Water-chemistry was used to assist in understanding the effect of human and natural activities on the Jordan and Yarmouk Rivers. Eighty-eight water samples were collected from different locations along the flow paths of both Jordan and Yarmouk Rivers, and analyzed for major ions. The analyzed water samples of Yarmouk River were predominantly alkaline water with prevailing chloride and sodium; and characterized with low TDS values that range from 571 to 801 mg l-1. The predominant water type of Jordan river is alkaline earth with prevailing chloride and increase portion of alkalies and characterized by high TDS value that range from 2914 to 3224 mg l-1. The sampling took place in different time periods between July 1996 and April 1996 to determine the effect of changing seasons on the chemistry of the studied rivers. From the upper to lower reaches of both Jordan and Yarmouk rivers, a systematic increase of most of the measured major ions concentrations is reported in July 1996. Strong variations were observed in the water chemistry between the different locations. As the distance increase from the mouth of the rivers, so did the salinity of the water. The study found that the Jordan River is affected by groundwater system and the related anthropogenic activities on both sides of the Jordan Valley; where saline groundwater is mainly resulted from ancient entrapped sea water or brine deep seated origin. The water which dilute Yarmouk river is a Ca+2-HCO3-. The in the ion concentrations in 1996 than those reported in 1969 is due to the increase of the anthropogenic effects. and Vplyv antropogénnych aprirodzených faktorov na kvalitu vôd riek Jordán a Jarmuk môže byt hodnotený aj pomocou hydrochemických analýz. Pozdlž tokov Jordán a Jarmuk bolo odobratých a analyzovaných 88 vzoriek vody. Vzorky vody rieky Jarmuk boli prevažne alkalické s prevládajúcimi iónmi chlóru a sodíka, charakterizované nízkymi hodnotami celkovej mineralizácie (TDS), ktorá bola v rozmedzí 571 - 801 mg l-1 . Voda v rieke Jordán je prevažne alkalická s dominantnými chloridmi a zvýšeným podielom alkalických iónov s vysokou TDS v rozmedzí 2914 - 3224 mg l-1 . Vzorky vody boli odobraté v case medzi aprílom a júlom 1996, aby sa dala urcit zmena chemizmu tokov pocas roka. Pocas júla 1996 bola zistená v oboch tokoch od pramena po ústie zvyšujúca sa koncentrácia sledovaných iónov. Medzi jednotlivými lokalitami boli zaregistrované velké rozdiely v koncentráciách sledovaných prvkov. Výskumom sa zistilo, že rieka Jordán je ovplyvnená podzemnými vodami aantropogénnou cinnostou na oboch brehoch. Slané podzemné vody sú dôsledkom predovšetkým dávneho záchytu morskej vody, a existencie solných vrstiev v povodí. Zmeny v koncentrácii iónov v riekach medzi rokmi 1969 a 1996 môžu byt dôsledkom antropogénnej cinnosti.
Semi-arid regions are characterized by important infrequent rainfall. They often occur in early autumn and give rise to devastating floods. Flooding problems at Wadi Mekerra, located in the Sidi Bel Abbes town (Northwest Algeria), was traditionally the main concern of researchers and government officials. In this work, the magnitude of raging flood wave in the studied catchment and the principal causes are discussed. After this, we present the main hydromorphometric features and the results of numerical simulations of flood wave. This simulation is done by using finite volume shock capturing schemes. It concerns applying the first order Godunov scheme and the second order Monotonic Central scheme. The Manning roughness coefficient was used as a calibration parameter. The comparison of numerical results with observed data confirms more stability and accuracy of applied numerical schemes in rising limb phase than in the falling limb phase. These results provide information on flood forecasting and monitoring of changes in the magnitude of the flow in Wadi Mekerra. and Semiaridné oblasti sú charakterizované významnými občasnými dažďami. Vyskytujú sa spravidla v jeseni a spôsobujú devastačné povodne. Povodne vo Wadi Mekerra v meste Sidi Bel Abbes (severozápadné Alžírsko) sú často problémom pre výskumníkov a vládnych úradníkov. Práca analyzuje devastačné povodne v tomto povodí. Okrem toho sa uvádzajú najdôležitejšie hydromorfomertrické charakteristiky a výsledky simulácií povodňovej vlny. Simulácia je aplikáciou Godunovovej schémy prvého rádu a Monotonickej centrálnej schémy druhého rádu. Ako kalibračný parameter bol použitý Manningov súčiniteľ drsnosti. Porovnanie simulovaných a pozorovaných údajov potvrdzuje väčšiu stabilitu a presnosť počas rastúcej vetvy prietokovej vlny, ako je tomu v klesajúcej fáze. Tieto výsledky sú informáciou o možnostiach predpovede a monitoringu povodní vo Wadi Mekerra.
