Channel Regime and Navigation Conditions of the Lower Don

GEOGRAPHY AND TOURISM, Vol. 6, No. 1 (2018), 77-85, Semi-Annual Journal eISSN 2449-9706, ISSN 2353-4524, DOI: 10.5281/zenodo.1314034 © Copyright by Kazimierz Wielki University Press, 2017. All Rights Reserved. http://geography.and.tourism.ukw.edu.pl

G.L. Gladkov1, V.M. Katolikov2 1 State University of Marine and River Fleet by the name of Adm. S.O. Makarova, Saint-Petersburg, Russia, email: [email protected]. 2 State Hydrological Institute, Saint-Petersburg, Russia

Channel regime and navigation conditions of the Lower Don

Abstract: The work relates to navigation conditions of the Lower Don. The research was performed on hydrological and sediment regimes of the Don River, downstream of the Kochetovsky hydraulic engineering complex. The impact of the planned Bagaevskiy Dam construction on hydraulic characteristics of the flow and deformation of the riverbed was also assessed. Materials collected during engineering and hydrometeorological surveys, the results of mathematical modelling and hydraulic studies completed as part of the design works on the facility – “The Bagaevskiy Dam construction on the Don River” – were used as input data. Keywords: hydrological regime, channel processes downstream of the dam, riverbed deformations, navigation, mathematical and hydraulic modelling

1. Introduction

The object of the present study is the section of cascade of a low-pressure hydrosystem was the Lower Don River located downstream of prepared by 1908. The project involved three the Kochetovsky hydraulic engineering com- stages of construction. The implementation of plex, which has the most difficult navigation the project was aimed at enabling the naviga- conditions in the area. The Lower Don is part tion on the Seversky Donets from the Don to of the Unified Deep Water System of Euro- Belgorod and Kharkov by vessels with a draft pean Russia and is one of the most congested of up to 1.7 m. sections of inland waterways of international The first stage of the construction of the importance in the Russian Federation. The Seversky–Donets system gateways – from the scheme of waterways of the Lower Don is mouth of the Seversky Donets to the village shown in Fig. 1. of Gundorovskaya (near the modern city of The hydrotechnical construction in the Donetsk) was launched in May 1911 and largely Lower Don basin was started in the early years completed by autumn 1913. The construction of the 20th century to ensure the supply of of the Kochetovsky hydraulic engineering com- coal, building materials and grain from the plex, located on the Don River, was started in Donbass in the regions of the Sea of Azov and 1914. The official opening of the Seversky– the Black Sea. In this context, the decision Donetsk river sluice system took place on 5 July about the necessity of locking the Seversky 1914, a few weeks before the outbreak of the Donets was made by the Ministry of Railways First World War. in 1903. At present, the Lower Don flow (Fig. 1) is A graduate of N.P. Puzyrevskiy Institute of regulated by the Tsimlyanskiy engineering Water Transport was the project developer. He complex (1952) and low-pressure cascade carried out detailed surveys on the Seversky hydrotechnical systems – Nicholas (1975), Donets in 1903–1904, and the project of the Constantine (1982) and Kochetov (1920). 78 G.L. Gladkov, V.M. Katolikov

Figure 1. The scheme of the Lower Don waterways

Currently, the navigation conditions of the the Tsimlyansk reservoir, the guaranteed nav- Lower Don are completely dependent on the igation depth (excluding surge phenomena water resources of the Tsimlyansk reservoir of the Sea of Azov) supported by dredging and, to a lesser extent, on the water flow in is 340 cm, which is less than the depths of the Northern Donets River and the Manych the Unified Deep Water System of European River. During a regular water discharge from Russia.

