{"id":4670,"date":"2018-04-11T10:16:34","date_gmt":"2018-04-11T09:16:34","guid":{"rendered":"https:\/\/www.vtei.cz\/?p=4670"},"modified":"2024-07-16T14:20:09","modified_gmt":"2024-07-16T13:20:09","slug":"trends-in-development-of-phosphorus-concentrations-in-orlik-and-slapy-reservoirs","status":"publish","type":"post","link":"https:\/\/www.vtei.cz\/en\/2018\/04\/trends-in-development-of-phosphorus-concentrations-in-orlik-and-slapy-reservoirs\/","title":{"rendered":"Trends in development of phosphorus concentrations in Orl\u00edk and Slapy reservoirs"},"content":{"rendered":"

<\/i> This article is available in Czech only. For translation or more information on this topic, please contact author.<\/h4>\n

 <\/p>\n

Souhrn<\/h2>\n

Na z\u00e1klad\u011b datov\u00fdch \u0159ad pro koncentrace fosforu (P) v\u00a0n\u00e1dr\u017e\u00edch Slapy a\u00a0Orl\u00edk a\u00a0v\u00a0jejich hlavn\u00edch p\u0159\u00edtoc\u00edch jsme zrekonstruovali vstup P z\u00a0povod\u00ed do t\u011bchto dvou n\u00e1dr\u017e\u00ed pro\u00a0obdob\u00ed 1961\u20132015 a\u00a0sestavili n\u00e1dr\u017eov\u00e9 modely retence P. Koncentrace P v\u00a0obou n\u00e1dr\u017e\u00edch rostly od 60.\u00a0let minul\u00e9ho stolet\u00ed a\u017e do roku 1991 a\u00a0pak za\u010daly klesat, v\u00a0n\u00e1dr\u017ei Slapy ale s\u00a0v\u00fdrazn\u011b zv\u00fd\u0161enou meziro\u010dn\u00ed variabilitou. Trendy koncentra\u010dn\u00edho n\u00e1r\u016fstu a\u00a0poklesu P byly odrazem v\u00fdvoje socio-ekonomiky v\u00a0povod\u00ed Vltavy, zejm\u00e9na stavu kanalizac\u00ed, vypou\u0161t\u011bn\u00ed odpadn\u00edch vod, aplikace hnojiv,\u00a0mno\u017estv\u00ed hospod\u00e1\u0159sk\u00fdch zv\u00ed\u0159at a\u00a0intenzity rybni\u010dn\u00edho chovu ryb. Anal\u00fdza retence P v\u00a0n\u00e1dr\u017e\u00edch uk\u00e1zala, \u017ee P akumulovan\u00fd v\u00a0sedimentech n\u00e1dr\u017ee v\u00a0dob\u011b rostouc\u00edho zat\u00ed\u017een\u00ed P z\u00a0povod\u00ed v\u00a0letech 1961\u20131990 se v\u00a0n\u00e1sleduj\u00edc\u00edm obdob\u00ed poklesu zat\u00ed\u017een\u00ed P op\u011bt uvol\u0148oval do vody a\u00a0tlumil vliv poklesu koncentrac\u00ed P v\u00a0p\u0159\u00edtoku do n\u00e1dr\u017e\u00ed. Po roce 1991 se v\u00a0n\u00e1dr\u017ei Slapy v\u00a0letn\u00edm obdob\u00ed koncentrace P za\u010daly za zv\u00fd\u0161en\u00fdch letn\u00edch pr\u016ftok\u016f zvy\u0161ovat a\u00a0podporovat\u00a0rozvoj fytoplanktonu, kde\u017eto v\u00a0such\u00fdch l\u00e9tech v\u00fdrazn\u011b klesaly a\u017e k\u00a0mezotrofii. Klimaticko-hydrologicky podm\u00edn\u011bn\u00e9 procesy tak v\u00a0posledn\u00ed dob\u011b zjevn\u011b p\u016fsob\u00ed proti klesaj\u00edc\u00edmu trendu zne\u010di\u0161t\u011bn\u00ed P a\u00a0zvy\u0161uj\u00ed eutrofizaci n\u00e1dr\u017ee navzdory poklesu zat\u00ed\u017een\u00ed P z\u00a0povod\u00ed.<\/p>\n\"\"<\/a>\n

\u00davod<\/h2>\n

Vysok\u00e9 koncentrace fosforu (P) zp\u016fsobuj\u00edc\u00ed\u00a0eutrofizaci jsou d\u016fvodem nepln\u011bn\u00ed po\u017eadavku R\u00e1mcov\u00e9 sm\u011brnice vodn\u00ed politiky EU (RVS) na dobr\u00fd ekologick\u00fd potenci\u00e1l u\u00a0zhruba dvou t\u0159etin n\u00e1dr\u017e\u00ed v\u00a0\u010cR [1]. Jako u\u00a0jin\u00fdch polutant\u016f, zne\u010di\u0161t\u011bn\u00ed povrchov\u00fdch vod fosforem poch\u00e1z\u00ed p\u0159edev\u0161\u00edm z\u00a0povod\u00ed a\u00a0pod\u00edlej\u00ed se na n\u011bm r\u016fzn\u00e9 antropogenn\u00ed vlivy, zejm\u00e9na infrastruktura vodn\u00edho hospod\u00e1\u0159stv\u00ed (vodovodn\u00ed s\u00edt\u011b, odkanalizov\u00e1n\u00ed obyvatelstva, \u00farove\u0148 \u010di\u0161t\u011bn\u00ed odpadn\u00edch vod aj.), urbanizace (n\u00e1r\u016fst nepropustn\u00fdch ploch v\u00a0n\u00e1vaznosti na jednotn\u00e9 kanaliza\u010dn\u00ed syst\u00e9my) a\u00a0zem\u011bd\u011blsk\u00e9 aktivity (obd\u011bl\u00e1v\u00e1n\u00ed p\u016fdy, hnojen\u00ed, chov hospod\u00e1\u0159sk\u00fdch zv\u00ed\u0159at), kter\u00e9 b\u011bhem posledn\u00edho p\u016flstolet\u00ed pro\u0161ly v\u00fdrazn\u00fdm v\u00fdvojem, a\u00a0to nejen v\u00a0\u010cR, ale i\u00a0jinde v\u00a0Evrop\u011b i\u00a0v\u00a0dal\u0161\u00edch \u010d\u00e1stech sv\u011bta [2\u20134]. Z\u00e1rove\u0148 se ukazuje, \u017ee na odnos \u017eivin z\u00a0povod\u00ed a\u00a0jejich n\u00e1sledn\u00fd kolob\u011bh ve\u00a0vod\u00e1ch tak\u00e9 p\u016fsob\u00ed zm\u011bna klimatu v\u00a0d\u016fsledku glob\u00e1ln\u00edho oteplov\u00e1n\u00ed t\u00edm, \u017ee ovliv\u0148uje sezonnost sr\u00e1\u017eek, pr\u016ftoky, teplotu vody a\u00a0v\u00a0hlubok\u00fdch jezerech a\u00a0n\u00e1dr\u017e\u00edch tak\u00e9 teplotn\u00ed stratifikaci [5\u20138].<\/p>\n

Koncentrace P je v\u00a0n\u00e1dr\u017e\u00edch a\u00a0jezerech \u0159\u00edzena jednak koncentrac\u00ed P v\u00a0p\u0159\u00edtoc\u00edch, rychlost\u00ed jeho sedimentace a\u00a0zp\u011btn\u00e9ho uvol\u0148ov\u00e1n\u00ed ze sedimentu do vodn\u00edho sloupce, p\u0159\u00edpadn\u011b recyklov\u00e1n\u00edm ve vodn\u00edm sloupci [9, 10]. Souhrnn\u00fdm v\u00fdsledkem v\u0161ech t\u011bchto proces\u016f je tzv. retence P, kter\u00e1 ud\u00e1v\u00e1, jak\u00e1 \u010d\u00e1st z\u00a0p\u0159\u00edsunu P je v\u00a0n\u00e1dr\u017ei zadr\u017eena. Koeficient retence (R) se pak definuje jako R\u00a0=\u00a01\u00a0\u2013\u00a0P\/Pin<\/sub>, kde: P je koncentrace fosforu v\u00a0n\u00e1dr\u017ei, pop\u0159. v\u00a0odtoku, a\u00a0Pin<\/sub> je p\u0159\u00edtokov\u00e1 koncentrace P. Retence P je nep\u0159\u00edmo \u00fam\u011brn\u00e1 pr\u016fto\u010dnosti \u010di hydraulick\u00e9mu zat\u00ed\u017een\u00ed n\u00e1dr\u017ee [11, 12], ale m\u016f\u017ee ji ovliv\u0148ovat tak\u00e9 mnoho dal\u0161\u00edch faktor\u016f, jako nap\u0159. tvarov\u00e1 morfologie a\u00a0hloubka n\u00e1dr\u017ee, p\u0159\u00edtokov\u00e1 koncentrace P, velikost zat\u00ed\u017een\u00ed P, anebo nosn\u00e1 kapacita dan\u00e9ho vodn\u00edho t\u011blesa pro r\u016fst fytoplanktonu [10, 13, 14], tak\u017ee retence P je v\u00a0ka\u017ed\u00e9m vodn\u00edm t\u011blese za dan\u00e9ho p\u0159\u00edsunu P do zna\u010dn\u00e9 m\u00edry specifick\u00e1 a\u00a0unik\u00e1tn\u00ed i\u00a0p\u0159es svou obecn\u011b platnou z\u00e1vislost na dob\u011b zdr\u017een\u00ed vody nebo pr\u016fto\u010dnosti. D\u016fsledkem je, \u017ee p\u0159edpov\u00edd\u00e1n\u00ed retence P podle pr\u016fm\u011brn\u00fdch vztah\u016f sestaven\u00fdch na z\u00e1klad\u011b \u00fadaj\u016f z\u00a0velk\u00e9ho mno\u017estv\u00ed morfologicky odli\u0161n\u00fdch n\u00e1dr\u017e\u00ed \u010di jezer lze prov\u00e1d\u011bt r\u016fzn\u00fdmi modely [10\u201314], ale v\u00a0ka\u017ed\u00e9m p\u0159\u00edpad\u011b je zat\u00ed\u017eeno zna\u010dnou nejistotou. I\u00a0s\u00a0t\u00edmto v\u011bdom\u00edm byl v\u00a0metodice hodnocen\u00ed ekologick\u00e9ho potenci\u00e1lu n\u00e1dr\u017e\u00ed RVS [15] pro nastaven\u00ed hrani\u010dn\u00edch limit\u016f pro jednotliv\u00e9 kategorie ekologick\u00e9 kvality pou\u017eit pr\u016fm\u011brn\u00fd model podle Vollenweidera kalibrovan\u00fd pro n\u00e1dr\u017ee [10], tj. R\u00a0=\u00a01,84\u03c40,5<\/sup>\/(1+1,84\u03c40,5<\/sup>), kde \u03c4 [rok] je teoretick\u00e1 doba zdr\u017een\u00ed vody v\u00a0n\u00e1dr\u017ei. Nicm\u00e9n\u011b je z\u0159ejm\u00e9, \u017ee nastaven\u00e9 limitn\u00ed hranice dobr\u00e9ho\/st\u0159edn\u00edho ekologick\u00e9ho potenci\u00e1lu mohou b\u00fdt pro n\u011bkter\u00e9 n\u00e1dr\u017ee pom\u011brn\u011b benevolentn\u00ed, pro jin\u00e9 naopak velmi p\u0159\u00edsn\u00e9.<\/p>\n

