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Procedia Engineering 150 ( 2016 ) 2358 – 2363

International Conference on Industrial Engineering, ICIE 2016 Hydrological Studies on the River around the Alexandrovsky OSV Water-Intake Facilities

E.D. Khetsuriani, V.P. Kostyukov, E.G. Ugrovatova*

Platov South-Russian State Polytechnic University (NPI), 132, St. Prosvescheniya, Rostov region, , 346428,

Abstract

This article shows the results of hydrological studies on the river Don around water-intake facilities in Rostov-on-Don. The factors of wind-surge influencing ecstatic increases in the water level of the receiving basin are presented. The uneven seasonal and long-term flow river regime leading to intensive channel deformations was evaluated. A low water discharge, causing an active rift deformation within the saddle was of a high river-forming significance for the natural water flow due to a high amount of water irrespective of the yearly water content. However, the river reformation occurred mostly during a high water discharge (flooding): the floodplain was subdivided into separate arrays of channels and creeks constituting several branches within the floodplain. These deformations facilitated the formation of the easily washed floodplain alluvium. These deformations occurred mainly during years with the abundant rainfall. For a relatively short period of time (the flood period) the most significant river bed deformation occurred during the natural flow. Hydrographs were drafted according to the results of the studies on the water- level regime. © 20162016 The The Authors. Authors. Published Published by byElsevier Elsevier Ltd. Ltd. This is an open access article under the CC BY-NC-ND license (Peer-reviewhttp://creativecommons.org/licenses/by-nc-nd/4.0/ under responsibility of the organizing). committee of ICIE 2016. Peer-review under responsibility of the organizing committee of ICIE 2016 Keywords: Water intake; flood; freezing; floodplain terraces; river bed deformation.

1. Introduction

The city of Rostov-on-Don performs water abstraction for agricultural and drinking water supply using the Alexandrovsky water-intake facilities: streamflow and scoop water intakes from river Don.

* Corresponding author. Tel.: +7-908-517-9988; fax: +7-863-525-5171 E-mail address: [email protected]

1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICIE 2016 doi: 10.1016/j.proeng.2016.07.326 E.D. Khetsuriani et al. / Procedia Engineering 150 ( 2016) 2358 – 2363 2359

Lower Don is a natural and man-made system in which the processes of river bed formation are determined not only by natural but also by man-made factors [4-5]. The following features of river-bed formation in a natural flow should be noted. The Lower Don Valley is large (up to 60km) at the top (above the mouth of the river Manych), includes a floodplain and 4 floodplain terraces, down the mouth of the river Manych it narrows to 10km. The cross- section of the valley is asymmetrical: the right bedrock valley slope is mainly steep (up to 530), the left side is staged floodplain with four terraces. The slopes of the current river-bed are small – 0,045 ‰. Deposits on the bedrock valley banks, the watershed plateau and the floodplain terraces are nor easy to wash away, the floodplain and channel alluviumare easily washed away. Due to this river bed deformation develop freely along the floodplain banks (75% of the whole river bed length), at the same time as the right bedrock valley bank limits deformation. The combination of small slope of the valley floor and easily washed sandy riverbed-forming alluvium led to low channel resistance, slightly increased to the lower reaches [6-14]. River Don has a spring flood type of hydrological regime, which is characterized by significant seasonal fluctuations in flow. Average annual water flow in the conditions of natural flow was 840 m3/s (Razdorskaya station, 1891-1951). The long-term plan included a decrease in water flow and pumps, linked to general climatic changes at the water intake facility [10]. Wind-surge and ecstatic increases in the water level of the receiving basin influenced the water-level regime at the river mouth area [15]. Seasonal and long-term uneven flow resulted in an intensive river bed deformation. Low water discharge, causing an active rift deformation within the saddle was of high river-forming significance for natural water flow due to a high amount of water irrespective of the yearly water content. However, river reformation occurred mostly during high water discharge (flooding): the floodplain was subdivided into separate arrays of channels and creeks, constituting several branches within the floodplain, favorable conditions were created for the straightening of bends (including those shallow enough) through breakthrough spurs bend and the formation of a straight floodplain flow. These deformations were facilitated by easily-washed floodplain alluvium: the flow quickly developed a river bed, formed by ducts or older-rivers and shifted to a new position. Such deformations occured most actively during years of abundant rainfall. [15-19]. Features of «river-bed forming water discharges» as formulated by N.I. Makkaveev [5] according to the data of V.V. Timofeeva for the gauging station of Razdorskaya [10] presented in table 1. The fact that Q passes for flooded floodplains even during periods of low rainfall (see table.1) implies that the reformation on the long run specific to that interval had a significant impact on the morphodynamics of the river- bed. Anthropogenic change fluvial processes of Lower Don at the regional level began with the creation of the [20-22].

