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A set of cloud-permitting-scale numerical simulations during January–February 2018 is used to examine the diurnal cycle (DC) of precipitation and near-surface variables (e.g., 2 m temperature, 10 m wind and convergence) over the Indo-Pacific Maritime Continent under the impacts of shore-orthogonal ambient winds (SOAWs). It is found that the DC of these variables and their variabilities of daily maxima, minima, and diurnal amplitudes vary over land, sea, and coastal regions. Among all variables, the DC of precipitation has the highest linear correlation with near-surface convergence (near-surface temperature) over coastal (noncoastal) regions. The correlations among the DCs of precipitation, wind, and heating are greater over the ocean than over land. Sine curves can model accurately the DCs of most variables over the ocean, but not over land. SOAWs act to influence the DC mainly by affecting the diurnal amplitude of the considered variables, with DC being stronger under more strengthened offshore SOAWs, though variable dependence and regional variability exist. Composite analysis over Sumatra reveals that under weak SOAWs, shallow clouds are dominant and cause a pre-moistening effect, supporting shallow-to-deep convection transition. A sea breeze circulation (SBC) with return flow aloft can develop rapidly. Cold pools are better able to trigger new updrafts and contribute to the upscale growth and inland migration of deep convection. In addition, warm gravity waves can propagate upward throughout the troposphere, thereby supporting a strong DC. In contrast, under strong SOAWs, both shallow and middle-high clouds prevail and persist throughout the day. The evolution of moistening and SBC is reduced, leading to weak variation in vertical motion and rainwater confined to the boundary layer. Large-scale winds, moisture, and convection are discussed to interpret how strong SOAWs affect the DC of Sumatra.

With the growing irrigation water scarcity, the researchers and policymakers are more concerned to improve the irrigation water use efficiency at farmers’ field level. The water-saving technologies provide greater control over water delivery to the crop root zone and reduce the non-beneficial evaporation from the crop field. Water productivity is an important concept for measuring and comparing water use efficiency. The present study tried to estimate the irrigation water use and physical water productivity of cotton under alternate furrow and drip irrigation methods in the Bhavnagar district of Gujarat. Results suggest that crop yield and physical water productivity were higher for cotton irrigated by drip method than alternate furrow method during normal rainfall and drought year. The irrigation water use under the drip method of irrigation was lower as compared to the alternate furrow method. In the case of total water (effective rainfall + irrigation water) use, per hectare crop yield and physical water productivity were higher for the drip method of irrigation than the alternate furrow method of irrigating cotton crop during normal rainfall and drought year. In the case of total water use (effective rainfall + irrigation water), it was lower for drip irrigation than the alternate furrow method of irrigating cotton crop during normal rainfall year and drought year. While estimating total water (effective rainfall + irrigation water) use, it was assumed that there is no return flow of water from the cotton field in the study area under both irrigation methods.

Increasing demand for water has put tremendous pressure on groundwater resources in the hard rock terrain, where groundwater is a major source of agriculture, domestic and industrial purposes. Here, in the present study, we have assessed groundwater abstraction and recharge using Groundwater Resources Estimation Committee-1997 (GEC-97) norms and Water Table Fluctuation approach for the Jhansi district in the Bundelkhand region, central India. The assessment of abstraction was about 50,943 hectare meters (ham), of which ~ 91% uses for agriculture and the remaining 9% for domestic and industrial practices. We have also assessed groundwater recharge based on all available sources such as canal, rainfall, irrigation return flow, surface water structures on an annual and seasonal scale. Our results suggest higher recharge of about 42% from irrigation return flow during non-monsoon season compared to monsoon season because of higher groundwater abstraction for irrigation purposes. The rainfall recharge was about 33% in the study area during the assessment year of 2016. In general, the assessed groundwater abstraction and recharge show marked spatial and seasonal variation across the study area. The assessment of groundwater resources during 2016 suggests a ‘safe’ category of groundwater development stage for Jhansi district. The high-spatial-resolution (block-wise) assessment suggests more than 60% groundwater development stage for two blocks in the Jhansi district required better groundwater management policy. The results obtained from the present study can be helpful for high-spatial-resolution groundwater resources management.

