Evaporation Basins Research Articles

A MIXED INTEGER LINEAR PROGRAMMING EVALUATION OF SALINITY AND WATERLOGGING CONTROL OPTIONS IN THE MURRAY‐DARLING BASIN OF AUSTRALIA

Pollution of the River Murray by salt imposes costs on domestic and industrial users in Adelaide and to irrigators on the River Murray. Salt enters the Murray‐Darling system through saline ground water aquifers and from irrigation and drainage of saline land. Irrigation and drainage generate benefits from improved agricultural productivity and impose costs through increased salt loads to the Murray‐Darling system. The salinity of the River Murray can be reduced by pumping highly saline ground water into evaporation basins before it enters the River Murray. This paper presents a mixed integer linear programming model which is used to determine the mix of ground water interception schemes and land improvement schemes that minimises the net present value (over a time horizon of 30 years) of total Murray‐Darling Basin costs due to salinity and waterlogging. By varying a target salinity level, the mix of works that yields various salinity targets in the River Murray at minimum cost is obtained. The sensitivity of the optimal solution to prescribed changes in costs and benefits of projects and to a longer planning horizon is examined.

Effect of precessional insolation changes on Cretaceous climate and cyclic sedimentation

The often striking presence of cyclical beddings has frequently been noted in Cretaceous marine sediment deposits. In many instances, these beddings appear to have periodicities similar to those of the Earth's orbit, i.e., its precession, obliquity, and eccentricity. Variations in the primary deposition of ocean sediments are strongly linked to atmosphere‐land‐ocean interactions. We report a set of numerical experiments using an atmospheric general circulation model that are designed to examine the sensitivity of mid‐Cretaceous climate to insolation changes due to the precessional cycle. We restrict attention to a single orbital parameter because most limestone/black shale bedded sequences were deposited at low latitudes, where precessional insolation variations predominate. We varied systematically the precessional index between the maximum positive and negative values calculated over the last 2 m.y. and used mid‐Cretaceous paleogeographic and paleotopographic reconstructions and zonally symmetric sea surface temperatures based on earlier work by Barron and Washington. Surface wetness and albedo values appropriate for grassland were prescribed uniformly over all land regions. To capture the seasonality of precession, we employed both perpetual January and perpetual July simulations. Changes in surface heating due to the imposed insolation anomalies resulted in a strong, basically linear response of monsoonal circulations, dominated by changes over the northern hemisphere. The hydrologic cycle shows a significant response over many regions. The low‐latitude proto‐South Atlantic region varies from a strong net sink for water vapor (excess precipitation) to a strong source (excess evaporation) over the precession cycle. This variation is consistent with an alternation between a stagnant, stratified ocean basin with anoxic bottom water and an evaporative basin that produces bottom water that is warm, saline, and oxygenated. The portion of the Tethys Ocean that overlays the limestone/black shale sequences now found in present‐day Italy does not exhibit comparable behavior, but the reconstruction of orography and basin boundaries in this region is less known. The simulations show, however, that as the monsoonal flow over south proto‐Asia intensifies, water vapor evaporated in this part of Tethys is prevented from crossing the proto‐Alps into the interior of the continent, thereby remaining in the Tethian drainage basin. As a result, central proto‐Asia shifts between arid and moist conditions with precessional variations. The water vapor budget over northeast Africa varies systematically from zero seasonality to a marked wet/dry seasonal cycle. The deposition of eolian material can be inferred from a combination of continental aridity, favorable mean wind directions, and significant wind variances. In our experiments the mean surface and upper winds often show a systematic response to precession, but surface wind variances show a systematic response only in isolated regions. Our simulations do not provide a simple mechanism to explain the cyclicity in eolian deposition that has been reported for north‐central Tethys.