Table 1 - Riverbed-forming water discharges and their provision before and after the regulation of flow of Lower Don (Razdorskaya station). Maximum epures of riverbed-forming discharges(Numerator – Q, ɦ3/ɫ; denominator – provision, %) Intervals Years of average water For the whole period Years of low rainfall Years of abundant rainfall Q content 1* 2** 1 2 1 2 1 2 12800 12740

0,1 0,2 7560 2991 6790 7565 3345 Upper – – – 0,3 0,5 0,5 0,8 1,0 2290 2150 2223 2975 2440 4,0 2,0 4,0 5,0 2,0 1480 1490 1471 1340 1520 Medium – – – 2,0 2,0 4,0 2,0 4,0 586 299 590 279 618 19,0 685 343 645 Lower 75,0 59,0 43,0 15,0 265 33,0 69,0 52,0 59,0 2360 E.D. Khetsuriani et al. / Procedia Engineering 150 ( 2016 ) 2358 – 2363

*1 – period of natural flow (1936-1950) **2 – period of regulated flow (1952-2003) After the Tsimlyansk reservoir was created deep erosions occurred downstream causing the level of water to drop. According to data from B.G. Fedorov [22], 15 years after the regulation of water flow, the bed reduction rate along the dam area of Lower Don was 0,08 – 0,10 m/year. The rate of erosion movement along the flow was not less than 10 – 12 km/year. The current flow reduction rate on the part of the river downstream from Razdorskaya station is estimated at 0,017 – 0,021 m/year, and the drop in level along the alignment of Razdorskaya station for a water discharge of 600 m3/s reached 0,85m (table 2). The drop in level is more significant at the end of the low rainfall period (up to 0,03 m/year).

Table 2 - Drop in water level for different water discharge at the Razdorskaya station «Drop» in level (m) for water discharge Years 300 m3/s 400 m3/s 500 m3/s 600 m3/s 1954 – 1976 0,50 0,40 0,30 < 0,20 1954 – 1984 – 0,60 – 0,70 0,50 0,30 – 0,40 1954 – 1992 – 0,80 0,70 0,50 – 0,60 1954 - 2000 – – – 0,80 – 0,85

Local control of the riverbed processes along Lower Don is carried out using transverse and longitudinal groins, dikes, strengthening the river banks, creating operational dredging and artificially straightening the bends [1-5]. The main morpho-dynamic type of the riverbed on Lower Don is meandering (with intermittent bends), for which 56,1% of the length of the river. Most of the meanders on Lower Don are at an early stage of development. The average ratio for the Lower Don channel tortuosity is 1.41. Developed and steep bends are a feature of the section of the river above Razdorskaya station, while new gentle bend segments are more common downstream (according to classification [14]). Current deformations of the meandering riverbed of Lower Don include longitudinal and/or transverse displacement meanders due to erosion/reclamation of river banks (Table 3). A comparison of the speed of current deformations of the meandering and less-meandering riverbed, according to data form N.I. Makkaveev and N.V. Khmeleva [12] for the period of natural flow has shown a decrease in the speed in horizontal channel deformations of more than 2 times.

