Environmental isotopes and noble gases in the deep aquifer system of Kazan Trona Ore Field, Ankara, central Turkey and links to paleoclimate

Environmental isotopes and noble gases in groundwater samples from the Kazan Trona Ore Field are studied to establish the temperature change between the Holocene and the late Pleistocene. Noble gas temperatures (NGTs) presented in this study add an important facet to the global paleotemperature map in the region between Europe and North Africa. The groundwater system under investigation consists of three different aquifers named shallow, middle and deep in which δ18O and δ2H vary from − 8.10‰ to − 12.80‰ and from − 60.89‰ to − 92.60‰ VSMOW, respectively. The average isotopic depletion between unconfined and confined parts of the system is − 2.5‰ in δ18O and − 20‰ in δ2H. It is not possible to explain this depletion solely with the elevation effect. Recharge temperatures derived from dissolved atmospheric noble gases reflect the current average yearly ground temperatures (13°C) for samples collected near the recharge area but are 3 to 8°C lower than today's temperatures in the deep aquifer system. Low 14C activities and high He excesses in the confined parts of the aquifer system suggest that the water in the deep aquifer was recharged during the last Pleistocene under considerably cooler climatic conditions

Analysis of groundwater dynamics in the complex aquifer system of Kazan Trona, Turkey, using environmental tracers and noble gases

The Eocene deposits of Kazan Basin in Turkey contain a rare trona mineral which is planned to be extracted by solution mining. The complex flow dynamics and mixing mechanisms as noted from previous hydraulic and hydrochemical data need to be augmented with environmental tracer and noble gas data to develop a conceptual model of the system for the assessment of the impacts of the mining and to develop sustainable groundwater management policies throughout the area. The tracers used include the stable isotopes of water (δ²H, δ¹⁸O), δ¹³C and ¹⁴C of dissolved inorganic carbon (DIC), tritium (³H), the chlorofluorocarbons CFC-11 and CFC-12, and the noble gases He and Ne. The system studied consists of three aquifers: shallow, middle, and deep. CFC data indicate modern recharge in the shallow system. The estimates of ages through ¹⁴C dating for the deeper aquifer system are up to 34,000 years. Helium concentrations cover a wide range of values from 5 × 10⁻⁸ to 1.5 × 10⁻⁵ cm³ STP/g. ³He/⁴He ratios vary from 0.09R_A to 1.29R_A (where R_A is the atmospheric ³He/4He ratio of 1.384 × 10⁻⁶), the highest found in water from the shallow aquifer. Mantle-derived 3He is present in some of the samples indicating upward groundwater movement, possibly along a NE–SW-striking fault-like feature in the basin

OPTIMAL OPERATION OF A RESERVOIR SYSTEM USING FORECASTS

The present study concerns the optimal operation of an existing multipurpose multireservoir system using forecasts. An optimization-simulation model was constructed for a system of four flood control reservoirs in the Green River Basin, Kentucky, having recreation and low-flow augmentation as secondary objectives. The resulting model, called GRBOSM, is designed for use in real-time as well as in long-run operations studies. GRBOSM consists of descriptive and prescriptive components. Its descriptive component consists of a segmented model comprising nine multi-input linear (MIL) models of the river system downstream of the four reservoirs. The prescriptive component is largely in the form of an operating policy algorithm that involves repeated solution of a mathematical program. The optimization technique employed to solve the mathematical program is Linear Programming. Each of the nine MIL model components of the segmented model represents a routing model for a reach between control stations. These models accept reach inflow, gaged tributary inflow(s), and rainfall over the ungaged side inflow area as inputs. Their outputs are the reach outlows. Three approaches to MIL-model construction were investigated. The results showed that a constrained linear systems estimation method gave better results than the ordinary least-squares method. The addition of an error model further improved the forecasting performance of the models. The development of the operating policy component involved an investigation of goals and priorities for reservoir operation. To that end the state variables of the system associated with the reservoirs and with the control stations were divided into time-varying target or ideal values or ranges. Deviations from the ideal state vector were then divided into various zones and different penalties were associated with different zones. By aggregating these penalties over an operating horizon, most of the goals and priorities for reservoir operation were commensurated into an overall measure of effectiveness of the system. The use of GRBOSM model in long-run reservoir operations studies has been demonstrated; system\u27s responses under various operating and hydrologic conditions were obtained. In particular, trade off curves between various objectives of the system were generated both for the winter and summer seasons by using historical hydrologic as well as synthetic model input data. The use of GRBOSM in real-time operations has been discussed also. It involves the use of forecast data during an operating horizon and the sensitivity analyses of operating decisions with respect to changes in those forecasts. The results obtained from the model are represented in an integrated set of graphs and tables that appropriately shows the recommended optimal release decisions and the resulting state of the system at the reservoirs and control stations throughout the operating horizon. The GRBOSM model, besides being computationally efficient, is flexible to allow the examination of the operation of a complex reservoir-river system for a variety of operational policies. Specific to the approach in designing the GRBOSM algorithm is that penalty weights and target levels and zones are among the input variables for each time step. This provides for the flexibility needed in real-time operations