Prvotn\u00edm z\u00e1m\u011brem na\u0161\u00ed studie bylo vyhodnotit p\u0159\u00ed\u010diny zm\u011bn koncentrace P v\u00a0\u010dasov\u00e9 \u0159ad\u011b nam\u011b\u0159en\u00e9 v\u00a0n\u00e1dr\u017ei Slapy od roku 1959 a\u017e do sou\u010dasnosti (tj. v\u00a0\u0159ad\u011b svou d\u00e9lkou a\u00a0po\u010d\u00e1tkem m\u011b\u0159en\u00ed unik\u00e1tn\u00ed minim\u00e1ln\u011b v\u00a0m\u011b\u0159\u00edtc\u00edch st\u0159edn\u00ed Evropy) a\u00a0pokusit se na jej\u00edm z\u00e1klad\u011b popsat v\u00fdvoj zdroj\u016f zne\u010di\u0161t\u011bn\u00ed povrchov\u00fdch vod fosforem v\u00a0povod\u00ed horn\u00ed Vltavy. Brzy po zah\u00e1jen\u00ed anal\u00fdz jsme v\u0161ak zjistili, \u017ee p\u0159i objas\u0148ov\u00e1n\u00ed kol\u00eds\u00e1n\u00ed koncentrace P v\u00a0n\u00e1dr\u017ei Slapy se neobejdeme bez rekonstrukce celkov\u00e9ho vstupu P do kask\u00e1dy n\u00e1dr\u017e\u00ed Orl\u00edk-Kam\u00fdk-Slapy, hydrologick\u00fdch ukazatel\u016f a\u00a0bez charakterizace retence P v\u00a0obou hlavn\u00edch n\u00e1dr\u017e\u00edch \u2013 Orl\u00edk a\u00a0Slapy. D\u00edky tomuto roz\u0161\u00ed\u0159en\u00ed studie se v\u0161ak poda\u0159ilo sestavit ucelen\u00fd datov\u00fd soubor, kter\u00fd dokl\u00e1d\u00e1, \u017ee fosforov\u00e9 zne\u010di\u0161t\u011bn\u00ed v\u00a0povod\u00ed Vltavy bylo nezanedbateln\u00e9 ji\u017e v\u00a060. letech minul\u00e9ho stolet\u00ed a\u00a0\u017ee koncentrace P v\u00a0n\u00e1dr\u017e\u00edch Orl\u00edk a\u00a0Slapy jsou do zna\u010dn\u00e9 m\u00edry ovliv\u0148ov\u00e1ny nejen p\u0159\u00edsunem P z\u00a0povod\u00ed a\u00a0hydrologi\u00ed, ale tak\u00e9 prom\u011bnlivou retenc\u00ed P v\u00a0n\u00e1dr\u017e\u00edch. Na\u0161e hodnocen\u00ed dokumentuje jednak v\u00fdvoj kl\u00ed\u010dov\u00fdch zdroj\u016f zne\u010di\u0161t\u011bn\u00ed P v\u00a0povod\u00ed, jednak ukazuje, \u017ee v\u00a0posledn\u00edm \u010dtvrtstolet\u00ed zm\u011bny klimatick\u00fdch podm\u00ednek ovliv\u0148uj\u00ed sezonn\u00ed dostupnost P pro r\u016fst fytoplanktonu a\u00a0pod\u00edlej\u00ed se na zv\u00fd\u0161en\u00e9 rozkol\u00edsanosti koncentrac\u00ed P v\u00a0letn\u00edm obdob\u00ed a\u00a0na v\u011bt\u0161\u00ed citlivosti n\u00e1dr\u017e\u00ed k\u00a0eutrofizaci.<\/p>\n

Charakteristika lokality, pou\u017eit\u00e1 data, metodika<\/h2>\n

Povod\u00ed horn\u00ed Vltavy (plocha 12\u00a0968\u2008km2<\/sup> k\u00a0hr\u00e1zi n\u00e1dr\u017ee Slapy, rozsah nadmo\u0159sk\u00fdch v\u00fd\u0161ek 271\u20131\u00a0378\u2008m n. m.) se p\u0159ev\u00e1\u017en\u011b rozkl\u00e1d\u00e1 na \u00fazem\u00ed p\u016fvodn\u00edho Jiho\u010desk\u00e9ho kraje (tj. v\u010detn\u011b okresu Pelh\u0159imov), se kter\u00fdm m\u00e1 t\u00e9m\u011b\u0159 shodnou celkovou plochu i\u00a0po\u010det obyvatel, tak\u017ee lze pro hodnocen\u00ed socio-ekonomick\u00fdch ukazatel\u016f vyu\u017e\u00edvat dostupn\u00e1 statistick\u00e1 krajsk\u00e1 data. Technick\u00e9 charakteristiky n\u00e1dr\u017e\u00ed Orl\u00edk, Kam\u00fdk a\u00a0Slapy jsou uvedeny v\u00a0tabulce 1<\/em>. Z\u00a0limnologick\u00e9ho hlediska Orl\u00edk pat\u0159\u00ed ke zvrstven\u00fdm dimiktick\u00fdm n\u00e1dr\u017e\u00edm vytv\u00e1\u0159ej\u00edc\u00edm letn\u00ed i\u00a0zimn\u00ed stratifikaci. Kam\u00fdk je siln\u011b pr\u016fto\u010dn\u00e1 nestratifikovan\u00e1 n\u00e1dr\u017e. Slapy jsou zvrstven\u00e1 monomiktick\u00e1 n\u00e1dr\u017e, kter\u00e1 v\u00a0zim\u011b nezamrz\u00e1 a\u00a0v\u00a0dob\u011b letn\u00ed stratifikace se vyzna\u010duje v\u00fdrazn\u00fdm zkratov\u00e1n\u00edm p\u0159\u00edtoku hypolimniem, proto\u017ee relativn\u011b chladn\u00e1 voda vypou\u0161t\u011bn\u00e1 z\u00a0hypolimnia n\u00e1dr\u017ee Orl\u00edk se ve Slapech zasunuje do spodn\u00edch vrstev, odkud je odtahov\u00e1na na turb\u00edny hydroelektr\u00e1rny v\u00fdpustmi v\u00a0hloubce cca 40\u2008m.<\/p>\n\"\"<\/a>\n

Obr. 1. Pr\u016ftokov\u011b v\u00e1\u017een\u00e9 pr\u016fm\u011brn\u00e9 ro\u010dn\u00ed koncentrace Pcelk<\/sub> v\u00a0n\u00e1dr\u017e\u00edch Orl\u00edk a\u00a0Slapy a\u00a0v\u00a0jejich p\u0159\u00edtoc\u00edch a\u00a0odtoc\u00edch v\u00a0obdob\u00ed 1961\u20132015, s\u00a0vyzna\u010den\u00edm hranice mezi dobr\u00fdm a\u00a0st\u0159edn\u00edm ekologick\u00fdm potenci\u00e1lem RVS (0,03\u2008mg\u2219l-1<\/sup> shodn\u011b pro ob\u011b n\u00e1dr\u017ee)
\nFig. 1. Flow-weighted average annual concentrations of total P in Orl\u00edk and Slapy reservoirs and their tributaries in the period 1961\u20132015, indicating the boundary between the good and moderate ecological potential of EU WFD (0.03\u2008mg\u2219l-1<\/sup> for both reservoirs)<\/h6>\n

