Assessment of climate change impact on water resources and design of adaptation technologies for water sector

Previous and Current Research

Climate change impacts, driven by temperature rises and shifts in precipitation patterns, could lead to changes in flood or drought frequency, water availability, and seasonality of water discharge. Such changes may have adverse effects on agricultural, energy, transport, and social sectors, dependent on water resources. To avoid the risks and damages associated with such impacts, adaptation strategies in regional water resource management have to be developed to ensure the readiness of the water-dependent sectors to meet the future challenges.

Ukraine is characterized by a relatively low availability of internal water resources compared to other countries in Europe: it ranked 124th among 181 countries by the amount of internal renewable water resources available per capita in 2014. Therefore, a comprehensive assessment of climate change impacts on the country’s water resources is vital. Surprisingly, such an assessment has not been performed for this large European country until now. In this study, the main aim was to take a first step in this direction and explore climate change impacts on water resources for several representative regions.

The water resources of Ukraine are vulnerable due to their limited total amount, uneven annual internal and external contributions to the total renewable water resources, and heterogeneous distribution of available water within the country. In this regard, the issue of the future is crucial for Ukraine.

Our group is one of leading Ukrainian research teams with enough potential to a comprehensive assessment of climate change impacts on the country’s water resources.

At the request of the State Water Agency of Ukraine, we conducted research of water resource changes in 19 representative river basins in Ukraine for the 21st century by applying a water balance method (WBM) driven by climate scenarios fr om the REMO model. According to this study, in the near future runoff mainly stays stable, especially in the mountainous regions, with small increases until 2040. Then, by the end of the century, a decrease in runoff was projected for almost all catchments, especially in the central and southern parts of Ukraine (Snizhko et al.,2014).

The water balance assessment of changes in the local water resources (climatic flow) on the base of climatic projection from A1B scenario, which depends on the ratio of the main elements of the water balance of precipitation and evaporation, shows (Snizhko at al., 2011), that since 2040 the cease of the surface low-water runoff in the dry years in Kherson, Odesa, Mykolayiv, Dnipropetrovsk and Zaporizhzhya regions is possible.

One should bear in mind that this refers to zonal water resources of local drainage, which are sensitive to the warming of the climate and, even in the current climate, periodically dry up in arid years.

The water supply of these regions does not depend directly on the water resources of the local drain, but the general warming trends that will be accompanied by rising air temperature, the amount of evaporation, and the reduction of precipitation are threatening the sources of water supply, irrigation (reservoirs, rates) and linear water management infrastructure (canals, water pipes). There may be significant losses of water resources during storage and transportation, and additional energy costs will be incurred for the operation of water facilities.

In subsequent years, this situation will deteriorate: local surface runoff will decrease, and the zone of a possible complete cessation of runoff will expand.

In 2041-2060, in the years of average water flow, it will cover the territories of the Kherson, Odesa, Mykolaiv and Zaporizhzhia regions. In 2061-2080 it will expand to Dnipropetrovsk, Zaporozhye, Kirovograd regions and the Crimea (See Figure 1. for details).

Figure 1. Distribution of projected local water resources (climatic flow) for period 2061-2080 between the administrative regions of Ukraine (average runoff layer for a long-term period, mm), scenario A1B.

The results of forecasting still suggest the presence of surface runoff in abundant water years before 2080 in most of the territory of Ukraine, except for Kherson and Odesa regions.

Within last years, we have conducted together with our partners from PIK (Germany) precise assessments of water runoff under impact of climate. One of the latest studies using the SWIM ecological and hydrological model and regional climate scenarios from the European interdisciplinary project IMPRESSIONS and 7 climate projections from RCP 4.5 and RCP 8.5 are joint Ukrainian-German studies carried out in recent years by the Kyiv National Taras Shevchenko University, Potsdam University and Potsdam Institute of Climate Studies (Didovets at al.,2017), (Didovets at al., 2019). Possible changes in water resources in various regions of Ukraine based on five indicator basins (the river Teterev, the Samara River, the Western Bug, the Tisza River and the Prut River) were assessed (See Figure 2. for details).

Figure 2. The projected future changes in areal catchment mean of river discharge in the basins under consideration for three scenarios and three future periods compared to the reference period shown as boxplots, wh ere the boxes show ranges between the 25th and 75th percentiles, and thick black lines show the median values.