2. Water-level regime and channel deformation downstream of the Kochetovsky Hydrotechnical Systems

The bottom and water levels in the studied sec- Channel processes downstream of the tion of the Lower Don have irreversibly decreased Kochetovsky hydrotechnical systems were for the past 100 years. These changes are asso- studied in several aspects, including analysis ciated with the construction and subsequent of horizontal and vertical adjustment in the operation of the cascade of waterworks on the researched section of the Lower Don (Gladkov Lower Don, as well as dredging works in the et al., 2017). After the implementation of the channel to ensure navigation conditions and Bagayevskaya hydrotechnical systems, naviga- mining of the river alluvium. Available data show tion problems occur mainly above the dam, in that the decline in water levels was observed the backwater conditions. along the entire length of the considered navi- After the commissioning of the Tsimlyansk gable area, but the magnitude of this decline hydrotechnical systems on the Lower Don, as decreases with the increasing distance from the a result of changes in the flow regime and due Kochetovsky hydrotechnical systems. to erosion processes occurring downstream According to preliminary estimates, the of the Kochetovsky hydrotechnical system, water-level lowering downstream of the the depths near the riverbank and in the main Kochetovsky hydrotechnical systems during current have been adjusted. Analysis of the 95% water consumption in the navigation hydrographic data for the period from 1961 season is about 180-190 cm. At the site of the to the present time shows that in the section Razdorskaya hydrological station, water levels of the Lower Don River located between the in the same period decreased by 120-140 cm, Kochetovsky hydrotechnical system and the and at the downstream Bagaevskiy station – by town of Aksay, the distribution of depths about 60 cm. And finally, in the section of the in the navigable waterway has changed sig- planned Bagayevskaya hydrotechnical complex, nificantly, largely in line with changes in the the water level in the hydrological conditions channel regime downstream of the dam. Over described above decreased by about 10–15 cm. the past decade, the intensity of bed deforma- Channel regime and navigation conditions of the Lower Don 79 tions on the navigable waterway has decreased were plotted along the line of the greatest depths compared to the previous period. and along the isobaths corresponding to the Under the designed conditions, the greatest expected depth of the waterway. threat to the navigation will be posed by insuf- The results of the analysis of the obtained ficient depths as a result of seasonal changes in materials prove that to date the situation in the the locations of riffles. In this regard, minimum survey area has largely stabilised. The surveyed depths at the shallows were analysed at this section shows small alternating planned dif- stage of the work. This analysis has shown that ferences in the channel depth. No significant no significant high-altitude deformations of the unidirectional deformation has been identified riffles should be expected in the conditions of in the channel section. This is primarily con- a regulated runoff. nected with the reduction of flood peaks by the In connection with the analysis of the planned Tsimlyanskiy reservoir and the limited water changes in the river section and based on the content in the river in recent years. In addition, materials collected during the channel surveys the river banks within the boundaries of certain carried out in 2006 and 2016, the planned posi- human settlements are protected from erosion tion of the initial profiles was corrected, which by riverbank stabilization.

3. Impact of the planned Bagayevsky reservoir on the upstream water levels

The construction of the reservoir on the river ation of the Bagaevskiy reservoir with the mark section that has been currently exposed to NWL 2.8 m BS, virtually in the entire range of anthropogenic factors will have a positive effect water discharge exceeding the instream flow in and some negative consequences. In this case, extremely dry years, will not affect the level and everything will depend on a water-level increase channel regime of the river in the downstream caused by backwater within the reservoir. section of the Kochetovsky hydrotechnical Thus, in the river section where, as a result system. of backwater, the water level will rise to a level In the lower reaches of the river, the value not exceeding the water levels recorded in of the additional floodplain area will increase, historical times (corresponding to the hydro- which consequently will have an impact on logical situation in the 1920s), we cannot talk the river regime. Thus, at the section of the about degradation, but rather about the resto- Razdorskaya hydrological station, additional ration of the hydrological regime of the river. In flooding (compared to 1917-1924) will occur other parts of the river, where floodwater levels when water discharge is about 600 m3/s or exceed the historical usual level due to backwa- less. Accordingly, with a water discharge of ters, additional flooding together with accom- 363 m3/s, the value of the additional water rise panying adverse consequences are possible. in the floodplain area will be approximately Data on the water levels and water flow 0.6 m. rates collected during observations carried At the downstream Bagaevskiy hydrological out at the Lower Don since the commission- post, additional (compared to 1927) flooding ing of the Kochetovsky hydrotechnical system associated with the construction of the dam (Polyakov, 1930) were analysed and compared will occur when water discharge is equal to with the results of hydraulic calculations. 930 m3/s or less. When water discharge is equal This made it possible to estimate the extent of to 363 m3/s, the value of the additional water changes in the water-level regime of the river. rise in the floodplain area will be approximately The obtained data indicate that in the imme- 1.9 m. diate downstream section of the Kochetovsky Finally, additional flooding will occur hydrotechnical system, the water levels can upstream of the planned dam when water dis- exceed the corresponding level of the normal charge is equal to 1,700 m3/s or less. The value curve for 1923-1925 only if the water discharge of the additional water rise in the floodplain is equal to or less than 200 m3/s. Thus, the cre- area will be about 2.3 m. 80 G.L. Gladkov, V.M. Katolikov

