FLOOD PROTECTION MEASURES OF

THE SLOVAK REPUBLIC

Ing. Peter Čadek, PhD.

The Slovak Water Management

Enterprise

• existing flood risk – occurrence of 3rd degree of flood

awareness according national the Flood protection Act

• potential occurrence of flood risks - set of potential non-

dimensional aggregated value represent natural potential of

maximal discharges occurrences and circumstance to

creation of floods divided to:

– regional potential characterised floods of lowlands and

alluviums

– local potential characterised of flesh floods

• impact of floods represented by the element of risks: human

health, cultural heritage, environment and economy activities

Selection / evaluation and weigting

criteria of areas with potential

significant flood risk

Factorial relative values of significance

of flood risk and potential of flood risks

• the percentage of days with the proven existence of flood risk

in relation to the overall reference period

• the categorization of a significant probable occurrence of

flood risk, expressed by relevant classes of local potential

and regional potential

Types of flood protection measures

measures to reduce (decelerate) run-off from river basin into the

water courses, to increase retention capability of river basin or to

support natural accumulation of water in the suitable areas –

measures at agricultural soils, in forests and urban areas

measures which reduce flood peak discharge – construction,

maintenance, repair or reconstruction of water structures or polders

measures which protect land from inundated water of water

courses – technical river training works, flood protection dykes,

walls, other linear flood protection structures

measures which protect land from inundated „inner waters“ –

installations (equipment) for pumping the „inner waters“

measures to ensure adequate flow capacity of the channels of

water courses – maintenance of river channels and their

vegetation, removal of deposits

Proposed climate change adaptation measures in the field of water management

PROPOSED MEASURES

IN STRATEGIC DOCUMENT

measures which decelerate runoff

from watersheds

measures which improve economy of

water management

measures which reduce

peak discharge of floods

measures focused at prevention of

water contamination

measures to protect land from inundated

waters of water courses

measures focused at improvement of

waste water treatment

measures focused at improvement

of river channels capacitymeasures focused at risk assessment

measures which increase actively controlled

volume of runoff from the territorymeasures in the research field

measures in the field of spatial planning

Distributed rainfall-runoff modelling1. ISSOP model / GIS application

developed by ESPRIT, Inc.2. Deterministic, physically based

model3. From WETSPA derived model

podpovrchový

odtok

podzemný

odtok

povrchový odtok Zrážky

Infiltrácia

Kapilárny

výstup

Evapotranspirácia

Priesak

Podpovrchový

odtok

Podzemný odtok

PÔDA

Povrchový odtok

NASÝTENÁ

ZÓNA

POVRCH

ATMO-

SFÉRA

Slnečné

žiarenie

ácia

Critical flood waves designingThesis: 100-year flood wave is affected

by 100-rainfall1. Runoff designed waves calculations2. Current landcover/landuse scenario3. Extreme forestation scenario4. Landcover/landuse optimizing

scenario

Assessment of possible impacts of current & proposed measures in catchments to achieve goals

Landscape data inputs1. Gridded DEM in 10 x 10 m resolution2. Soil types3. Landcover/Landuse4. Stream network& Many derived synthetic layers

Estimation of designed rainfall1. N-year maximum daily rainfalls map2. Rainfall event duration equals to

catchment time of concetration3. In time-equal rainfall intensity

Extreme landcover / landusechange1. Keep urbanized & industrial

areas unchanged2. Afforestation of other LCLU

with potential naturalvegetation

Current landcover / landuse

Optimal landcover / landuse change1. Keep urbanized & industrial areas

unchanged2. Landcover / landuse types change

of areas with runoff coefficienthigher 60 %

3. Arable lands change to pasturesor grasslands

4. Other landcover / landuse typeschange to forest by potentialnatural vegetation

Mean change: – 4.85 %Category with highest mean

change:

Catchments up to 2 km²

– 9.5 %But huge range: - 40 % - 0 %

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Pe

rcen

tual

chan

ge f

rom

pe

akd

isch

arge

Area [km²]

Determination Between Catchment Area & Effectiveness

-45

-35

-25

-15

-50 50 100 150 200 250 300 350 400 450 500

Focused on catchments up to 500 km² areaAverage evaluated area: 422 km²

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

up

to

2 k

m²

up

to

5 k

m²

up

to

10

km

²

up

to

50

km

²

up

to

10

0 k

m²

up

to

25

0 k

m²

up

to

50

0 k

m²

up

to

10

00

km

²

up

to

25

00

km

²

up

to

50

00

km

²

Pe

rce

ntu

al c

han

ge

Mean percentual change from peak discharge by area categories

Thank you for you attention