The North Shandong Coastal Current (NSCC) is an important transporting route for sediment, drifting algae, and spilled oil from the Bohai Sea to the Yellow Sea. This study investigated the features and formation mechanism of the NSCC using observational data of current velocity and a numerical coastal ocean model. Our results confirmed the existence of the NSCC in the sense of climatological current in winter when northerly wind prevails in the Bohai Sea and Yellow Sea. The magnitude of the NSCC in the monthly time scale ranged 0.07–0.12 m/s and the current direction was parallel to the coastline. The detided residual current on the pathway of the NSCC was unstable, but variable with the local wind speed. The residual current was well correlated with northerly wind speed and tended to be parallel to coastline with the increase of wind speed. Strong wind plays key roles in the formation of eastward mean flow on the pathway of the NSCC in winter. We found that strong wind can generate a stronger eastward current in the southern side of the northern Yellow Sea, but a smaller westward return flow during the strong wind relaxation period. The asymmetry of wind-related residual current during and after strong wind events accounts for the formation of the eastward NSCC. A momentum analysis was performed using the numerical model results during strong wind events. We found that the barotropic pressure gradient was the dominant driving force of the residual current both during and after a strong wind event.

This paper presents the results of 2D and 3D numerical simulations of sea circulation and water mass exchange for a marina with hypothetical dimensions (L/B=2 and L/B=0.5) to calculate the return flow factor. The return flow factor b was analyzed in relation to the marina entrance width, sea current velocity outside the marina (0, 1, 2, and 5 cm/s) and the sea surface level oscillation dynamics. The basic comparative parameter is the e-flushing time, Tf. The intensity of forced circulation is calculated to achieve time Tf of less than 10 days. The impact of the wind field on the e-flushing time for different marina widths was analyzed using a 3D numerical model. The numerical simulation results indicate that the e-flushing time Tf depends on the amplitude of the tidal signal, secondary to the width of the marina inlet, and the smallest amount on the velocity field in the outer region. Conversely, the return flow factor b depends on the width of the marina entrance, less on the tidal signal amplitude, and least on the current velocity outside the marina if currents are ≥ 1 cm/s. Forced circulation of 1 m3/s is only required for the marina with a smaller tidal amplitude (position Dubrovnik) to achieve Tf

Exhumed high-pressure/low-temperature (HP/LT) metamorphic rocks provide insights into deep (∼20–70 km) subduction interface dynamics. On Syros Island (Cyclades, Greece), the Cycladic Blueschist Unit preserves blueschist-to-eclogite facies oceanic- and continental-affinity rocks that record the structural and thermal evolution linked to Eocene subduction. Despite decades of research, the metamorphic and deformation history (P-T-D) and timing of subduction and exhumation are matters of ongoing discussion. We suggest that Syros comprises three coherent tectonic slices and that each slice underwent subduction, underplating, and syn-subduction return flow along similar P-T trajectories, but at progressively younger times. Subduction and exhumation are distinguished by lineations and ductile fold axis orientations, and are kinematically consistent with previous studies that document top-to-the-S-SW shear (prograde-to-peak subduction), top-to-the-NE shear (blueschist facies exhumation), and then E-W coaxial stretching (greenschist facies exhumation). Amphibole zonations record cooling during decompression, indicating return flow above a cold slab. Multi-mineral Rb-Sr isochrons and compiled metamorphic geochronology show that the three slices record distinct stages of peak subduction (53–52, ∼50, and 45 Ma) that young with structural depth. Retrograde blueschist and greenschist facies fabrics span ∼50–40 and ∼43–20 Ma, respectively, and also young with structural depth. Synthesized data sets support a revised tectonic framework for Syros, involving subduction of structurally distinct coherent slices and simultaneous return flow of previously accreted tectonic slices in the subduction channel shear zone. Distributed, ductile, dominantly coaxial return flow in an Eocene-Oligocene subduction channel proceeded at rates of ∼1.5–5 mm/yr and accommodated ∼80% of the total exhumation of this HP/LT complex., Tectonics, 41 (6)

