CN1041337C - Two-reservoir combined anti-deposit technique - Google Patents

Abstract

The present invention relates to a two-reservoir combined anti-deposit technique which is used for solving the reservoir silt deposit problem in hydraulic engineering. In the past, a large reservoir is always constructed in a channel segment; the reservoir capacity is rapidly lost by the silt deposit. Two minor reservoirs are simultaneously constructed in the two-reservoir combined anti-deposit technique; an upstream reservoir only stores non flood season water; a downstream reservoir mainly stores flood season water. Silt in the downstream reservoir is washed away by water stored in the upstream reservoir to achieve the purpose that the two reservoirs have no silt deposit. The two-reservoir combined anti-deposit technique can greatly decrease silt reservoir capacity, and can correspondingly decrease the engineering scale and the investments of the reservoirs. Compared with the large reservoir, the effective service period of the reservoirs can be increased in multiples.

Description

Two-reservoir combined anti-deposit technique

The present invention is that the retaining silt enters down the storehouse with flood towards becoming silted up behind a kind of upward storehouse flood, following storehouse retaining in flood season silt, use the combined anti-deposit method that the empty storehouse of reservoir filling dashes the discharge reservoir that becomes silted up again, solved the reservoir sediment accumulation problem, be applicable to the river Lai Shui that retains the silt of carrying under one's arms.

On the river, build reservoir before, always determine to plan to build the scale of reservoir according to landform geological conditions and output.Building up the back retaining at reservoir must sediment trapping, and reservoir is aging gradually by the silt alluvial, and because of tank silt quantity is very big, desilting is in fact impossible, and this problem can not find solution always.The reservoir of on heavily silt-carrying river, building, the alluvial of silt storage capacity is very fast, and effective life, is short, and consequently the reservoir engineering scale is big, and returns of investment are very low.China has built many reservoirs on heavily silt-carrying river in the last thirty years, suffer the threat of silt alluvial, and this threat is increasing, and the gesture of swallowing up large quantities of reservoirs is arranged more.The husky technology of row that past adopts, mainly be reservoir in not retaining in flood season, perhaps retaining seldom, flood velocity is big, and is very short by the reservoir time, flood sediment is with coming with walking, and can wash away the part silt of original alluvial in the storehouse, recovered part storage capacity; Flood silt alluvial when the reservoir is reduced, prolong the reservoir effective life, perhaps can keep the scouring and silting in reservoir balance.These technical measures have the effect that subtracts silt, anti-silt and recovered part storage capacity.There are many problems but implement, most of reservoirs are as adopting these technical measures, not retaining of reservoir in flood season or retaining are very few, influencing reservoir to a great extent supplies water, produce in the scope that reservoir is related to and had a strong impact on, thereby accept these Prevention Technique big difficulty is arranged, in fact can fully use the reservoir of these technology not a lot of for number.If one on the Heavenly Stems and Earthly Branches of the heavily silt-carrying river stream many reservoirs are arranged, adopt upper pond to block silt, lower storage basin is based on the associating operational mode of retaining, though can bring into play the reservoir benefit preferably, lower storage basin can provide water at that time.After but upper pond was become silted up, lower storage basin promptly was subjected to the serious threat of silt alluvial.More than existing row's sand subtracts the silt measure to delaying reservoir sedimentation, have certain effect, but it is also far apart to subtract the determine basic demand of reservoir sedimentation problem of silt effect disassociation.This problem not only perplexs water conservancy circle personage for many years always, also causes personages of various circles of society's common concern.In fact the silt of heavily silt-carrying river is the biggest obstacle of these river water resources of exploitation always.

Reducing the two-reservoir combined anti-deposit technique of tank silt storage capacity, is exactly the severe siltation problem that exists at the heavily silt-carrying river reservoir, through exploring the way that proposes.This technology is a section, or two less reservoirs of contiguous section construction, replaces single big village, often used in village names, and two reservoirs are united utilization, can obtain gratifying row's sand and subtract the silt effect, have very high comprehensive benefit.

