rkmenista Tu n n U a z t b s e CAMP4ASB i k k i i j s t Climate Adaptation&Mitigation a a T n Program for Aral Sea Basin n K a t a s z z CENTRAL ASIA a y k g h r s y t K a n Climate Change and Hydrology in Central Asia A Survey of Selected River Basins Climate Change and Hydrology in Central Asia: A Survey of Selected River Basins © 2019, Regional Environmental Centre for Central Asia This publication may be reproduced in whole or in part in any form for educational or non-profit purposes without special permission from the copyright holders, provided acknowledgement of the source is made. Acknowledgement: Climate Adaptation and Mitigation Program for Aral Sea Basin (CAMP4ASB) sponsored by the Inter- national Development Association (IDA) of the World Bank has provided support for the process of developing methods, approaches, and tools for decision-making support and knowledge products on climate change in Central Asia. Disclaimers: The views expressed in this document are those of the authors and do not necessarily reflect views of the partner organizations and governments. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever concerning the legal status of any country, territory, city or area or of its authorities, or concerning delimitation of its frontiers or boundaries. We regret any errors or omissions that may unwittingly have been made. This report is based on the research by the group of national experts: Alia Nurbatsina (Kazakhstan), Alexander Pak (Uzbekistan), and Vokhid Hamidov (Tajikistan) using the Soil and Water Integrated Model (SWIM) for long-term and short-to-medium term river flow forecasts. Scientific supervision of the national experts on hydrology modelling and SWIM application: Anastasia Lobanova and Iulii Didovets, Potsdam Institute for Climate Impact Research (PIK) Management of the CAMP4ASB project in the Regional Environmental Centre for Central Asia: Iskandar Abdullaev (Executive Director), Irina Bekmirzaeva (Program Manager) Contributors: Atabek Umirbekov and Zhanna Babagalieva Edited and produced by Zoï Environment Network, Geneva Cartography: Matt Beilstein Layout: Carolyne Daniel Climate Change and Hydrology in Central Asia A Survey of Selected River Basins Introduction Selected river basins RUSSIA Bukthyrma River Esil River KAZAKHSTAN Zeravshan UZBEKISTAN River KYRGYZSTAN CHINA TURKMENISTAN TAJIKISTAN Kofarnihon River Murghab River 10 Esil and Zhabai Representative of Central Asia’s flatland climate and hydrology systems, these rivers orig- inate in the vast northern grasslands of Kazakhstan. Their average flow is modest, but spring floods can be significant and water flow can vary from year to year. 14 Bukhtarma A powerful mountain river with sources in the Altai Mountains with whitewater rapids fed by glaciers and snow, the Bukhtarma’s scenic environment makes it a popular tourist des- tination. 16 Zeravshan With origins in glaciers in the Pamir-Alai Mountains of Tajikistan, the Zeravshan carries its waters to the ancient and densely populated areas of Samarkand and Bukhara, Uzbeki- stan, home to 6 million people. 18 Kofarnihon Rising in the high snowy mountains of central Tajikistan, the Kofarnihon flows through highly contrasting climates from wet to dry and icy cold to desert hot, and boasts diverse water uses for irrigation, municipal needs and industries. 20 Murghab Originating in the dry highlands of central Afghanistan, the Murghab flows into Turkmen- istan and ends at an ancient oasis. Agriculture is the predominant water user in the basin. 5 Water flow in the rivers of Central Asia is defined by a multitude of factors – climate, terrain and soil types, and weather extremes. This report highlights key research findings on five important river basins across Central Asia, and presents the visual material with short annota- tions for a lay readership. Temperature, precipitation, the extent of permanent snow cover in the basin and the amount of water and snow (melt water equivalent), along with sun radiation and evaporation are the key meteorological factors that define the hydrological conditions. Soil and vegetation cover, slopes, and geological factors as well as human regulation and diversions of water flow play a great role in mitigating or exaggerating flood intensity and the water distribution across a basin. The Soil and Water Integrated Model, applied in this analysis allows rep- resentation of a river basin as a system. It simulates the hydrological, biogeochemical and vegetation process- es, and integrates the anthropogenic impacts of water storage, irrigation and water withdrawals into the mod- elling framework. The national hydrometeorological services of the Cen- tral Asian countries are producing weather forecasts for 5–7 days that are 80–90 per cent accurate. Producing seasonal weather outlooks is a more difficult task. Hy- drological forecasts rely on weather forecasts, and users are mainly interested in longer-term seasonal predic- tions and flood peak