With the advancement of drilling technology along with assured availability of electricity ground water extraction for irrigation started increasing. The current study carried out at research farm of Raipur campus of Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh facing the same problem. Study is performed with the aim to increase the utilisation of available surface water in the study area carried by diversion canal from one diversion structure (called Bharri dam) constructed on the rivulet in the study area (called Chhokranala). Actual carrying capacity of the diversion canal and other 6 drains in the study area was worked out on the basis of their existing dimensions and grades. Required discharge required to be carried out by the diversion canal and other six drains were also worked out on the basis of drainage coefficient. Based on the comparison of required discharge capacity with actual discharge capacity revised dimensions were proposed to drain out the study command quickly during the heavy rainfall. Total annual ground water recharge from the study area was assessed as 4,01,880 m³, which is sum of ground water recharges through infiltration, return flow due to surface irrigation by diversion canal, return flow due to bore well irrigation and recharge from tank/ponds (67,500 m³, 1,41,800 m³, 1,86,400 m³ and 6,180 m³ respectively).

The study area, between Borg El Arab and El Hammam, is recently subjected to intensive land reclamation projects aiming to cultivate about 57000 feddans. It is supplied by two main sources of irrigation, i.e. the surface water as a main source (Bahig canal and El Hammam canal), and the groundwater from more than 600 shallow wells tapping the Ralat aquifer (calcareous sandstone) of Plio-Pleistocene age as a supplement source. During the last three decades (1985 – 2014), conjunctive use of surface water together with groundwater has resulted in serious hydrologic problems e.g. water losses, canal seepage and water logging, where the depth to water level has risen up from about 20 m (1985) to less than 5.0 m (2014). Meanwhile, the groundwater salinity decreased during this period from more than 5000 ppm to less than 2000 ppm, indicating a dilution effect by seeped water. The water seepage from the dissecting canals is estimated in the present work by 65.18 x 106 m3/year replenishing the groundwater system in the down gradient areas. Might as well, the irrigation return flow through permeable soil in the study area is estimated by 4.125 x 106 m3/year due to the applied flood irrigation technique. In other words, 95% of the total groundwater replenishment is from the canal seepage, while only 5% from direct percolation. The investigation of wells tapping the Ralat aquifer in the study area has indicated that water levels are ranging from 21.0 m to 1.0 m above mean sea level. More than 57.6 x 106 m3/year (average 84% of the natural groundwater discharge) are pumping from such wells to get water of about 2000 ppm salinity, indicating a significant hydraulic connection between the surface water canals and the underlying aquifer. The calculated water balance of the Ralat aquifer has resulted in an amount of annual surplus water of the order of 11.705 x 106 m3/year as groundwater storage.

International audience; Large proportions of rain water and snowmelt infiltrate into the subsurface before contributing to stream flow and stream water quality. Subsurface flow dynamics steer the transport and transformation of contaminants, carbon, weathering products and other biogeochemistry. The distribution of groundwater ages with depth is a key feature of these flow dynamics. Predicting these ages are a strong test of hypotheses about subsurface structures and time varying processes. CFC‐based groundwater ages revealed an unexpected groundwater age stratification in a 0.47 km2 forested catchment called Svartberget in northern Sweden. An overall groundwater age stratification, representative for the Svartberget site, was derived by measuring CFCs from 9 different wells with depths of 2 m to 18 m close to the stream network. Immediately below the water table, CFC‐based groundwater ages of already 30 years that increased with depth were found. Using complementary groundwater flow models, we could reproduce the observed groundwater age stratification and show that the 30 year lag in rejuvenation comes from return flow of groundwater at a subsurface discharge zone that evolves along the interface between two soil types. By comparing the observed groundwater age stratification with a simple analytical approximation, we show that the observed lag in rejuvenation can be a powerful indicator of the extent and structure of the subsurface discharge zone, while the vertical gradient of the age‐depth relationship can still be used as a proxy of the overall aquifer recharge even when sampled in the discharge zone. The single age stratification profile measured in the discharge zone, close to the aquifer outlet, can reveal the main structure of the groundwater flow pattern from recharge to discharge. This groundwater flow pattern provides information on the participation of groundwater in the hydrological cycle and indicates the lower boundary of hydrological connectivity.