Pro charakterizaci kvality vody byla pou\u017eita: (i) Data z\u00a0dlouhodob\u00e9ho sledov\u00e1n\u00ed n\u00e1dr\u017ee Slapy Hydrobiologick\u00fdm \u00fastavem Biologick\u00e9ho centra AV\u00a0\u010cR, v.\u00a0v.\u00a0i.\u00a0(HB\u00da), kter\u00e9 prob\u00edhalo nep\u0159etr\u017eit\u011b od r. 1959 v\u00a0t\u0159\u00edt\u00fddenn\u00edch intervalech v\u00a0profilu Neb\u0159ich (nad \u017divoho\u0161\u0165sk\u00fdm mostem) a\u00a0po dobu omezen\u00fdch \u010dasov\u00fdch \u00fasek\u016f tak\u00e9 na p\u0159\u00edtoku do n\u00e1dr\u017ee (Vltava \u2013 Kam\u00fdk nad Vlt.) a\u00a0na odtoku (VN Slapy \u2013 v\u00fdtok). Po celou dobu sledov\u00e1n\u00ed byl analyzov\u00e1n celkov\u00fd fosfor (Pcelk<\/sub>) citlivou limnologickou metodou (s\u00a0mez\u00ed stanovitelnosti 0,003\u2008mg\u2219l-1<\/sup>) po mineralizaci s\u00a0kyselinou chloristou [16\u201318]. (ii) Data z\u00a0provozn\u00edho sledov\u00e1n\u00ed jakosti povrchov\u00fdch vod prov\u00e1d\u011bn\u00e9ho podnikem Povod\u00ed Vltavy, st\u00e1tn\u00ed podnik (PVL) a\u00a0jeho p\u0159edch\u016fdci od r. 1963 v\u00a0m\u011bs\u00ed\u010dn\u00edch intervalech v\u00a0profilech Vltava \u2013 T\u00fdn n\/Vlt., Lu\u017enice \u2013 Kolod\u011bje (pop\u0159. od r.\u00a02013 Bechyn\u011b), Otava \u2013 P\u00edsek, Lomnice \u2013 Doln\u00ed Ostrovec, Skalice \u2013 Varva\u017eov, VN Orl\u00edk \u2013 hr\u00e1z, Vltava \u2013 Solenice (v\u00fdtok VN Orl\u00edk; od r. 1972), Mastn\u00edk \u2013 Rad\u00ed\u010d (od r. 2011), VN Slapy \u2013 hr\u00e1z a\u00a0VN \u0160t\u011bchovice \u2013 hr\u00e1z (od r. 1979). Koncentrace Pcelk<\/sub> se v\u00a0t\u011bchto datov\u00fdch \u0159ad\u00e1ch za\u010daly analyzovat a\u017e po\u010d\u00ednaje rokem 1990. V\u00a0d\u0159\u00edv\u011bj\u0161\u00edm obdob\u00ed byla data Pcelk<\/sub> zrekonstruov\u00e1na jako sou\u010det jej\u00edch d\u00edl\u010d\u00edch slo\u017eek, tj. Pcelk<\/sub> = PO4<\/sub>-P + RNP + PP, kde: PO4<\/sub>-P je ortofosfore\u010dnanov\u00fd P, kter\u00fd byl p\u0159\u00edmo analyzov\u00e1n od r. 1972 jako rozpu\u0161t\u011bn\u00fd reaktivn\u00ed P a\u00a0v\u00a0p\u0159edchoz\u00edch letech byl dopo\u010dten z\u00a0regresn\u00edch z\u00e1vislost\u00ed na pr\u016ftoku, pop\u0159. tak\u00e9 na teplot\u011b vody, kalibrovan\u00fdch pro ka\u017ed\u00fd jednotliv\u00fd profil; RNP je rozpu\u0161t\u011bn\u00fd nereaktivn\u00ed P, kter\u00fd byl vypo\u010dten z\u00a0koncentrace CHSKMn<\/sub> pomoc\u00ed\u00a0regresn\u00ed rovnice RNP [mg\u2219l-1<\/sup>] = 0,0015 \u00d7 CHSKMn<\/sub> [mg\u2219l\u2011<\/sup>1<\/sup>] z\u00edskan\u00e9 pro toky v\u00a0povod\u00ed Mal\u0161e, jej\u00ed\u017e platnost byla ale ov\u011b\u0159ena tak\u00e9 na n\u011bkolikalet\u00fdch datech pro\u00a0n\u00e1dr\u017e Orl\u00edk (profil hr\u00e1z, 1990\u20131991) a\u00a0Slapy-Neb\u0159ich (1998\u20132016) (Hejzlar, nepublikovan\u00e1 data); a\u00a0PP je nerozpu\u0161t\u011bn\u00fd (partikulovan\u00fd) fosfor, kter\u00fd byl vypo\u010dten z\u00a0regresn\u00edch vztah\u016f na koncentraci su\u0161iny nerozpu\u0161t\u011bn\u00fdch l\u00e1tek (NL105), pop\u0159. tak\u00e9 ztr\u00e1t\u011b \u017e\u00edh\u00e1n\u00edm (NL550), kalibrovan\u00fdch pro jednotliv\u00e9 profily. Pro hodnocen\u00ed dlouhodob\u00fdch koncentra\u010dn\u00edch trend\u016f statistick\u00fdmi metodami byly pro v\u0161echny lokality vypo\u010dteny m\u011bs\u00ed\u010dn\u00ed pr\u016fm\u011bry. Pro hodnocen\u00ed spln\u011bn\u00ed\/p\u0159ekro\u010den\u00ed limit\u016f pro dobr\u00fd ekologick\u00fd potenci\u00e1l podle RVS [15] byly v\u00a0profilech n\u00e1dr\u017e\u00ed VN Orl\u00edk \u2013 hr\u00e1z a\u00a0Slapy \u2013 Neb\u0159ich vypo\u010dteny pr\u016fm\u011brn\u00e9 hodnoty za\u00a0obdob\u00ed duben a\u017e \u0159\u00edjen.<\/p>\n

Denn\u00ed pr\u016ftokov\u00e1 data v\u00a0p\u0159\u00edtoc\u00edch do n\u00e1dr\u017ee Orl\u00edk poch\u00e1zej\u00ed z\u00a0m\u011b\u0159en\u00ed na limnigrafick\u00fdch stanic\u00edch \u010cesk\u00e9ho hydrometeorologick\u00e9m \u00fastavu (\u010cHM\u00da) Vltava \u2013 Hlubok\u00e1 n\/Vlt., pop\u0159. Vltava\u00a0\u2013 \u010cesk\u00e9 Bud\u011bjovice (po r. 1990), Lu\u017enice \u2013 Bechyn\u011b, Otava \u2013 P\u00edsek, Lomnice \u2013 Doln\u00ed Ostrovec, Skalice \u2013 Varva\u017eov; p\u0159\u00edtok do n\u00e1dr\u017e\u00ed z\u00a0nem\u011b\u0159en\u00e9ho zbytku povod\u00ed v\u010detn\u011b pr\u016ftoku v\u00a0profilu Mastn\u00edk \u2013 Rad\u00ed\u010d byl vypo\u010dten hydrologickou analogi\u00ed na z\u00e1klad\u011b pr\u016fm\u011brn\u00e9ho odtoku z\u00a0povod\u00ed Lomnice a\u00a0Skalice. \u00dadaje o\u00a0k\u00f3t\u00e1ch hladiny, odb\u011brech hydroelektr\u00e1ren a\u00a0celkov\u00e9m odtoku byly z\u00edsk\u00e1ny z\u00a0p\u00edsemn\u00fdch hodinov\u00fdch z\u00e1znam\u016f, pop\u0159. po roce 1990 z\u00a0elektronick\u00e9 datab\u00e1ze arch\u00edvu provozn\u00edho sledov\u00e1n\u00ed Vltavsk\u00e9 kask\u00e1dy v\u00a0pra\u017esk\u00e9m centr\u00e1ln\u00edm vodohospod\u00e1\u0159sk\u00e9m dispe\u010dinku PVL. Odtok z\u00a0n\u00e1dr\u017e\u00ed byl n\u00e1sledn\u011b zrekonstruov\u00e1n metodou bilancov\u00e1n\u00ed mno\u017estv\u00ed p\u0159it\u00e9kaj\u00edc\u00ed vody a\u00a0aktu\u00e1ln\u00edch zm\u011bn objemu vody v\u00a0n\u00e1dr\u017e\u00edch s\u00a0krokem 1\u00a0hodina. Dlouhodob\u00e1 denn\u00ed klimatick\u00e1 data v\u00a0m\u011b\u0159\u00edc\u00edch stanic\u00edch T\u00e1bor a\u00a0\u010cesk\u00e9 Bud\u011bjovice poch\u00e1z\u00ed z\u00a0datab\u00e1ze\u00a0\u010cHM\u00da.<\/p>\n

Bilan\u010dn\u00ed v\u00fdpo\u010dty ro\u010dn\u00edho mno\u017estv\u00ed P p\u0159in\u00e1\u0161en\u00e9ho do n\u00e1dr\u017e\u00ed p\u0159\u00edtoky a\u00a0mno\u017estv\u00ed P odt\u00e9kaj\u00edc\u00edho z\u00a0n\u00e1dr\u017e\u00ed byly prov\u00e1d\u011bny v\u00a0m\u011bs\u00ed\u010dn\u00edm kroku vyn\u00e1soben\u00edm pr\u016fm\u011brn\u00e9ho m\u011bs\u00ed\u010dn\u00edho pr\u016ftoku a\u00a0pr\u016fm\u011brn\u00e9 koncentrace P z\u00a0dat nam\u011b\u0159en\u00fdch v\u00a0dan\u00e9m m\u011bs\u00edci a\u00a0sumac\u00ed do ro\u010dn\u00edch hodnot. Z\u00a0celkov\u00e9ho ro\u010dn\u00edho mno\u017estv\u00ed\u00a0P a\u00a0mno\u017estv\u00ed vody protekl\u00e9 v\u00a0dan\u00e9m profilu pak byla vypo\u010dtena pr\u016ftokov\u011b v\u00e1\u017een\u00e1 pr\u016fm\u011brn\u00e1 koncentrace. Do vstupu P do n\u00e1dr\u017ee byla zahrnuta rovn\u011b\u017e atmosf\u00e9rick\u00e1 depozice na z\u00e1klad\u011b m\u011b\u0159en\u00ed mno\u017estv\u00ed a\u00a0slo\u017een\u00ed sr\u00e1\u017eek na n\u00e1dr\u017ei Slapy v\u00a0profilu Neb\u0159ich Hydrobiologick\u00fdm \u00fastavem BC AV \u010cR. Pr\u016fm\u011brn\u00e1 ro\u010dn\u00ed hodnota depozice Pcelk<\/sub> v\u00a0obdob\u00ed 1979\u20132015 byla 9 \u00b1 2\u2008mg\u2219m-2<\/sup>, co\u017e p\u0159edstavuje z\u00a0hlediska celkov\u00e9ho zat\u00ed\u017een\u00ed n\u00e1dr\u017ee fosforem nev\u00fdznamn\u00e9 mno\u017estv\u00ed, tj. < 1\u00a0%.<\/p>\n

Socioekonomick\u00e9 ukazatele charakterizuj\u00edc\u00ed r\u016fst populace, zem\u011bd\u011blsk\u00e9 aktivity a\u00a0v\u00fdvoj komun\u00e1ln\u00ed infrastruktury poch\u00e1zej\u00ed ze statistick\u00fdch ro\u010denek \u010cesk\u00e9ho statistick\u00e9ho \u00fa\u0159adu pro Jiho\u010desk\u00fd kraj.<\/p>\n

Retence P v\u00a0n\u00e1dr\u017e\u00edch byla hodnocena pomoc\u00ed empirick\u00e9ho modelu zalo\u017een\u00e9ho na vztahu retence \u017eivin a\u00a0hydrauliky n\u00e1dr\u017ee podle Chapra [12]. Model pou\u017e\u00edv\u00e1 z\u00e1kladn\u00ed rovnici s\u00a0definov\u00e1n\u00edm retence R: Po<\/sub> = Pin<\/sub>(1 \u2013 R), kde Po<\/sub> je pr\u016fm\u011brn\u00e1 ro\u010dn\u00ed koncentrace P v\u00a0odtoku z\u00a0n\u00e1dr\u017ee; Pin<\/sub> je objemov\u011b v\u00e1\u017een\u00e1 koncentrace P v\u00a0celkov\u00e9m p\u0159\u00edtoku do n\u00e1dr\u017ee, tj. pod\u00edl l\u00e1tkov\u00e9ho mno\u017estv\u00ed P vstupuj\u00edc\u00edho do n\u00e1dr\u017ee ze v\u0161ech zdroj\u016f (p\u0159\u00edtoky, atmosf\u00e9rick\u00e1 depozice atd.) a\u00a0celkov\u00e9ho vstupu vody do n\u00e1dr\u017ee. V\u00a0tomto modelu je retence z\u00e1visl\u00e1 na hydraulick\u00e9m zat\u00ed\u017een\u00ed podle vzorce: R = \u03bdP<\/sub>\/(\u03bdP<\/sub> + qw<\/sub>), kde \u03bdP<\/sub> [m\u2219a-1<\/sup>] je sou\u010dinitel sedimenta\u010dn\u00ed rychlosti P v\u00a0n\u00e1dr\u017ei (sou\u010dinitel reakce 1. \u0159\u00e1du pro retenci P) a\u00a0qw<\/sub> [m a-1<\/sup>] je hydraulick\u00e9 zat\u00ed\u017een\u00ed n\u00e1dr\u017ee vzta\u017een\u00e9 na plochu jej\u00ed hladiny. Hodnoty \u03bdP<\/sub> byly vypo\u010dteny pro n\u00e1dr\u017ee Orl\u00edk a\u00a0Slapy z\u00a0nam\u011b\u0159en\u00fdch dat Po<\/sub>, Pin<\/sub> a\u00a0qw<\/sub> pomoc\u00ed vztahu vznikl\u00e9ho spojen\u00edm a\u00a0\u00fapravou dvou v\u00fd\u0161e uveden\u00fdch rovnic: \u03bdP<\/sub>\u00a0=\u00a0qw<\/sub>(Pin<\/sub> \u2013 Po<\/sub>)\/Po<\/sub>.<\/p>\n