In the Teterev River basin, an increase of runoff is expected in the winter months and early spring, reaching a peak in March-April. In summer months, changes in drainage are not expected in the near future (until 2040), but in 2041-2070 and in 2071-2100, a slight decrease in drainage is expected (up to 17%). There is a probability of stopping the drain during the summer period for all forecasted periods. Autumn’s months are characterized by a steady increase in drainage. In the basin of the Western Bug, an increase in drainage is expected compared to a control period for all seasons with a slight sporadic decrease in the spring months in the near and far future according to all scenarios.

In 2020, together with colleagues from Germany, we conducted an assessment of climate change impacts on water availability across Ukraine using global hydrological models. Six global hydrological models were evaluated for their performance in the historical period in the basins under study. Future river discharge was simulated by using the best performing model and all available models driven by bias-corrected GCM projections from the ISIMIP project under the RCP 2.6 and RCP 8.5 scenarios.

The results show precipitation increase up to 10 % under RCP 2.6, and variable changes from -14 % to +10 % under RCP 8.5 by the end of the century. The projections show the decreasing mean annual river discharge in the majority of basins for the middle (2040–2070) and far future (2071–2100) periods under both RCPs, and the decrease is stronger under RCP 8.5. The seasonal changes are characterised by a decrease in summer and a small to moderate increase in winter months in most of the basins. The highest reduction of mean annual discharge was projected for the Pripyat, Southern Bug and Dniester basins, reaching up to -30 % to the end of the century under RCP 8.5 (Fig.3).

Fig. 3. Projected changes in mean annual river discharge simulated by the WaterGAP2 model for eight river basins for two future periods under RCP2.6 and RCP 8.5. Upper box lines indicate 75th percentile, lower – 25th percentile and the middle lines present median; vertical lines show minimal and maximal values.

Climate change is manifested not only in reducing the water flow in the future, but also in a significant change in the hydrological regime of water bodies. The most dangerous manifestations of the change in the hydrological regime are catastrophic floods and flash floods. The regional manifestation of these phenomena is wide enough. This is primarily the Carpathian region: Transcarpathia (Transcarpathian region), Prykarpattya (Lviv, Ivano-Frankivsk and Chernivtsi regions). The territory of the Carpathians (Tyzsa, Dniester and Prut basins) is one of the most flood-prone regions in Europe. Floods in the Carpathians are natural phenomena common to this territory. They are determined here by the frequency, intensity of development and simultaneous spread on a large area (up to 10-30 thousand km²), often with significant destructive consequences.

Our newest study (Didovets at al.,2019) for rivers of the Carpathian region of Ukraine (Tisza and Prut), reported investigates climate change impacts on flood risk in the region, and uncertainty related to hydrological modelling, downscaling techniques and climate projections. The climate projections used in the study were derived from five GCMs, downscaled either dynamically with RCMs or with the statistical downscaling model XDS. The resulting climate change scenarios were applied to drive the eco-hydrological model SWIM, which was calibrated and validated for the catchments in advance using observed climate and hydrological data. The changes in the 30-year flood hazards and 98 and 95 percentiles of discharge were evaluated for the far future period (2071–2100) in comparison with the reference period (1981–2010).

The majority of model outputs under RCP 4.5 show a small to strong increase of the 30-year flood level in the Tisza ranging from 4.5% to 62% (See Figure 4.6. for details), and moderate increase in the Prut ranging from 11% to 22% (See Figure 4 for details)

Figure 4. Flood frequency curves of simulated discharge rates for a) GCM-XDS and b) GCM-RCM projections, based on the GEV distribution fit to the annual maxima in the reference and far future periods for the Tisza catchment (Source:Didovets at al.,2019).

The impact results under RCP 8.5 are more uncertain with changes in both directions due to high uncertainties in GCM-RCM climate projections, downscaling methods and the low density of available climate stations. The largest increase in flood during a thirty-year period of more than 40% was modeled on the basis of HadGEM2-RCA4 for the Tisza (both RCP) and the Prut (RCP 8.5).

Taking into account the available modeling results, one should expect an increase in the deficit of water resources in the zone of unsustainable agriculture - in the southern regions of Ukraine as early as by the middle of the XXI century. At the same time, water sector of Ukraine will face the problem of devastating water effects in connection with the strengthening of the river's float regime.

