Frequency of Floodplain Spills in the Tisza River Valley at Vylok (Transcarpathia, Ukraine)

Record-breaking floods occurred in the autumn of 1998 and the spring of 2001 in the lowlands of Transcarpathia,as well as in the areas of Hungary and Romania bordering Ukraine,which caused severe damage.Our research was to determine the frequency of floods.The fluctuation of precipitation values brings about the increased frequency of the rivers’inundation as well.The research is based on the data of the Tisza River’s inundation onto the flood plain near Vylok,as well as the precipitation data of the Rakhiv meteorological station.Both data series include the data of the latest 46 years(1970-2015),highlighting the pre-flood period of 1970-2001.To evaluate the data,we used linear trend analysis,which was edited using the Microsoft Excel spreadsheet program.The results of the study showed that no particular changes in precipitation were observed,but the frequency of flood waves and the coverage of the floodplain with water showed a gradually increasing trend.The results of studying the amount of precipitation and the Tisza River’s inundation:in recent decades the frequency of flood wave formation and the coverage of the flood plain with water show a gradually increasing tendency.

Soft Sediment Deformation Structures in the Sediment Deposits of Ganga River and Its Oxbow Lakes in Parts of Indo-Gangetic Plain: Implications for Quake Proxies and Paleoseismicity Tracking

The Late Quaternary thick sedimentary fills of the Ganga basin predominantly consist of unconsolidated fluvial sandy deposits which are often intercalated with mud. These deposits at various places record the evidence of earthquakes, which occurred in the recent geological past. The evidence is contained and manifested in the form of Soft Sediment Deformation Structures (SSDSs). Saturated sediments/muds/soils are liquefied by earthquake tremors which either generate SSDS or produce structural discordance in the pre-existing sedimentary structures. The present study reports the occurrence of SSDS, e.g. load and associated flame structures, clastic dikes and sill structures, slump structures and sedimentary breccias, etc. from the Ganga River and adjacent oxbow lake sediment deposits. An attempt has been made to establish the origin of soft sediment structures of this region in accordance with its neotectonic history and in turn, identification of seismic structural proxies to delineate paleoseismic events in this region with futuristic implications. The preservation of soft sediment deformation structures in large numbers with multiple geomorphology and scale, in the river and adjoining lake sediments, is indicative of frequent earthquakes of high magnitude consequent to tectonic activism in the Himalayan region.

The Challenges of Road Construction in Zambia’s Western Province:A Case Study of the Mongu-Kalabo Road Project

Availability of good quality local construction materials is a major component of road construction as it contributes greatly to the cost of construction.Reserves of good quality construction material may be readily available in some parts of Zambia while in some parts like the Western Province,sources of suitable construction materials are scarce.The lack of suitable construction materials in Western Province has affected the construction,rehabilitation and maintenance of roads in this area as materials have to be hauled from distant sources to site.Plans to construct an all-weather road to ease the transport challenges and ensure development for the people of Western Province started as far back as 1966 but were first affected in 2002 when the first attempt to construct an all-weather paved road embankment across the flood plain was made.This paper discusses some of the challenges faced in road construction projects in Zambia’s Western Province,specifically focussing on the Mongu-Kalabo road construction project as a case study.The various challenges faced on this project include financing(high construction cost),challenging terrain(deep Kalahari sands and seasonal flooding)and lack of suitable road construction materials are discussed.The Government of the republic of Zambia has prioritised infrastructure development and has thus embarked on the construction of the 34 km of the Mongu-Kalabo Road Embankment which will include twenty-five bridges across the Barotse Flood Plain at a cost of US$286 million.The potential benefits of constructing the Mongu-Kalabo road to the people of Western Province and the country at large,which include opening up trade with neighbouring Angola,are also discussed.

Impact of dam on inundation regime of flood plain wetland of punarbhaba river basin of barind tract of Indo-Bangladesh

Present study raises a serious issue of wetland loss and transformation due to damming and water di-version.At present study,it is noticed that overall rainfall trend(-0.006)of the study period(1978-2015)remains unchanged but riparian wetland area is attenuated after damming both pre monsoon(March to May)and post monsoon season(October to December).Total wetland area in pre-and post-monsoon seasons is respectively reduced from 42.2 km^(2) to 27.87 km^(2),and from 277.85 km^(2) to 220.90 km^(2) in post dam period.Transformation of frequently inundated wetland area into sparsely inundated wetland is mainly triggered by flow modification due to installation of Komardanga dam and Barrage over Punarbhaba and its major tributary Tangon river.Sparsely inundated seasonal wetland area is rapidly reclaimed for agricultural practice.This extreme issue will invite instability in socio-ecological setup of the neighbouring region.

HYBRID SIMULATION OF THE HYDRAULIC CHARACTERISTICS AT RIVER AND LAKE CONFLUENCE

The hydraulic characteristics at the confluence reach of river and lake are influenced by multiple factors such as inflow,topography and vegetation resistance,and are very complicated.In this article,the confluence reach of Yangtze River and Dong-ting Lake is selected as a special example and a hybrid model is built to study the flow at this confluence,with the consideration of the interactions between aquatic vegetation and flow.Validation tests and calculations show that the model is effective and highly accurate.The simulations show that the separation levee at the confluence reach may change the discharge capacity in the flood plain,which would be enhanced in the upper reach of the levee,hardly changed in the middle reach and reduced at the lower place.Moreover,the separation levee also limits the water exchange between the Yangtze River and Dong-ting Lake.

EVALUATION OF STAGE-DISCHARGE RELATIONSHIP IN COMPOUND CHANNELS

Experimental results were compared with the computed results obtained from the nine most well-known methods for computation of discharge in a compound channel. The results demonstrate a high accuracy of the divided channel method with the horizontal division lines, while the length of division line is included within the calculation of the wetted perimeter. In addition, as relative depth increases, the results of the all methods converge to each other and also in case of steeper slopes in lower relative depths, more agreements between different calculated methods and experimental results were observed. Furthermore, the results show the effects of the maximum momentum transfer on the horizontal interface between the main channel and flood plains, while further angular distance from the horizontal interface toward the vertical interface between main channel and flood plains causes gradual decrease of momentum transfer effects.