Real-time estimation of the return drilling fluid during oil well drilling is investigated in this study. Online fluid level measurements from a Venturi channel which can be placed on the return flowline is used with a model-based estimator. A reduced order, 1-D, mathematical equation is used for the open flow in the Venturi channel for Newtonian or non-Newtonian fluid types. The volumetric fluid flow rate is estimated using a moving horizon estimator in real-time. The friction factor is also estimated together with the fluid flow rate. The effect of the variation of the channel slope on the flow rate estimation induced by the vibration of the channel during its operation is also studied. The method requires only two level measurements in the Venturi channel together with the channel geometry. The method is validated using a laboratory scale Venturi flow system. The proposed method shows promising potential to be used as a real-time return flow rate measurement in conventional drilling systems. Adaptive Moving Horizon Estimator for Return Flow Rate Estimation using Fluid Levels of a Venturi Channel

Irrigation is the largest water use in the western United States. The Upper Snake Rock Conservation Effects Assessment Project in southern Idaho began in 2005 to quantify the impacts of conservation practices in this irrigated watershed. The objective of this study was to determine the changes in the watershed water balances as farmers converted furrow irrigated fields to sprinkler irrigation from 2006 to 2016. More than 75% of annual watershed inflow was irrigation water diverted into the watershed from the Snake River and distributed through canals to 82,000 ha of cropland, while annual precipitation was only 10% to 23% of the annual inflow. Approximately 30% of the annual watershed inflow flowed back to the Snake River as irrigation return flow. Water balances showed that irrigation exceeded evapotranspiration (ET) in the spring and fall, indicating that irrigation diversions could be reduced early and late in the irrigation season. Annual irrigation project efficiency, defined as ET divided by the amount of diverted irrigation water, varied from 61% to 73%, but project efficiency did not increase as the amount of cropland that was sprinkler irrigated increased from 46% in 2006 to 59% in 2016. The only significant trends indicating that increasing sprinkler irrigation impacted the water balances were increasing irrigation project efficiency in July and increasing irrigation return flow during the irrigation season. Farmers may be applying less irrigation water with sprinkler irrigation compared to furrow irrigation, which could have caused return flow to increase since irrigation diversions did not change with the supply-based water allocation. Irrigation scheduling based on soil moisture measurement or daily ET would help irrigation application match crop water needs on individual fields. For the entire irrigation project, irrigation efficiency could improve if irrigation diversions into the watershed could be adjusted to more closely match ET in the spring and fall, which may require structural changes to the canal system and policy changes for the Snake River reservoir system.

HighlightsPrivate and public irrigation development was important for expanding agricultural production in the western U.S.The Twin Falls Canal Company is an excellent example of a successful Carey Act project.Cooperative efforts during the last 30 years have dramatically improved the water quality of irrigation return flow.Electricity generated by six hydroelectric facilities improves the sustainability of the irrigation project.Abstract. Private and public irrigation development projects were fundamental to bringing irrigation to arid regions of the western U.S. The Twin Falls Canal Company in southern Idaho provides a case study of private and public irrigation development because the project was developed by private investors under the Carey Act and receives a portion of its irrigation water supply from U.S. Bureau of Reclamation reservoirs. The project survived initial financial struggles and waterlogged soil to focus on sustaining crop production by reducing chronic furrow irrigation erosion and nutrient losses in irrigation return flow. Average sediment loss from the project was 460 kg ha-1 in 1970. A cooperative effort by the canal company, state and federal agencies, and farmers improved water quality by installing sediment ponds on fields, applying polyacrylamide with furrow irrigation, converting from furrow to sprinkler irrigation, and constructing water quality ponds on irrigation return flow streams. From 2006 to 2018, more sediment and total phosphorus flowed into the watershed than returned to the Snake River, and the project removed 13,000 Mg of sediment and 30 Mg of total phosphorus from the Snake River each year. However, nitrate-N from subsurface drainage was lost at 10 kg ha-1 each year, or 800 Mg year-1, for the entire watershed. While sediment and phosphorus concentrations in irrigation return flow have decreased, these concentrations were still greater than the irrigation water, indicating that more can be done to reduce the project’s influence on water quality in the Snake River. Keywords: Nitrogen, Phosphorus, Sediment, Soluble salts, Water quality.