Evaporation Minus Precipitation and Density Fluxes for the North Atlantic

Abstract Estimates of evaporation (E) over the North Atlantic Ocean by Bunker have been combined with estimates of precipitation (P) by Dorman and Bourke to produce new annual and seasonal maps of E–P and surface density flux. Although uncertainties about precipitation algorithms and exchange coefficients still presist, it is felt that the high spatial resolution of these data set permits an estimate of E–P that is a significant improvement over previous work. The maps of E–P show considerably more detail than earlier maps, including a previously uncharted minimum with a northeast to southwest trend across the subtropical gyre. The two regions of maximal E–P display a close connection with continental air flows off Africal and North America, suggesting that the relative narrowness of the North Atlantic contributes to its status as a net evaporation basin. The zonally integrated E–P values are combined with river runoff estimates to obtain the meridional flux of freshwater, which can be compared with fluxe...

Water mass formation in the Gulf of California

The Gulf of California is a long, narrow marginal sea lying between the Baja California peninsula and the mainland of Mexico. Air‐sea fluxes of heat and moisture in the gulf are enhanced because of geographical isolation from the Pacific provided by the mountainous Baja California peninsula. In the northern gulf, annual evaporation rates are about 1 m y−1. Unlike most evaporative basins, however, the gulf gains heat from the atmosphere at an annual average rate of 20 to 80 W m−2 (Bray, 1988). Given the unusual air‐sea forcing of the gulf, what form or forms should water mass formation take? The annual moisture loss and heat gain require that high‐salinity surface water be transported downward to an intermediate depth and that cold, fresh inflow be transported upward to an intermediate depth. This is accomplished through several mechanisms. (1) Winter convection: this occurs only in a limited geographical region, the Wagner Basin of the far northern gulf, except in El Niño–Southern Oscillation years, when convection appears to be more widespread. (2) Dispersion of convected water in small eddylike features: this occurs within a large‐scale southward transport possibly driven by the large‐scale density gradient associated with atmospheric fluxes. (3) An anticyclonic circulation in the northern gulf: this is found south of the convection region and transports high‐salinity water off the shallow shelves and to substantial depths, where it may mix with water of central gulf origin. (4) Tidal mixing: most of the energy available for mixing in the northern gulf derives from the tides. In particular, tidal mixing over the sill in the island region is responsible for the substantial reduction in salinity of northern gulf waters as they enter the central gulf.

Reuse and disposal of higher salinity subsurface drainage water — A review

At present the “dilution by discharge” to usable water supplies is the most widely practiced “disposal” alternative. There is little incentive for the individual farmers to change and undertake direct reuse. Continuing water supply degradation in many areas however is likely to force changes in this practice but direction will need to come from basinwide policy makers. The most practical immediate step for reducing this degradation appears to be improved “on-farm” irrigation management to include better water distribution and use to reduce the volume of drainage water as recent results indicate that this is likely to reduce the pollution potential of the discharge. Gaining a better understanding of the crop use of shallow water tables will also help in reducing drainage water volumes. Several researchers are finding significant crop water use even with poor quality shallow groundwater. Expansion of this work to irrigation scheduling would greatly increase our understanding of drainage flow reductions. Recent research by Rhoades (1988a, 1988b) and others show that several options for drainage water reuse for crop production are available but that much more work is needed to make it widely applicable to commercial production practices. There is a need to increase research on reuse of drainage water in areas underlain by shallow brackish and saline ground water tables. Expansion of this work will greatly increase our options for reuse. Eventually use and reuse of subsurface drainage water will produce a water so brackish or saline that its further use for crop production, wetlands enhancement or agroforestry is nil. At this point, using the common practice of blending with low salinity water will not add to the total usable supply available for evapotranspiration and may even reduce it (Rhoades, 1988a). The good quality supply thus becomes the delivery and disposal system and the responsibility for coping with the added salt from the drainage water then becomes the responsibility of the downstream water user. This may or may not be acceptable. Isolating the unusable brackish or saline drainage requires a disposal point. Evaporation basins are beginning to be used but salt and trace element buildup in these disposal systems may make them only an interim or temporary solution. Eventually the salt must be transported and discharged to an acceptable disposal site. Historically, this has been the ocean. The amount of salt discharged to the ocean each year by drainage systems is not likely to exceed that which would normally be discharged by the natural river system which are providing the irrigation supply water. The need however, will be to ensure that the concentrated brines at the point of discharge do not cause localized problems with the marine life-cycle system, especially fishery resources.

