13 Particularities of Drain Liquid in the Small Wetland of Braila …
447
320–340 kg/s, i.e. one-third of the flow of alluviums that flowed on the Danube in
natural conditions [37, 38].
A key element for successful management of the computing program is the availability of the required data in the study area, especially in electronic format. For this
purpose, a spatial database is created. The spatial data collected were: topography,
liquid flows, river basin boundaries, land uses/cover and soil types. For the intended
area, there have been determined three stages of slope delimitation, the distance
error being from 0 to 2%; 2 to 4%; > 4% (Fig. 13.4). The low slope of the terrain
leads, especially when the water level is low, to a slow flow of water, which on some
channels has a direction opposite to normal upstream flow.
There have been outlined 15 hydrographical reception sub-basins feeding the
Danube and a series of channels of the Danube, along with channels belonging
to each reception sub-basin (Fig. 13.5). It was done based on the digital model
of the terrain, with a resolution 1 at 25 m, and on the predefined data regarding
the hydro geographical basins and the hydrographical network in the studied area,
using the ArcSwat application. To each defined hydrographical sub-basin, there has
been attributed a closing section resulting, thus, in 15 control sections of the main
characteristic elements (Fig. 13.6). The problem with this area is the delimitation
of the hydrographical basins on land with small slopes, entirely different than the
hydrographical basins from the hills or the mountains.
A feature of the lower course of the Danube is the fact that the amounts of sludge
alluviums have small values, which vary between 0 and 40 kg/s and represent about
5% of the total alluvial transport. In the sections Vadu Oii and Braila, which limit
downstream Balta Ialomitei and Balta Braila respectively, the flows of dragged alluviums have values of 1–3% of the total quantity of alluviums. In the sections on
the main branches of the Balta Brailei hydrographic system, there were no flows of
dragged alluviums.
In order to define the hydrological units, there have been introduced data about
the usage of the terrain, soils, and slopes. The hydrographical basins thus determined
have been classified into 5 subunits of agricultural use, considering the usage of the
land: agricultural, forestry of the wetlands and the surfaces exclusively covered by
water or buildings (Fig. 13.7). Of the ecosystems identified here, 50% are natural,
30% are semi-natural and 20% are man-made [39]. Because the territory is subjected
to flood periods and water withdrawal periods each year, the two types of ecosystems,
terrestrial and aquatic, are interdependent, creating a specific Danube biomass. There
is no strict territorial and temporal delimitation between these types of ecosystems,
with a periodic succession and replacement.
A number of about 150 plant species have been identified in the wetland system in
the Small Wetland of Braila. Among the most common wood species are: the willow
(Salix alba, Salix cinerea, Salix fragilis), the poplar (Populus alba, Populus nigra),
the ulmus (Ulmus foliacea), the myricaria (Myricaria germanica), the blackberry
(Rubus caesius). The most common wet plant species are: reed (Phragmites australis), cattail (Typha latifolia, Typha angustifolia), Scirpus lacustris, Lythrum salicaria, Galium palustre, Euphorbia palustris, Solanum dulcamara, Sium latifolium,
Glyceria maxima, Stachys palustris, Butomus umbellatus, Iris pseudacorus.
447
320–340 kg/s, i.e. one-third of the flow of alluviums that flowed on the Danube in
natural conditions [37, 38].
A key element for successful management of the computing program is the availability of the required data in the study area, especially in electronic format. For this
purpose, a spatial database is created. The spatial data collected were: topography,
liquid flows, river basin boundaries, land uses/cover and soil types. For the intended
area, there have been determined three stages of slope delimitation, the distance
error being from 0 to 2%; 2 to 4%; > 4% (Fig. 13.4). The low slope of the terrain
leads, especially when the water level is low, to a slow flow of water, which on some
channels has a direction opposite to normal upstream flow.
There have been outlined 15 hydrographical reception sub-basins feeding the
Danube and a series of channels of the Danube, along with channels belonging
to each reception sub-basin (Fig. 13.5). It was done based on the digital model
of the terrain, with a resolution 1 at 25 m, and on the predefined data regarding
the hydro geographical basins and the hydrographical network in the studied area,
using the ArcSwat application. To each defined hydrographical sub-basin, there has
been attributed a closing section resulting, thus, in 15 control sections of the main
characteristic elements (Fig. 13.6). The problem with this area is the delimitation
of the hydrographical basins on land with small slopes, entirely different than the
hydrographical basins from the hills or the mountains.
A feature of the lower course of the Danube is the fact that the amounts of sludge
alluviums have small values, which vary between 0 and 40 kg/s and represent about
5% of the total alluvial transport. In the sections Vadu Oii and Braila, which limit
downstream Balta Ialomitei and Balta Braila respectively, the flows of dragged alluviums have values of 1–3% of the total quantity of alluviums. In the sections on
the main branches of the Balta Brailei hydrographic system, there were no flows of
dragged alluviums.
In order to define the hydrological units, there have been introduced data about
the usage of the terrain, soils, and slopes. The hydrographical basins thus determined
have been classified into 5 subunits of agricultural use, considering the usage of the
land: agricultural, forestry of the wetlands and the surfaces exclusively covered by
water or buildings (Fig. 13.7). Of the ecosystems identified here, 50% are natural,
30% are semi-natural and 20% are man-made [39]. Because the territory is subjected
to flood periods and water withdrawal periods each year, the two types of ecosystems,
terrestrial and aquatic, are interdependent, creating a specific Danube biomass. There
is no strict territorial and temporal delimitation between these types of ecosystems,
with a periodic succession and replacement.
A number of about 150 plant species have been identified in the wetland system in
the Small Wetland of Braila. Among the most common wood species are: the willow
(Salix alba, Salix cinerea, Salix fragilis), the poplar (Populus alba, Populus nigra),
the ulmus (Ulmus foliacea), the myricaria (Myricaria germanica), the blackberry
(Rubus caesius). The most common wet plant species are: reed (Phragmites australis), cattail (Typha latifolia, Typha angustifolia), Scirpus lacustris, Lythrum salicaria, Galium palustre, Euphorbia palustris, Solanum dulcamara, Sium latifolium,
Glyceria maxima, Stachys palustris, Butomus umbellatus, Iris pseudacorus.