Tabulka 1. Hlavn\u00ed technick\u00e9 charakteristiky sledovan\u00fdch n\u00e1dr\u017e\u00ed (pr\u016fm\u011bry 1961\u20132015)
\nTable 1. Main technical characteristics of the studied reservoirs (averages 1961\u20132015)<\/h5>\n\"\"<\/a>\n

Statistick\u00e9 metody pou\u017eit\u00e9 pro anal\u00fdzu datov\u00fdch \u0159ad zahrnovaly zejm\u00e9na: (i) sezonn\u00ed Kendall\u016fv test [19], co\u017e je neparametrick\u00e1 metoda pro detekci monot\u00f3nn\u00edch trend\u016f; (ii) line\u00e1rn\u00ed regresn\u00ed anal\u00fdzu a\u00a0korela\u010dn\u00ed anal\u00fdzu (MS Excel 2010) pro hodnocen\u00ed vztah\u016f mezi veli\u010dinami; (iii)\u00a0segmentovou regresn\u00ed anal\u00fdzu [20], kter\u00e1 byla vyu\u017e\u00edv\u00e1na pro detekci zlomov\u00fdch bod\u016f v\u00a0datov\u00fdch \u0159ad\u00e1ch (program SegReg vyvinut\u00fd v\u00a0Institute for Land Reclamation and Improvement, Nizozemsko; http:\/\/www.waterlog.info\/segreg.htm). V\u0161echny statistick\u00e9 testy byly prov\u00e1d\u011bny na hladin\u011b v\u00fdznamnosti \u03b1 = 0,05.<\/p>\n

Trendy v\u00fdvoje koncentrac\u00ed Pcelk<\/sub><\/h2>\n

Pr\u016ftokov\u011b v\u00e1\u017een\u00e9 pr\u016fm\u011brn\u00e9 ro\u010dn\u00ed koncentrace Pcelk<\/sub> v\u00a0n\u00e1dr\u017e\u00edch Orl\u00edk, Slapy i\u00a0v\u00a0jejich p\u0159\u00edtoc\u00edch (obr. 1<\/em>) m\u011bly b\u011bhem obdob\u00ed 1961\u20132015 charakteristick\u00fd pr\u016fb\u011bh s\u00a0postupn\u00fdm n\u00e1r\u016fstem vrchol\u00edc\u00edm na p\u0159elomu 80. a\u00a090. let minul\u00e9ho stolet\u00ed, rychl\u00fdm poklesem do roku 2005 a\u00a0pak s\u00a0pom\u011brn\u011b vyrovnan\u00fdmi hodnotami. Nejv\u00fdrazn\u011bj\u0161\u00ed n\u00e1r\u016fst (z\u00a0hodnot kolem 0,15\u2008mg\u2219l-1<\/sup> \u2013 cca do roku 1975), vrchol (0,25\u2008mg\u2219l-1<\/sup> v\u00a0letech 1989\u20131990) a\u00a0pokles (na cca 0,13\u2008mg\u2219l-1<\/sup> od roku 2007) m\u011bly koncentrace Pcelk<\/sub> v\u00a0celkov\u00e9m p\u0159\u00edtoku do n\u00e1dr\u017ee Orl\u00edk, co\u017e bylo v\u00fdsledkem kombinace trend\u016f v\u00a0d\u00edl\u010d\u00edch p\u0159\u00edtoc\u00edch, z\u00a0nich\u017e pr\u016ftokov\u011b nejv\u00fdznamn\u011bj\u0161\u00ed je Vltava p\u0159iv\u00e1d\u011bj\u00edc\u00ed do n\u00e1dr\u017ee 35\u00a0% vody a\u00a0d\u00e1le Otava (30\u00a0%) s\u00a0Lu\u017enic\u00ed (28\u00a0%), kde\u017eto ostatn\u00ed p\u0159\u00edtoky jsou relativn\u011b mal\u00e9 (Lomnice 2\u00a0%; Skalice 2\u00a0%, zbytek povod\u00ed 3\u00a0%). Z\u00a0hlavn\u00edch p\u0159\u00edtok\u016f p\u0159in\u00e1\u0161ela do n\u00e1dr\u017ee Orl\u00edk nejvy\u0161\u0161\u00ed koncentrace Pcelk<\/sub> Lu\u017enice, u\u00a0n\u00ed\u017e byl ve srovn\u00e1n\u00ed s\u00a0Vltavou i\u00a0Otavou pokles v\u00a0posledn\u00edch cca 30 letech relativn\u011b i\u00a0absolutn\u011b nejni\u017e\u0161\u00ed. V\u00a0n\u00e1dr\u017ei Orl\u00edk se p\u0159\u00edtokov\u00e1 koncentrace Pcelk<\/sub> v\u00fdrazn\u011b sni\u017eovala a\u00a0v\u00a0odtoku byla p\u0159ibli\u017en\u011b polovi\u010dn\u00ed. Celkov\u00fd p\u0159\u00edtok do n\u00e1dr\u017ee Slapy byl oproti odtoku z\u00a0n\u00e1dr\u017ee Orl\u00edk m\u00edrn\u011b nav\u00fd\u0161en v\u00a0d\u016fsledku zne\u010di\u0161t\u011bn\u00fdch bo\u010dn\u00edch p\u0159\u00edtok\u016f, reprezentovan\u00fdch v\u00a0na\u0161\u00ed studii nejvodn\u011bj\u0161\u00edm z\u00a0nich, potokem Mastn\u00edk (p\u0159iv\u00e1d\u00ed do n\u00e1dr\u017ee Slapy 55\u00a0% vody bo\u010dn\u00edch p\u0159\u00edtok\u016f, \u010di 1,5\u00a0% celkov\u00e9ho p\u0159\u00edtoku).\u00a0Koncentrace Pcelk<\/sub> se v\u00a0n\u00e1dr\u017ei Slapy sni\u017eovala sedimenta\u010dn\u00edmi procesy zhruba o\u00a030\u00a0% na rozmez\u00ed 0,065\u20130,09\u2008mg\u2219l-1<\/sup>. Pr\u016fm\u011brn\u00e9 koncentrace Pcelk<\/sub> b\u011bhem vegeta\u010dn\u00edho obdob\u00ed (duben\u2013\u0159\u00edjen) v\u00a0hladinov\u00e9 vrstv\u011b, je\u017e se pou\u017e\u00edvaj\u00ed p\u0159i hodnocen\u00ed ekologick\u00e9ho potenci\u00e1lu RVS, byly v\u00fdrazn\u011b ni\u017e\u0161\u00ed ne\u017e odtokov\u00e9 koncentrace, co\u017e je typick\u00e9 pro stratifikovan\u00e9 n\u00e1dr\u017ee se spodn\u00edm vypou\u0161t\u011bn\u00edm, kter\u00e9 zp\u016fsobuje zkratov\u00e1n\u00ed p\u0159\u00edtoku hypolimniem a\u00a0jeho omezen\u00e9 prom\u00edch\u00e1v\u00e1n\u00ed s\u00a0hladinovou vrstvou. V\u00a0posledn\u00edch dek\u00e1d\u00e1ch tyto koncentrace v\u00a0n\u00e1dr\u017ei Slapy kol\u00edsaly kolem limitn\u00ed hranice pro dobr\u00fd ekologick\u00fd potenci\u00e1l 0,03\u2008mg\u2219l-1<\/sup> (je\u017e je shodn\u00e1 pro n\u00e1dr\u017e Slapy i\u00a0Orl\u00edk [15]), kde\u017eto v\u00a0n\u00e1dr\u017ei Orl\u00edk byly tyto koncentrace a\u017e na v\u00fdjimky vy\u0161\u0161\u00ed (obr. 1<\/em>).<\/p>\n\"\"<\/a>\n

Obr. 2. V\u00fdvoj socio-ekonomick\u00fdch ukazatel\u016f v\u00a0povod\u00ed n\u00e1dr\u017ee Slapy: (a) celkov\u00fd po\u010det obyvatel, populace p\u0159ipojen\u00e1 ke kanalizaci a\u00a0ke kanalizaci s\u00a0\u010cOV; (b) export P z\u00a0bodov\u00fdch zdroj\u016f do povrchov\u00fdch vod a\u00a0specifick\u00e1 produkce P obyvatelstvem do odpadn\u00edch vod (Pspec<\/sub>); (c) aplikace P v\u00a0hnojivech, hustota dobytka na zem\u011bd\u011blsk\u00e9 p\u016fd\u011b a\u00a0intenzita rybni\u010dn\u00edho chovu ryb
\nFig. 2. Development of socio-economic indicators in the Slapy catchment: (a) total population (populace celkem), population connected to sewerage (kanalizace) and sewerage with WWTP (kanalizace + \u010cOV); (b) export of P from point source to surface water and specific P production by population to wastewater (Pspec<\/sub>); (c) P application in fertilizers, livestock density on farmland, and intensity of fish pond production<\/h6>\n