In Kushiro River basin, inundation is likely to occur due to heavy rain, since the river-bed slope is very gentle in the downstream portion, which has natural levees. Consequently, in past floods, river discharge was observed to increase slowly and a delay of a few days in peak river discharge was observed compared to the peak precipitation. Therefore, we applied a distributed hydrological model, Geophysical fluid CIRCulation model (GeoCIRC), to reproduce such flood discharge in Kushiro River. GeoCIRC is based on object-oriented programming and various hydrological processes, such as infiltration flow, underground water flow, surface flow, and river flow can be implemented easily. We proposed a model that can incorporate the effect of return flow using storage function by introducing new parameters, such as storage time and time lag. This was done to consider not only the flood inundation in Kushiro River but also the return flow from flood inundation to the river flow. As a result, we obtained high Nash-Sutcliffe coefficients for river discharge for two large flood events.

Wastewater treatment facility receives, in addition to the influent, the return flow after sewage sludge treatment. Thus, the organic load on the facility increases as well as the nitrogen and phosphorus content load. There was studied the effect of different stages of sewage sludge treatment (sludge thickening, mechanical dewatering, storage on the grit bays and in the gathering ponds) on ammonium nitrogen content in the incoming flow. It is established that the most concentrated water by ammonium nitrogen is the return water from the gathering ponds, but the less concentrated is the supernatant water from sludge lagoons. Taking into account volume of the return flow the secondary ammonium nitrogen load from the every stage of sewage sludge treatment is calculated. It is revealed the seasonal and climatic impact on the gathering ponds return flow composition; it is shown that the biggest fluctuations occur in spring-summer period. The dependence of ammonium nitrogen content in the return flow on sludge thickening process time in the sludge lagoons is determined. The load contribution on the treatment facility by ammonium nitrogen in the return flow was 3% in the relation to this in the influent. The conclusion was made that with the existing technology of sewage sludge treatment the isolated scheme of return water treatment is not required. The comparative analysis on the effect of thermophilic and mesophilic conditions of anaerobic sewage sludge treatment on ammonium nitrogen content in the liquor was carried out. It was found that the higher ammonium nitrogen secondary load is created by the liquor of thermophilically treated sewage sludge: it is 16,4% versus 11,8% of mesophilically treated. Hence, the including of anaerobic sewage sludge treatment in the scheme significantly increases the load on treatment facility by ammonium nitrogen. In the conditions of cascade denitrification the distribution of incoming in the denitrification zones water flow is of great importance for providing required content of readily available organic substances. The change of ammonium nitrogen content in this flow will require the adjustment of its volume. На споруди очищення стічних вод крім основного потоку надходять зворотні потоки після обробки осадів. При цьому збільшується навантаження на споруди як за органічними речовинами, так і за вмістом сполук азоту і фосфору. Вивчено вплив різних стадій обробки осадів (мулоущільнення, механічне зневоднення, депонування на піскоплощадках і в ставкахнакопичувачах) на вміст азоту амонійного у зворотних водах. Встановлено, що найбільш концентрованими за азотом амонійним є зворотні води зі ставків-накопичувачів, а найменш – надмулові води з мулоущільнювачів. З урахуванням обсягу вторинних потоків було розраховано вторинне навантаження по азоту амонійному для кожної стадії обробки осадів. Виявлено сезонно-кліматичну залежність складу зворотних потоків зі ставківнакопичувачів, показано, що найбільші коливання спостерігаються у весняно-літній період. Визначено залежність вмісту азоту амонійного у зворотних водах від тривалості ущільнення осадів у мулоущільнювачах. Внесок азоту амонійного зі зворотними потоками склав 3% по від вмісту, що надходив з вихідними стічними водами. Зроблено висновок, що при існуючій технології обробки осадів стічних вод, не є потрібною окрема схема для очищення зворотних вод. Проведено порівняльний аналіз впливу термофільних та мезофільних умов анаеробної обробки осадів на вміст азоту амонійного у рідкій фазі. Виявлено, що використання термофільного режиму обробки осадів спричинюю вище вторинне навантаження по азоту амонійному, а саме 16,4% проти 11,8% за мезофільних умов. Таким чином, включення в схему анаеробної обробки осадів значно збільшує навантаження на очисні споруди за таким показником, як азот амонійний. В умовах каскадної денітрифікації важливе значення має розподіл потоків стічних вод, що надходять до зони денітрифікації, для забезпечення необхідного вмісту легкодоступних органічних речовин. Зміна концентрації азоту амонійного в цих потоках робить потрібним коригування їх об'ємів.

