Sustainable Irrigated Agricultural Production of Countries in economic Transition: Challenges and Opportunities (A case study of Uzbekistan, Central Asia)

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

Twenty years of groundwater evolution in the Triassic sandstone aquifer of Lorraine: Impacts on baseline water quality

International audienceThe Lorraine Triassic Sandstone Aquifer (LTSA), which has already been the subject of a chemical and radioisotopic study (1979), is used to investigate the impacts of 20 a of large scale pumping on baseline water quality. In parallel, new sampling of the aquifer (2001) provides new inorganic geochemical data (including trace elements) that allow improving the knowledge of baseline conditions and hydrochemical functioning of a major sandstone aquifer. The good correlation between 14 C activities, temperature and depth along the main flow line indicate regular downgradient trends and possible water stratification. Unreactive tracers, mainly stable isotope ratios 18 O and 2 H, as well as C isotopes are used to define a timescale for the aquifer, showing two groups of groundwater, namely of modern and Holocene age, and late Pleistocene age, with a mixing zone. Baseline quality is then represented by a wide range of concentrations , mainly the result of time-dependent water-rock interaction, as already observed elsewhere in Tri-assic sandstone aquifers. Some trace elements such as Li, Rb, Cs, which are not limited by solubility constraints, show linear trends. During saturated flow downgradient, the chemistry is also specifically characterised by a regular increase in Na and Cl (and locally SO 4) as a result of evaporite dissolution related to overlying or basement limits. The aquifer is mostly oxidising with a redox boundary marked by U decrease, some 40 km from outcrop. Groundwater abstraction since the 1970s has created a strong lowering (10-150 m) of the water table, especially from 1970 to 1980. Based on nine boreholes, previously sampled in 1979, a decreasing evolution in radiocarbon content of the TDIC, together with significant evolution of 18 O content, indicate that old groundwater has moved upgradient. The major difference in terms of baseline evolution is observed using Cl and Na concentration and, locally, SO 4 , indicating an increasing influence of water circulation involving overlying or basement formations, or of mixing with Permian waters. From the point of view of aquifer management, the perceptible NO 3 increase could provide information on the progress of any contamination under the aerobic conditions. In addition, the few key elements, indicators of disequilib-rium, related to overlying or deep waters, should be included in regular monitoring programmes

Sedimentation of reservoirs in Uzbekistan: a case study of the Akdarya Reservoir, Zerafshan River Basin

International audienceThe major rivers of Central Asia (Amu Darya, Syr Darya and Zerafshan) are turbid watercourses. Thus many man-made water reservoirs are affected by high sedimentation rates. It is of strategic importance to rationally quantify available water resources in existing reservoirs to ensure a guaranteed water supply to the different water users. Recent drought years and physical deterioration of hydraulic structures urged authorities to re-estimate the water availability in reservoirs of Uzbekistan for the sustainable use of the scarce water resources and safe operation of hydraulic infrastructure. This paper presents the results after the application of a geostatistical approach to assess the water resources availability in the Akdarya reservoir of Uzbekistan. The geostatistical approach creates digital surfaces that represent relatively accurate reservoir bottom conditions and support automated reservoir volumes and surface areas calculations. This in turn significantly reduces time, work load and financial burdens for sedimentation survey projects

Facts and Perspectives of Water Reservoirs in Central Asia: A Special Focus on Uzbekistan

International audienceThe political transformation of the Central Asian region has induced the implosion of the interconnected physical hydraulic infrastructure and its institutional management systems. Land-locked Central Asian countries with their climatic conditions and transboundary water resources have been striving to meet their food security, to increase the agricultural production, to sustain the energy sectors and to protect the environment. The existing water reservoirs are strategic infrastructures for irrigation and hydropower generation. The upstream countries (Tajikistan and Kyrgyzstan) favor the reservoirs operation for energy supply while the downstream countries (Uzbekistan, Turkmenistan and Kazakhstan) push on the irrigation use. This paper overviews the current challenges and perspectives (technical, institutional and legal regulations) of man-made water reservoirs in Central Asia with special focus on Uzbekistan

Geostatistical approach for the assessment of the water reservoir capacity in arid regions: a case study of the Akdarya reservoir, Uzbekistan

International audienceThe paper presents the results of a new geostatistical approach to generate bathymetric surface models from point measurement converted into continuous contour surfaces of reservoir bottoms in Uzbekistan. Sedimentation of reservoirs raises engineering, environmental and economical issues for the communities around the world in areas affected by a 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 surveying is a traditional method that is carried out for the estimation of reservoir volumes and surface areas of 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, workload and financial burdens for reservoir sedimentation projects. This research proposes the use of geostatistical approach to assess the reservoir sedimentation in the Akdarya reservoir of Uzbekistan. The 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 the volume and surface area at a given water elevation. The 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 resource availability for water operators to manage natural resources and hydraulic infrastructure in a sustainable manner

Distribution of trace elements in waters and sediments of the Seversky Donets transboundary watershed (Kharkiv region, Eastern Ukraine)

International audienceThis paper reports on the aquatic chemistry of trace elements in terms of spatial and temporal distribution, but also pollution sources in the transboundary watershed of the Seversky Donets River (Ukraine/Russia). Bed sediments and filtered water were collected from the Udy and Lopan Rivers at sites from the river source in the Belgorod region (Russia) to rural and urban areas in the Kharkiv region (Ukraine) in May and August 2009. Priority trace elements (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn), an urban tracer (Ag) and additional metals (Co, Mo, V) and Th were measured in stream water and sediments. The low levels and variability of Th-normalized concentrations indicated the absence of geochemical anomalies in the upstream part of the rivers and suggested that these data represent a regional baseline for trace elements in bed sediments. In contrast, water and sediments within the city of Kharkiv were contaminated by Ag, Pb, Cd, Cu, Cr and Zn, which are mainly attributed to municipal wastewater inputs and urban run-off. Results of the environmental quality assessment showed that element concentrations in the sediments can be considered as potentially toxic to aquatic organisms in sites downstream of the wastewater discharges

