Uzbekistan experience in V&A assessments for water resources

Current status of work Regional climate scenarios construction on the base of the GCM outputs Selection of appropriate scenarios with taking into account the high level of their uncertainty Analysis of previous results in the field of water resources assessment and evaluation of priorities 1. Climate change impact on the hydrological regime of the Amudarya and Syrdarya rivers 2. Climate change impact on the irrigation regime and water supply Adaptation and calibration of the methodologies for water resources assessment (baseline period) Carrying out the assessments using adopted models

To construct the regional climate scenarios the outputs of GCMs collected in database SCENGEN were used with application of the MAGICC (Model for the Assessment of Greenhouse-gas Induced Climate Change). Outputs in grid points of six GCMs have been averaged for the purpose of uncertainty reduction. Regional climate scenarios Downscaling method based on the multiple linear regression has been applied. Grid points SCENGEN and reference stations of Uzbekistan Reference stations of nearby mountain territory

Observed and expected changes of annual air temperature in Uzbekistan (averaging of six models, mid climate sensitivity). Observation data Conclusion: it is possible to consider only two scenarios ( A2 and B2 )

5 Uzbekistan belongs to the semi-arid and arid zones, which are under natural water deficit. Intensive water use for irrigation needs is the main cause of the Aral Sea crisis. Different nature of the runoff processes in the mountains and in the plains has led to the division of the territory into the - zone of runoff formation situated in uplands and - water dispersal area where the runoff is withdrawn for irrigation purposes and evaporates. Irrigated areas. Tashkent y u S r d a y y r r a a a m A d

At present water of rivers in the Aral Sea Basin are completely regulated and distributed among water users. According to interstate agreements Uzbekistan receives from 43 to 52km3 of water annually. The main consumer of water resources is irrigated farming, which uses over 90 % of the available water. Water resources formation Kirgizstan Tajikistan Turkmenistan Afghanistan Uzbekistan

Main river basins in the runoff formation zone River basins are divided into hydrological sub-regions Chircik-Ahangaran Rivers of Chatcal ridge Rivers of Chatcal ridge Rivers of Fegana ridge Rivers of Fegana ridge Rivers of Alay ridge Rivers of Alay ridge Zeravshan river basin Zeravshan river basin Panj river basin Panj river basin Kafirnigan river basin Kafirnigan river basin

To assess climate change impact on water resources the model of river runoff formation developed at the Central Asian Research Hydro- meteorological Institute has been selected. The model permits to take into account the main regularities of surface water formation under climate factors. Challenges Assessment of spatial distribution of precipitation and other meteorological parameters considering altitude and orographic features Adaptation of each model to conditions of information deficiency Adaptation of the software Model of snow cover formation Model of melted and rain water entering Model of glacier runoff formation. Model of runoff transformation Model’s blocks

Changes in number of snow measurement points in Uzbekistan To describe precipitation and temperature fields in the mountain area adequate network of observation is required. Our main challenge is significant reduction of observation points in mountain territory. Other challenges are caused by occurred climate change Snow storage reduction Degradation of glaciation

Example of precipitation data restoring Comparison of measured and restored precipitation mm mm MeasuredRestored

Model simulation of the snow storage at the end of March Snow cover in the mountains is an important feeding source for the rivers of Uzbekistan. At present the snow contribution in river runoff amounts to 60-75%. Model simulation of the integrated snow storage shows their decrease in all spring months Ugam -Hodjikent mln.m 3 Years

Glaciological observations have been organized in runoff formation zone since In the past years the glaciological observations practically have been stopped. Currently only the separate glacial areas are estimated on the base of satellite information. km 2 ? ? ? ? Reduction of the glacier area in the separate river basins

Updating of base Data recovering Estimating quality Parameters of Transformations model Estimating quality Adaptation of Models Data base Updating parameters of models Adaptation of models is necessary due to: 1. Information deficit 2. Changing snow storage 3. Changing glaciation Addressing these problems allows starting an estimation of water resources components under realization of climate scenarios. Adaptation of software Spatial generalization of different components Gathering and analysis of available data Estimating quality

Pskem river Results of adaptation and parametrization of the models: Real description of runoff formation during the year Measured runoff Calculated Calculated snow contribution glacier contribution rain contribution

Assessment of inflow to Charvak water reservoir Pskem + Chatkal rivers B2 scenario, 2030 Current norm

Climate change impact on the irrigation regime and water supply The CROPWAT and ISAREG (The Irrigation Scheduling Simulation Model by the Institute of Agronomy, Technical University of Lisbon) models were selected. Depending on data availability, various time step computations can be used. Input data include: Meteorological data - precipitation and reference evapotranspiration or weather data to compute evapotranspiration; Crop data - crop coefficients and soil water depletion for crop growth stages, root depths and the water-yield response factor; Soil data - available soil water, soil water content at planting, potential groundwater contribution. The ISAREG model permits to simulate alternative irrigation schedules for different levels of admissible crop water stress and various water constraints.

Calibration and validation (not only in the framework of SNC preparation). The calibration and validation of ISAREG were performed by comparing observed and simulated soil water content on the base of field observations. The crop coefficients, water-yield response factor, parameters for estimating the groundwater contribution and others factors were adjusted for local conditions. Obtained results have shown a good agreement between field observations and model simulation, which allow the use of the model to assess climate change impact and selection of adaptation options. Changes in number of evaporation measurement points in Uzbekistan Currently the evaporation measurement network in Uzbekistan is insufficient. Average difference between measured and calculated evaporation is about 10% at separate points.

Изменение испаряемости на уровень г. по сценарию А2 и В2 относительно базового периодаИзменение испаряемости на уровень г. по сценарию А2 и В2 относительно базового периода The most significant growth of evaporation will be occurred at the cold period of the year. Example of estimated potential evaporation Annual water demand for irrigation, m 3 /ha (baseline period) RegionCottonWinter wheat Bukhara Tashkent Fergana Sherabad At present, the water demand for irrigation needs is very high. The expected increase in evaporation will reduce water availability.

Assessment of future water demand using CROPWAT and ISAREG models. Integration of sectoral impact assessments on water resources and agriculture and for analyzing adaptation options with application of the WEAP model. On the most territory of Uzbekistan water withdrawal varies from 60 to 100% of the total volume of renewable water resources. The current problem of water supply may become more severe due to climate change and population growth. Selection and implementation of adaptation measures are necessary for country’s sustainable development. According to the estimation of runoff formation regime, climate change will lead to increase of runoff variability and probability of extreme phenomena (droughts, intensive freshets, mudflows). Planning work: Assessment of possible extreme values (quantiles of 10 and 90% probability within of climate scenarios)