Trendy socioekonomick\u00fdch ukazatel\u016f v povod\u00ed<\/h2>\n

Socioekonomick\u00e9 ukazatele se v\u00a0povod\u00ed n\u00e1dr\u017ee Slapy b\u011bhem posledn\u00edho p\u016flstolet\u00ed v\u00fdrazn\u011b vyv\u00edjely, s\u00a0nejv\u011bt\u0161\u00edmi zm\u011bnami zhruba do poloviny 90. let minul\u00e9ho stolet\u00ed (obr. 2<\/em>). Po\u010det obyvatel se zv\u011bt\u0161oval jen m\u00edrn\u011b, ale z\u00e1sadn\u011b se m\u011bnila velikost populace p\u0159ipojen\u00e9 na kanalizaci a\u00a0\u010dist\u00edrny odpadn\u00edch vod (obr.<\/em>\u00a02a<\/em>), jako i\u00a0\u00fa\u010dinnosti \u010cOV z\u00a0hlediska odstra\u0148ov\u00e1n\u00ed P. V\u00fdrazn\u00fdmi zm\u011bnami pro\u0161la tak\u00e9 specifick\u00e1 produkce P obyvatelstvem do komun\u00e1ln\u00edch odpadn\u00edch vod (obr.<\/em>\u00a02b<\/em>), kter\u00e1 a\u017e do po\u010d\u00e1tku 90. let rostla v\u00a0d\u016fsledku zvy\u0161ov\u00e1n\u00ed pou\u017eit\u00ed fosf\u00e1tov\u00fdch detergent\u016f a\u00a0pot\u00e9 klesla ve dvou vln\u00e1ch \u2013 po uzav\u0159en\u00ed dohody Ministerstva \u017eivotn\u00edho prost\u0159ed\u00ed \u010cR s\u00a0v\u00fdrobci detergent\u016f o\u00a0omezen\u00ed koncentrace fosforu v\u00a0detergentech v\u00a0roce 1995 a\u00a0\u00fapln\u00e9m legislativn\u00edm z\u00e1kazu fosf\u00e1tov\u00fdch detergent\u016f v\u00a0maloobchodn\u00edm prodeji v\u00a0roce 2006. V\u00fdsledkem t\u011bchto zm\u011bn byl dramatick\u00fd v\u00fdvoj v\u00a0mno\u017estv\u00ed P ve vypou\u0161t\u011bn\u00fdch odpadn\u00edch vod\u00e1ch (obr. 2b<\/em>), kter\u00e9 od 60. do 90.\u00a0let minul\u00e9ho stolet\u00ed postupn\u011b nar\u016fstalo a\u017e na v\u00edce ne\u017e \u010dty\u0159n\u00e1sobek, ale pak nastal obrat a\u00a0mno\u017estv\u00ed vypou\u0161t\u011bn\u00e9ho P za\u010dalo po\u010d\u00e1tkem 90. let klesat po proveden\u00fdch intenzifikac\u00edch v\u011bt\u0161\u00edch \u010cOV (nad 10 000 EO), kter\u00e9 byly vybavov\u00e1ny technologiemi pro zv\u00fd\u0161en\u00e9 odstra\u0148ov\u00e1n\u00ed P. V\u00a0zem\u011bd\u011blsk\u00e9m sektoru se zvy\u0161ovaly do konce 80. let aplikace P v\u00a0miner\u00e1ln\u00edch hnojivech z\u00a010 na 37\u2008kg\u2219ha\u2011<\/sup>1<\/sup> a\u00a0v\u00a0organick\u00fdch hnojivech z\u00a015 na 20\u2008kg\u2219ha\u2011<\/sup>1<\/sup>, ale pak nastal jejich v\u00fdrazn\u00fd pokles. Intenzita ro\u010dn\u00ed produkce rybni\u010dn\u00edho chovu ryb vzrostla z\u00a0po\u010d\u00e1te\u010dn\u00ed hodnoty cca 230\u2008kg\u2219ha\u2011<\/sup>1<\/sup> na > 500\u2008kg\u2219ha\u2011<\/sup>1<\/sup> v\u00a090. letech a\u00a0do konce sledovan\u00e9ho obdob\u00ed se udr\u017eovala na t\u00e9to \u00farovni (obr. 2c<\/em>).<\/p>\n

Tabulka 2. Korela\u010dn\u00ed vztahy mezi ro\u010dn\u00ed pr\u016fm\u011brnou koncentrac\u00ed Pcelk<\/sub> v\u00a0celkov\u00e9m p\u0159\u00edtoku do n\u00e1dr\u017ee Orl\u00edk a\u00a0ro\u010dn\u00edmi hodnotami socio-ekonomick\u00fdch ukazatel\u016f v\u00a0povod\u00ed (Bod. z. P\u00a0\u2013 bodov\u00e9 zdroje P v\u00a0povod\u00ed; Pspec<\/sub> \u2013 specifick\u00e1 produkce P obyvatelstvem do komun\u00e1ln\u00edch odpadn\u00edch vod; XK<\/sub> \u2013 pod\u00edl obyvatel p\u0159ipojen\u00fdch na kanalizaci; X\u010cOV<\/sub> \u2013 pod\u00edl obyvatel p\u0159ipojen\u00fdch na kanalizaci s\u00a0\u010cOV; Hnoj. org. \u2013 hnojen\u00ed P v\u00a0organick\u00fdch hnojivech; Hnoj. min. \u2013 hnojen\u00ed P v\u00a0miner\u00e1ln\u00edch hnojivech; Dobytek \u2013 hustota dobytka na zem\u011bd\u011blsk\u00e9 p\u016fd\u011b; Chov ryb \u2013 ro\u010dn\u00ed produkce rybni\u010dn\u00edho chovu ryb) pro\u00a0r\u016fzn\u00e1 \u010dasov\u00e1 obdob\u00ed
\nTable 2. Correlation between the annual average concentration of total P in the total inflow into the Orl\u00edk reservoir and the annual values of socio-economic indicators in the catchment (Bod. z. P \u2013 point sources of P in catchment; Pspec<\/sub> \u2013 specific P production by population to wastewater; XK<\/sub> \u2013 proportion of population connected to sewerage; X\u010cOV<\/sub> \u2013 proportion of population connected to sewerage with WWTP; Hnoj.org. \u2013 fertilisation of farmland with manure; Hnoj. min. \u2013 mineral fertilisers; Dobytek \u2013 livestock on farmland; Chov ryb \u2013 annual fish pond production) in different time periods<\/h5>\n\"\"<\/a>\n

Korela\u010dn\u00ed anal\u00fdza prok\u00e1zala pro celkov\u00e9 obdob\u00ed 1961\u20132015 statisticky v\u00fdznamn\u00e9 pozitivn\u00ed vztahy mezi ro\u010dn\u00ed pr\u016fm\u011brnou koncentrac\u00ed Pcelk<\/sub> v\u00a0p\u0159\u00edtoku do n\u00e1dr\u017ee Orl\u00edk a\u00a0zat\u00ed\u017een\u00edm P z\u00a0odpadn\u00edch vod, specifickou produkc\u00ed P obyvatelstva do odpadn\u00edch vod a\u00a0hnojen\u00edm organick\u00fdmi i\u00a0miner\u00e1ln\u00edmi hnojivy, tj. se v\u0161emi\u00a0ukazateli s\u00a0maximem na p\u0159elomu 80. a\u00a090. let minul\u00e9ho stolet\u00ed (tabulka<\/em>\u00a02<\/em>). Pro d\u00edl\u010d\u00ed obdob\u00ed p\u0159ed a\u00a0do roku 1991 byly zji\u0161t\u011bny v\u00fdznamn\u00e9 korelace tak\u00e9 pro pod\u00edly p\u0159ipojen\u00fdch obyvatel na kanalizaci i\u00a0na kanalizaci s\u00a0\u010cOV a\u00a0pro velikost produkce chovu ryb. V\u00a0obdob\u00ed 1961\u20131990 byly korelace s\u00a0t\u011bmito ukazateli pozitivn\u00ed, kde\u017eto v\u00a0obdob\u00ed 1991\u20132015 negativn\u00ed, co\u017e znamen\u00e1, \u017ee v\u00fdznam a\u00a0pod\u00edl t\u011bchto d\u00edl\u010d\u00edch ukazatel\u016f z\u00a0hlediska celkov\u00fdch zdroj\u016f P v\u00a0povod\u00ed z\u00a0kvantitativn\u00edho hlediska nebyl rozhoduj\u00edc\u00ed. Korela\u010dn\u00ed anal\u00fdza nedok\u00e1\u017ee jednozna\u010dn\u011b rozli\u0161it m\u00edru vlivu jednotliv\u00fdch autokorelovan\u00fdch veli\u010din, co\u017e je p\u0159\u00edpad v\u011bt\u0161iny veli\u010din zahrnut\u00fdch do t\u00e9to anal\u00fdzy, nicm\u00e9n\u011b i\u00a0tak lze z\u00a0v\u00fdsledk\u016f ud\u011blat jednozna\u010dn\u00fd z\u00e1v\u011br o\u00a0tom, \u017ee jak bodov\u00e9 zdroje P, tj. vypou\u0161t\u011bn\u00ed komun\u00e1ln\u00edch odpadn\u00edch vod, tak dif\u00fazn\u00ed zdroje P, tj. zem\u011bd\u011blsk\u00e9 hospoda\u0159en\u00ed, pop\u0159. tak\u00e9 s\u00a0ryb\u00e1\u0159stv\u00edm, jsou hlavn\u00edmi p\u0159isp\u011bvateli ke zne\u010di\u0161t\u011bn\u00ed n\u00e1dr\u017e\u00ed Orl\u00edk a\u00a0Slapy fosforem. K\u00a0zodpov\u011bzen\u00ed ot\u00e1zky, kter\u00fd z\u00a0t\u011bchto dvou typ\u016f zdroj\u016f kvantitativn\u011b p\u0159eva\u017eoval, by v\u0161ak bylo t\u0159eba mnohem podrobn\u011bj\u0161\u00edho rozboru \u010dasov\u00fdch \u0159ad odnosu\u00a0P z\u00a0d\u00edl\u010d\u00edch subpovod\u00ed, zejm\u00e9na s\u00a0vyhodnocen\u00edm z\u00e1vislost\u00ed odnosu na pr\u016ftoku a\u00a0velikosti do\u010dasn\u00e9 i\u00a0trval\u00e9 retence P v\u00a0\u0159\u00ed\u010dn\u00ed s\u00edti, rybn\u00edc\u00edch a\u00a0jin\u00fdch n\u00e1dr\u017e\u00edch.<\/p>\n