Trends of labile trace metals in tropical urban water under highly contrasted weather conditions

International audienceThe spatio-temporal trend of trace metals (Cd, Co, Cr, Cu, Ni, Pb, and Zn) in a tropical urban estuary under the influence of monsoon was determined using diffusive gradient in thin films (DGT) in situ samplers. Three different climatic periods were observed: period 1, dry with dredging activity; period 2, intermediate meaning from dry to wet event; and period 3, wet having continuous rainfall. Conforming to monsoon regimes, these periods correspond to the following: transition from winter to summer, winter, and summer monsoons, respectively. The distinction of each period is defined by their specific hydrological and physico-chemical conditions. Substantial concentrations of the trace metals were detected. The distribution and trend of the trace metals under the challenge of a tropical climate were able to follow using DGT as a sensitive in situ sampler. In order to identify the differences among periods, statistical analyses were performed. This allowed discriminating period 2 (oxic water) as significantly different compared to other periods. The spatio-temporal analysis was then applied in order to distinguish the trend of the trace metals. Results showed that the trend of trace metals can be described according to their response to (i) seasonal variations (Cd and Cr), (ii) spatio-temporal conditions (Co, Cu, Ni, and Pb), and (iii) neither (i) nor (ii) meaning exhibiting no response or having constant change (Zn). The correlation of the trace metals and the physico-chemical parameters reveals that Cd, Co, Cu, and Cr are proportional to the dissolved oxygen (DO), Cd and Ni are correlated pH, and Zn lightly influenced by salinity

FONCTIONNEMENT HYDROGEOLOGIQUE ET ARCHIVES PALEOCLIMATIQUES D'UN AQUIFERE PROFOND MEDITERRANEEN <br />Etude géochimique et isotopique du bassin miocène de Valréas (Sud-Est de la France)

A hydrogeochemical survey of the Valreas Miocene aquifer has been carried out from 1997 to 2000. The purpose of this survey is to have an improved knowledge of the system using a set of isotopic and geochemical data. The isotopes include those of water molecule (18O, 2H, 3H) and inorganic carbon (13C and 14C), whereas the geochemical data are noble gases and major ions. Radiocarbon activities decrease from 100 pmc in the recharge area to less than 1 pmc in the confined aquifer providing ages from present day to 30 000 years BP.18O and 2H data show a strong isotopic contrast between unconfined and confined aquifer, the later having depleted values. The 18O/2H relationship clearly distinguishes the atmospheric pattern?s influence of the Atlantic (d≈10) and the Western Mediterranean area (d≈14). Deuterium excess does not show demarcation between Pleistocene and Holocene waters. Palaeorecharge temperatures deduced from noble gases indicate that the Last-Glacial is 7°C cooler than the Holocene. Radiogenic helium concentrations increase gradually with groundwater residence time in the aquifer giving a relative age to water. Hydrogeochemical data from the recharge area show that groundwater is polluted by anthopogenic sources from their NO3-, SO42- and Cl- high concentrations. There is also evidence of water-rock interaction from the evolution of the chemical facies where Na+ and K+ tend to dominate in the deeper aquifer probably due to reaction with clay minerals as against Ca2+ in the recharge zone. Velocity of flow estimated for the confined aquifer using the radiocarbon data gives a rate of 0,2 m/year, however this contrasts with estimates of 2 m/year from hydraulic data. In conclusion a conceptual model has been produced to describe the functioning of the aquifer.Une étude hydrogéologique a été entreprise sur les eaux de l'aquifère miocène du bassin de Valréas (Vaucluse). Celle-ci vise à améliorer la connaissance du fonctionnement du système grâce à une étude détaillée combinant une vaste gamme d'outils isotopiques et géochimiques qui inclut : les isotopes stables de la molécule d'eau (18O et 2H), les isotopes du carbone minéral dissous (13C et 14C), le tritium, les gaz rares et les éléments chimiques majeurs. Les activités 14C décroissent depuis environ 100 pcm dans la zone de recharge, jusqu'à des valeurs inférieures à 1 pcm dans l'aquifère captif. Les âges calculés révèlent la présence d'eau dont le temps de séjour atteint plus de 30 000 ans dans la partie confinée. Les teneurs en 18O et 2H mettent en évidence un fort contraste isotopique entre aquifère libre et aquifère captif, et l'étude de la relation 18O/2H souligne la particularité des circulations atmosphériques régionales, sous influence mixte atlantique et méditerranéenne. L'excès en deutérium calculé à partir des eaux anciennes suggère la persistance de ce schéma depuis le Pléistocène. Les paléotempératures de recharge déduites des concentrations en gaz rares fournissent une différence de température entre le Tardiglaciaire et l'Holocène de l'ordre de 7°C et les teneurs en hélium radiogénique montrent une évolution graduelle avec l'augmentation du temps de séjour. La géochimie des eaux met en évidence la sensibilité des eaux du réservoir miocène aux pollutions d'origine anthropique. Les minéraux argileux sont à l'origine d'échanges de bases dont l'intensité est proportionnelle au temps de séjour. La comparaison des vitesses hydrauliques et des vitesses radioisotopiques indique une grande différence dans les deux méthodes concernant la partie captive de l'aquifère, suggérant l'existence d'eaux quasi-stagnantes dans l'aquifère confiné. A l'issue de cette étude un modèle conceptuel de fonctionnement de l'aquifère est proposé