Given the expected deterioration in the availability of water resources for the population and the economy, our group is conducting research on the design of technologies for adapting the water sector to climate change. The obtained results were included in the reports of UNEP:

TECHNOLOGY NEEDS ASSESSMENT REPORT ADAPTATION. 2019.

https://tech-action.unepdtu.org/wp-content/uploads/sites/2/2019/09/final-ukraine-tna-adaptation-report.pdf

BARRIER ANALYSIS AND ENABLING FRAMEWORK REPORT

https://tech-action.unepdtu.org/wp-content/uploads/sites/2/2020/06/baef-ukraine-adaptation.pdf

Collaboration:

·                  Potsdam University, Germany (Prof.Axel Bronstert)

·                  Potsdam Institute for Climate Impact Research (PIK), Germany (Dr.Valentina. Krysanova, Dr. Iulii Didovets)

·                  Technical University of Denmark, Denmark (Dr.Sara Traerup)

·                  University of Cape Town, Republic of South Africa (Dr. Jiska de Groot)

Future Projects and Goals

• assessment of changes in seasonal distribution of water flow under climate change  

• hydrological drought probability assessment

• water sector adaptation measure development

Group leader: Prof. S.Snizhko

 The team:

Doctor of Science, Ass. Prof. O. Shevchenko

Dr. I. Didovets (PostDoc researcher at the Climate Resilience department Potsdam Institute for Climate Impact Research; former PhD Student at the Department of Meteorology and Climatology of TSNUK)

PhD student M.Matviienko

PhD student I.Kostyrko

Former team members:

Dr. I. Kuprikov

Dr. I. Pavelchuk

Selected Publications

1.Snizhko S., Kuprikov I., Shevchenko O. (2012): Assessment of changes in rivers water flow in Ukraine on the basis of water‑balance models. Physical Geography and Geomorphology, vol. 2(66). P. 157 ‑161.

2.Snizhko S., Pavelchuk E., Didovets Y. (2014): The study of time trends in water runoff and assess of their significance with Mann‑ Kendall test. Hydrology, hydrochemistry and hydroecology, vol. 2(33). P. 8‑16.

3. Didovets I., Lobanova N., Snizhko S., Bronstert A., Krysanova V. (2017): Assessment of Climate Change Impacts on Water Resources in Three Representative Ukrainian Catchments Using Eco‑Hydrological Modelling. Water. – 2017. ‑18 P. doi:10.3390/w9030204.

4. Didovets I., Bronstert A., Snizhko S., Balabukh V., Krysanova V. (2019) Climate change impact on regional floods in the Carpathian region. Journal of Hydrology: Regional Studies. DOI:10.1016/j.ejrh.2019.01.002.

5.Didovets I, Krysanova V, Snizhko S, Bronstert A. (2019) Assessment of climate change impact on floods in the Upper Prut and Tisza River catchments (Ukraine). EGU General Assembly Conference Abstracts 19, 16355

6.Snizhko S., Shevchenko O., Didovets I. at al. (2019): Climate monitoring data application in the technological regional assessment scheme and simulation of water flow//Monitoring of Geological Processes and Ecological Condition of the Environment. DOI: 10.3997/2214‑4609.201903241

7.Grebin V., Didovets I., Obodovskiy O., Snizhko S. at al. (2020): River Runoff in Ukraine Under Climate Change Conditions. LAP Lambert Academic Publishing. 140P. ISBN: 978‑620‑2‑67675‑5.

8.Shevchenko O., Oliinyk R., Snizhko S., Svintsitska H., Kostyrko I. (2020): Indexing of Heatwaves in Ukraine. Water 12, 962. https://doi.org/10.3390/w12040962.

9.Snizhko S., Obodovskiy O., Shevchenko O. at al. (2020): Regional assessment changes of the river runoff of Ukrainian Carpathians region under climate changes. Ukrainian Geographical Journal. DOI: 10.15407/ugz2020.02.020.

10.Obodovskiy O., Danko K., Snizhko S., Pochayevets O., Lukyanets O. (2020): Methodic Aspects of Hydroecological Assessment of Hydropower Potential of the Plain Rivers' (by Example of Dnieper Right‑Bank Rivers). Hydrobiological Journal 56(4). P.84‑102. DOI:10.1615/HydrobJ.v56. i4.70

   Scopus Author ID: 55801496000

https://www.scopus.com/authid/detail.uri?authorId=55801496000

Contacts

E-Mail: snizhkosi@gmail.com

ORCID https://orcid.org/0000-0002-2696-687X

ResearchGate https://www.researchgate.net/profile/Snizhko-Sergiy