INSTREAM FLOW. Dr Iwona Lejcuś r.

Transcription

1 INSTREAM FLOW Dr Iwona Lejcuś r.

2 INSTREAM FLOW is a flow limiting volume below which flows should not be diminished as a result of economy activity. This flow should ensure the protection of the stream and conservation of species biodiversity of organisms that inhabit it, even under extreme use. 2

3 Instream flow - methods of calculation 3

4 Among the methods for determining instream flow there are: Ecologically justified instream flow Instream flow according to the method of Kostrzewa I (hydrological criterion) Instream flow according to the method of Kostrzewa II (k according to regional formula) Instream flow according to the małopolska method Instream flow according to fishing and angling criterion 4

5 Hydrological basis for calculation are multiannual flows observed in watergauge sections: monthly low flow (NQm) average monthly low flow (SNQm) average low flow (SNQ) winter minimum flow (NNQ) 5

6 Ecologically legitimate flow Q i ekol. [m 3 /s] - The methodology was developed and agreed by the Polish and German experts within the W1 Group for the Lusatian Neisse (2000) - This flow stream is to ensure the protection and conservation of species diversity of organisms that inhabit it, and the functioning of aquatic and waterdependent ecosystems with a maximum water use. - The basis for determining the instream flow, were the requirements of ichthyofauna. 6

7 Ecologically legitimate flow Q i ekol. [m 3 /s] -On the Lusatian Neisse two lands were designated, ie. land of grayling in the upper course of the river and the land of barbel in the middle and lower course of the river. Boundary on height of the village Bratków - Marienthal -For selected water-gauges (based on multiannual flow) in order to determine Q i ekol. by analysis of the relationship between Q(V śr. ) flow rate and average velocity [m/s] as well as Q(T max ) flow rate and the stream depth (the depth of water needed to keep the living space [m]) 7

8 Ecologically legitimate flow Q i ekol. [m 3 /s] - As a point of reference to the instream flow, multiannual average low flow was assumed as a characteristic flow that is closest to the designated instream flow. -For the purposes of the balance it was assumed that the instream flow in longitudinal profile of Lusatian Neisse between water gauges, changes in proportion to the increase in the catchment in uncontrolled sections (areas). 8

9 Ecologically legitimate flow Q i ekol. [m 3 /s] Water-gauge Q n [m 3 /s] Porajów 2,20 Sieniawka 3,52 Zgorzelec 6,74 Przewóz 7,60 Klein Bademeusel 10,1 Gubin 8,04 9

10 Instream flow according to the method of Kostrzewa I (hydrological criterion) - Hydrobiological conditions, conditioning the behavior of the basic forms of flora and fauna, were also accepted as a fundamental criterion - Takes into account relation between the instream flow and the low annual average flow of multiannual period (SNQ) in correlation between hydrological type of catchment and its area 10

11 Instream flow according to the method of Kostrzewa I (hydrological criterion) -Parametric method (simplified) in the standard variant, calculated according to the formula Q nh NNQ k parameter depends on the catchment area and the hydrological type of river Q nh I = k SNQ [m 3 /s] hydrological type of river Specific yield q = SSQ / A [l/(s*km 2 )] lowland q < 4,15 transitional and piedmont 4,15 q 13,15 montane q > 13,15 Catchment area [km 2 ] Coefficient k [-] < , ,58 > ,50 < 500 1, , ,52 > ,50 < 300 1, , , ,55 > ,50 11

12 Instream flow according to the method of Kostrzewa II (k according to regional formula) Q nh II = k SNQ [m 3 /s] k coefficient modified by the regional formula k ( a b* SSq)* e 0,5*( F / s) 2 c where a, b, c, s are the parameters of the values from the table. SSq - average low flow of the multiplicity [l/s/km 2 ] parameter value a b c s 0,434 0,0283 0,

13 Instream flow according to the malopolska method - developed by T. Stochliński, mainly used for comparative purposes - in this method the instream flow is variable for each month 13

14 Instream flow according to the malopolska method -This method is based on the analysis of average and minimum monthly low flows (for good ecological status) Q n = SNQm [m 3 /s] where: NQm low monthly flow m 3 /s Whereas for the assumed moderate ecological status: Q n = NNQm + (SNQm NNQm) /2 where: SNQm average monthly low flow NNQm minimum monthly low flow 14

15 Instream flow according to fishing and angling criterion - It is based on the discernment of ichthyology - There is applied the division of rivers into two basic groups: salmonids rivers and lowland fish rivers - The phases of life and growth of these groups occur in different periods Period Salmonids Lowland fish Development and spawning III-IV or IX-XI III-VI Growth V-VIII VII-XI 15

16 Instream flow according to fishing and angling criterion - Determined on the basis of average low flows (SNQ) in particular months: Qn = min {x 1, x 2, x n } [m 3 /s] where: x 1, x 2, x n average low flows in particular months for the development and spawning periods and for the period of growth - During overwintering (XII - II) instream flow for both groups is the minimum winter flow (NNQ) 16

17 Q [m 3 /s] Instream flow selected methods of calculation Instream flow designated by Kostrzewa method (variant I and II) obtain one value for whole year. 2 0 XI XII I II III IV V VI VII VIII IX X czas [miesiąc] MK 1 MK 2 R-W MAŁ. U. differences values of Q n calculated calculated by Kostrzewa parametric method are about 10% Sample graph of instream flow determined by different methods. 17

18 Q [m 3 /s] Instream flow selected methods of calculation XI XII I II III IV V VI VII VIII IX X czas [miesiąc] MK 1 MK 2 R-W MAŁ. U. Large differences arise when comparing values of Q n calculated ia. according to fishing and angling criterion or malopolska method which differentiate Q n value in particular months or other time intervals, but often is higher then values calculated by Kostrzewa parametric method. Sample graph of instream flow determined by different methods. 18

19 In water resources balancing it seems that reasonable Q n is the one designated by fishing and angling criterion because the values are different in the hydrological year, which directly corresponds with natural functioning of catchments ecosystems and allows to meet basic environmental goals, and thus achieve and maintain good water status, set by the WFD and the Habitats and Birds Directives. 19

20 Instream flow The behavior of instream flow, in addition to maintain the quality of water and restoration of patency of the Neisse and the Lower Oder allow a restoration of fish like Vimba vimba and Salmo salar in the Neisse. These fish species are bi-environmental, anadromous - they live in the sea, and for a period of spawning in the rivers join.

21 Barbus barbus Aspinus aspinus Leuciscus leuciscus Land barbel (Barbus barbus) has the following characteristics: - The average decrease - The average current of the river high flow - In the bottom of the river dominance of coarse sand and gravel - Water temperature up to 18 º C

22 Thymallus thymallus Chondrostoma nasus Squalius cephalus Land grayling (Thymallus thymallus) has the following characteristics: - Large decrease - Swift current of the river - Average flow (critical period March- May) - In the bottom of the river dominance of coarse gravel - Water temperature up to 15 C

23 In the Neisse river impediments for migrating aquatic organisms (mainly fish), in addition to abnormal patency of the river caused by the number of hydropower and hydraulic structures (most of which was built in the first half of the twentieth century), may also be a cause of invariant flow.

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25 Vielen Dank für Ihre Aufmerksamkeit Iwona Lejcuś Institute of Meteorology and Water Management National Research Institute Wrocław Branch Wrocław, ul.: Parkowa