutable most aquatc organms. Fledglng fh mmature stages aquatc nsects are extremely senstve to ph levels below 5. Most aquatc speces prefer ph near neutral but can wthst a ph n a range about 6 (7 ntrfers to 8.5 (Novotny, hanges n ph can also affect aquatc lfe ndrectly alterng or aspects chemtry. Low ph levels accelerate release heavy metals sedments on stream bottom. The heavy metals can reduce chance survval most aquatc organms (Explorng Envronment Water Qualty, Overall seasonal ph was n alkalne range wth ERS (September to December regterng most alkalne condton. There were sgnfcant dfferences between seasons as revealed stattcal analys wth EDS regterng hghest ph Electroconductvty (E A one-way between-groups analys varance was conducted to explore mpact season on E, as measured over a perod four seasons. There was no stattcally sgnfcant dfference at p <.05 level n E four seasons: F (3, 182 = 1.50, p =.22.

10 40 Kabunga NAHIYUNDE hrpn NAMAKANDO Salty conducts electrcty more readly than purer. Theree, electrcal conductvty routnely used to measure salnty. The types salts (ons causng salnty usually are chlordes, sulphates, carbonates, sodum, magnesum, calcum potassum. Whle an approprate concentraton salts vtal aquatc plants anmals, salnty that beyond normal range any speces organm wll cause stress or even death to that organm. Salnty also affects avalablty nutrents to plant roots (Water Lfe & Greenng Australa, n.d.. Dependng on type salts present, salnty can ncrease clarty. At very hgh concentratons, salts make denser, causng salnty gradatons wthn an unmxed column slghtly ncreasng depth necessary to reach table n ground bores. Electrcal conductvty n ways affected : geology sols; l use, such as agrculture (rrgaton, urban development (removal vegetaton, sewage effluent dcharges, ndustral development (ndustral dcharges; flow (electrcal conductvty generally lowest durng hgh flows ncreases as flows decrease, wth extreme levels occurrng durng droughts; run-f; ground nflows; temperature; evaporaton dluton (Waterwatch Australa, ontamnated dcharges can change s electrcal conductvty n varous ways. example, a falng sewage system raes conductvty because ts chlorde, phosphate, ntrate content, but an ol spll would lower conductvty. The dcharge heavy metals nto a body can rae conductvty as metallc ons are ntroduced nto way (bd. Despte wde varatons observed n E s several outlers as revealed boxplots, re was no sgnfcant dfference across seasons Dsolved Oxygen (DO A one-way between-groups analys varance was conducted to explore mpact season on DO, as measured over a perod twelve months. As n prevous cases, seasons were dvded nto four. There was a stattcally sgnfcant dfference at p <.05 level n DO four seasons: F (3, 182 = 5.10, p =.00. Despte reachng stattcal sgnfcance, actual dfference n mean scores between groups was rar mnor. The effect sze, calculated usng eta squared, was.08. Posthoc comparons usng Tukey HSD test ndcated that mean score ERS (M = 10.00, SD = 2.40 was sgnfcantly dfferent LRS (M = 8.60, SD = 1.40, EDS (M = 8.90, SD = 1.70 LDS (M = 9.00, SD = Adequate DO necessary good qualty. Its depleton n assocated wth mcroorganms decomposng much organc matter n a body (Hll, Oxygen a necessary element to all ms lfe. Natural stream purfcaton processes requre adequate oxygen levels n order to support aerobc lfe ms. Ahluwala Malhotra (2007 argue that f amount DO hgh, degree self-purfcaton hgh; n such cases, mlder treatment requred. As DO levels n drop below 5.0 ppm, aquatc lfe put under stress; lower concentraton, greater stress. Novotny (2002 contends that qualty nvestgatons toxctes studes ndcate that DO content most mportant parameter protectng fh aquatc bota. Oxygen dsolves n at very low concentratons. The atmosphere 20% oxygen or 200,000 ppm can reach concentraton up to 10.0 ppm oxygen dsolved n ts (Wrght, ERS dffered sgnfcantly or seasons; t had hghest amount DO, mplyng that most oxygenated durng th season. Despte some monthly outlers below recommended 5 ppm, all seasonal averages ndcated healthy condtons along Zambez Rver shed Total Suspended Solds (TSS A one-way between-groups analys varance was conducted to explore mpact season on TSS, as measured over a perod twelve months. There was no stattcally sgnfcant dfference at p <.05 level n TSS four seasons: F (3, 182 = 2.20, p =.09. Total suspended solds (TSS nclude all partcles suspended n whch wll not pass through a flter. Suspended solds are present n santary waste many types ndustral waste. There are also nonpont sources suspended solds, such as sol eroson agrcultural constructon stes. As levels TSS ncrease, a body begns to lose ts ablty to support a dversty aquatc lfe. Suspended solds absorb heat sun, whch ncreases temperature subsequently decreases levels DO (warmer holds less oxygen than cooler. Photosyns also decreases, snce less lght penetrates (Hll, As less oxygen produced plants algae, re a furr drop n DO levels. Hgh TSS levels can also destroy fh habtat because suspended solds settle to bottom can eventually blanket rver bed. Suspended solds can smor eggs fh aquatc nsects, can suffocate newly-hatched nsect larvae. Suspended solds can also harm fh drectly cloggng glls, reducng growth rates, lowerng restance to dease. As

