In this paper a comparison of methods for estimating rainfall-runoff model parameters in ungauged basins based on geographical location are presented. As a pilot basin the Hron River basin in Slovakia with an available daily flow, precipitation and air temperature time series needed for calibration to obtain model parameter values in subcatchments was selected. The rainfall-runoff model was calibrated using a daily time step at 23 subcatchments. The Nearest Neighbour, Lumped Basin and Best Similarity Index methods were used to transfer the model parameters from the gauged to ''ungauged'' subcatchments. Finally, the effectiveness of the estimation method for ungauged basins was tested by comparing the model simulations to observed hydrographs and computing the Nash-Sutcliffe optimization criterion. The results were finally compared, and the best method was recommended for practical application by estimating of the rainfallrunoff model parameters in an ungauged catchment in this region. and V štúdii sú prezentované výsledky nepriamych metód odhadu parametrov zrážkovo-odtokového modelu na povodiach bez priamych hydrologických pozorovaní, ktoré sú založené na geografickej polohe povodí. Povodie Hrona bolo vybrané ako pilotný región s 23 čiastkovými povodiami, ktoré mali dostupné časové rady pozorovaní priemerných denných prietokov, zrážok a teploty vzduchu, potrebné na kalibráciu modelu. Zrážkovo-odtokový model bol v týchto podpovodiach nakalibrovaný na údajoch s denným časovým krokom. Následne boli použité na regionalizáciu parametrov modelu metódy Nearest Neighbour (Metóda najbližšieho suseda), Lumped Basin (Metóda sústredeného povodia) a Best Similarity Index methods (Metóda najlepšej podobnosti). Kvalita regionalizačných metód sa overovala pomocou optimalizačného kritéria Nash-Sutcliffe. Najlepšie výsledky boli dosiahnuté Metódou najlepšej podobnosti, ktorá môže byť v praxi odporúčaná na odhad parametrov zrážkovo-odtokového modelu na testovanom povodí.
Conceptual degree-day snow models are often calibrated using runoff observations. This makes the snow models dependent on the rainfall-runoff model they are coupled with. Numerous studies have shown that using Snow Cover Area (SCA) remote sensing observation from MODIS satellites helps to better constrain parameters. The objective of this study was to calibrate the CemaNeige degree-day snow model with SCA and runoff observations. In order to calibrate the snow model with SCA observations, the original CemaNeige SCA formulation was revisited to take into account the hysteresis that exists between SCA and the snow water equivalent (SWE) during the accumulation and melt phases. Several parametrizations of the hysteresis between SWE and SCA were taken from land surface model literature. We showed that they improve the performances of SCA simulation without degrading the river runoff simulation. With this improvement, a new calibration method of the snow model was developed using jointly SCA and runoff observations. Further analysis showed that the CemaNeige calibrated parameter sets are more robust for simulating independent periods than parameter sets obtained from discharge calibration only. Calibrating the snow model using only SCA data gave mixed results, with similar performances as using median parameters from all watersheds calibration.
This paper deals with the formation of snowmelt-driven floods in two experimental microbasins located in Slovakia’s highlands (300-400 m a.s.l) near the town of Povazska Bystrica, Slovakia in March 2006. The first basin (Rybarik) encompasses an area of 0.119 km2 and is used primarily for agriculture; while the Lesný basin with its catchment area of 0.0864 km2 is characterized as a forested land. The maximal specific outflow from the Rybárik basin was observed on March 28, 2006, with 281.3 l s-1 km-2, peaking at 3 p.m. with 422 l s-1 km-2. In the Lesný basin, the maximum outflow was observed on March 29, 2006, with its peak of 523 l s-1 km-2 at noon. In the second part the long-term trend of snow water equivalent (SWE) modeled by the HBV-light rainfall-runoff model in the Rybarik and Lesny microbasins were evaluated. After the model verification, the daily values of SWE for the period 1965/66-2005/06 were calculated for Rybarik and Lesný microbasins. From the results it follows, that, after a temporal decline in the maxima of snow depth and of SWE in the 1990s, SWE started to increase in 2002 again. The historically highest values of SWE were simulated in both experimental microbasins in the winter season of 2005/06. and V príspevku je analyzovaná tvorba povodňového odtoku počas povodne z topenia sa snehu v marci 2006 na príklade dvoch experimentálnych mikropovodí lokalizovaných vo vrchovinovej časti Slovenska pri Považskej Bystrici (300–400 m n.m.), konkrétne z poľnohospodársky využívaného mikropovodia Rybárik (0,119 km2 ), a zo zalesneného mikropovodia Lesný (0,0864 km2 ). Maximálny meraný špecifický odtok z povodia Rybárik bol 281 l s-1 km-2 28. marca 2006 (vrchol 422 l s-1 km-2 o 15.00 hod.). Maximálny meraný špecifický odtok z povodia Lesný 263,7 l s-1 km-2 bol zaznamenaný 29. marca 2006 (vrchol 523 l s-1 km-2 o 12.00 hod.). V druhej časti príspevku je analyzovaný dlhodobý vývoj vodnej hodnoty snehu (SWE) v povodí Rybárik a Lesný, modelovanej zrážko-odtokovým modelom HBV-light. Po kalibrácii a verifikácii modelu boli modelom vypočítané denné vodné hodnoty snehu za 42-ročné obdobie 1965/66–2005/06. Z výsledkov vyplýva, že po dočasnom poklese maxím vodnej hodnoty snehu SWE v deväťdesiatych rokoch minulého storočia od roku 2002 došlo k opätovnému zvýšeniu vodnej hodnoty snehu. V zimnej sezóne 2005/06 bola vypočítaná najvyššia hodnota SWE od začiatku pozorovaní v oboch mikropovodiach.