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For the fulfillment of the thirsty ambition of self-sufficiency of the Soviets for cotton production, the arid Central Asian region and in particular Uzbekistan has been extensively exploited. In fact, vast tracts of deserts have been converted into irrigated agricultural lands without proper consideration to environment and technical standards. As a result trends in natural resource degradation (soil salinity, desertification, water quality) as well as declining crop yields have dramatically increased. The agricultural sector is the backbone for employment, food security and export revenues of the Central Asian countries. Since the independence of the Central Asian countries (after the breakup of the former Soviet Union) the situation has changed dramatically in terms of institutional, political and technical systems. Political transition, which is defined as a shift from once planned centralized economy to a market-driven one, has introduced 'new' concepts like land tenure, water rights and different kinds of ownership. All of such transformations have impacted the agricultural production in Central Asia. The institutional change can be described as decentralization of the farming systems i.e., transition from the former state collective farms into the smaller forms of private farms. The institutional interventions are aimed to increase agricultural production through improving water management. It is arguable that private production systems are the most effective business driven forces but the situation is quite different in Central Asia due to the irrigated agriculture. The biggest challenge for a sustainable irrigated agricultural production lies in the recent reforms of water management sector in Central Asia and Uzbekistan. The water users associations have been established for replacing the former collective farming systems for irrigation water distribution and maintenance of irrigation infrastructures at on-farm level. The intention of the national government was to shift the operation, maintenance and management of irrigation infrastructures to non government institutions (decentralization). However, these institutions have not fulfilled their promising tasks because of i) a rapid increase of number of private farms along canals; ii) the cropping structure is mosaic with different crop water requirements against the former monoculture; iii) a poor financial, trained and technical capacities of new established institutions; iv) a state ordered agricultural production quota system (for cotton and wheat). This paper analyzes the historical aspects of transformation in the farming production institutions in Central Asia with special focus on Uzbekistan and comprehensively overviews the main current challenges facing the farming system and potential opportunities for reversing the situation.

Sedimentation processes in man-made water reservoirs reduce their main asset: the volume storage capacity. This raises engineering, environmental and economic issues for the communities around the world and in particular for the areas affected by strong water deficit. Because of Uzbekistan's arid climatic conditions and uneven spatial and temporal water resources distribution, responsive and innovative water availability assessment surveys of all major water reservoirs are required. Bathymetric survey is a traditional method that is carried out for the estimation of reservoir volumes and surface areas for the corresponding reservoir stages in order to assess the water availability. Volume and surface area differences derived from multiple surveys of a reservoir provide storage loss estimates over time due to sedimentation. However, two main factors such as intensive field data measurement and post data-processing often limit the frequency of these surveys. Alternatively, innovative depth measurement technologies coupled with contouring and surface mapping programs provide automated reservoir volume and surface area calculations. This significantly reduces time, work load and financial burdens for reservoir sedimentation projects. This study deals with the use of a geostatistical approach to assess the reservoir sedimentation in the Akdarya reservoir in Uzbekistan. Geostatistical approach includes (semi-) variogram analysis and interpolation (kriging and simulations (turning bands)) techniques predicting values at unsampled locations for generating digital bathymetric surface models of reservoir bottom conditions in order to calculate volume and surface area at given water elevation. Simulation enables to have range of reservoir volumes and surface areas with the same probability in comparison to the kriging and traditional methods. This gives a real estimation of the water resource availability for operators and managers to sustainably manage natural resources and hydraulic infrastructure., Cette étude porte sur l'utilisation des outils de la géostatistique pour évaluer l'importance des phénomènes de sédimentation dans le barrage Akdarya en Ouzbékistan. Les analyses de variogrammes et les techniques d'interpolation par krigeage ont permis de générer des données dans les zones non échantillonnées du barrage. A l'aide des données de terrain complétées par les données produites par les outils géostatistiques, de nouvelles cartes bathymétriques du barrage ont été générées et ont permis de calculer de façon précise l'évolution du volume d'eau stocké en fonction du taux de sédimentation.