Could road constructions be more hazardous than an earthquake in terms of mass movement?

Roads can have a significant impact on the frequency of mass wasting events in mountainous areas. However, characterizing the extent and pervasiveness of mass movements over time has rarely been documented due to limitations in available data sources to consistently map such events. We monitored the evolution of a road network and assessed its effect on mass movements for a 11-year window in Arhavi, Turkey. The main road construction projects run in the area are associated with a hydroelectric power plant as well as other road extension works and are clearly associated with the vast majority (90.1%) of mass movements in the area. We also notice that the overall number and size of the mass movements are much larger than in the naturally occurring comparison area. This means that the sediment load originating from the anthropogenically induced mass movements is larger than its counterpart associated with naturally occurring landslides. Notably, this extra sediment load could cause river channel aggregation, reduce accommodation space and as a consequence, it could lead to an increase in the probability and severity of flooding along the river channel. This marks a strong and negative effect of human activities on the natural course of earth surface processes. We also compare frequency-area distributions of human-induced mass movements mapped in this study and co-seismic landslide inventories from the literature. By doing so, we aim to better understand the consequences of human effects on mass movements in a comparative manner. Our findings show that the damage generated by the road construction in terms of sediment loads to river channels is compatible with the possible effect of a theoretical earthquake with a magnitude greater than Mw = 6.0.

Przekształcenie obszaru wysoczyzny lessowej pod wpływem gospodarczej działalności człowieka w neoholocenie (na wybranych przykładach z okolic Mozgawy, Ponidzie Pińczowskie)

The Mozgawa area, located in the Ponidzie Pińczowskie Region (SE part of the Nida River Basin), is a very good example of response of the natural environment to the progressive human impact. The research conducted there indicates that before the appearance of the first Neolithic farmers, the relief of the area was different to the modern one. Constant and intensive agricultural use of the loess plateau and the adjacent slopes (started in the Neolithic period some 5890±100 BP) led to the filling of the valley bottoms and local depressions with deluvial deposits, the thickness of which reaches up to 12 m. The deposition of these sediments and elevation of the surface level in the subordinate areas resulted in the creation of the Mozgawka River channel since the begining of the Roman Period. Formerly it was impossible (as it was within the depression) and the runoff was only through the karst system. Since that moment it has also started the accumulation of the alluvial fan, the progradation of which leads to the pushing of the Nida River channel towards the East.

Reconstruction of Nineteenth-Century Channel Patterns of Polish Carpathians Rivers from the Galicia and Bucovina Map (1861–1864)

Historical maps are often the only source of information allowing for the regional reconstructions of river channel patterns in the past. In the Polish Carpathians, analyses of historical channel patterns were performed mostly in river reaches scale. In this paper, the Galicia and Bucovina map (1861–1864) (the Second military survey of the Habsburg Empire) was used to reconstruct and map the historical channel patterns of seven rivers from the Polish Carpathians. It was found that, in the nineteenth century, rivers in the western part of the study area (Soła, Skawa, Raba, Dunajec) supported a multi-thread channel pattern, whereas rivers in the eastern part (Wisłoka, San, Wisłok) present a mostly single-thread channel pattern. These differences probably result from the higher relief energy and precipitation, lower proportions of forests in the catchments, and more frequent floods favouring high sediment supply to the fluvial system, and thus the formation of multi-thread reaches in the western part of the study area. At the local scale, the most important factor supporting multi-thread channel pattern development was the availability of gravel sediments in the wide valley floor sections. The formation of anabranching reaches with a single mid-channel form was probably associated with the channel avulsion process. There is no clear evidence linking the change in the channel pattern type with an abrupt change in the river channel slope. This study confirms the usefulness of the second military survey map of the Habsburg Empire for the regional reconstruction of river channel pattern types.

Connection between Anthropogenic Water Diversion and Hydrodynamic Condition in Plain River Network

The increase in the rate of water renewal driven by hydrodynamics contributes to improving the water quality of the plain river network. Taking the lakeside river network in Wuxi as an example, through numerical simulation, polynomial fitting, correlation analysis, and principal component analysis, the hydrodynamic responses of urban lake-connected river networks to water diversion and hydrodynamic grouping were researched. Based on numerical model and influence weight analysis, we explored the improvement of hydrodynamic conditions of plain river network with strong human intervention and high algal water diversion. The results showed that: (1) The relationship between water diversion impact on river network flow velocity and water diversion flux was not as simple a linear relationship. It could be reflected by polynomial. The water transfer interval in dry season with high hydrodynamic efficiency (HE) was lower than 10 m3/s and higher than 30 m3/s, and the HE increased significantly when the water transfer flow was higher than 20 m3/s in the wet season. (2) According to the main hydrodynamic driving factors, the channels in the river network could be divided into three types: water conservancy projects, river and lake water level difference, and river channel characteristic. The correlations of rivers’ flow velocity in each group were very high. (3) The influence weights of water conservancy projects, river and lake water level difference, and river channel characteristic on the whole river network dynamics were 65, 21, and 12.4%, respectively, and the other factors contributed 1.6% of the weight.