Retence fosforu v n\u00e1dr\u017e\u00edch<\/h2>\n

Relativn\u00ed mno\u017estv\u00ed zadr\u017een\u00e9ho P (neboli koeficient retence R) v\u00a0n\u00e1dr\u017ei Orl\u00edk v\u00a0letech 1972\u20132015, pro n\u011b\u017e se n\u00e1m poda\u0159ilo zrekonstruovat p\u0159\u00edtokov\u00e9 i\u00a0odtokov\u00e9 koncentrace, kol\u00edsalo v\u00a0rozmez\u00ed od 0,31 do 0,58\u2008s\u00a0pr\u016fm\u011brem (\u00b1 sm\u011brodatnou odchylkou) 0,44 \u00b1 0,06 a\u00a0bylo zhruba o\u00a0polovinu vy\u0161\u0161\u00ed ne\u017e byla hodnota R v\u00a0n\u00e1dr\u017ei Slapy, tj. pr\u016fm\u011br 0,30 \u00b1 0,05 pro obdob\u00ed 1979\u20132015 (obr. 3a<\/em>). Hodnoty R byly nejvy\u0161\u0161\u00ed v\u00a080. letech s\u00a0m\u00edrnou (statisticky nev\u00fdznamnou) tendenc\u00ed k\u00a0poklesu v\u00a0pozd\u011bj\u0161\u00edch letech. Odli\u0161nosti v\u00a0retenci R mezi ob\u011bma n\u00e1dr\u017eemi i\u00a0meziro\u010dn\u00ed variabilitu R lze p\u0159ipsat na vrub hlavn\u011b rozd\u00edl\u016fm doby zdr\u017een\u00ed vody v\u00a0n\u00e1dr\u017e\u00edch a\u00a0meziro\u010dn\u00edmu kol\u00eds\u00e1n\u00ed pr\u016ftok\u016f, proto\u017ee sou\u010dinitel sedimenta\u010dn\u00ed rychlosti \u03bdP<\/sub> nab\u00fdval v\u00a0obou n\u00e1dr\u017e\u00edch srovnateln\u00fdch pr\u016fm\u011brn\u00fdch hodnot, tj. 95 \u00b1 33\u2008m\u2219a\u2011<\/sup>1<\/sup> v\u00a0n\u00e1dr\u017ei Orl\u00edk a\u00a0105 \u00b1 36\u2008m\u2219a\u2011<\/sup>1<\/sup> v\u00a0n\u00e1dr\u017ei Slapy. Zm\u011bny \u03bdP<\/sub> v\u00a0pr\u016fb\u011bhu sledovan\u00e9ho obdob\u00ed prob\u00edhaly v\u00a0obou n\u00e1dr\u017e\u00edch v\u00edcem\u00e9n\u011b soub\u011b\u017en\u011b (obr. 3b<\/em>), tak\u017ee mezi jejich ro\u010dn\u00edmi hodnotami \u03bdP <\/sub>byl siln\u00fd korela\u010dn\u00ed vztah, vysv\u011btluj\u00edc\u00ed 52\u00a0% variability (obr. 3c<\/em>). P\u0159\u00ed\u010diny variability hodnot \u03bdP<\/sub> jsme testovali pomoc\u00ed korela\u010dn\u00ed anal\u00fdzy a\u00a0v\u00edcen\u00e1sobn\u00e9 line\u00e1rn\u00ed regresn\u00ed anal\u00fdzy a\u00a0hledali jsme souvislosti nap\u0159. s\u00a0koncentracemi a\u00a0slo\u017een\u00edm forem P v\u00a0p\u0159\u00edtoc\u00edch do n\u00e1dr\u017e\u00ed, pr\u016ftokem, teplotou vody \u010di klimatick\u00fdmi veli\u010dinami. Jako jedin\u00e1 statisticky v\u00fdznamn\u00e1 p\u0159\u00ed\u010dina byla nalezena pozitivn\u00ed z\u00e1vislost \u03bdP<\/sub> na absolutn\u00ed velikosti p\u0159\u00edsunu P do n\u00e1dr\u017ee, kter\u00e1 se ale li\u0161ila ve velikosti sm\u011brnice v\u00a0obdob\u00edch p\u0159ed rokem 1990 a\u00a0v\u00a0obdob\u00ed 1991\u20132015 (obr. 3d, e<\/em>). Do roku 1990, tj. obdob\u00ed rostouc\u00edho odnosu P z\u00a0povod\u00ed, dok\u00e1zala tato z\u00e1vislost vysv\u011btlit u\u00a0obou n\u00e1dr\u017e\u00ed p\u0159es 70\u00a0% variability a\u00a0jej\u00ed sm\u011brnice byla strm\u011bj\u0161\u00ed ne\u017e od roku 1991, kdy p\u0159\u00edsun P z\u00a0povod\u00ed postupn\u011b klesal a\u00a0vztah mezi \u03bdP<\/sub> a\u00a0p\u0159\u00edsunem P do n\u00e1dr\u017e\u00ed byl voln\u011bj\u0161\u00ed, s\u00a0vysv\u011btlenou variabilitou 37\u00a0%. Toto zji\u0161t\u011bn\u00ed je zaj\u00edmav\u00e9, proto\u017ee nab\u00edz\u00ed vysv\u011btlen\u00ed, pro\u010d koncentrace P v\u00a0n\u00e1dr\u017e\u00edch neklesaly \u00fam\u011brn\u011b sni\u017eov\u00e1n\u00ed jejich p\u0159\u00edtokov\u00fdch koncentrac\u00ed. Krom\u011b toho, extrapolace \u03bdP<\/sub> v\u00a0regresn\u00ed rovnici do nulov\u00e9 hodnoty umo\u017e\u0148uje odhadnout, jak se sediment meziro\u010dn\u011b pod\u00edlel na sni\u017eov\u00e1n\u00ed \u010di zvy\u0161ov\u00e1n\u00ed zat\u00ed\u017een\u00ed n\u00e1dr\u017ee fosforem. V\u00a0obdob\u00ed do roku 1990 jsou pro\u00a0ob\u011b n\u00e1dr\u017ee \u00faseky na ose x<\/em> (p\u0159\u00edsun P do n\u00e1dr\u017ee) vyt\u00ednan\u00e9 regresn\u00ed p\u0159\u00edmkou kladn\u00e9, tak\u017ee sediment byl tehdy schopen P v\u00e1zat cca des\u00edtky\u00a0t P za rok, kde\u017eto po roce 1991 jsou tyto \u00faseky z\u00e1porn\u00e9, co\u017e indikuje naopak velkou pravd\u011bpodobnost uvol\u0148ov\u00e1n\u00ed P ze sedimentu. Do roku 1990, kdy rostl p\u0159\u00edsun P z\u00a0povod\u00ed, se zjevn\u011b vytv\u00e1\u0159ela v\u00a0sedimentech n\u00e1dr\u017e\u00ed z\u00e1soba\u00a0P, ze kter\u00e9 se v\u00a0dal\u0161\u00edm obdob\u00ed sni\u017eov\u00e1n\u00ed p\u0159\u00edsunu P do n\u00e1dr\u017e\u00ed fosfor postupn\u011b uvol\u0148uje a\u00a0tlum\u00ed pokles koncentrace ve vodn\u00edm sloupci. Popsan\u00e1 situace nen\u00ed pro n\u00e1dr\u017ee ojedin\u011bl\u00e1. Vliv vnit\u0159n\u00edho zat\u00ed\u017een\u00ed P ze sediment\u016f na koncentrace P a\u00a0na zbrz\u010fov\u00e1n\u00ed jejich poklesu po sn\u00ed\u017een\u00ed extern\u00edho zat\u00ed\u017een\u00ed P z\u00a0povod\u00ed byl prok\u00e1z\u00e1n v\u00a0\u0159ad\u011b studi\u00ed \u2013 nap\u0159. u\u00a0n\u011bmeck\u00e9 n\u00e1dr\u017ee Wahnbach [21] nebo u\u00a0severoamerick\u00fdch [22\u201324] \u010di africk\u00fdch [25] n\u00e1dr\u017e\u00ed; zna\u010dn\u00fd potenci\u00e1l k\u00a0uvol\u0148ov\u00e1n\u00ed P ze sediment\u016f v\u00a0jihomoravsk\u00e9 n\u00e1dr\u017ei Vranov uk\u00e1zali Jan a\u00a0kol. [26]. Pro dosa\u017een\u00ed limitn\u00ed koncentrace pro dobr\u00fd ekologick\u00fd potenci\u00e1l v\u00a0n\u00e1dr\u017e\u00edch Orl\u00edk i\u00a0Slapy je tedy pot\u0159eba po\u010d\u00edtat s\u00a0vy\u0161\u0161\u00edm rozsahem opat\u0159en\u00ed ke sn\u00ed\u017een\u00ed odnosu P v\u00a0povod\u00ed, ne\u017e jak by se dalo p\u0159edpokl\u00e1dat na z\u00e1klad\u011b velikosti retence v\u00a0dob\u011b s\u00a0nejvy\u0161\u0161\u00edm zne\u010di\u0161t\u011bn\u00edm.<\/p>\n\"\"<\/a>\n

Obr. 3. Ukazatele retence P v\u00a0n\u00e1dr\u017e\u00edch Orl\u00edk a\u00a0Slapy: (a) relativn\u00ed retence vypo\u010dten\u00e1 z\u00a0celkov\u00e9ho zat\u00ed\u017een\u00ed a\u00a0odtokov\u00e9 koncentrace P; (b) sou\u010dinitel sedimenta\u010dn\u00ed rychlosti \u03bdP<\/sub>; (c)\u00a0korela\u010dn\u00ed vztah mezi ro\u010dn\u00edmi hodnotami \u03bdP<\/sub> v\u00a0n\u00e1dr\u017e\u00edch Orl\u00edk a\u00a0Slapy; (d) z\u00e1vislost \u03bdP<\/sub> v\u00a0n\u00e1dr\u017ei Orl\u00edk na p\u0159\u00edsunu P v\u00a0obdob\u00ed n\u00e1r\u016fstu zat\u00ed\u017een\u00ed (1972\u20131990) a\u00a0v\u00a0obdob\u00ed jeho poklesu (1991\u20132015); (e) z\u00e1vislost \u03bdP<\/sub> v\u00a0n\u00e1dr\u017ei Slapy na p\u0159\u00edsunu P v\u00a0obdob\u00ed n\u00e1r\u016fstu zat\u00ed\u017een\u00ed (1979\u20131990) a\u00a0v\u00a0obdob\u00ed jeho poklesu (1991\u20132015)
\nFig. 3. Indicators of P retention in reservoirs Orl\u00edk and Slapy: (a) relative retention calculated from the total load and outflow concentration of P; (b) coefficient of P settling rate \u03bdP<\/sub>; (c)\u00a0correlation between annual values of \u03bdP<\/sub> in reservoirs Orl\u00edk and Slapy; (d) dependence of \u03bdP<\/sub> in the Orl\u00edk reservoir on the P-load during the period of increase of the load (1972\u20131990) and during the period of its decline (1991\u20132015); (e) dependence of \u03bdP<\/sub> in the Slapy reservoir on the P-load during the period of increase of the load (1979\u20131990) and during the period of its decline (1991\u20132015)<\/h6>\n

Dlouhodob\u00e1 a sezonn\u00ed variabilita koncentrace P v n\u00e1dr\u017ei Slapy<\/h2>\n

