Karst springs in Slovenia - trend analysis

Kraški izviri in vodonosniki so pomemben vir pitne vode, zato je poznavanje dinamike sprememb hidroloških značilnosti kraških izvirov še kako pomembno. V prispevku predstavljamo analizo hidroloških trendov, ki smo jo izvedli za 14 izbranih kraških izvirov na območju Slovenije. Za obdobje od leta 1961 do 2013 so bili analizirani trendi najmanjših, srednjih in največjih letnih pretokov. Dodatno smo analizirali trende padavin, temperature vode in temperature zraka. Preučili smo tudi odvisnost med padavinami in pretoki ter temperaturo vode in zraka. Ugotovili smo, da se najmanjši in srednji letni pretoki zmanjšujejo. Pri analizah največjih letnih pretokov ni bilo mogoče zaznati izrazitega padajočega ali naraščajočega trenda. Za temperaturo zraka so bili rezultati trenda pozitivni in statistično značilni z izbrano stopnjo značilnosti. Na nekaterih padavinskih postajah se je pokazalo izrazito upadanje letne količine padavin. Ker je odvisnost med letno količino padavin in povprečnimi letnimi pretoki relativno visoka, je ravno zmanjševanje padavin ob višji temperaturi lahko razlog za zmanjševanje malih in srednjih pretokov. Poleg tega so zadrževalni časi kraških izvirov relativno kratki. Ker so obravnavani kraški izviri v večji meri na območjih, kjer v poletnih mesecih pogosto prihaja do težav s preskrbo s pitno vodo, lahko ob podobni dinamiki procesov tudi v prihodnosti pričakujemo težave s pomanjkanjem vode, kar nakazujejo tudi izračuni podnebnih modelov.Karst springs and aquifers are important sources of drinking water, so knowledge about the dynamics of changes in the hydrological characteristics of karst springs is especially important. This paper presents a hydrological trend analysis conducted for 14 karst springs in Slovenia. The trends of low, mean, and high annual flows were analyzed for the period from 1961 to 2013. Additionally, changes in annual rainfall, air temperature, and water temperature were investigated. The relationship between precipitation and discharges was also examined, as well as that between water and air temperature. Results indicate that low and mean flows in the selected springs are decreasing. In the case of high flows, no significant decreasing or increasing trend could be detected. For air temperature, the trend results were positive and statistically significant with the selected significance level. Some precipitation stations showed a significant decrease in the annual rainfall. Because the relationship between annual precipitation and mean flows is relatively high, the rainfall decrease could be the main reason for the decrease in low and mean flows. Moreover, the retention times of karst springs are relatively short. Some of the investigated springs are located in the Mediterranean part of the country where issues with drinking water supply occur commonly in the summer. If a similar dynamic continues, water scarcity problems can be expected in the future. The climate change models also predict such dynamic