Surface water flow and subsurface flow have traditionally been investigated separately and simulators have been developed over the years, to model each of these systems. Growing interest in conjunctive water management, and need for simulations of surface/subsurface flow and their interactions has lead to the linking of models of the respective domains. This study from Dharoi command area, using MODFLOW, showed pertaining to the second layer of the calibrated model. The first layer is a thin soil cover layer of about 3 m uniform thickness. Top layer is kept under unconfined water table condition, where as the next layer is given the scope of transforming between water table to confined state and vice versa depending upon the fluctuation of the computed water level with respect to the bottom boundary of the top layer. No recharge and discharge options other than a single boundary condition of average May water level in the extreme north-east grid has been allowed. This calibration is based upon matching the observed and computed average gradient of the water table (hydraulic gradient) and nothing to do with matching the point to point values of the observation wells as that could lead to misappropriation in respect of hydrologic condition. Over all gradient of the water table in the area of interest is computed as 0.23 m per km in comparison to an observed hydraulic gradient of 0.3 m per km. The rivers such as Sabarmati downstream of Dharoi dam and up to Bijapur, Rupen and Pushpawati are activated in the transient run. Conductance value is considered as 0.0001 m/sec for all the rivers. proximity of the second layer under unconfined state. Comparisons of water levels in selected locations. Overall match between the trends and the point values indicate that the calibrated model transient run can be considered as base case and various options can be studied with this model. Visual MODFLOW is very effective to know the present scenario of ground water flow, water level of aquifer, wells, also point values indicate that the calibrated model transient run can be considered as base case and various options can be studied with this model. Visual MODFLOW is very effective to know the present scenario of ground water flow, water level of aquifer, wells, also distribution of spatial recharge, specific yield distribution. It gives very close result to the observed value.

The production of nursery crops demands substantial irrigation, with overhead irrigation the most common method of application; however, this method is inefficient with respect to water used and the precision with which it is applied, resulting in the generation of irrigation return flow and concomitant agrochemical export. Microirrigation systems such as individual container spray stakes provide water directly to crops thus applying water more efficiently than overhead systems but may be more costly in terms of installation (smaller pipes and components; however, a greater quantity of pipes and components) and maintenance. The study was conducted at the Michigan State University Research Nursery, where four ornamental shrub taxa were produced in #3 (11.3 L) containers using a control with 19 mm overhead irrigation per day and a conventional phosphorus fertilizer (Conv) (19-2.16-6.64), compared with four treatments: a static, daily (2 L per container) spray stake irrigation (SS2Lpd) and conventional phosphorus fertilizer; a static daily (2 L per container) spray stake irrigation and low phosphorus fertilizer (LowP) (19-1.62-6.64); spray stake irrigation based on substrate volumetric water content (theta) (up to 2.4 L per container) (SS theta) and conventional fertilizer; and spray stake irrigation based on theta (up to 2.4 L per container) and low phosphorus fertilizer. Spray stakes reduced irrigation by 76-80% compared to the overhead control, and reduced the generation of both surface and subsurface irrigation return flow (IRF), mitigating the movement of both N and P (over 98% reduction in surface IRF). Plant growth index (GI) was measured on 12 June 2017 and 6 October 2017, followed by a destructive harvest to measure shoot dry weight, and shoot nutritional content. For all four taxa, microirrigation systems were capable of producing plants of equivalent GI and shoot nutritional concentration; however, plants receiving the low phosphorus fertilizer produced less shoot biomass. Microirrigation is effective in reducing water use, water lost to IRF (particularly surface IRF), and associated fertilizer movement, while maintaining crop size. National Institute of Food and Agriculture, U.S. Department of Agriculture through the SCRI Clean WateR3 Project [2014-51181-22372]; National Institute of Food and Agriculture, U.S. Department of Agriculture through the Hatch project [MICL02473, MICL02403, VA-136312, FLA-SWS-005496, 1011745]; MSU Project GREEEN Published version This material is based upon work supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture through the SCRI Clean WateR3 Project, award number 2014-51181-22372, and Hatch project numbers MICL02473, MICL02403, VA-136312, FLA-SWS-005496, 1011745, and MSU Project GREEEN. The authors appreciate the material support from Spring Meadow Nursery (Grand Haven, MI), and Harrell's Inc. (Lakeland, FL USA), as well as the operational support provided by Dan Kort, Shital Poudyal, Deborah Trelstad, Dana Ellison, Dr. John Lea-Cox, Dr. Bruk Belayneh. Public domain – authored by a U.S. government employee