11 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data revealed HSD test, re was no sgnfcant dfference n TSS s across seasons. The PV as set ZBS was not exceeded across four seasons Total Dsolved Solds (TDS A one-way between-groups analys varance was conducted to explore mpact season on TDS, as measured over a perod twelve months. There was no stattcally sgnfcant dfference at p <.05 level n TSS four seasons: F (3, 182 = 1.50, p =.22. TDS n drnkng may come natural sources, sewage, urban run-f, ndustral waste, (WHO, 1996 chemcals used n treatment process, or materal ppng or hardware used to convey. Elevated TDS have resulted natural envronmental features such as: mneral sprngs, carbonate deposts, salt deposts, sea ntruson. Or sources may nclude: drnkng treatment chemcals, storm agrcultural runf, pont/non-pont waste dcharges (Oram, As was case wth TSS, re was no sgnfcant dfference n TDS across seasons ts PV was not exceeded Alkalnty as ao 3 A one-way between-groups analys varance was conducted to explore mpact season on alkalnty, as measured over a perod twelve months. There was no stattcally sgnfcant dfference at p <.05 level n alkalnty as ao 3 four seasons: F (3, 182 =.4, p =.74. The ablty surface s to neutralze acdc nputs depends on carbonate (O 3 2- bcarbonate (HO 3 - expressed as alkalnty (Novotny, In natural, alkalnty due to presence HO 3 -, SO 3 2-, HSO 3 -, O 3 2- OH -. Sometmes, presence salts weak organc acds bnd H + thus results n ncreasng concentraton OH - ons (Ahluwala & Malhotra, Most alkalnty n surface comes ao 3, beng leached rocks sol. Th process enhanced f rocks sol have been broken up any reason, such as mnng or urban development. Lmestone contans especally hgh levels ao 3. Alkalnty sgnfcant n treatment waste drnkng because t wll nfluence treatment processes such as anaerobc dgeston. Bard ann (2008, p. 594 have ponted out that alkalnty a lake sometmes used bologt as a measure ts ablty to support aquatc plant lfe, a hgh ndcatng a hgh potental fertlty. Water may also be unsutable use n rrgaton f alkalnty level n hgher than natural level alkalnty n sol (APE, n.d.. Th study dd not fnd any sgnfcant dfference across four seasons n alkalnty as ao 3. However, boxplots reveal that several locatons exceeded recommendable s alkalnty; several outlers were observed as revealed Fgure 7, Fgure 11 to Fgure Turbdty (TB A one-way between-groups analys varance was conducted to explore mpact season on turbdty, as measured over a perod twelve months. There was no stattcally sgnfcant dfference at p <.05 level n turbdty four seasons: F (3, 182 = 2.60, p =.053. Unfltered storm runf n streams, lakes, ponds, oceans can have a sgnfcant mpact on qualty. As storm flows over l surface, t pcks up pollutants lke sedments, nutrents, pathogens, debr, toxns varous or chemcals. Polluted storm runf not only lowers qualty but can harm or kll fh or wldlfe. example, excessve amounts sedment n can destroy aquatc habtats. Nonpont source polluton comes, prmarly, ran whch runs over lawns, parkng lots, cty streets, est, constructon stes. There was no sgnfcant dfference n TB across four seasons although boxplot revealed skewed dtrbuton several outlers towards hgher levels n ERS LRS Total Phosphorus (TP A one-way between-groups analys varance was conducted to explore mpact season on TP, as measured over a perod twelve months. There was a stattcally sgnfcant dfference at p <.05 level n TP four seasons: F (3, 182 = 3.10, p =.03. The effect sze, calculated usng eta squared, was.05. Post-hoc comparons usng Tukey HSD test ndcated that mean score ERS (M = 269.8, SD = was sgnfcantly dfferent LDS (M = , SD = LRS (M = , SD = , EDS (M = , SD = dd not dffer sgnfcantly any or season. Phosphorus, a nutrent essental to growth organms, commonly lmtng factor n prmary productvty surface bodes. TP ncludes amount phosphorus n soluton (reactve n partcle m. Agrcultural dranage,