Two reservoirs are united the mode of utilization, upper pond only holds sand content water in non-flood season seldom, and before arriving flood season with the storehouse in unspent water in time change lower storage basin over to, recover the river course of reservoir area, the flood river course that recovers of flowing through directly enters lower storage basin, and the part of retaining institute silt sand taken out of from reservoir, this has just guaranteed that upper pond does not become silted up substantially.The task of lower storage basin mainly is to retain sediment yield to account for annual next husky water in flood season more than 90%, and silt is except that letting out part under water with reservoir spillway, and remaining silt all blocks in the storehouse.Upper pond planning have sweep away swimming storehouse silt dash silt storage capacity, the fraction of the year of abundance of water, the lower storage basin retaining uses up, or with its emptying, discharges water from upper pond then and sweep away swimming storehouse silt, and in time will dash the silt discharge reservoir that rises.The flow and the sand content of dashing silt all can be controlled because upper pond discharges water, and be few towards silt efficient high water usage.The silt that can enlargement discharge the fraction of the year coming water more washes away the part bed load makes lower storage basin keep not becoming silted up substantially, has guaranteed lower storage basin retaining utilization condition.Husky anti-silt of two-reservoir combined row compared with single big storehouse, and silt storage capacity is very little, can reduce the reservoir engineering scale significantly, improves the construction investment benefit.

The section, Nan Zhuan valley of Hutuohe River, 30 years on average come the water yield 50500 * 10 ⁴m ³, come the outstanding admixture sand 1065 * 10 in the sand ⁴T pushes away admixture sand 126 * l0 ⁴T.As arranging two reservoirs in the planning of adjacent section, in transferring 30 years husky series, only consider that more diluvial free flow row is husky, do not consider that density current row is husky, lower storage basin forms the husky flood of free flow row and has 20 times, reduces lower storage basin silt 6897 * 10 ⁴T, remaining silt 24113 * 10 ⁴T blocks in the storehouse, and discharging water from upper pond, dashing becomes silted up discharges reservoir.

The sand content of lower storage basin water-use for scouring and warping outbound is calculated with following formula. $Q_8=\mathrm{Q\ρ}=\mathrm{\ψ}\frac{Q^{1.6}{J}^{1.3}}{B^{0.6}}$

In the formula:

Q ₈---the silt discharge that dashes silt is in t/s;

Q---the water-use for scouring and warping flow is with m ³/ s meter;

J---the river longitudinal gradient is with radiometer;

B---wide towards the rivers or streams choked up by silt of mud and sand in m;

ρ---sand content is with t/m when dashing silt ³Meter;

ψ---for having with t, m, s is the coefficient of unit.

The lower storage basin silt overwhelming majority is to become silted up in the storehouse in the flood season of high flow year, and flood backlash is then become silted up, and silt has little time fixed; Wash away having along journey in the silt process, headcut scour is also arranged, coefficient ψ adopts 300.The river width of section, Nan Zhuan valley is about 120～140m, and is close with stable river width, river course longitudinal gradient 3.0 ‰ in the storehouse, and different sand contents towards the silt flow are calculated as follows table.

Flow (m 3/s)	100	200	400	600
					Sand content (t/m 3)	0.241	0.365	0.553	0.707

Sanmenxia Reservoir control water level on 27 days～August 4 July in 1974 is dashed and is become silted up reservoir inflow 1470m ³/ s, sand content 180kg/m ³Outbound flow 1510m ³/ s, the husky sand content 203kg/m of bottom outlet row ³Black pine woods reservoir flood detention row is husky again, puts peak flood flow 190m in storage on August 19th, 1975 ³/ s, sand content 256kg/s, outbound peak flood flow 8.8m ³/ s, sand content reaches 718kg/m ³Dashing becomes silted up is the clear water of using upper pond, calculates sand content and only adopts 200kg/m ³Be tied to lower storage basin in 30 years towards silt sand 24113 * 10 ⁴T, water 120570 * 10 ⁴m ³At continuous par and the husky storage capacity 2176 * 10 of the accent in low flow year ⁴m ³The husky alluvial of bed load storage capacity 1024 * 10 ⁴m ³Reserve the silt storage capacity 1000 * 10 of suspended load sand ⁴m ³Husky analog computation result is transferred in water transfer, as following table:

The storage capacity title	Regulate storage capacity (10 4m 3)	Towards silt storage capacity (10 4m 3)	Silt storage capacity (10 4m 3)	Transfer husky storage capacity (10 4m 3)	Add up to	Remarks
							Upper pond	14000	5000	1000		20000	Silt storage capacity is for reserving
Lower storage basin	9000		2024	2176	13200	Silt storage capacity is for reserving