Table 3 - Rate of horizontal deformation of meandering and less-meandering channels of Lower Don Average rate of displacement of meanders for the period, m/year Period longitudinal displacement transverse displacement 1704 – 1949. [12] 4,5 3,5 1956 – 2006. 2,1 1,4

Hence, under conditions of regulated hydrological regime macroforms of the channel do not develop, while channel forms of the third type cease to exist, or transform into channel forms of the second type. This, as a whole, shows the tendency to simplify the hierachy of channel forms, created under conditions of natural flow. The qualitative evaluation of the parameters of channel marks (microforms) performed in accordance to ȼɋɇ–163-83. Bed length l m upon steady movement of water is determined according to the following dependency:

C 2268,7 lH ˜3 6,5 ˜3 49,9 m g 9,81

Where ɋ – is the Chezy coefficient calculated on the vertical with an average flow on the slope for the river width, m0,5/s; ɇ- is the depth of the flow on the vertical, m. E.D. Khetsuriani et al. / Procedia Engineering 150 ( 2016) 2358 – 2363 2361

Height of the bed h m should be calculated using the following dependency: h= 0,25ɇ for ɇ < 1 m; h= 0,2 + 0,1ɇ for ɇ > 1 m; h 0, 2˜ 0,1 6,5 0,85 m . The rate of bed displacement ɋ , m/day is defined by the equation: C = 0,019 ȣ Fr3 or the monogram (ȼɋɇ–163-

83, annex 5); in the formula X – is the average rate of flow above the bed, ɦ/ɫ; Fr X / gH For X = 0,83 m/s, the rate of bed displacement ɋ = 1,7 m/day The period of bed movement established for the profile per day is determined by the formula

l 49,9 W 29 days. C 1, 7

2. Channel morphometry

Analysis of morphometric measurements of flow along the bed of river Don in Aksai led to the following results (Fig. 1, 2).

Fig.1. ņ Changes in channel width depending on the water level in it.

Fig. 2. ņChanges in average depth of the channel depending on water flow.

For average discharges of spring floods (discharges, close to riverbed formation) channel width does not exceed 290m. Changes in the average depth of the channel (see. Fig.2) may reflect considerably deep deformation in the 2362 E.D. Khetsuriani et al. / Procedia Engineering 150 ( 2016 ) 2358 – 2363

alignment, associated with either the movement of bottom ridges or dredging, or both of them. For water discharges close to riverbed formation, the calculated average depth for ridge forms is equal to: ɇ0 = 6,5m. Morphometric analysis of river Don at the alignment of Aksai is performed using the formulae: Average depth of sandy riverbeds under conditions of free formation:

1/M0 1/3,117 HQ00 D p 0,571˜ 1700 6,17 m measured  6,5 m .

The width of riverbed for a formation water discharge:

1/m 1/0,50 BkH 0 3˜ 6,17 342,8 m measured  290 m

The difference between the calculated and measured width of the channel point out the cramped conditions of channel formation at the alignment. Under cramped formation conditions the average depth of the channel is equal to:

1/M 1/1,113 §·Qp §·1700 Hc D ¨¸ 1, 5˜¨¸ 7, 04 m ©¹Bc ©¹290

The difference between the measured and calculated depth is 0,54m or 7,7 %. It should be noted that the value 6,50m established for a water discharge rate of 1550 m3/s, which is less than channel-forming water discharge. The

average flow rate for channel-forming water discharge will be X = 0,83m/s; the maximum rate Xmax = 1,21 ɦ/ɫ.

3. Conclusions

As a result of the analysis and research performed to assess the impact of channel processes on the regime of water intake structures of Alexandrovsky OSV, the following conclusions were made: x under natural conditions, a complex hierarchy of channel forms was formed in Lower Don. The mechanism of intensive channel reformation is the formation of floodplains during flooding and the displacement of the main flow of the river into them (or the old river), leading to substantial changes in the planned outline of the channel within a short period of time; x regulated flow changed the channel-forming role at a regional flow level. The current conditions of channel processes are characterized by a reduction in flow a simplification of the hierarchy of channel forms in Lower Don. Channel deformations include its horizontal displacement due to the erosion of the river banks, which contributes towards increasing channel tortuosity and causes a gradual change in its planned outlines; x vertical deformation of the riverbed in the calculated alignment (Aksai) is characterized by the movement of the ridged forms and alternating (relative to the average mark) bottom position changes, that is, the "current" position

of the bottom mark: ZZi ɫɪ r0,85 ɦ. Reference

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