12 42 Kabunga NAHIYUNDE hrpn NAMAKANDO waste, certan ndustral dcharges are typcal sources phosphorus can contrbute to eutrophcaton surface bodes (Bard & ann, Phosphorus can lead to populaton exploson photosyntc bactera blue-green algae (Ahluwala & Malhotra, oncentratons phosphorus n, ar, sol are measured to assess present stuaton. Wth tradtonal measurng methods, t only possble to determne envronmental problems caused n past. Early recognton future loadng, as well as dentfcaton effectve measures, enables potental decrease later loadng. Both are possble only wth measures envronmental protecton on whole system, whch ntegraton, l, ar, wll be based solely on preventon. sustanable rver basn management, re a strong need to evaluate dfferent opton strateges. Only thus wll avalable resources be appled n most advantageous, sustanable way (Drolc et al., As TP, HSD revealed that ERS was sgnfcantly dfferent LDS, all or seasons dd not dffer sgnfcantly. ERS regtered hghest TP loadngs followed LRS. The results show that partcularly worse durng rany season, a consequence stormy farms, unsewered onste santaton nfrastructure ndustres Ammona-Ntrogen (NH 3 -N A one-way between-groups analys varance was conducted to explore mpact season on NH 3 -N, as measured over a perod twelve months. There was a stattcally sgnfcant dfference at p <.05 level n NH 3 -N four seasons: F (3, 179 = 14.70, p =.00. Despte reachng stattcal sgnfcance, actual dfference n mean scores between groups was qute small. The effect sze, calculated usng eta squared, was.2. Post-hoc comparons usng Tukey HSD test ndcated that mean score ERS (M =.00, SD =.00 was sgnfcantly dfferent LRS (M = 60.10, SD = 83.64, EDS (M = 36.50, SD = LDS (M = 42.30, SD = In addton, LRS dffered sgnfcantly EDS. At ph 7.00 or below, most ammonacal ntrogen wll be onzed as ammonum. At ph levels greater than 9.00 proportons nononed ammona wll ncrease. The nononzed ammona toxc to fh, whle onzed ammona a nutrent to algae aquatc plants also exerts dsolved oxygen dem (Novotny, Ammona (NH 3 manly generated agrcultural sources, wth major pont sources found partcularly near ntensve lvestock poultry farms. Ammona polluton causes both acdfcaton sols a decrease n rchness plant speces (European ommson, NH 3 -N a consttuent n raw domestc waste. The fndngs th study show that ERS dffered sgnfcantly all seasons. Th partly because re was no flow n some sampled locatons ( example Kalomo Quay are ephemeral rvers hence no parameters were analysed. LRS EDS dffered sgnfcantly, wth mer regterng hgher NH 3 -N loadng compared to latter. 4. Dcusson on polluton wth Water Polluton Index 4.1 Season omparon Parameters exceedng r PVs WPI In proceedng secton, ten parameters consdered n th study are compared relatve to what expected to be found n Table 5. The Averages Stard Devaton (SDs Ten Parameters n Four Seasons orrespondng PVs Mn Max Mean Mn Max Mean Mn Max Mean Mn Max Mean SD SD SD Unt PVs ERS ERS ERS LRS LRS LRS EDS EDS EDS LDS LDS LDS SD T ph E μs/cm DO mg > TSS mg TDS mg Alkanlty as ao 3 mg Turbdty NTU TotalP μg Ammona-Ntrogen μg 1250 nd nd nd nd nd, not determned; NTU, Nephelometrc Turbdty Unt