Hydrochemical studies carried out on the groundwater in north eastern part of Jordan valley, Jordan, revealed the confinement of groundwater to two partly overlapping Upper Cretaceous and Tertiary-Quaternary aquifers. Values of Base Exchange Index (r1) and Meteoric Genesis Index (r2) indicate that the groundwater is essentially Na-SO4 type and belongs mainly to the category of Deep Meteoric Percolation type. Major processes responsible for the hydrochemistry of groundwater are: weathering of carbonate and silicate minerals aided by H2CO3 and H2SO4, oxidation of sulphide minerals, domestic waste water, irrigation return flow, reverse and direct ion exchange reactions as well as connate saline water. Values of Water Quality Index indicate the occurrence of excellent and good quality potable water at majority of bore well locations. The groundwater belongs essentially to (C3S1) and (C4S2) irrigation water classes of Richards (1954) and is suitable for cultivation of semi-salt tolerant and salt tolerant crops. Keywords: Hydrogeochemistry, Sources of dissolved solids, Water Quality Index, Jordan valley region, Jordan

When a ship model test is performed in a tank, particularly when the tank is small and the ship model is relatively large, the blockage effect will inevitably occur. With increased ship model scale and speed, the blockage effect becomes more obvious and must be corrected. In this study, the KRISO 3600 TEU Container Ship (KCS) is taken as a model and computational fluid dynamics techniques and ship resistance tests are applied to explore the mechanism and correction method of the blockage effect. By considering the degrees of freedom of the sinkage and trim, the resistance of the ship model is calculated in the infinite domain and for blockage ratios of 1.5%, 1.8%, 2.2%, and 3.0%. Through analysis of the free surface, pressure distribution, and flow field around the ship model, the action law of the blockage effect is studied. The Scott formula and mean flow correction formula based on the average cross sectional area are recommended as the main correction methods, and these formulas are improved using a factor for the return flow velocity correction based on comparison of the modified results given by different formulas. This modification method is verified by resistance test data obtained from three ship models with different scale ratios.

The 1960 M9.5 Valdivia and 1964 M9.2 Alaska earthquakes caused a decimeters high secondary zone of uplift a few hundred kilometers landward of the trench. We analyze GPS data from the 2010 M8.8 Maule and 2011 M9.0 Tohoku-Oki earthquakes to reveal the persistent existence of a secondary zone of uplift due to great earthquakes at the megathrust interface. This uplift varies in magnitude and location, but consistently occurs at a few hundred kilometers landward from the trench and is likely mainly coseismic in nature. This secondary zone of uplift is systematically predicted by our 2D visco-elasto-plastic seismo-thermo-mechanical numerical simulations, which model both geodynamic and seismic cycle timescales. Through testing hypotheses in both simple and realistic setups, we propose that a superposition of two physical mechanisms could be responsible for this phenomenon. First, a wavelength is introduced through elastic buckling of a visco-elastically layered fore-arc that is horizontally compressed in the interseismic period. The consequent secondary zone of interseismic subsidence is elastically rebound during the earthquake into a secondary zone of relative uplift. Second, absolute and broader uplift is ensured through a mass conservation-driven return flow following accelerated slab penetration due to the megathrust earthquake. The dip and width of the seismogenic zone and resulting (deep) coseismic slip seem to have the largest affect on location and amplitude of the secondary zone of uplift. These results imply that subduction and mantle flow do not occur at constant rates, but are rather modulated by earthquakes. This suggests a link between deep mantle and shallow surface displacements even at time scales of minutes.