Thermohaline circulation in the Gulf of California

The Gulf of California, a narrow, semienclosed sea, is the only evaporative basin of the Pacific Ocean. As a result of evaporative forcing, salinities in the gulf are 1 to 2 ‰ higher than in the adjacent Pacific at the same latitude. This paper examines the thermohaline structure of the gulf and the means by which thermohaline exchange between the Pacific and the gulf occurs, over time scales of months to years. In addition to evaporative forcing, air‐sea heat fluxes and momentum fluxes are important to thermohaline circulation in the gulf. From observations presented here, it appears that the gulf gains heat from the atmosphere on an annual average, unlike the Mediterranean and Red seas, which have comparable evaporative forcing. As a result, outflow from the gulf tends to be less dense than inflow from the Pacific. Winds over the gulf change direction with season, blowing northward in summer and southward in winter. This same seasonal pattern appears in near‐surface transports averaged across the gulf. The thermohaline circulation, then, consists of outflow mostly between about 50 m and 250 m, inflow mostly between 250 m and 500 m, and a surface layer in which the direction of transport changes with seasonal changes in the large‐scale winds. Using hydrographic observations from a section across the central gulf, total transport in or out of the northern gulf is estimated to be 0.9 Sv, heat gain from the atmosphere is estimated to be 20 to 50 W m−2, and evaporation is estimated to be 0.95 m yr−1. These estimates are annual averages, based on cruises from several years. Seasonal variations in thermohaline structure in the gulf are also examined and found to dominate the variance in temperature and density in the top 500 m of the water column. Salinity has little seasonal variability but does exhibit more horizontal variablility than temperature or density. Major year‐to‐year variations in thermohaline structure may be attributable to El Niño‐Southern Oscillation events.

Mesozoic Paleo-Oceanography of Atlantic and Western Interior Seaway: ABSTRACT

Mesozoic oceans were filled with warm, salty water formed in marginal seas in the arid zones, rather than by cold water from polar sources as is the modern ocean. The early Atlantic and Gulf of Mexico were sites of significant salt extraction, serving as evaporative basins refluxing dense brine to the world ocean. As connection with the world ocean became better established, salt deposition in these basins ceased but sea level rose in response to growth of the mid-ocean ridge system, resulting in extensive flooding of the continents. Marginal seas and that part of the seaway through the Western Interior of North America lying in the arid zone then became sites of formation of plumes of dense, warm, salty, oxygen-poor water. These dominated the structure of the adjacent oc ans. Periodic filling of individual basins by especially dense warm salty bottom water caused partial overturning and high productivity, followed by temporary stagnation and oxygen depletion, with the result that organic carbon-rich sediments were preserved. Because such anoxic events were dependent on local climatologic factors they were not necessarily synchronous in different basins. End_of_Article - Last_Page 579------------

South Australia's approach to salinity management in the River Murray

According to recent estimates, annual economic losses in South Australia due to River Murray salinity amount to $4 million. At constant prices they would rise to $10 million annually in the absence of remedial action. In recognition of the valley-wide problem, the three River Murray States and the Commonwealth have developed, with the aid of consultants, a co-ordinated programme for controlling drainage and salinity problems. The programme is now being implemented. The South Australian contribution consists of six measures, varying from the $13.2 million (1980/81 values) Noora Scheme, which will divert saline drainage water to an evaporation basin out of the valley, to agricultural measures such as improving irrigation practices to reduce saline accessions to groundwater and to drainage systems. Development of this set of measures was greatly aided by a public involvement programme. As a result of these initiatives, South Australia's salinity objectives will be achieved in the immediate future, but unless further control measures are identified and implemented, salinities will continue to increase, and by the year 2000 will again greatly exceed objective levels. An extensive research, monitoring and investigation programme is under way to help identify further opportunities for salinity mitigation and to aid in future decision making. Improvements in on-farm water application efficiency, and management of the whole River Murray, having regard to salinity as well as water quantity objectives, appear to present important opportunities.

