Possible ways to improve sediment deposition in the Nemunas delta

Abstract

The deposition of sediment in the inundated fioodpiains of rivers, particularly in their deltas, improves the water quality of the rivers themselves and of their receivers. It would be very useful if ways to increase the amount of sediment deposition could be identified. An investigation into a number of possibilities was carried out in the delta of the River Nemunas. Various factors can influence the increase or decrease of sediment deposition, e.g. the increase of water discharge flowing through the river valley, the growth of bushes on the floodplain, the building of road banks across the valley and changes in growth stages of grass (which affect its ability to entrap sediments). The effects of these factors are discussed, and the most successful ways for improvement in the Nemunas delta are proposed. Similar methods may also be applicable in other river deltas.

Mathematical Modeling of the Suspended Sediment Dynamics in the Riverbeds and Valleys of Lithuanian Rivers and Their Deltas

“…Thus, the volume of sediments deposited in the floodplain is quite large. Such amounts of sediments per unit floodplain area have been found in our field investigations (Rimkus & Vaikasas, 2010;Rimkus et al, 2007;Lamsodis & Vaikasas, 2005;Vaikasas & Rimkus, 2003). In periodically flooded meadows, the grasses actually entrap the sediments and favour self-cleaning of the rivers.…”

“…Therefore it was investigated the means and factors influencing the sediment deposition in the valleys. (Rimkus & Vaikasas, 2010). These factors are: 1.…”

“…In reservoirs, anaerobic processes and algal populations tend to dominate, and eutrophication may occur if there is an excess of nutrients in the water and sediments (WFD, 2007;Povilaitis, 2008). Thus, ecosystems can be influenced to a large extent and the water quality may get worse (Vaikasas & Dumbrauskas, 2010;Rimkus & Vaikasas, 2010;Olli, 2008). Therefore, it is necessary to analyse these processes and reduce their negative influence by choosing optimal methods of hydro-energy employment.…”

The fluctuation of calcium and magnesium concentrations in the floodwater in the Nemunas and Minija lowlands

“…(Katutis, 2007). Various factors can influence the increase or decrease of sediment deposition, e.g., the increase of water discharge flowing through the river valley (Rimkus, Vaikasas, 2010). The pulsing of river discharge is considered to be a major driving force that determines the degree of connectivity, the exchange of matter and the processing of organic matter and nutrients across river-floodplain gradients (Schulz-Zunkel et al, 2013).…”

Simulating the influence of the height of HPP dams on the environmental conditions in small river Virvyte

“…In the reservoirs, anaerobic processes and algal populations tend to dominate, and eutrophication may occur if there is an excess of nutrients in the water and sediments (Povilaitis 2008). Thus, ecosystems can be affected to a large extent when the exchange of water and sediments becomes difficult or impossible and the water quality may get worse (Fraley et al 2007;Hohensinner et al 2004;Vaikasas, Dumbrauskas 2010;Rimkus, Vaikasas 2010). Therefore, it is necessary to analyse these processes and reduce their negative influence by choosing optimal methods of hydro-energy employment.…”