Thus, the analysis of the water level regime additional flooding in the coastal zone. In com- of the Lower Don, carried out while taking parison with the present water levels within the into account the lowering of the normal water boundaries of the proposed reservoir, the flood levels downstream of the Kochetovsky hydro- range will be relatively large. technical system, allows to reduce the issue of

4. Flow velocity regime in the backwater zone

The construction of the reservoir will change However, it should be borne in mind that, as the flow velocity regime in the backwater zone. a result of significant erosion of the bottom that The largest scale of flooding will occur in the occurred in the upper part of the analysed sec- river section directly adjacent to the planned tion of the river between the Kochetovsky dam barrage. The impact of the planned barrage on and the village Razdorskaya and in the down- the water level and the flow regime will decrease stream section, the flow velocity has signifi- along the increasing upstream distance from its cantly decreased compared to the early 1950s. location. The regime of flow velocities in the researched To analyse the impact of backwater levels on section of the Lower Don are presented in Fig. the flow velocity regime along the river, hydro- 2. The figure presents longitudinal profiles of logical measurements of the river channel con- average vertical flow velocity along the lines of ducted in 2016 were used. According to these the greatest depths with the water discharges of data, plots presenting the relationship between 1,100 m3/s and 363 m3/s in usual and project the flow velocity and discharges were prepared conditions (with NWL 2.0 m BS), according to along with plots presenting the above parame- the results of hydraulic calculations. ters for the increased water level upstream of the Based on these data, we can conclude that flow projected Bagaevskiy reservoir with two values velocities in the main part of the channel are of NWL, equal to 2.8 m BS, and 2.0 m BS. sufficient to support the bed load transport The obtained results indicate that the stron- along the analysed section of the river (from the gest influence of the planned reservoir on the downstream section of the Kochetovsky hydro- flow velocity regime can be observed at low technical system to Aksay), when discharges water discharges in the immediate vicinity related to fishery permits are not exceeded. of the dam. In the conditions of backwater at In the upper part of the section from the NWL 2.8 m BS, the flow velocity will decrease dam to the mouth of the river Aksay (3,050.0– 2.4 times (at NWL 2.0 m BS – 1.9 times). At 3,051.0 km along the navigable waterway), the Bagaevskiy hydrological station, this ratio average flow velocities (with the exception of is already 1.7 times lower (1.4 times). In the some calculated oscillations) are in the range of area of Razdorskaya, these values will be sig- 0.95-1.05 m·s-1 with no trend regarding changes nificantly lower. along the river. Under these circumstances, we

