This document proposes a solution for fish migration on the Somesul Mic River upstream and downstream of the Manastur Dam in Cluj Napoca, Romania. Currently, the fish ladder at the dam is inoperable and blocks migration of important fish species. The proposed solution involves modifying the existing fish ladder by removing obstacles, cutting a rectangular opening, and adding two concrete modules above the dam that would guide water and fish in a gradual slope. This low-cost solution aims to restore longitudinal connectivity on the river and protect biodiversity while not impacting the dam structure. If implemented, it could help reestablish migratory fish populations and the ecological balance of the ecosystem.

1. ©Department of Geography. Valahia University of Targoviste
Annals of Valahia University of Targoviste. Geographical Series
Tome 14/2014 Issues 2
http://fsu.valahia.ro/images/avutgs/home.html
SOLUTION FOR FISH MIGRATION ON THE SOMEŞUL MIC RIVER UPSTREAM –
DOWNSTREAM OF MĂNĂŞTUR DAM IN CLUJ NAPOCA
Răzvan VOICU1
, Petre BRETCAN2
1National Institute of Hydrology and Water Management, Sos. Bucuresti-Ploiesti 97, Bucuresti, cod 013686,
România, Tel.: +40-21-3181115, Fax.: +40-21-3181116, Email: rzvnvoicu@yahoo.com,
2 Valahia University of Targoviste, Department of Geography, st. Lt. Stancu Ion, no.34-36, 130024,
Târgoviște, Dâmbovița, tel: (04) 0245206105, Romania
Abstract
Hydrotechnical constructions (discharge sills, dams etc) located across the watercourse Somes Mic block
migration of two important migratory fish species: barbel (Barbus barbus - rare species, protected Habitats
Directive (Annex V), annex 4A of Low nr.462 and Red List of RBDD) and nase (Chondrostoma nasus -
protected by Bern Convention - Appendix III). Mănăştur Dam located in Cluj Napoca has a fish passage
inoperable. Also, the national legislative framework regarding the water policy (Water Law no. 107, with
subsequent amendments, NT No. / 2006 OM 1163/2007), reflecting the European directives, mentions the
obligation to ensure construction works in order to protect the fish migration and also to maintain the ecological
balance in the reservoirs. Therefore, this article aims to provide a solution for migration fish fauna, designed to
restore longitudinal connectivity. The proposed migration system are based on the gravitational fall of water
and will lead to the restoration of the longitudinal connection of the Someşul Mic River. This paper represent a
part of a complex study regarding the restoration of longitudinal connectivity of Someşul Mic River
accomplished in a framework of a more large Programme of Measures for restoring longitudinal and lateral
connectivity of Someşul Mic River. The issue of ecological restoration of water courses is a matter of public
interest and has emerged as a result of the effects of human impact caused by the following factors:
industrialization, urbanization, agricultural and zootechnical activities, and hydro-morphological pressures.
Rivers restoration includes a large variety of methods, mainly aimed to restore the natural functions of rivers
altered after anthropic interventions.
Keywords: ecobiome’s functionality, fish migration, Somesul Mic River, longitudinal connectivity, dam.
1. INTRODUCTION
Longitudinal connectivity within a hydrographic network refers to the ways in which
organisms move and also to energy and material exchanges located throughout the water (Lucas &
Baras, 2001; Amoros & Bornette 2002). Discontinuation of longitudinal connectivity of water
courses caused by waterworks (sills and dams) has a major impact on sediment transport,
hydrological regime, downstream moving and biota migration (Amoros & Petts, 1993; Vannote et.
al. 1980).
Since the minor riverbeds are influenced both by longitudinal and lateral movements,
through the modification of the matter and energy quantities in the hydro-system (Armstrong, 1996;
Larinier, 2001; Vannote et al. 1980), the continual monitoring of their effects is a very topical
problem (Berra T. 2001). The modification of the longitudinal connectivity of the rivers produces
direct effects on the fish populations, influencing the way they travel, reproduce and feed (Gross et