We develop an idealised one dimensional (cross-shore) morphodynamic model that couples wave, tide and sediment dynamics to study the effect and evolution of a shoreface nourishment. Sediment fluxes driven by wave skewness, wave asymmetry (both onshore) and return flow (offshore) are considered. With the aid of new analytical expressions for the skewness and standard deviation of wave velocity and acceleration, sediment fluxes are calculated. Nourishment is viewed as a perturbation to the system in equilibrium that is subject to the divergence of the perturbed sediment flux and a gravity driven diffusion term. Depending on the location, a nourishment may provide a feeder or lee effect. In moderate and mild wave conditions, the evolution of a nourishment primarily depends on the relative location of nourishment and break point. Placed well offshore of the break point, the nourishment induces an overall positive perturbation in sediment flux, resulting in onshore migration (feeder effect). Located closer to the break point, the nourishment induces an earlier wave breaking, which dissipates part of the wave energy (lee effect), leading to a negative sediment flux perturbation around this break point and a positive sediment flux perturbation around the break point of the un-nourished beach. Depending on the intensity of the earlier breaking, the nourishment either migrates onshore (weak break) or splits into onshore and offshore moving parts (strong break). The relative importance of the diffusion term and the divergence of perturbed sediment flux may lead to a primarily migrating or decaying evolution of nourishment. In storm wave conditions, the nourishment tends to move offshore due to the predominance of return flow driven sediment flux. The sensitivity to wave period and tide are also studied. Model results are consistent with observations, as well as prevailing theory on cross-shore sediment transport.

We report on experiments of turbulent particle-laden plumes descending through a stratified environment. We show that provided the characteristic plume speed $(B_{0}N)^{1/4}$ exceeds the particle fall speed, where the plume buoyancy flux is $B_{0}$ and the Brunt–Väisälä frequency is $N$, then the plume is arrested by the stratification and initially intrudes at the neutral height associated with a single-phase plume of the same buoyancy flux. If the original fluid phase in the plume has density equal to that of the ambient fluid at the source, then as the particles sediment from the intruding fluid, the fluid finds itself buoyant and rises, ultimately intruding at a height of about $0.58\pm 0.03$ of the original plume height, consistent with new predictions we present based on classical plume theory. We generalise this result, and show that if the buoyancy flux at the source is composed of a fraction $F_{s}$ associated with the buoyancy of the source fluid, and a fraction $1-F_{s}$ from the particles, then following the sedimentation of the particles, the plume fluid intrudes at a height $(0.58+0.22F_{s}\pm 0.03)H_{t}$, where $H_{t}$ is the maximum plume height. This is key for predictions of the environmental impact of any material dissolved in the plume water which may originate from the particle load. We also show that the particles sediment at their fall speed through the fluid below the maximum depth of the plume as a cylindrical column whose area scales as the ratio of the particle flux at the source to the fall speed and concentration of particles in the plume at the maximum depth of the plume before it is arrested by the stratification. We demonstrate that there is negligible vertical transport of fluid in this cylindrical column, but a series of layers of high and low particle concentration develop in the column with a vertical spacing which is given by the ratio of the buoyancy of the particle load and the background buoyancy gradient. Small fluid intrusions develop at the side of the column associated with these layers, as dense parcels of particle-laden fluid convect downwards and then outward once the particles have sedimented from the fluid, with a lateral return flow drawing in ambient fluid. As a result, the pattern of particle-rich and particle-poor layers in the column gradually migrates upwards owing to the convective transport of particles between the particle-rich layers superposed on the background sedimentation. We consider the implications of the results for mixing by bubble plumes, for submarine blowouts of oil and gas and for the fate of plumes of waste particles discharged at the ocean surface during deep-sea mining.

The results of estimated calculations of fluxes of particles of the working fluid in peripheral regions from the axial direction of the jet of a magnetoplasmodynamic (MPD) thruster with an external magnetic field with a power of 100 kW as well as the results of measurements in laboratory conditions of reverse fluxes of Li particles from the thruster are presented. Return flow measurements were conducted using the quartz microbalance method. Calculations and measurements of particle fluxes indicate that their values do not exceed ~10–8–10–7 g cm–2 s–1.