Figure 2. Longitudinal profiles of flow velocities in the navigable waterway Channel regime and navigation conditions of the Lower Don 81 should expect the movement of bedload sedi- up to 3,020.0-3,025.0 km along the navigation ment as ripple marks with minor vertical and route, the average flow velocity increases by horizontal deformation of the channel. 0.5–0.65 m·s-1. In this section, limited sedi- Along the section from the mouth of the ment movement and slight deformation of the Aksay river to the estuary of the Old Don river bottom are possible at individual shallows. (3,050.0-3,065.0 km), flow velocities along Downstream flow velocities vary consid- the river are consistently reduced and reach erably. In the section from the Porechensky an average of about 0.8 m·s-1. Compared with branching to Kh.Bagaevsky, the average water the above site, a decrease in the intensity of velocity gradually decreases along the navi- sediment transport and the predominance of gation route. At 3,065.0-3,070.0 km along the alluvium accumulation are to be expected. In navigation route, the flow velocity in regular this case, ripple marks are gradually flattened, conditions (without backwater conditions) similarly to the upstream section of the river. will be 0.30-0.40 m·s-1. At such flow velocities, Approximately the same values of flow transport of sediments in the river ceases. velocities (0.7-0.9 m·s-1) will be observed in In the lower section, the tendency for reduc- the lower reaches of the river, in the section ing the water velocity along the river will con- between 3,065.0 km and the Aksay town. More- tinue, but with a lesser intensity. The average over, the amplitude of flow velocities from the flow velocity values on the navigation route upper boundary of the section to the designed near the Aksay town will be about 0.30 m·s-1. hydrotechnical system reaches a larger varia- Thus, the results of the calculations indi- tion of the calculated values than in the lower cate that with low water consumption without part of this site. backwater conditions, transport of bedload In the autumn low-water period, the is possible in negligible amounts in the upper designed Bagaevskiy hydrotechnical system third part of the analysed river section, located will work in backwater conditions. The average approximately at 3,040.0 km from the Koche- flow velocities along the navigation course at tov hydrotechnical system along the navigation the water discharge of 363 m3/s for contempo- route. In the regular downstream conditions, rary and design conditions presented in Fig. 2 the flow velocities will not be sufficient to move allow to estimate changes in the flow velocity sediment. in backwater conditions created at NWL 2.0 m In the design conditions, with a reduced of BS. flow velocity resulting from the distribution of Under regular conditions, the flow velocity backwater over the entire length of the analysed of the midstream varies along the length of the section, a complete cessation of sediment trans- considered section of the river. Along the sec- port should be expected. tion from the Kochetov hydrotechnical system

5. Measures to improve the navigation conditions and to maintain the riverbed in the backwater zone

At present, navigation conditions of the Lower tion conditions in these areas. The effect of the Don are significantly limited due to problems planned works on the hydraulic characteristics with the movement of vessels within the mean- of the flow, riverbed deformation and the water ders. Molchanovskoye and Semikarakorsk levels were also assessed. shallows and the Porechenskoe meander are Hydraulic calculations for different values the most difficult rapids on this waterway at the of water discharges downstream of the dam of highest average annual volume of dredging and the Kochetovsky hydrotechnical system were at the greatest radius of curvature within the performed. The results of these calculations meanders. have shown that to assess the sustainability of In this regard, recommendations were the proposed meander trimming measures, developed within the framework of the proj- the amount of the discharge corresponding to ect for the major improvement of the naviga- the fishery water release under regular con- 82 G.L. Gladkov, V.M. Katolikov ditions should be adopted. At lower values of which are supposed to be situated within the water discharges, under backwater conditions boundaries of towns. Their inclusion in the (in navigation period) and without backwa- project of the hydrotechnical system and the ter conditions (in non-navigation period), the reservoir is connected with the need to protect transport capacity of the stream is insufficient the shoreline in urban boundaries from flood- to transport the sediment down the river. ing and possible destruction. Hydraulic calculations were performed at The second group of measures for bank pro- different water discharges for temporary condi- tection should include such facilities, which tions and conditions of straightening the nav- will need to be built on the river banks outside igation route in the areas of the Semikarakor the towns to protect the banks from possible meander and the Porechen meander. These cal- erosion by the stream, especially during spring culations have shown that straightening of the flood conditions and fishery water releases. navigation route does not lead to an intensifica- Particular attention in this case should be paid tion of the channel process in the sections sub- to fishery releases, as proper management of ject to dredging and will not cause additional water resources after the construction of the lowering of the water levels downstream of the dam can have positive effects. Such facilities Kochetovsky hydrotechnical system. should prevent uncontrolled erosion of the Therefore, implementation of certain mea- river banks, which could eventually lead to the sures and facilities is possible in areas where deterioration of shipping conditions. major improvements in the navigation condi- Finally, the third group of structures should tions are required. All types of the planned river include facilities designed to protect the river bank protection works, depending on their banks from the impact of waves generated by purpose and the type of construction, should passing vessels at a normal backwater level in be conditionally divided into three groups. the reservoir. This impact will be significant, The first group of facilities for river bank particularly if the navigation rout is close to the protection should include capital structures, river bank.