The Mediterranean-Dead Sea Project: A Mathematical Model and Dynamic Optimization of a Solar-Hydroelectric Power Plant

The Dead Sea, part of the Jordon Rift Valley, lies at an elevation of about 400 m below sea level at a distance of only 70 km from the Mediterranean. In this paper, a mathematical model is derived simulating the dynamic behavior of a solar-hydroelectric power plant, utilizing the difference in elevation between the Mediterranean Sea and the Dead Sea by conducting Mediterranean water to the Dead Sea, partly by tunnel. This model was applied to determine the optimal control of inlet water to the evaporation basin of the Dead Sea, through the entire life of the plant, by dynamic programming methods. The optimization results were also utilized for determination of plant engineering parameters such as the diameter and gradient of the sea water tunnel.

Saline Groundwater Inflows to River Murray in South Australia: ABSTRACT

The River Murray flows for 650 km of its total length of 2,600 km through South Australia, where it meanders in an incised channel across a floodplain 1 to 10 km wide, and is underlain by 500 m of predominantly Tertiary bryozoal limestone and sand of the Murray basin. Natural groundwater in the basin commonly has a salinity of 30,000 mg/l. Groundwater gradients are relatively flat (0.25 m/km) and flow is generally toward the river and reflects the recharge from the higher country of the basin margins, about 250,000 sq km in area. The Tertiary sediments form aquifers of moderate transmissivity (200 to 500 cu m/day/m). Some inflows of saline groundwater are present naturally through the river bed but most inflows are the result of man-made structures and practices. The waters of the River Murray are vitally important to South Australia for domestic supplies and for irrigation of citrus orchards along the river banks. This irrigation has resulted in the buildup of groundwater mounds which are relieved by a tile drainage system. Drainage water, now of increased salinity, is pumped to evaporation basins on the floodplain close to the river. The raised water levels in these basins and also in the river weir system have increased inflows of saline groundwater to the river. In drought years these salt accessions can make the water unsuitable for irrigation. Piezometers have been established to monitor the regional groundwater regime, the irrigation groundwater mounds, and the effect of raised water levels in storage basins. The mechanisms of leakage from these basins have been studied to determine remedial measures necessary to intercept and remove saline-groundwater underflow. Alternative evaporation basins sited End_Page 1431------------------------------ on impermeable clay have been located away from the river floodplain. Pumping schemes for the transport of drainage water to the basins are proposed. End_of_Article - Last_Page 1432------------

Closure to “Potential Evaporation and River Basin Evaporation”

Closure to “Potential Evaporation and River Basin Evaporation”

Discussion of “Potential Evaporation and River Basin Evaporation”

Discussion of “Potential Evaporation and River Basin Evaporation”

Schwefel-isotopen verhältnisse von evaporiten aus deutschland; Ein beitrag zur kenntnis von δ34S im meerwasser-sulfat

δ 34 S data are reported for 100 samples of evaporite sulphates from Germany. Normal Zechstein (Permian) evaporites give δ 34S = +11.5 ± 1 %. which is expected to be the value for the Permian marine sulphate. Late evaporites within the different evaporation cycles are depleted in 34S by about 2%.. This may be due to fractionation by diffusion between the layered solutions within the evaporation basin. Muschelkalk and Keuper (both Triassic) evaporites give +20.5 and +17.5%., Malm (Upper Jura) +17.5%., Oligocene (Tertiary) ≈ +12 ± 1%.. Regarding the influx of terrestrial sulphate into the evaporation basins we suggest the marine values to be: Muschelkalk ≈ +21%. Keuper ≈ +17.5%. (?). Malm between +18 and +19%. and Oligocene between +16 and + 17%. (??).

The Problem of Transformation and Utilization of the Water Resources of the Volga River and the Caspian Sea

AbstractThe authors review expected water requirements within the Volga-Caspian basin for industry, agriculture, fisheries and municipal uses and plans for the diversion of the streams of northern European Russia to the south to support the level of the Caspian Sea. They suggest that the diversion of part of the flow of the northern streams and isolation of the natural evaporation basin of the Kara-Bogaz-Gol will be sufficient to maintain the Caspian Sea level at −28 meters. Previous articles on the Caspian problem appeared in Soviet Geography, September 1961, January 1962, and June 1963.