Investigation of sustainable development potential for Ulubey Aquifer System, Turkey

This study investigates sustainable development potential for Ulubey aquifer system which serves as an important water supply for Usak province (Turkey). In recent years, growing population, accelerating industrial activities and decreasing rainfall, as well as contamination of the surface water resources, made groundwater indispensable to meet the freshwater demands of Usak province. Therefore, a sustainable groundwater development plan has to be set up by determining the sustainable yield of the system, which is the aim of this study. To achieve this goal, a mathematical groundwater flow model is constructed in order to test the alternative development scenarios. Results show that the system preserves equilibrium conditions under present stresses. The future effects of possible increases in stresses are also simulated and based on the dynamic responses of the system to changing stresses; sustainable yield and sustainable pumping rate of the aquifer are determined and compared with the safe yield of the system

Trend Analyses of Meteorological Variables and Lake Levels for Two Shallow Lakes in Central Turkey

Trend analyses of meteorological variables play an important role in assessing the long-term changes in water levels for sustainable management of shallow lakes that are extremely vulnerable to climatic variations. Lake Mogan and Lake Eymir are shallow lakes offering aesthetic, recreational, and ecological resources. Trend analyses of monthly water levels and meteorological variables affecting lake levels were done by the Mann-Kendall (MK), Modified Mann-Kendall (MMK), Sen Trend (ST), and Linear trend (LT) methods. Trend analyses of monthly lake levels for both lakes revealed an increasing trend with the Mann-Kendall, Linear, and Sen Trend tests. The Modified Mann-Kendall test results were statistically significant with an increasing trend for Eymir lake levels, but they were insignificant for Mogan lake due to the presence of autocorrelation. While trend analyses of meteorological variables by Sen Test were significant at all tested variables and confidence levels, Mann-Kendall, Modified Mann-Kendall, and Linear trend provided significant trends for only humidity and wind speed. The trend analyses of Sen Test gave increasing trends for temperature, wind speed, cloud cover, and precipitation; and decreasing trends for humidity, sunshine duration, and pan evaporation. These results show that increasing precipitation and decreasing pan evaporation resulted in increasing lake levels. The results further demonstrated an inverse relationship between the trends of air temperature and pan evaporation, pointing to an apparent “Evaporation Paradox”, also observed in other locations. However, the increased cloud cover happens to offset the effects of increased temperature and decreased humidity on pan evaporation. Thus, all relevant factors affecting pan evaporation should be considered to explain seemingly paradoxical observations

Trend Analyses of Meteorological Variables and Lake Levels for Two Shallow Lakes in Central Turkey

Trend analyses of meteorological variables play an important role in assessing the long-term changes in water levels for sustainable management of shallow lakes that are extremely vulnerable to climatic variations. Lake Mogan and Lake Eymir are shallow lakes offering aesthetic, recreational, and ecological resources. Trend analyses of monthly water levels and meteorological variables affecting lake levels were done by the Mann-Kendall (MK), Modified Mann-Kendall (MMK), Sen Trend (ST), and Linear trend (LT) methods. Trend analyses of monthly lake levels for both lakes revealed an increasing trend with the Mann-Kendall, Linear, and Sen Trend tests. The Modified Mann-Kendall test results were statistically significant with an increasing trend for Eymir lake levels, but they were insignificant for Mogan lake due to the presence of autocorrelation. While trend analyses of meteorological variables by Sen Test were significant at all tested variables and confidence levels, Mann-Kendall, Modified Mann-Kendall, and Linear trend provided significant trends for only humidity and wind speed. The trend analyses of Sen Test gave increasing trends for temperature, wind speed, cloud cover, and precipitation; and decreasing trends for humidity, sunshine duration, and pan evaporation. These results show that increasing precipitation and decreasing pan evaporation resulted in increasing lake levels. The results further demonstrated an inverse relationship between the trends of air temperature and pan evaporation, pointing to an apparent ``Evaporation Paradox{''}, also observed in other locations. However, the increased cloud cover happens to offset the effects of increased temperature and decreased humidity on pan evaporation. Thus, all relevant factors affecting pan evaporation should be considered to explain seemingly paradoxical observations