The Effect of Urban Drainage on The Determination The Time of Storage In The City Development Area

Increasing development activities in various fields in Surabaya will impact the occurrence of flooding, where the growth of residential buildings changes the function of the drainage area into runoff land. Therefore, there is a need for regional drainage recommendations. This study aims to provide a reference for a safe number that follows the storage needs and the duration of the peak partial drainage required by the region, following the study of water resources science. The data needed are rainfall data, average area, land function, and land slope maps. This study uses a 5-year return period probability. Moreover, the Nakayasu Hydrograph method is also used. It has a grace period starting from the rain surface to the top of the hydrograph, the area of the watershed, and the length of the main river channel. The comparison of the length of time of concentration (Tc) of the area with the length of waiting for time (Tp) of the urban drainage hydrograph shows that the area’s Tc value is greater than the Tp value of the urban drainage.

Improvement of the method of combined plans for the analysis of channel re-formations of a water body on the example of the oka river section

The article discusses the ways of improving the method of combined plans for a water body channel reformations analysis on the example of a section of the Oka River. The main disadvantages of the existing classical approach to the analysis of channel processes through the channel surveys separate isobaths’combination are highlighted. A new approach to combining digital models of the river bed relief obtained from the hydrographic surveys results is proposed. Two directions of surface comparison are shown for the subsequent analysis of channel processes. For a qualitative assessment of channel changes, it is proposed to construct a new surface of vertical deformations and visualize it in color gradation or using lines of equal vertical deformations. For a quantitative assessment of channel processes, the use of a cartogram of vertical channel deformations is considered, and the numerical parameters for assessing the stability of the river channel are introduced. For the considered section of the Oka river channel, the main indicators of channel processes were obtained and analyzed using the proposed updated method. Separately, the calculation of the most optimal grid size was performed when constructing a cartogram of vertical channel deformations.

Environmental assessment of the estimated dredging volumes on the Ob River

The object of the study is the impact of dredging in the Ob riverbed on individual components of the environment, in particular, ichthyofauna. The volumes of transit and capital dredging in the river channel on the crossing sections that are difficult for navigation have been determined and substantiated. To calculate the damage, a method to determine the loss of ichthyofauna was used, taking into account the death of benthic and planktonic organisms in turbidity plumes and on the bottom areas subjected to development by dredgers and buried under dumped fills. It has been established that the greatest losses of ichthyomass will occur in the sections of the Upper Ob (up to the Novosibirsk reservoir) and the Middle Ob (up to the mouth of the Tom River), which is explained by the presence of numerous crossovers that impede navigation and require constant dredging. In the Lower Ob, the negative impact on benthos, plankton and ichthyofauna will be insignificant due to the small number of small crossovers. The volumes of dredging in the fairway required to maintain guaranteed depths and dimensions have a certain environmental load, the level of which is not critical for the ecosystems of a large river. However, when creating large-scale capital bypass channels, it can increase sharply in certain years. By reducing the load, a stable shipping lane can be created and the frequency of dredging operations at each of the crossover sections can be reduced. The advantages and disadvantages of the used damage assessment method are noted.

Modelling long-term alluvial-peatland dynamics in temperate river floodplains

Peat growth is a frequent phenomenon in European river valleys. The presence of peat in the floodplain stratigraphy makes them hotspots of carbon storage. The long-term dynamics of alluvial peatlands are complex due to interactions between the peat and the local river network, and as a result, alluvial-peatland development in relation to both regional and local conditions is not well understood. In this study, a new modelling framework is presented to simulate long-term peatland development in river floodplains by coupling a river basin hydrology model (STREAM – Spatial Tools for River basins and Environment and Analysis of Management options) with a local peat growth model (modified version of DigiBog). The model is applied to two lowland rivers in northern Belgium, located in the European loess (Dijle (Dyle) River) and sand (Grote Nete River) belts. Parameter sensitivity analysis and scenario analysis are used to study the relative importance of internal processes and environmental conditions on peatland development. The simulation results demonstrate that the peat thickness is largely determined by the spacing and mobility of the local river channel(s) rather than by channel characteristics or peat properties. In contrast, changes in regional conditions such as climate and land cover across the upstream river basin have been shown to influence the river hydrograph but have a limited effect on peat growth. These results demonstrate that alluvial-peatland development is strongly determined by the geomorphic boundary conditions set by the river network and as such models must account for river channel dynamics to adequately simulate peatland development trajectories in valley environments.