6. Analysis of the Bagaevsky hydraulic engineering structures on the hydraulic model

Modern design of hydraulic structures incor- the long-term experimental studies. To date, the porates hydraulic modelling of these struc- method of hydraulic modelling has been suc- tures and sections of riverbeds, within which cessfully tested in the study of a large number these structures are located. There are various of hydraulic structures and engineering activi- methods of modelling, but in principle all of ties on water bodies (Klaven et al., 2011). them are divided into two groups: methods of Experimental studies of the Bagaevsky mathematical hydrodynamic modelling, start- hydraulic engineering structures were car- ing with simple hydraulic calculations, and ried out at the Hydraulic Laboratory of the methods of physical hydraulic modelling on State Hydrological Institute (SHI) on the spa- a spatial hydraulic rigid or deformable models, tial hydraulic model of the Don River section starting with experiments in hydraulic flumes. and the structures built at a scale of 1:100 (see The worldwide practice of the optimal design Figure 3). of hydrotechnical objects follows the path of Hydraulic studies of the model were carried using “hybrid” modelling, which combines out for several versions of the channel conditions, both mathematical methods and methods of corresponding to different stages of construction physical modelling on spatial hydraulic models of the designed structures. The modern natural (Gladkov et al., 2016). condition of the Don riverbed was adopted as The methodology of designing and con- the first option, for which the hydraulic model structing rigid spatial hydraulic models was was verified with the actual data. developed at the Department of Channel Pro- The second option for conducting the cesses of the State Hydrological Institute during research was the so-called “construction case”. Channel regime and navigation conditions of the Lower Don 83

Figure 3. General view of the hydraulic model of the Don river section

In this case, the right branch of the river is individual structures of the hydroelectric com- blocked by temporary dams for the whole plex to ensure safe navigation conditions, and period of construction of the spillway dam, to evaluate their effectiveness experimentally. and the water flows through the left branch. To The physical model was calibrated based on ensure navigation in the left branch during the the materials of engineering-hydrometeoro- construction period, a shipping slit is designed logical surveys in natural conditions. The dis- with sufficient dimensions to allow the flood- tribution of water discharges between the arms water flow. obtained on the model, the regime of current And finally, as the third option in the velocities and the relief of the free water surface hydraulic model, the design state was consid- are in satisfactory agreement with the actual ered, when all facilities were built and operated data. in the regular mode. Within the framework of First of all, the hydraulic flood conditions this research cycle, the kinematics of the river were studied on the model during the con- flow was studied under different operating construction period of the hydraulic engineering ditions of the spillway structures. structures, when the right navigable branch All variants were investigated at different of the river would be blocked and the 150-m- water flow rates and water levels in the river, wide shipping slit will be created in the left covering the most minimal and the highest cal- branch. culated values. As a result of these studies, fields Model studies showed that under these con- of surface current velocities and bottom jets, ditions in the left branch at the cross-section longitudinal profiles of the free water surface of the Bagaevsky engineering structures, the and the boundaries of possible deformations maximum of current velocities at the max- of the river bottom and the river banks were imum water discharges increases 1.7 times obtained. and reaches 1.90 m·s-1. At the sites located The performed research has revealed the downstream from the site of the engineering main features of the kinematic structure of the structures, the river channel narrows and the flow under different operating conditions of current velocities increase even more, reaching the hydraulic engineering structures at various values of 2.30 m·s-1. An increase in the current water flow rates and water levels. The obtained velocities during the floods in this period was data made it possible to develop some recom- observed along the entire left bank of the river, mendations on the structural improvement of which may cause its dangerous erosion. 84 G.L. Gladkov, V.M. Katolikov