warnings – a daunting task asso- ciated with a high degree of responsibility for human lives, crops, energy production, water regulation and in- frastructure. Climate change projections are inherently 6 uncertain, since they depend on estimates of global Flows in the Kofarnihon depend on the amount of snow greenhouse emissions, global atmospheric processes in winter and the amount and intensity of rainfall in and climate models. Medium and high emission scenar- spring. Rising temperatures will melt snowpack earlier ios were used in these studies. and add water management challenges. None of the models can project precipitation amounts The Zeravshan and Kofarnihon play vital roles in irrigation or type – rain or snow – with confidence for specific river and crop cultivation in Uzbekistan and Tajikistan. Water basins, especially in the mountain areas. At the regional management efficiency in agriculture can be improved scale, however, the northern parts of Central Asia are starting from water intakes, pumps and canals, down to expected to become somewhat wetter, while the south- the field and plant level – through drip irrigation, im- ern parts become drier – a continuation of recently proved leveling and crop selection. Many farmers are observed trends as monitored by the North Eurasian already using these adaptation approaches to conserve Climate Centre and portrayed in the recent national water and protect the soil. Others are harvesting rainwa- communications to UNFCCC. Mountain regions have ter and guarding against extreme weather and climate their own climates, and may feature a mosaic of con- variability with greenhouses and protective plantings. trasting trends. All models show moderate-to-strong cli- Authorities are improving coordination and prepared- mate warming from 2°C to 6°C by the middle and end ness measures, cleaning drainage systems and revising of this century, compared to the current climate. protections against flooding in the Esil and Bukhtarma. The water flow projections were averaged for the peri- Of the rivers in this survey, the Murghab is the most ods up to 2040, 2041–2070 and 2071–2100, and com- vulnerable to climate change, and is likely to experi- pared with the baseline of 1981–2010. Little or no signif- ence significant reductions in water flow in the coming icant changes in hydrology could be seen before 2040 decades. The implications for water security, especially in any of the river basins. Beyond this point, changes are among downstream agricultural users, are serious. likely and their significance will grow over time. As temperatures rise more precipitation is likely to fall Seasonal peaks of water flow are likely to shift to ear- as rain instead of snow, and ice and snowpack are likely lier in the year. Peak flow for the Esil River is likely to to decline due to less snow and higher temperatures. increase. Shrinking glaciers in the Bukhtarma and Zer- These changes will affect river flows in terms of both tim- avshan basins and faster snow melt in spring mean that ing and amount of discharges. The discharge graphs for less water will be available in summer – a troubling pros- the rivers show projections under two climate scenarios pect in the densely populated middle and lower areas based on selected greenhouse gas emission pathways – of the Zeravshan basin, which rely heavily on irrigation. moderate (RCP 4.5) vs. strong (RCP 8.5) warming. 7 Hydrology of rivers Climate change in the mountains of Central Asia and impacts on water resources 3 1 4 2 Seasonal shift More pronounced 1 in water availability 2 inter-annual water fluctuations Climate change Future Present Baseline JFMAMJJASOND Present Future Months Years Snow pack declining due 3 With glaciers Without glaciers 4 to warmer temperatures mm °C Glacier water Seasonal supply diminished glacial melt contribution Years Present 50-70 years from now River ow declining Glaciers contribute important Less water security due to increased evaporation part of ow in hot and dry in hot and dry years summer months Climate change in the northern steppes of Central Asia and impacts on water resources Water 1 Snow Ice Frozen soil 2 Peak seasonal flow 1 and flood 2 Flooding extent Peak ow increase due to more precipitation and Future rapid snow melt Future Present Present JFMAMJJASOND Climate change in southern deserts and highlands of Central Asia and impacts on water resources Significant reduction in flow Present Flow decrease due to less precipitation and higher temperatures Future JFMAMJJASOND Months irrigation canal Esil and Zhabai The Esil starts as a typical small flatland river in Central Asia with an average flow of 4 m3 of water per second at Tobolsk Astana, the major city in the basin. Further downstream, 1168 (Irtysh) the Zhabai sub-basin drains an area of 8,800 km2 and has Ust-Ishim an average flow of 8 m3 per second. Together the basins Irty 81 sh cover an area of 177,000 km2 and are the largest system Tyumen in the survey.