Accurate estimation of precipitation in mountain catchments is challenging due to its high spatial variability and lack of measured ground data. Weather radar can help to provide precipitation estimates in such conditions. This study investigates the differences between measured and radar-estimated daily precipitation in the mountain catchment of the Jalovecký Creek (area 22 km2, 6 rain gauges at altitudes 815–1900 m a.s.l.) in years 2017–2020. Despite good correlations between measured and radar-based precipitation at individual sites (correlation coefficients 0.68–0.90), the radar-estimated precipitation was mostly substantially smaller than measured precipitation. The underestimation was smaller at lower altitude (on average by –4% to –17% at 815 m a.s.l.) than at higher altitudes (–35% to –59% at 1400–1900 m a.s.l.). Unlike measured data, the radar-estimated precipitation did not show the differences in precipitation amounts at lower and higher altitudes (altitudinal differences). The differences between the measured and radar-estimated precipitation were not related to synoptic weather situations. The obtained results can be useful in preparation of more accurate precipitation estimates for the small mountain catchments.
The heterogeneity of water flow and solute transport was assessed during radioactive tracer infiltration experiment in a black clay loam soil using modified methods to estimate the effective cross section (ECS) and the degree of preferential flow (DPF). The results of field and numerical experiments showed that these parameters characterized the heterogeneity of water flow in the soils unequivocally. The ECS decreases non-linearly and the DPF increases linearly with an increase of the bypassing ratio (ratio of macropore flow rate to total flow rate). The ECS decreased and the DPF increased with depth, which suggests an increase in the heterogeneity of water flow with depth. The plot of the DPF against ECS values calculated from the tracer experiment data was consistent with the relationship obtained by the numerical simulation assuming preferential flow in the neighbourhood of three probes.
Hydrological processes research remains a field that is severely measurement limited. While conventional tracers (geochemicals, isotopes) have brought extremely valuable insights into water source and flowpaths, they nonetheless have limitations that clearly constrain their range of application. Integrating hydrology and ecology in catchment science has been repeatedly advocated as offering potential for interdisciplinary studies that are eventually to provide a holistic view of catchment functioning. In this context, aerial diatoms have been shown to have the potential for detecting of the onset/cessation of rapid water flowpaths within the hillslope-riparian zone-stream continuum. However, many open questions prevail as to aerial diatom reservoir size, depletion and recovery, as well as to their mobilisation and transport processes. Moreover, aerial diatoms remain poorly known compared to freshwater species and new species are still being discovered. Here, we ask whether aerial diatom flushing can be observed in three catchments with contrasting physiographic characteristics in Luxembourg, Oregon (USA) and Slovakia. This is a prerequisite for qualifying aerial diatoms as a robust indicator of the onset/cessation of rapid water flowpaths across a wider range of physiographical contexts. One species in particular, (Hantzschia amphioxys (Ehr.) Grunow), was found to be common to the three investigated catchments. Aerial diatom species were flushed, in different relative proportions, to the river network during rainfall-runoff events in all three catchments. Our take-away message from this preliminary examination is that aerial diatoms appear to have a potential for tracing episodic hydrological connectivity through a wider range of physiographic contexts and therefore serve as a complementary tool to conventional hydrological tracers.
Snow accumulation and melt are highly variable. Therefore, correct modeling of spatial variability of the snowmelt, timing and magnitude of catchment runoff still represents a challenge in mountain catchments for flood forecasting. The article presents the setup and results of detailed field measurements of snow related characteristics in a mountain microcatchment (area 59 000 m2 , mean altitude 1509 m a. s. l.) in the Western Tatra Mountains, Slovakia obtained in winter 2015. Snow water equivalent (SWE) measurements at 27 points documented a very large spatial variability through the entire winter. For instance, range of the SWE values exceeded 500 mm at the end of the accumulation period (March 2015). Simple snow lysimeters indicated that variability of snowmelt and discharge measured at the catchment outlet corresponded well with the rise of air temperature above 0°C. Temperature measurements at soil surface were used to identify the snow cover duration at particular points. Snow melt duration was related to spatial distribution of snow cover and spatial patterns of snow radiation. Obtained data together with standard climatic data (precipitation and air temperature) were used to calibrate and validate the spatially distributed hydrological model MIKE-SHE. The spatial redistribution of input precipitation seems to be important for modeling even on such a small scale. Acceptable simulation of snow water equivalents and snow duration does not guarantee correct simulation of peakflow at shorttime (hourly) scale required for example in flood forecasting. Temporal variability of the stream discharge during the snowmelt period was simulated correctly, but the simulated discharge was overestimated.