Therefore, in order to ensure the stability of 0.25 m·s-1, which does not comply with regula- the left bank of the river during the construc- tory requirements. tion period, it was recommended to strengthen To regulate the structure of surface currents the left bank of the branch with rubble groynes. and to create favourable conditions for nav- The location of these groynes and their dimen- igation at the entrance to the navigation lock sions, providing the most effective protection of channel, additional experimental studies on the the bank, were determined during the research hydraulic model were carried out and relevant on the model. recommendations were developed. In addition, it was found that during the The results of the experiments carried out floods in the construction period, raising the by the SHI have shown that the spatial struc- water level (at 0.1-0.15 m) upstream from the ture of the flows at the boundary of the apron is construction site and increasing the average complicated and detached currents arise on the slope of the free water surface will be insignifi- boundary of the apron. It leads to the forma- cant and not dangerous. tion of the local erosion pits on the unprotected Materials of the experimental studies of bottom and erosion of the apron. the kinematic structure of the flow and its In this regard, to ensure the stability of this hydraulic characteristics confirm the validity facility in the lower part of the Bagaevsky hydro- and reliability of the adopted design decisions technical complex, it was recommended to rein- and parameters of culverts (gates). Under the force the river bottom adjacent to the apron by design conditions, after the completion of a 30-m-wide stone backfill. It was recommended the Bagaevsky engineering complex, the pos- to use a stone with a diameter of 0.20 m. sibility of local bottom erosion in the lower In general, the studies carried out on the part of the site under normal conditions is physical model have confirmed the high effi- reduced. ciency and validity of the basic design engi- Analysis of the model has shown that when neering solutions and allowed to make indi- the water discharges exceed 600 m3/s, veloci- vidual adjustments to improve the safety and ties of the transverse current at the entrance reliability of the operation of the Bagaevsky to the navigation channel increase and exceed hydraulic engineering complex.

7. Conclusions

There is a long history (over 100 years) of hydrosystems on the Lower Don. The construc- hydraulic engineering construction on the Don tion of this cascade will ensure the free passage River and its tributaries. During this time, due of large-capacity fleet in this area and will con- to the interception of the flow by a higher cas- tribute to the rational use of water resources for cade of waterworks, water levels on the Lower the benefit of all water users. Don decreased in one direction. This had a neg- The research on the hydraulic model made it ative impact on the status of navigation and the possible to assess the validity of the decisions on water supply in floodplains in the coastal area the main parameters of the planned Bagaevsky of the river. In this study, we have examined Hydrosystem. The creation of a low-pressure hydrological and riverbed regimes of the Don hydrosystem with a reservoir on the Lower Don River to ensure the safety of navigation in its will facilitate the completion of the hydrau- lower reaches. lic engineering construction and will allow to The planned Bagaevsky hydrosystem is obtain an additional effect from the operation the lower stage of the cascade of low-pressure of the whole construction complex. Channel regime and navigation conditions of the Lower Don 85

References Gladkov G.L., Chalov R.S., Berkovich K.M., 2016. Hydromorphology of channels of navigable rivers. [In:] Gladkov G.L. (Ed.), SPb.: GUMRF [in Russian with English Abstract]. Gladkov G.L., Katolikov V.M., Shurukhin L.A., 2017. Ensuring of the navigational conditions in the Lower Don. [In]: Design, construction and operation of hydraulic structures of waterways: Proceedings of the conference, GUMRF: 196-216 [in Russian with English Abstract]. Klaven A.B., Kopaliani Z.D., 2011. Studies and Hydraulic Modeling of River Flow and Cannel Processes – Spb. Nestor-History, [in Russian with English Abstract]. Polyakov B.V., 1930. Hydrology of the Dona River Basin – Rostov on Don. Office of the chief engineer of the construction of the Volga-Don [in Russian].