2. al. 1988; Jackson et al. 2002; Vannote et al. 1980), and the understanding of the new modalities of
adaptation of the fish populations plays an important role in ecological reconstruction, in the
restoring of the interrelations and in the hydro-systems’ functionality (Larinier & Travade, 1999;
Naiman & Bilby, 2001).
The disturbance of the aquatic biotops, through the modification of the reproduction and
migration areas for fish species affects the whole food chain (Northcote 1998; Vannote et al. 1980).
The analysis of this correspondence realized on the basis of detailed studies highlights the role of
the main abiotic factors responsible for the modification of the biological communities, including
fish communities, in Somesul Mic River (Bănărescu, 1964).
The isolation and fragmentation of the habitats through the modification of the longitudinal
and lateral connectivity of the rivers, through the reduction of the floodable areas and the
modification of the rivers’ functional areas (Larinier, 2001), has led to the reduction of the
biodiversity conservation capacity (Jungwright, 1996; Jungwirth et al. 1998).
The protection of the rivers’ ecological integrity and biodiversity can be realized as well by
restoring the longitudinal and lateral connectivity (Toroimac 2009; Ionus 2013) and implementing
the European legislation (Water Framework Directive 2000/60/EC) as well as the Romanian one.
Given that Romania is part of the European Union, it has the obligation to implement the
provisions of the Water Framework Directive 2000/60/EC, transposed into Romanian legislation by
the Water Law 107/1996 as supplemented and amended (Voicu, 2014) (Act 310/2004, Law 112 /
2006; Act 161/2006 – Norms regarding the classification of ground water quality in order to
stabilize the ecological status of water bodies and Ministerial Order 1163/2007 on technical projects
for designing and realizing hydro-technical arrangement and re-arrangement works for water
courses) (Voicu&Voicu, 2014).
The long-term anthropic intervention realized through the presence of hydro-technical
constructions (Cada, 1998) within the basin area and direct or diffuse pollution results in a gradual
degradation of the ecosystems. The presence of treatment stations (having a low efficiency in the
case of certain pollutants) and that of waste platforms determine a higher pollution level (Szigyártó,
2013) and a lower water quality in certain sectors of the course of Someşul Mic River and of its
tributaries (Avram, 2011)
2. MATHERIAL AND METHODS
2.1. Study area
The hydrographic basin of Somesul Mic River develops around Cluj County and partially
Bihor County, and one can easily identify both its upper and its lower basin (Serban, 2007). The
morphological evolution of the hydrographic basin determined the sinewy aspect of the water
courses, the drainage occuring along the general direction North-East. The hydrological regime of
Somesul Mic River and its tributaries is determined by the specific climate conditions, a gap of
about one month being present between the occurence of the maximal precipitations and the
maximal debits (Serban, 2007). The values of the average specific flows increase simultaneously to
the increase of the average altitude of the basin, and the coefficient of the average flow has a similar
spatial distribution (Serban, 2007) because of the good drainage of the precipitations and given the
presence of impermeable rocks (Batinas & Sorocovschi, 2012).
The construction of storage lakes in the hydrographic basin (Serban, 1999) determined the
modification of the rivers’ hydrological regime, both under the aspect of the liquid flows and in
point of the solid flows, the spring season (40-45%) continuing to be the one during which the
largest flows and volumes are transported through the riverbed (fig. 1). The arrangement of the
hydrographic basin of Somesul Mic River was realized in two stages: during the first stage (1968-
1980), the storage lakes (Gilau, Tarnita, Fantanele etc.) and the water adduction and derivation
works were realized, whereas during the second stage (1980-1990) the latter were put into operation
(Serban, 2007).

3. Figure 1. Temporal distribution of seasonal mean flow upstream (a) and downstream (b)
of Gilau dam
3. RESULT AND DISCUSION
Mănăştur dam fish ladder was built inappropriately for the migration of migratory fish
species living in the Someşul Mic River. Inside this fish ladder the speed is too high; there is also a
lot of turbulence created by concrete sheet piles located within the migration system (fig. 2). The
slope is too big for fish to migrate (fig. 3), therefore it should be designed and built again.
Consequently such engineering solution that will not affect the fish ladder or the dam structure must
be proposed. The water speed downstream of Mănăştur dam is about 1m/s and the water flow of
about 5.5 m3
/s. River slope is 0.5 percent (%).
Figure 2 and figure 3 Fish ladder dam located on the Mănăştur dam
The first thing to do is eliminate dissipaters (concrete flanges) inside the fish ladder. Then a
rectangle must be cut on the left vertical wall of the fish ladder (fig. 4). The vertical walls of the fish
ladder will be lifted by the means of two concrete triangles with sides smaller than 30 cm (fig. 4).
After more than 40 cm downstream of the rectangular crenel, a concrete sheet pile completely
blocking the water flow inside the fish ladder shall be fixed (fig. 5).