The Jadro River with total length of 4.3 km and average annual discharge of 7.9 m3 s-1 is a relatively small river on the east coast of the Adriatic Sea, close to Split. Field campaign measurements were made to estimate salt intrusion in the Jadro estuary in July 2012. This measurement confirmed the stratified character of the estuary where fresh water flows in a thin layer over denser sea water. Furthermore, a numerical model was set up for simulating unsteady stratified flow without mixing between the layers. The model is applied for the Jadro River and field measurements are used for calibration. In addition, the steady state of stratification within the estuary is analyzed by a box model which assumes mixing between layers. Results of the numerical and the box models were compared. The flushing time estimated with the box model is approximately 1.5 day for summer steady conditions. Numerical analysis however shows that the residence time is much larger owing to flow unsteadiness.
Increasing our understanding of the main processes acting in small Mediterranean catchments is essential to planning effective soil and water conservation practices in semi-arid areas. A monitoring program of a Sicilian catchment started in 1996 and ended in 2006. The factors driving the hydrological response for 170 events with runoff generation and 46 with sediment production were specified. The catchment response varied greatly over the year. Rainfall intensity was a poor driver of runoff generation, whereas both the simulations made with the Thornthwaite-Mather water balance model and hydrograph recession analyses, pointed to the chief importance of wet antecedent conditions and soil saturation processes in runoff generation. The influence of rainfall spatial variability was also examined. SSC-Q relationships, classified by following their shapes for all sediment production events, suggested that the principal role of small poorly vegetated hillslope patches was as sediment sources and confirmed the complexity of the hydrological response in this small Mediterranean catchment.
The climatic variability and climate changes in the geological history of Earth are correlated with the environmental development. A special attention is paid to the impact of changing climate on the water resources and hydrological cycle. Possible impact of man's activities on the climatic variability is also discussed. Can the regulation of such activities slow down or bring to a stop the forthcoming climate change? A comparison of data from the Holocene period and from modern history indicates that the climatic variability and climate change have been always produced by external periodic phenomena and occasional cataclysmic events. In other words, the climate has never been stable and administrative measures limiting man's influence on the climate can bring only partial results. Considering that the climatic change is an unavoidable process, following measures should be taken: First, alternative scenarios of possible climatic development, would it be cooling or warming, should be set up. Second, preventive and protective methodologies need to be prepared for each scenario well in advance. Third, technologies facilitating man's survival and everyday life under changed climatic situation should be developed. and Klimatická variabilita a změny klimatu jsou sledovány v geologické historii Země a korelovány s historií životního prostředí. Zvláštní pozornost se věnuje vlivu měnícího se klimatu na vodní zdroje a hydrologický cyklus. Také je diskutován vliv činnosti člověka ve vztahu ke klimatu. Je možné redukcí takových aktivit zpomalit nebo zcela zastavit klimatické změny? Porovnání dat z holocénu a moderní historie ukazuje, že klimatická variabilita a změny byly vždycky vyvolávány mimozemskými periodickými vlivy, případně občasnými katastrofickými jevy. Jinými slovy, klima nikdy nebylo stabilní. Proto také administrativní opatření, omezující vliv člověka na klima, mohou být úspěšná pouze do jisté míry. Uvážíme-li, že klimatická variabilita i její hydrologické následky jsou nevyhnutelné, je třeba připravit příslušné scénáře možných klimatických změn, ať už souvisí s ochlazováním nebo oteplováním. Pro každý ze scénářů je třeba navrhnout metody preventivních a ochranných opatření s dostatečným předstihem. Konečně bude třeba vypracovat nové technologie usnadňující život člověka ve změněných klimatických podmínkách.