Jednotliv\u00e9 koncentrace Pcelk<\/sub> nam\u011b\u0159en\u00e9 v\u00a0n\u00e1dr\u017ei Slapy v\u00a0profilu Neb\u0159ich b\u011bhem nep\u0159etr\u017eit\u00e9\u00adho 57let\u00e9ho sledov\u00e1n\u00ed se pohybovaly v\u00a0\u0159\u00e1dov\u00e9m rozmez\u00ed 0,010\u20130,120\u2008mg\u2219l\u2011<\/sup>1<\/sup> a\u00a0pr\u016fm\u011brn\u00e9 ro\u010dn\u00ed koncentrace v\u00a0rozmez\u00ed 0,031\u20130,077\u2008mg\u2219l\u2011<\/sup>1<\/sup> (obr.<\/em>\u00a04<\/em>). Pro cel\u00e9 obdob\u00ed (1961\u20132015) Kendall\u016fv test neprok\u00e1zal \u017e\u00e1dn\u00e9 statisticky v\u00fdznamn\u00e9 monot\u00f3nn\u00ed trendy ani pro pr\u016fm\u011brn\u00e9 ro\u010dn\u00ed, ani pro sezonn\u00ed koncentrace Pcelk<\/sub>. Pou\u017eit\u00ed segmentov\u00e9 regrese ale prok\u00e1zalo v\u00a0roce 1992 pro ro\u010dn\u00ed koncentrace Pcelk<\/sub> zlomov\u00fd bod, kter\u00fd rozd\u011blil \u010dasovou \u0159adu na dva \u00faseky se statisticky v\u00fdznamn\u00fdmi trendy v\u00a0obdob\u00ed 1961\u20131991\u2008s\u00a0trendem n\u00e1r\u016fstu 0,6\u00a0\u00b5g\u00a0l-1<\/sup>\u2219a\u2011<\/sup>1<\/sup> a\u00a0v\u00a0obdob\u00ed 1992\u20132015\u2008s\u00a0trendem poklesu -0,9 \u00b5g\u00a0l-1<\/sup>\u2219a\u2011<\/sup>1<\/sup>.<\/p>\n\"\"<\/a>\n

Obr. 4. Koncetrace Pcelk<\/sub> v\u00a0profilu Slapy-Neb\u0159ich v\u00a0obdob\u00ed 1960\u20132016
\nFig. 4. Concentration of total P in the Slapy-Neb\u0159ich profile in the period 1960\u20132016 (black line with points \u2013 measured data in 3 week intervals; red line \u2013 annual averages)<\/h6>\n

Sezonn\u00ed koncentrace Pcelk<\/sub> byly nejni\u017e\u0161\u00ed v\u00a0letn\u00edm a\u00a0nejvy\u0161\u0161\u00ed v\u00a0zimn\u00edm obdob\u00ed (obr. 5<\/em>). V\u00a0\u010dasov\u00fdch \u0159ad\u00e1ch\u00a0zimn\u00edch a\u00a0jarn\u00edch koncentrac\u00ed byl segmentovou regres\u00ed zji\u0161t\u011bn, obdobn\u011b jako pro ro\u010dn\u00ed koncentrace, zlomov\u00fd bod v\u00a0roce 1992\u2008s\u00a0rostouc\u00edm trendem v\u00a0obdob\u00ed 1961\u20131991 a\u00a0klesaj\u00edc\u00edm trendem v\u00a0obdob\u00ed 1992\u20132015 (obr. 5a, c<\/em>). Letn\u00ed a\u00a0podzimn\u00ed koncentrace byly rozpt\u00fdlen\u00e9 a\u00a0\u017e\u00e1dn\u00e9 \u010dasov\u00e9 trendy u\u00a0nich prokazateln\u00e9 nebyly. Nicm\u00e9n\u011b, ve variabilit\u011b letn\u00edch koncentrac\u00ed byly identifikov\u00e1ny dva protich\u016fdn\u00e9 \u010dasov\u00e9 trendy p\u0159i\u00a0pr\u016fm\u011brn\u00e9m pr\u016ftoku nad a\u00a0pod 100\u2008m3<\/sup>\u2219s\u20111<\/sup>, tj. s\u00a0poklesem koncentrac\u00ed Pcelk<\/sub> p\u0159i pr\u016ftoku <\u00a0100\u2008m3<\/sup>\u2219s\u20111<\/sup> a\u00a0s\u00a0jejich n\u00e1r\u016fstem p\u0159i pr\u016ftoku > 100\u2008m3<\/sup>\u2219s\u20111<\/sup> (obr. 5c<\/em>). Regresn\u00ed anal\u00fdza vztahu letn\u00edch koncentrac\u00ed Pcelk<\/sub> a\u00a0pr\u016ftoku pro dv\u011b obdob\u00ed (1963\u20131991 a\u00a01992\u20132015) uk\u00e1zala,<\/sub> \u017ee koncentrace Pcelk<\/sub> byly do roku 1991 na pr\u016ftoku nez\u00e1visl\u00e9, kde\u017eto po roce 1991 se p\u0159i zv\u00fd\u0161en\u00e9m pr\u016ftoku za\u010daly v\u00fdrazn\u011b zvy\u0161ovat (obr.\u00a06<\/em>). Pro podzimn\u00ed obdob\u00ed vzhledem k\u00a0velk\u00e9mu rozptylu dat \u017e\u00e1dn\u00e9 trendy ani z\u00e1vislosti zji\u0161t\u011bny nebyly.<\/p>\n

Trendy environment\u00e1ln\u00edch veli\u010din<\/h2>\n

Zm\u011bny klimatick\u00fdch a\u00a0hydrologick\u00fdch podm\u00ednek na Slapsk\u00e9 n\u00e1dr\u017ei od roku 1961 jsou uk\u00e1z\u00e1ny na obr. 7<\/em>.<\/p>\n\"\"<\/a>\n

Obr. 5. \u010casov\u00e9 \u0159ady pr\u016fm\u011brn\u00fdch sezonn\u00edch koncentrac\u00ed Pcelk<\/sub> v\u00a0n\u00e1dr\u017ei Slapy; \u010d\u00e1ry ukazuj\u00ed statisticky v\u00fdznamn\u00e9 (p < 0,05) line\u00e1rn\u00ed regresn\u00ed trendy
\nFig. 5. Time series of average seasonal concentrations of total P in the Slapy reservoir; the lines show statistically significant (p < 0.05) linear regression trends<\/h6>\n

Hladinov\u00e1 teplota vody nam\u011b\u0159en\u00e1 p\u0159i t\u0159\u00edt\u00fddenn\u00edch odb\u011brech za\u010dala r\u016fst koncem 80. let minul\u00e9ho stolet\u00ed a\u00a0zv\u00fd\u0161ila se do sou\u010dasnosti v\u00a0pr\u016fm\u011bru o\u00a0cca\u00a01,5\u2008\u00b0C (obr. 7a<\/em>). Sezonn\u00ed Kendall\u016fv test prok\u00e1zal statisticky v\u00fdznamn\u00fd (p\u00a0<\u00a00,01) trend n\u00e1r\u016fstu se sm\u011brnic\u00ed 0,03\u2008\u00b0C a-1<\/sup> za cel\u00e9 obdob\u00ed \u010di 0,08\u2008\u00b0C\u00a0a-1<\/sup> v\u00a0obdob\u00ed 1987\u20132015. V\u00fdznamn\u00e9 rostouc\u00ed trendy teploty vody byly prok\u00e1z\u00e1ny v\u00a0posledn\u00edch letech i\u00a0pro v\u0161echny \u010dty\u0159i ro\u010dn\u00ed sezony, p\u0159i\u010dem\u017e zlomov\u00fd bod po\u010d\u00e1tku teplotn\u00edho n\u00e1r\u016fstu u\u00a0nich segmentov\u00e1 regrese na\u0161la v\u00a0rozmez\u00ed let 1987\u20131990. Velmi podobn\u00e9 zm\u011bny v\u00a0teplot\u011b vody byly pops\u00e1ny u\u00a0\u0159ady evropsk\u00fdch jezer, nap\u0159. v\u00a0Bodamsk\u00e9m jeze\u0159e v\u00a0N\u011bmecku [27], ve \u0161v\u00fdcarsk\u00fdch jezerech [28] \u010di ve \u0160v\u00e9dsku\u00a0[29] a\u00a0jsou p\u0159ipisov\u00e1ny glob\u00e1ln\u00ed klimatick\u00e9 zm\u011bn\u011b [28\u201330].<\/p>\n

Pro pr\u016fm\u011brn\u00e9 ro\u010dn\u00ed \u010di sezonn\u00ed pr\u016ftoky v\u00a0n\u00e1dr\u017ei Slapy jsme Kendallov\u00fdm testem nebo segmentovou regres\u00ed nena\u0161li \u017e\u00e1dn\u00e9 statisticky v\u00fdznamn\u00e9 trendy nebo zlomov\u00e9 body. Nicm\u00e9n\u011b, u\u00a0pr\u016fm\u011brn\u00fdch m\u011bs\u00ed\u010dn\u00edch pr\u016ftok\u016f jsme zjistili, \u017ee rozd\u011blen\u00ed jejich hodnot bylo odli\u0161n\u00e9 v\u00a0obdob\u00ed 1961\u20131990 a\u00a01991\u20132015 (obr. 7<\/em>\u2008b,c<\/em>), p\u0159i\u010dem\u017e v\u00a0obdob\u00ed 1991\u20132015 byly pr\u016ftoky nevyrovnan\u011bj\u0161\u00ed, na jedn\u00e9 stran\u011b s\u00a0vy\u0161\u0161\u00ed frekvenc\u00ed ni\u017e\u0161\u00edch pr\u016ftok\u016f, na druh\u00e9 stran\u011b s\u00a0v\u011bt\u0161\u00edm po\u010dtem extr\u00e9mn\u011b vysok\u00fdch hodnot. Ud\u00e1losti s\u00a0extr\u00e9mn\u011b vysok\u00fdmi pr\u016ftoky v\u00a0obdob\u00ed 1991\u20132015 se vyskytovaly p\u0159edev\u0161\u00edm v\u00a0letn\u00edm, pop\u0159. v\u00a0pozdn\u011b jarn\u00edm obdob\u00ed.<\/p>\n\"\"<\/a>\n

Obr. 6. Regresn\u00ed vztahy mezi pr\u016fm\u011brnou koncentrac\u00ed Pcelk a pr\u016ftokem v n\u00e1dr\u017ei Slapy v letn\u00edch m\u011bs\u00edc\u00edch (VI\u2013VIII) ve dvou obdob\u00edch: 1963\u20131991 and 1992\u20132015
\nFig. 6. Regression relations between the average concentration of total P and the flow in the Slapy reservoir in the summer months (VI\u2013VIII) in two periods: 1963\u20131991 and 1992\u20132015<\/h6>\n