4. concrete sheet pile for a complete blockage of the fish ladder
high wall made of concrete plate
rectangular crenel
Mănăştur dam
Figure 4 Positioning the crenel and the vertical walls of the fish ladder
concrete sheet pile
fish ladder
Figure 5 Positioning the concrete sheet pile inside the fish ladder – indicative scheme
The entire amount of the water flow captured by the fish ladder flows through the
rectangular crenel. Because inside the fish ladder the water speed must be lower than the river water
speed, the horizontal surface of the fish ladder is covered by concrete on an inclined plane (fig. 6).

5. concrete sheet pile
rectangular crenel
horizontal surface covered by concrete (inclined plane) of the fish ladder
Figure 6 Positioning the concrete surface (inclined plane)
inside the fish ladder – indicative scheme
Four-fifths of the rectangular crenel will undertake the entire amount of water flow from the
arranged fish ladder. The concrete sheet pile blocking the water flow inside the fish ladder can also
calm down the water stream next to the crenel due to the wave propagating that is almost
nonexistent next to the crenel area due to the afflux. The distance between the concrete sheet pile
and the crenel can be calculated in the laboratory of hydraulics without any difficulty.
The distance between the bottom of the crenel and the multiannual average level of the river
should not exceed 30 cm. This new channel undertaking water from the crenel will be about 65 cm
height and 3 cm thick and will be made of concrete (fig. 7). The new canal will consist of two
modules M1 and M2 forming an angle of 90°. M1 module will be supported by the fish ladder
upstream and by two concrete pillars downstream (fig. 8) the M1 and M2 modules have in common
the concrete pillars. There are also other concrete pillars close to the water level (fig. 9)
concrete sheet pile rebuilt fish ladder
metal rivet
concrete canal undertaking water and fish fauna of the existing fish ladder
concrete pillar
module M2
concrete pillar for
support module M2
Şomesul Mic river
Figure 7 Positioning the two modules M1 and M2 Figure 8 Positioning the two pillars in relation
– indicative scheme to the water level – indicative scheme

6. Mănăştur Dam
module M1
module M2
the joining area between modules M1 and M2
concrete sheet pile
the Someșul Mic River water level
Figure 9 General scheme of the fish migration system over the dam Mănăştur – indicative scheme
The modules M1 and M2 will be approximately 1,5 meters and 4 meters, respectively.
During winter the modules M1 and M2 can be detached from the existing fish ladder and stored in
proper places for that they can be reassembled again in spring. The execution costs are lower than
for a typical fish ladder. For good results, the two modules can follow the example of some Alaska
steep pass (fig. 10 and fig. 11).
Figure 10 The Plimoth Grist Mill river (US)
(Source: http://blogs.plimoth.org/milltale/?tag=alaskan-steep-pass)

7. Figure 11 Glover Mill Pond Dam on the Herring Brook (US)
(Source: http://northsouthrivers.blogspot.ro/2011/11/normal.html)
CONCLUSION
The study of the effects of the longitudinal connectivity modification in relation to the
migration of the fish species over the transversal hydro-technical works can yield important data
useful to protect biodiversity and restore the populations in order to reestablish the ecological
balance. The technical solutions proposed for reestablishing the longitudinal connectivity of
Somesul Mic River downstream/upstream from Manastur Dam aim to preserve biodiversity and
maintain the ecological balance of the ecosystems. Subsequent detailed studies could lead, on the
one hand, to an increasingly detailed knowledge of the migration periods and of the migratory
flows, and, on the other hand, to the improvement and completion of the technical solutions
proposed.
This system of fish migration upstream – downstream of the dam Mănăştur provides
longitudinal connectivity of the Somesul Mic River representing an important issue in the local lotic
ecosystem restoration. The solution proposed in this paper is practical, is not expensive, it can be
developed without any expensive technology and does not affect the dam structure.
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