The paper evaluates the results of a 6-year-monitoring of the eco-hydrological influence of Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus silvatica L.) forest stands on the hydro-physical properties of snow cover. The experiment was carried out in the artificially regenerated 20-25-year-old forest stands approaching the pole timber stage in the middle mountain region of the Polana Mts. - Biosphere reserve situated at about 600 m a.s.l. during the period of maximum snow supply in winters of years 2004 -2009. Forest canopy plays a decisive role at both the snow cover duration and spring snow melting and runoff generation. A spruce stand is the poorest of snow at the beginning of winter. High interception of spruce canopy hampers the throughfall of snow to soil. During the same period, the soil surface of a beech stand accumulates greater amount of snow. However, a spruce stand accumulates snow by creating snow heaps during the periods of maximum snow cumulation and stand´s microclimate slows down snow melting. These processes are in detail discussed in the paper. The forest stands of the whole biosphere reserve slow down to a significant extent both the snow cover melting and the spring runoff of the whole watershed. and Práca hodnotí výsledky 6-ročného terénneho monitoringu eko-hydrologického vplyvu porastov smreka obyčajného (Picea abies (L.) Karst.) a buka lesného (Fagus silvatica L.) na hydrofyzikálne vlastnosti snehovej pokrývky. Experiment prebiehal v rokoch 2004 - 2009 počas obdobia s maximálnou zásobou snehu na výskumnej ploche v stredohorskej oblasti (nadmorská výška okolo 600 m n.m.) v Biosférickej rezervácii Poľana v 20- až 25- ročnom umelo obnovenom poraste vo fáze žrďoviny. Koruny porastu zohrávajú rozhodujúcu úlohu, ako pri topení snehu, tak aj pri formování odtoku. Začiatkom zimnej sezóny sa v smrekovom poraste nachádza menej snehu. Vysoká intercepcia smrekov bráni v prenikaní snehu k pôde. V rovnakom období sa na pôde v bukovom poraste akumuluje vačšie množstvo snehu. Smrekový porast však vďaka akumulovaniu snehu pri tvorbe snehových kôp počas obdobia s maximálnou kumuláciou snehu ako aj vďaka porastovej mikroklíme spomaľuje topenie snehu. V článku podrobne opisujeme tieto procesy. Porasty celej biosférickej rezervácie sa významne podieľajú na spomaľovaní ako topenia sa snehu, tak aj jarného odtoku z celého povodia.
The problem of understand natural processes as factors that restrict, limit or even jeopardize the interests of human society is currently of great concern. The natural transformation of flood waves is increasingly affected and disturbed by artificial interventions in river basins. The Danube River basin is an area of high economic and water management importance. Channel training can result in changes in the transformation of flood waves and different hydrographic shapes of flood waves compared with the past. The estimation and evolution of the transformation of historical flood waves under recent river conditions is only possible by model simulations. For this purpose a nonlinear reservoir cascade model was constructed. The NLN-Danube nonlinear reservoir river model was used to simulate the transformation of flood waves in four sections of the Danube River from Kienstock (Austria) to Štúrovo (Slovakia) under relatively recent river reach conditions. The model was individually calibrated for two extreme events in August 2002 and June 2013. Some floods that occurred on the Danube during the period of 1991-2002 were used for the validation of the model. The model was used to identify changes in the transformational properties of the Danube channel in the selected river reach for some historical summer floods (1899, 1954 1965 and 1975). Finally, a simulation of flood wave propagation of the most destructive Danube flood of the last millennium (August 1501) is discussed.