Z\u00e1v\u011br<\/h2>\n

Anal\u00fdza dlouhodob\u00fdch dat koncentrac\u00ed Pcelk<\/sub> v\u00a0n\u00e1dr\u017e\u00edch Orl\u00edk a\u00a0Slapy uk\u00e1zala z\u0159etelnou souvislost s\u00a0r\u016fzn\u00fdmi f\u00e1zemi socio-ekonomick\u00e9ho v\u00fdvoje v\u00a0povod\u00ed a\u00a0se zm\u011bnami klimatick\u00fdch a\u00a0hydrologick\u00fdch podm\u00ednek. Rostouc\u00ed a\u00a0klesaj\u00edc\u00ed trendy koncentrac\u00ed a\u00a0bilance P v\u00a0p\u0159\u00edtoku do n\u00e1dr\u017e\u00ed i\u00a0v\u00a0n\u00e1dr\u017e\u00edch samotn\u00fdch v\u00a0obdob\u00edch 1961\u20131990 a\u00a01991\u20132015 odpov\u00eddaly zm\u011bn\u00e1m zdroj\u016f zne\u010di\u0161t\u011bn\u00ed v\u00a0povod\u00ed, tj. zejm\u00e9na zat\u00ed\u017een\u00ed povrchov\u00fdch vod fosforem z\u00a0komun\u00e1ln\u00edch odpadn\u00edch vod a\u00a0zem\u011bd\u011blstv\u00ed. P\u0159i sni\u017eov\u00e1n\u00ed zat\u00ed\u017een\u00ed povrchov\u00fdch vod fosforem v\u00a0obdob\u00ed 1991\u20132015 hr\u00e1ly velkou roli zm\u011bny v\u00a0ekonomice a\u00a0environment\u00e1ln\u00ed legislativ\u011b \u010cR. Anal\u00fdza retence P v\u00a0n\u00e1dr\u017e\u00edch uk\u00e1zala, \u017ee P akumulovan\u00fd v\u00a0sedimentech n\u00e1dr\u017ee v\u00a0dob\u011b rostouc\u00edho zat\u00ed\u017een\u00ed P z\u00a0povod\u00ed v\u00a0obdob\u00ed 1961\u20131990 se v\u00a0n\u00e1sleduj\u00edc\u00edm obdob\u00ed poklesu zat\u00ed\u017een\u00ed P za\u010dal uvol\u0148ovat a\u00a0zp\u011btn\u011b obohacuje koncentraci Pcelk<\/sub> ve vodn\u00edm sloupci a\u00a0tlum\u00ed vliv poklesu koncentrac\u00ed P v\u00a0p\u0159\u00edtoku do n\u00e1dr\u017e\u00ed.<\/p>\n

V\u00a0p\u0159\u00edpad\u011b hladinov\u00e9 koncentrace Pcelk<\/sub> v\u00a0n\u00e1dr\u017ei Slapy v\u00a0letn\u00edm obdob\u00ed byly p\u0159\u00ed\u010diny dlouhodob\u00e9 variability komplexn\u011bj\u0161\u00ed a\u00a0krom\u011b zm\u011bn zat\u00ed\u017een\u00ed P z\u00a0povod\u00ed z\u00e1visely tak\u00e9 na klimatick\u00fdch a\u00a0hydrologick\u00fdch podm\u00ednk\u00e1ch, tj. hlavn\u011b n\u00e1r\u016fstu teploty a\u00a0zv\u011bt\u0161ov\u00e1n\u00ed nerovnom\u011brnosti pr\u016ftoku. N\u00edzk\u00fd pr\u016ftok podporuje v\u00a0n\u00e1dr\u017ei Slapy prodlu\u017eov\u00e1n\u00ed doby stratifikace a\u00a0pokles koncentrace P v\u00a0povrchov\u00e9 vrstv\u011b. Naopak ud\u00e1losti s\u00a0vysok\u00fdm pr\u016ftokem zp\u016fsobuj\u00ed i\u00a0v\u00a0letn\u00edm obdob\u00ed naru\u0161en\u00ed stratifikace, prom\u00edch\u00e1v\u00e1n\u00ed hlubok\u00fdch vrstev vody (z\u00a0hypolimnia bohat\u00e9ho na P, jednak d\u00edky vysok\u00fdm p\u0159\u00edtokov\u00fdch koncentrac\u00edm, a\u00a0tak\u00e9 v\u00a0d\u016fsledku uvol\u0148ov\u00e1n\u00ed P ze sediment\u016f) s\u00a0epilimniem a\u00a0zvy\u0161ov\u00e1n\u00ed koncentrace P. Proto se variabilita letn\u00edch koncentrac\u00ed P v\u00a0n\u00e1dr\u017ei za\u010dala po roce 1990 zvy\u0161ovat a\u00a0stala se z\u00e1vislou na pr\u016ftoku. Tento mechanismus vede paradoxn\u011b k\u00a0situaci, kdy letn\u00ed koncentrace Pcelk<\/sub> v\u00a0epilimniu mohou p\u0159i vysok\u00e9m pr\u016ftoku r\u016fst (a\u00a0eutrofizovat n\u00e1dr\u017e v\u00edce ne\u017e v\u00a0minulosti) navzdory obecn\u00e9mu poklesu zat\u00ed\u017een\u00ed P i\u00a0poklesu zimn\u00edch a\u00a0jarn\u00edch koncentrac\u00ed Pcelk<\/sub>.<\/p>\n

Na\u0161e v\u00fdsledky ukazuj\u00ed, \u017ee zm\u011bna klimatu m\u016f\u017ee v\u00e9st k\u00a0v\u011bt\u0161\u00ed citlivosti vodn\u00edho ekosyst\u00e9mu n\u00e1dr\u017e\u00ed v\u016f\u010di p\u0159\u00edsunu \u017eivin a\u00a0m\u016f\u017ee zp\u016fsobovat zvy\u0161ov\u00e1n\u00ed jejich eutrofizace i\u00a0p\u0159i stabiln\u00edm nebo klesaj\u00edc\u00edm vn\u011bj\u0161\u00edm zat\u00ed\u017een\u00ed P. Tato skute\u010dnost vyzdvihuje nutnost dal\u0161\u00edho sni\u017eov\u00e1n\u00ed vn\u011bj\u0161\u00edch zdroj\u016f P. Vodohospod\u00e1\u0159i a\u00a0spr\u00e1vci povod\u00ed by m\u011bli pokra\u010dovat ve sv\u00e9m \u00fasil\u00ed o\u00a0maxim\u00e1ln\u00ed eliminaci zdroj\u016f zne\u010di\u0161t\u011bn\u00ed P v\u00a0povod\u00ed, proto\u017ee vlivem dopad\u016f zm\u011bny klimatu pravd\u011bpodobn\u011b nebude mo\u017en\u00e9 dos\u00e1hnout po\u017eadovan\u00e9ho ekologick\u00e9ho potenci\u00e1lu podle RVS o\u00a0vod\u011b bez dal\u0161\u00edho sn\u00ed\u017een\u00ed zat\u00ed\u017een\u00ed fosforem, ne\u017e k\u00a0jak\u00e9mu do sou\u010dasnosti do\u0161lo.<\/p>\n\"\"<\/a>\n

Obr. 7. Ukazatele klimatick\u00fdch a\u00a0hydrologick\u00fdch podm\u00ednek v\u00a0n\u00e1dr\u017ei Slapy b\u011bhem 1961\u20132015: (a)\u00a0\u010dasov\u00e1 \u0159ada pr\u016fm\u011brn\u00fdch ro\u010dn\u00edch teplot vody v\u00a0hladinov\u00e9 vrstv\u011b s\u00a0odli\u0161en\u00fdm obdob\u00edm 1987\u20132015, kdy byl prok\u00e1z\u00e1n rostouc\u00ed trend; (b) pr\u016fm\u011brn\u00fd m\u011bs\u00ed\u010dn\u00ed p\u0159\u00edtok (s\u00a0vyzna\u010den\u00edm extr\u00e9mn\u00edch m\u011bs\u00edc\u016f); (c) kumulativn\u00ed distribu\u010dn\u00ed funkce pr\u016ftoku v\u00a0obdob\u00edch 1961\u20131990 a\u00a01991\u20132015
\nFig. 7. Indicators of climatic and hydrological conditions in the Slapy reservoir during 1961\u20132015: (a) time series of average annual surface water temperatures with a\u00a0distinguished period 1987\u20132015 when a\u00a0growing trend has been proven; (b) average monthly inflow (with the indication of extreme months); (c) the cumulative distribution function of the flow in periods 1961\u20131990 and 1991\u20132015<\/h6>\n

Pod\u011bkov\u00e1n\u00ed<\/h3>\n

Studie byla podpo\u0159ena projektem Grantov\u00e9 agentury \u010cR \u010d. 15-04034S: Odr\u00e1\u017eej\u00ed dlouhodob\u00e1 data o\u00a0zooplanktonu Slapsk\u00e9 n\u00e1dr\u017ee civiliza\u010dn\u00ed a\/nebo klimatick\u00e9 zm\u011bny v\u00a0minul\u00fdch 50 letech? Auto\u0159i d\u011bkuj\u00ed st\u00e1tn\u00edmu podniku Povod\u00ed Vltavy za poskytnut\u00ed provozn\u00edch dat ze sledov\u00e1n\u00ed jakosti vody a\u00a0hydrologick\u00fdch ukazatel\u016f, zejm\u00e9na pak pracovn\u00edk\u016fm vodohospod\u00e1\u0159sk\u00e9ho dispe\u010dinku za spolupr\u00e1ci p\u0159i z\u00edsk\u00e1v\u00e1n\u00ed provozn\u00edch a<\/em>\u00a0hydrologick\u00fdch dat pro n\u00e1dr\u017ee Vltavsk\u00e9 kask\u00e1dy z\u00a0p\u0159ed-digit\u00e1ln\u00edho obdob\u00ed.<\/em><\/p>\n

\u00a0<\/em><\/p>\n

P\u0159\u00edsp\u011bvek byl publikov\u00e1n ve sborn\u00edku konference Vodn\u00ed n\u00e1dr\u017ee 2017, ISBN 978-80-905368-5-2.<\/p>\n","protected":false},"excerpt":{"rendered":"

Based on existing phosphorus data series in the Slapy and Orl\u00edk reservoirs and their main tributaries, we reconstructed P inputs to the reservoirs from the catchment during 1961\u20132016 and compiled empirical models of P retention. <\/p>\n","protected":false},"author":8,"featured_media":4605,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[86,87,89],"tags":[96,1189,1190,1191],"coauthors":[1133,1134,1135,1136],"class_list":["post-4670","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hydraulics-hydrology-and-hydrogeology","category-hydrochemistry-radioecology-microbiology","category-water-technology-water-supply-waste-water-treatment","tag-climate-change","tag-eutrophication","tag-phosphorus-retention","tag-socio-economic-indicators"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4670","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/comments?post=4670"}],"version-history":[{"count":2,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4670\/revisions"}],"predecessor-version":[{"id":30453,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4670\/revisions\/30453"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/4605"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=4670"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=4670"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=4670"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=4670"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}