13 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data 2011 Fgure 11. Early Ran Season (ERS comparon parameters exceedng r PVs Fgure 12. Late Ran Season (LRS comparon parameters exceedng r PVs 43

14 44 Kabunga NAHIYUNDE hrpn NAMAKANDO Fgure 13. Early Dry Season (EDS comparon parameters exceedng r PVs Fgure 14. Late Dry Season (LDS comparon parameters exceedng r PVs unpolluted samples. The mnmum, maxmum mean s parameters are compared to r PVs. In-depth analyses parameters are here presented season as depcted Fgure 11 to Fgure 14. Of ten parameters, TSS, turbdty, TP exceeded r PVs n some seasons n contrast to alkalnty as ao3 whch exceeded ts PV n all seasons as depcted Fgure 11 to Fgure 14.

15 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data Local haractertcs Polluton Fgure 15 Fgure 16 (usng polluton ndex show an mportant pattern that most compromed samples came trbutares that feed Zambez Rver. Amongst outstng locatons whch were most polluted are Quay rver (WPI= 6.40, Karba at Sanyat-furr (WPI= 5.28, Kalomo Rver (WPI = 4.76 Deka rver (WPI = 4.65, Kanznze Rver (WP = 1.95, Karba at Gatche Gatche (WPI = Fgure 15. omparon Polluton Locaton usng WPI 4.3 Seasonal haractertcs Polluton Furrmore, data obtaned usng WPI as presented n Fgure 17 shows whch season(s have notable polluton problems data clearly shows that LDS charactered very safe wth reference to ten parameters that were focus th study. When 17 locatons are furr compared r overall contrbuton to qualty, t was found that trbutares dchargng nto Karba/ Zambez Rver had most compromed as shown WPI s Quay Rver, Karba at Sanyat-furr, Kalomo Deka Rvers.

16 46 Kabunga NAHIYUNDE hrpn NAMAKANDO Fgure 16. Spatal Dtrbuton Polluton Locaton usng WPI on Lake Karba, Zambez Rver ts trbutares Source: Map data 2012 Google Fgure 17. omparon polluton season usng WPI In addton t can be argued, as shown n Fgure 17, that deteroraton n qualty clmaxes n LRS qualty gradually mproves towards EDS untl t attans ts best level n LDS bee qualty tumbles agan n ERS. The pattern constent wth onset ran season n October ndcatng that pollutants are washed to rver banks furr nl close to nsde human settlements.

