The aim of this study is to understand the seasonalities of runoff and precipitation and their controls along two transects in Peru and one transect in Austria. The analysis is based on daily precipitation data at 111 and 61 stations in Peru and Austria, respectively, and daily discharge data at 51 and 110 stations. The maximum Pardé coefficient is used to quantify the strength of the seasonalities of monthly precipitation and runoff. Circular statistics are used to quantify the seasonalities of annual maximum daily precipitation and annual maximum daily runoff. The results suggest that much larger spatial variation in seasonality in Peru is because of the large diversity in climate and topography. In the dry Peruvian lowlands of the North, the strength of the monthly runoff seasonality is smaller than that of precipitation due to a relatively short rainy period from January to March, catchment storage and the effect of upstream runoff contributions that are more uniform within the year. In the Peruvian highlands in the South, the strength of the monthly runoff seasonality is greater than that of precipitation, or similar, due to relatively little annual precipitation and rather uniform evaporation within the year. In the Austrian transect, the strength of the runoff seasonality is greater than that of precipitation due to the influence of snowmelt in April to June. The strength of monthly regime of precipitation and runoff controls the concentration of floods and extreme precipitation in Peruvian transects. The regions with strong monthly seasonality of runoff have also extreme events concentrated along the same time of the year and the occurrence of floods is mainly controlled by the seasonality of precipitation. In Austria, the monthly runoff maxima and floods occur in the same season in the Alps. In the lowlands, the flood seasonality is controlled mainly by summer extreme precipitation and its interplay with larger soil moisture.
The analyses of precipitation and runoff data along topographic gradients in Peru and Austria showed that, overall, in Peru the spatial variation in seasonality is much larger than in Austria. This is because of the larger diversity in climate and topography.
Soil water repellency causes at least temporal changes in the hydrological properties of a soil which result in, among other things, suboptimal growing conditions and increased irrigation requirements. Water repellency in soil is more widespread than previously thought and has been identified in many soil types under a wide array of climatic conditions worldwide. Consequences of soil water repellency include loss of wettability, increased runoff and preferential flow, reduced access to water for plants, reduced irrigation efficiency, increased requirement for water and other inputs, and increased potential for non-point source pollution. Research indicates that certain soil surfactants can be used to manage soil water repellency by modifying the flow dynamics of water and restoring soil wettability. This results in improved hydrological behavior of those soils. Consequently, the plant growth environment is also improved and significant water conservation is possible through more efficient functioning of the soil. and Vodoodpudivosť pôdy spôsobuje prinajmenšom dočasné zmeny v hydrologických vlastnostiach pôdy, ktoré okrem iného môžu viesť k suboptimálnym podmienkam rastu rastlín a k zvýšenej potrebe závlah. Vodoodpudivosť pôdy je rozšírenejší jav, ako sa pôvodne predpokladalo; bola identifikovaná v mnohých pôdnych typoch a klimatických podmienkach na celom svete. Dôsledkom vodoodpudivosti pôdy je strata zmáčavosti, zvýšený povrchový odtok a preferenčné prúdenie, znížená dostupnosť vody a iných vstupov pre rastliny, znížený účinok závlah, zvýšené požiadavky na vodu a iné vstupy, ako aj zvýšené riziko plošného znečistenia. Výskum naznačuje, že niektoré povrchovo aktívne látky (soil surfactants) môžu upraviť vodoodpudivosť pôdy obnovením omáčania a modifikáciou dynamiky vody. Výsledkom je zlepšenie hydrologických vlastností pôdy. Podobne, výsledkom je zlepšenie prostredia pre rast rastlín, zvýšenie retencie vody v pôde a teda aj efektívnejšia funkcia pôdy.
River runoff and sediment transport are two related random hydrologic variables. The traditional statistical analysis method usually requires those two variables to be linearly correlated, and also have an identical marginal distribution. Therefore, it is difficult to know exactly the characteristics of the runoff and sediment in reality. For this reason, copulas are applied to construct the joint probability distribution of runoff and sediment in this article. The risk of synchronous-asynchronous encounter probability of annual rich-poor runoff and sediment is also studied. At last, the characteristics of annual runoff and sediment with multi-time scales in its joint probability distribution space are simulated by empirical mode decomposition method. The results show that the copula function can simulate the joint probability distribution of runoff and sediment of Huaxia hydrological station in Weihe River well, and that such joint probability distribution has very complex change characteristics at time scales.
The need for a better understanding of factors controlling the variability of soil water content (θ) in space and time to adequately predict the movement of water in the soil and in the interphase soil-atmosphere is widely recognised. In this paper, we analyse how soil properties, surface cover and topography influence soil moisture (θ) over karstic lithology in a sub-humid Mediterranean mountain environment. For this analysis we have used 17 months of θ measurements with a high temporal resolution from different positions on a hillslope at the main recharge area of the Campo de Dalías aquifer, in Sierra de Gádor (Almería, SE Spain). Soil properties and surface cover vary depending on the position at the hillslope, and this variability has an important effect on θ. The higher clay content towards the lower position of the hillslope explains the increase of θ downslope at the subsurface horizon throughout the entire period studied. In the surface horizon (0-0.1 m), θ patterns coincide with those found at the subsurface horizon (0.1-0.35 m) during dry periods when the main control is also exerted by the higher percentage of clay that increases downslope and limits water depletion through evaporation. However, in wet periods, the wettest regime is found in the surface horizon at the upper position of the hillslope where plant cover, soil organic matter content, available water, unsaturated hydraulic conductivity (Kunsat) and infiltration rates are higher than in the lower positions. The presence of rock outcrops upslope the θ sampling area, acts as runoff sources, and subsurface flow generation between surface and subsurface horizons also may increase the differences between the upper and the lower positions of the hillslope during wet periods. Both rock and soil cracks and fissures act disconnecting surface water fluxes and reducing run-on to the lower position of the hillslope and thus they affect θ pattern as well as groundwater recharge. Understanding how terrain attributes, ground cover and soil factors interact for controlling θ pattern on karst hillslope is crucial to understand water fluxes in the vadose zone and dominant percolation mechanisms which also contribute to estimate groundwater recharge rates. Therefore, understanding of soil moisture dynamics provides very valuable information for designing rational strategies for the use and management of water resources, which is especially urgent in regions where groundwater supports human consume or key economic activities.
In the paper there the questions of selection of representative period for the hydrological characteristics assessment are discussed. Also the characteristics of runoff and precipitation for the periods 1931-1980 and 1961-2000 are presented. The main components of water balance in Slovakia are the basis for comparison of both periods. The assessment of development of runoff condition during the last decades is presented. and V referáte sa diskutujú otázky výberu reprezentatívneho obdobia pre stanovenie hydrologických charakteristík. Ďalej sa uvádzajú charakteristiky odtoku a zrážok za obdobia 1931-1980 a 1961-2000. Na základe hodnotenia hlavných komponentov hydrologickej bilancie Slovenska sa obidve obdobia porovnávajú a opisuje sa vývoj odtokových pomerov ostatného obdobia.