148 research outputs found

    Analyzing the Lake Urmia restoration progress using ground-based and spaceborne observations

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    Lake Urmia, located in the North West of Iran, was once the most extensive permanent hypersaline lake in the world. Unsustainable water management in response to increasing demand together with climatic extremes have given rise to the lake's depletion during the last two decades. The Urmia Lake Restoration Program (ULRP) was established in 2013 and aims to restore the lake within a 10-year program. This study aims to monitor these restoration endeavours using spaceborne and ground-based observations. We analyzed the in-situ water level, the surface water extent, and the water volume of the lake. The water storage change of the Urmia Lake catchment is quantified using the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On satellite observations, which gives us a holistic view of hydrological components. Our analysis shows a positive trend of 14.5 cm/yr, 204 km2/yr, and 0.42 km3/yr in the time series of lake water level, lake water area, and water volume from 2015 to 2019 which indicates a short-lived stabilization of Lake Urmia. This has been achieved mainly due to an increase of 0.35 km3/yr in inflow from rivers to the lake, predominantly driven by anomalous precipitation events in 2016 and early 2019. However, the long-term trend from 2003 to 2019 still shows negative values of −22 cm/yr, −200 km2/yr, and −0.72 km3/yr for the water level, the surface area, and the water volume of the lake, respectively. The stabilization seems to be fragile however, since most of the increase in the water volume of the lake has spread over the large shallow southern region with high evaporation potential during hot seasons. Furthermore, due to the high correlation between the lake water level and precipitation, the recovery observed in 2016 and the first half of 2019 might not continue in case of a long drought period

    Evolution of the oceanic and continental crust during Neo-Proterozoic and Phanerozoic

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    In present, contribution paleogeographical maps for the time interval 0.6 Ga BP to present are analyzed in terms of (a) the ratio between continental to oceanic crust areas in order to estimate the speed of continental growth and (b) the surface motion of continental plates under the influence of global forces of tidal friction and Eotvos force ("pole-fleeing"). It is concluded that the area of the continents during the Phanerozoic was growing and it exhibited a rate similar to 0.5 km(3)/year. It is also found that beside the westward-oriented tidal frictional forces the Eotvos force can play also a role in tectonical processes. It is shown that the continental plates on average tend to find a position close to the equator during the whole investigated 600 Ma time interval
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