The aggregate storage capacity 33200 * 10 in two storehouses ⁴m ³, if with single big storehouse, silt storage capacity 43000 * 10 ⁴m ³, runoff overyear storage 14000 * 10 ⁴m ³, storage capacity 7000 * 10 ⁴m ³, aggregate storage capacity 64000 * 10 ⁴m ³If reservoir barrage concrete gravity dam, period of validity was used only 50 years in the big storehouse of the single high dam in 75% left and right sides that two little storehouse dam project amounts are the big storehouse of single high dam engineering quantity, and the effective life in two little storehouses of weir be 100 years, two kinds reservoir programmes when water supply fraction 75%, output is 33200 * 10 ⁴m ³, still, the water that comes in high flow year in non-flood season can be controlled in the little storehouse of weir, makes flood discharge be increased to 38700 * 10 ⁴m ³, be that 30 years series comes 76.6%, two storehouse of the water yield can control towards become silted up row husky flow and sand content, irrigate for quoting muddy water, improve irrigated area soil, increasing soil fertility provides condition.To the reservoir downstream river course, can control the silt of dashing in riverbed, also favourable to river flood control and water drainage.

Now construction of reservoir is all avoided broad lake type and location, valley pattern storehouse as far as possible, and it is big that reason is that this class reservoir generally floods migration circle, not only compensates the cost height, and the problem complexity; After this reservoir of heavily silt-carrying river is become silted up, even want recovered part storage capacity all very difficult.In fact great rivers and middle and small river all have the relatively more suitable banded river valley of section, valley and width, for planning location, the preferred storehouse of reservoir provides condition.Two-reservoir combined anti-deposit reservoir, storage capacity are than little many in single big storehouse, and the condition of preferred location, storehouse is relatively good.The success of any incident all is with good conditionsi, guarantees the condition that lower storage basin does not become silted up substantially here, and the location, storehouse that is exactly lower storage basin will be selected in the section, valley, or not wide section, river valley, and this condition is not harsh.The practice of reservoir engineering now illustrates, the reservoir that groove storage capacity has comparative advantage, even river course, reservoir area longitudinal gradient is very little, muddy with empty storehouse row after reservoir is become silted up, row is muddy for control water level, and groove storage capacity all recovers well.Large reservoir as the Sanmenxia Gorge, river course longitudinal gradient 0.31 ‰, 40km place before the dam, being become silted up in the section of river width 800m, dashes this phase library of back that becomes silted up and hold and recover the river width 800～1000m after the recovery substantially.The valley reservoir can all be a groove storage capacity basically, and the not wide reservoir overwhelming majority in river valley is a groove storage capacity, and the reservoir storage capacity that become silted up all recovers easily.Preferred this class libraries location of lower storage basin, not only can reduce water-use for scouring and warping, what is more important can not provide abundant reliable conditions for lower storage basin does not become silted up substantially, is very important concerning lower storage basin, thereby emphasize more, should preferably better location, downstream water Kuku in preferred location, storehouse.

The reservoir that threatened by the silt alluvial if in contiguous section two reservoirs are arranged, is transformed into the reservoir of two-reservoir combined anti-deposit utilization, can reduce reservoir sediment accumulation.Have only a reservoir, the husky favourable principle of row of becoming silted up according to liquidating increases upper pond or the lower storage basin of building a storage capacity suitable scale, and the method with two-reservoir combined anti-deposit also can reduce reservoir sediment accumulation significantly, removes or alleviates the threat of silt to reservoir.

Claims (3)

1, the husky anti-deposit technique of a kind of reservoir row is characterized in that in contiguous section simultaneously or successively builds upper and lower two reservoirs and carry out combined anti-deposit.

2, anti-deposit technique according to claim 1 is characterized in that the storehouse in non-retaining in flood season, flood season empty storehouse or few retaining, and river Lai Shui washes away row's silt with flood season, and the silt that becomes silted up during the retaining in the storehouse is entered storehouse down.

3, anti-deposit technique according to claim 1 is characterized in that down storehouse retaining in flood season, empty storehouse time or create empty storehouse condition behind flood, and use the empty storehouse of reservoir filling and wash away row and become silted up, the silt that becomes silted up during the retaining in the storehouse is discharged reservoir.