We computed annual precipitation totals for six catchments in the West and High Tatra Mountains (Roháčska, Jalovecká, Žiarska, Račkova, Tichá and Kôprová dolina) for hydrological years 1989-1998 using different interpolation and extrapolation methods. Precipitation estimates for the entire period as well as for particular hydrological years were used to compute evapotranspiration from the hydrological balance equation. The results have shown that although we used all existing precipitation data from the region along with the sophisticated methods to estimate catchment precipitation, yet, the water balance of the mountain catchments was not explained satisfactorily. and V práci sú vypočítané ročné zrážkové úhrny v šiestich povodiach Západných a Vysokých Tatier (Roháčska, Jalovecká, Žiarska, Račkova, Tichá a Kôprová dolina) pomocou rôznych interpolačných a extrapolačných metód pre hydrologické roky 1989 až1998, aj pre priemerné ročné úhrny za celé obdobie. Pre zrážkové úhrny určené rôznymi metódami bol z rovnice hydrologickej bilancie vypočítaný výpar a výsledky boli vyhodnotené opäť pre celé obdobie, aj pre jednotlové hydrologické roky. Získané výsledky ukazujú, že ani pri použití všetkých existujúcich údajov a moderných výpočtových metód existujúca meracia sieť nedáva uspokojivú odpoveď na pochybnosti, ktoré vznikajú pri určení základných prvkov hydrologickej bilancie v jednotlivých horských povodiach.
The paper provides basic information on hydrological research performed in the mountain catchment of the Jalovecký creek, the Western Tatra Mountains by the Institute of Hydrology of the Slovak Academy of Sciences since the mid-1980-ties. The research was devoted to better understanding of spatial distribution of precipitation, soil moisture, snow cover, evapotranspiration and runoff generation. First part of the paper brings an overview of the results. Second part of the paper is devoted to the water balance of the catchment in hydrological years 1989-2005 and estimation of mean transit time of water in the catchment as given by the tracer method using the stable environmental isotope of 18O. Catchment mean annual precipitation in the studied period was 1562 mm. It varied from 1116 mm in the year of 2003 to 1854 mm in 2001. Mean annual runoff was 1015 mm and it varied between 703 mm in 2003 and 1284 mm in 1998. Mean annual air temperature at catchment mean elevation (1500 m a.s.l.) was 3.5 °C. Interpertation of δ18O in precipitation and runoff from the period 1991-2002 gave the mean transit time of 13 months. Direct application of measured values in precipitation provided more realistic results than the input data series prepared according to recommendations found in the literature. and Príspevok poskytuje základné informácie o hydrologickom výskume, ktorý vykonáva od druhej polovice 80. rokov 20. storočia Ústav hydrológie SAV v horskom povodí Jaloveckého potoka v Západných Tatrách. Výskum poskytol poznatky o priestorovom rozdelení atmosférických zrážok, vlhkosti pôdy, snehovej pokrývke, evapotranspirácii a tvorbe odtoku vo vysokohorskom prostredí. Stručný prehľad niektorých z nich uvádzame v prvej časti príspevku. Druhá časť príspevku za zaoberá hydrologickou bilanciou povodia za obdobie 1989-2005 a určením priemernej doby prechodu vody povodím pomocou metódy stopovačov, pričom bol použitý stabilný prírodný izotop kyslíka 18O. Priemerný ročný úhrn zrážok v povodí v období 1989-2005 bol 1562 mm (od 1116 mm roku 2003 do 1854 mm v roku 2001). Priemerný ročný odtok z povodia bol 1015 mm (od 703 mm v roku 2003 do 1284 mm v roku 1998). Priemerná ročná teplota vzduchu v priemernej nadmorskej výške povodia 1500 m n.m. bola 3,5 °C. Interpretáciou hodnôt δ18O v zrážkach a v odtoku za obdobie 1991-2002 bola určená priemerná doba prechodu 13 mesiacov, čo je časový úsek porovnateľný s tradičným hydrologickým rokom. Použili sme pritom dve varianty prípravy hodnôt δ18O v zrážkach (vstup do hydrologického cyklu povodia). Priame použitie meraných hodnôt dalo realistickejší výsledok, ako rad vstupných hodnôt upravený podľa odporúčaní z literatúry.