Analysis of groundwater dynamics in the complex aquifer system of Kazan Trona, Turkey, using environmental tracers and noble gases

The Eocene deposits of Kazan Basin in Turkey contain a rare trona mineral which is planned to be extracted by solution mining. The complex flow dynamics and mixing mechanisms as noted from previous hydraulic and hydrochemical data need to be augmented with environmental tracer and noble gas data to develop a conceptual model of the system for the assessment of the impacts of the mining and to develop sustainable groundwater management policies throughout the area. The tracers used include the stable isotopes of water (δ²H, δ¹⁸O), δ¹³C and ¹⁴C of dissolved inorganic carbon (DIC), tritium (³H), the chlorofluorocarbons CFC-11 and CFC-12, and the noble gases He and Ne. The system studied consists of three aquifers: shallow, middle, and deep. CFC data indicate modern recharge in the shallow system. The estimates of ages through ¹⁴C dating for the deeper aquifer system are up to 34,000 years. Helium concentrations cover a wide range of values from 5 × 10⁻⁸ to 1.5 × 10⁻⁵ cm³ STP/g. ³He/⁴He ratios vary from 0.09R_A to 1.29R_A (where R_A is the atmospheric ³He/4He ratio of 1.384 × 10⁻⁶), the highest found in water from the shallow aquifer. Mantle-derived 3He is present in some of the samples indicating upward groundwater movement, possibly along a NE–SW-striking fault-like feature in the basin

Kışladağ露天金矿(土耳其乌萨克省)疏干排水量计算及采后矿坑湖预测

The KA +/- AYladag gold mine (UAYak, Turkey) has operated since 2006 and is projected to close by 2030, leaving a large open pit. We quantified dewatering requirements during the operational period, predicted pit lake formation during the post-closure period, and assessed the likely impacts on groundwater resources. Groundwater inflow into the pit during 17 years of mining was calculated using analytical and numerical models. The analytical model yielded lower inflow rates because it does not account for groundwater that will be released from storage. Post-closure, pit lake water balance calculations show that the system will reach equilibrium 585 years after dewatering ceases and that lake levels will stabilize at 816 m above sea level (masl). Further analysis indicated that 830 masl is a critical level, below which the pit will behave as a sink; above that, it will be a flowthrough system that could possibly affect downgradient groundwater quality

矿坑疏水及其对地下水资源影响评价:以土耳其西部卡尔丹哥镍矿(Caldag Nickle Mine)为例

Dewatering requirements of three open pits located in western Turkey and the impact of dewatering on groundwater resources were evaluated using a three-dimensional numerical groundwater flow model. The groundwater was modeled using MODFLOW software and the dewatering was simulated using the MODFLOW Drain Package. The drain cell configurations were determined by pit boundaries; invert elevations of drains corresponded to the bench elevations in the mining schedule, which varied dynamically among the three pits. Transient model runs were conducted for the 21 years of mine life to calculate the monthly dewatering rates. Simulation results indicate that the average groundwater inflow to the excavations is 3.64 L/s, excluding the effects of direct rainfall into the pits and surface water flow from the benches. Long term (80 years) simulations were conducted to predict the amount of drawdown at the water supply wells in the area. The results indicate that 21 years of mining will not significantly impact the water levels in these wells. However, natural discharge from the springs near the pits will be exhausted by the dewatering

Impacts of climatic variables on water-level variations in two shallow Eastern Mediterranean lakes

Variations in temperature and precipitation have direct impacts on the physical, chemical and biological characteristics of the shallow lakes. This paper examines the possible linkages between climate variables and the water levels of shallow interconnected Lakes Mogan and Eymir, located 20 km south of Ankara in Central Anatolia. The variations in the lakes' water levels during 1996-2015 are studied and the impacts of climate variables on the lake levels are assessed to address the long-term consequences. The nonparametric Mann-Kendall test was used to quantify trends in the climate variables and the lakes' level fluctuations between the observation periods 1998-2007 and 2008-2014. Statistical analyses results showed that precipitation and temperature have crucial influence on the variations in the lakes' levels. The projected increase in temperature and decrease in precipitation over the next century may produce substantial decreases in lake levels, with consequent drying of both lakes