17 Evaluaton seasonal patterns qualty n Zambez Rver Basn, usng Zambez Rver Authorty (ZRA data oncluson The fndngs th study reveal that qualty deteroraton along Lake Karba, Zambez Rver ts trbutares partcularly n a crtcal condton durng rany reason. ERS had a WPI 3.72 LRS had a WPI 4.02 hence more care partcularly needed when usng shed (shown n Fgure 16 durng se seasons. Furrmore, usng prncpal factor analys, ten parameters yelded four factors most predomnant (as evdenced factor loadngs factors controllng qualty along shed are: factor 1 domnated turbdty, factor 2 domnated TDS, factor 3 domnated DO factor 4 temperature. These parameters were found to be very momentous, as revewed factor loadngs, n explanng qualty across seasons. By far bggest problems (frequently exceedng r PVs were caused turbdty followed alkalnty as ao 3, n TSS to a less extent total phosphorus. It also mportant to note that trbutares feedng Lake Karba are most polluted. Furrmore, shed s (after traversng between Zamba Zmbabwe flows nto neghbourng Mozambque results show that extng Lake Karba generally free any sgnfcant polluton, across all seasons, probably a consequence dlutng effect vast resources Lake. However, t vtally mportant to alert users banks furr downstream some hazards found n wth changng seasons especally durng late rany season. Acknowledgement The authors would lke to earnestly express r grattude to Zambez Rver Authorty provdng raw rver data on Zambez Rver, Karba dam ts trbutares. References Ahluwala, V. K., Malhotra, S. (2007, Envronmental Scence. Boca Raton: R press. APE. (n.d., What Alkalnty? Water ontamnaton. [Accessed 5 May 2012] Bard,., ann, M. (2008, Envronmental hemtry (4th ed.. New York: W. H. Freeman ompany. hou, et al., (2000, Sorpton Selected Organc ompounds Water to a Peat Sol Its Humc-Acd Humn Fractons: Potental Sources Sorpton Nonlnearty. Envronmental Scence & Technology, 34(7, Dombrowsky, I. (2007, onflct, ooperaton Insttutons n Internatonal Water Management: An Economc Analys. heltenham, UK Northampton, MA: E. Elgar. Drolc et al., (2002, Estmaton sources total phosphorus n a rver basn assessment alternatves rver polluton reducton. Envronment Internatonal, 28(5, European ommson. (2006, Scence Envronmental Polcy DG Envronmental News Alert Servce. [Accessed 10 May 2012]. Explorng Envronment Water Qualty. (2004, Acd Mne Dranage: ph. [Accessed 15 May 2012] Hll, M. K. (2010, Understng Envronmental Polluton (3rd ed.. ambrdge Unversty Press. Lehr, J. et. al., (1980, Domestc Water Treatment. New York, NY: McGraw-Hll Book ompany. Magadza, M. (2006, Bactera n Zambez lkely cause fh dease. Scence Development Network. [Accessed 3 Aprl 2012] Mpe, L. R., Tawa, M. (1998, Populaton Dynamcs Emergng ompetton Water Use n Zambez Rver Basn, A. de Sherbnn D.Vctora eds., Water Populaton Dynamcs: ase Studes Polcy Implcatons (1st US - 1st Prntng.. Amercan Assocaton Advancement Scence. Nemerow, N. L., Sumtomo, H., (1970, Benefts Water Qualty Enhancement. Report No DAJ, prepared US Protecton Agency. Syracuse Unversty, Syracuse, NY. Novotny, V. (2002, Water Qualty: Dffuse Polluton Watershed Management, 2nd Edton (2nd ed.. Wley. Nwasco. (n.d., Or Water Leglaton. leglaton.php [Accessed 6 June 2012] Oram, B. (2007, Total Dsolved Solds: Sources Total Dsolved Solds (Mnerals n Drnkng Water. Wlkes Unversty, Envronmental Engneerng Earth Scences Department, enter Envronmental Qualty. [Accessed 25 Aprl 2012] Pallant, J. (2007, SPSS Survval Manual A Step Step Gude to Data Analys Usng SPSS Wndows, (3 rd ed. Madenhead:

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