Approximating the optimal groundwater pumping policy in a

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地下水评估价技术指南

地下水评估价技术指南英文回答：Groundwater Valuation Techniques: A Technical Guide.Groundwater is a valuable resource that is often taken for granted. It is the source of drinking water formillions of people around the world, and it is also usedfor irrigation, industrial purposes, and recreation. However, groundwater is a finite resource, and it is important to manage it wisely.One of the most important aspects of groundwater management is valuing it. This can be a complex task, as groundwater is not a traded commodity and there is no market price for it. However, there are a number of different techniques that can be used to value groundwater.The following are some of the most common groundwater valuation techniques:Cost-based approaches: These approaches estimate the cost of developing and using groundwater resources. This can include the costs of drilling wells, installing pumps, and constructing treatment facilities.Market-based approaches: These approaches use market prices for water to estimate the value of groundwater. This can be done by comparing the prices of water from different sources, such as surface water or desalinated water.Income-based approaches: These approaches estimate the value of groundwater based on the income that it generates. This can be done by calculating the value of the crops that are irrigated with groundwater or the value of the products that are manufactured using groundwater.Hedonic pricing: This approach uses statistical techniques to estimate the value of groundwater based on the prices of properties that are located near groundwater resources.The choice of which groundwater valuation technique to use will depend on a number of factors, such as the availability of data and the specific objectives of the valuation.中文回答：地下水评估价技术指南。

土壤饱和含水率英文

土壤饱和含水率英文Soil Saturation Moisture ContentSoil is a crucial component of the Earth's surface, playing a vital role in supporting various ecosystems and human activities. One of the fundamental properties of soil is its moisture content, which is a measure of the amount of water present in the soil. The soil saturation moisture content, also known as the soil saturation point, is a crucial parameter that determines the maximum amount of water that a soil can hold before becoming saturated.Understanding the soil saturation moisture content is essential for various applications, including agriculture, civil engineering, and environmental management. In agriculture, it helps farmers determine the appropriate irrigation schedules and ensure optimal plant growth. In civil engineering, it is crucial for assessing the stability of soil structures, such as foundations and slopes. In environmental management, it is essential for understanding the water cycle, predicting flood risks, and managing water resources.The soil saturation moisture content is influenced by several factors, including soil texture, soil structure, and the presence of organicmatter. Soil texture refers to the relative proportions of sand, silt, and clay particles in the soil. Sandy soils, for example, have larger pore spaces and tend to have a lower saturation moisture content compared to clay soils, which have smaller pore spaces and can hold more water.Soil structure, on the other hand, refers to the arrangement of soil particles and the formation of aggregates. Well-structured soils with good aggregation tend to have a higher saturation moisture content due to the presence of larger pore spaces. Organic matter in the soil also plays a crucial role in increasing the soil's water-holding capacity, as it can absorb and retain moisture more effectively than mineral soil particles.To measure the soil saturation moisture content, various methods can be used, including laboratory analysis, field measurements, and remote sensing techniques. Laboratory analysis involves taking soil samples and determining the moisture content using gravimetric or volumetric methods. Field measurements can be performed using soil moisture sensors, which measure the electrical conductivity or dielectric properties of the soil to estimate the moisture content.Remote sensing techniques, such as satellite or aerial imagery, can also be used to estimate the soil moisture content over larger areas. These methods rely on the relationship between the soil's reflectanceor emissivity and its moisture content, and they can provide valuable information for large-scale applications, such as regional water management or drought monitoring.Once the soil saturation moisture content is known, it can be used to inform various decisions and management practices. In agriculture, the information can be used to optimize irrigation schedules, reduce water waste, and improve crop yields. In civil engineering, it can be used to assess the stability of soil structures and inform the design of foundations, slopes, and other infrastructure.In environmental management, the soil saturation moisture content is crucial for understanding the water cycle and predicting the occurrence of floods and droughts. It can also be used to inform the management of water resources, such as the allocation of water for different uses and the implementation of conservation measures.In conclusion, the soil saturation moisture content is a fundamental property of soil that has far-reaching implications for various applications. Understanding and accurately measuring this parameter is essential for effective soil and water management, as well as for addressing the challenges posed by climate change and other environmental factors. By leveraging the knowledge and tools available, we can better manage our soil and water resources, ensuring their sustainability for generations to come.。

对水资源保护的看法英语作文

对水资源保护的看法英语作文The Importance of Water Conservation and Protection.Water, often referred to as the elixir of life, is a crucial component of our existence. It sustains all forms of life on Earth, from the smallest microorganisms to the largest mammals, including ourselves. The significance of water cannot be overstated, yet its value is often overlooked in our daily lives. The current state of water resources worldwide calls for urgent action and a renewed focus on water conservation and protection.The availability of clean and potable water isessential for human health and well-being. Water is involved in almost every bodily function, from digestion to circulation. However, with the growing population and increasing urbanization, the demand for water is outstripping its supply. This imbalance is exacerbated by factors such as climate change, pollution, and wasteful water use practices.Climate change, in particular, is having a profound impact on water resources. Rising temperatures lead to increased evaporation, drying up of rivers and lakes, and changes in precipitation patterns. These changes not only affect the quantity of water available but also its quality. Pollutants and contaminants, often carried by runoff from urban and agricultural areas, contaminate surface and groundwater sources, rendering them unsafe for human consumption.In addition to climate change, human activities also contribute significantly to water scarcity and pollution. Irrigation practices, industrial waste discharge, and sewage outflow are among the primary sources of water pollution. These activities release harmful chemicals,heavy metals, and nutrients into water bodies, causing eutrophication and toxic accumulation.To address these challenges, water conservation and protection measures are crucial. Water conservationinvolves the efficient use of water resources to minimizewaste and maximize benefits. Simple practices like fixing leaky faucets, using water-saving appliances, and harvesting rainwater can significantly reduce water consumption. Agricultural practices such as drip irrigation and conservation tillage can also help conserve water while improving crop yields.Water protection, on the other hand, focuses on preventing pollution and maintaining water quality. This involves the establishment of water treatment facilities, strict enforcement of environmental regulations, and the promotion of sustainable development practices. For instance, waste management practices that ensure proper disposal of solid and liquid waste can prevent pollution of water bodies. Similarly, promoting the use of renewable energy and reducing greenhouse gas emissions can mitigate the impact of climate change on water resources.Moreover, public awareness and education are essential in water conservation and protection efforts. People need to understand the value of water and their role in its conservation. Educational campaigns and community-basedinitiatives can raise awareness about water scarcity and pollution issues, encouraging individuals and communities to adopt water-saving practices.In conclusion, water conservation and protection are paramount for sustainable development and the well-being of future generations. The challenges we face in water management are complex and require a multifaceted approach. By combining efforts at the individual, community, and policy levels, we can ensure the availability of clean and potable water for ourselves and future generations.。

词典

aquifer
含水层
aquifer [hydrology] 含水层
aquifer depletion [management] aquifer test aquifer, confined aquifer, perched aquifer, semi-confined
含水层疏干含水层试验承压含水层上层滞水含水层半承压含水层
the measurement of constituents in a water supply which determine alkaline conditions. The alkalinity of water is a measure of its capacity to neutralize acids. See pH. Sediments deposited by flowing rivers. Depending upon the location in the floodplain of the river, different-sized sediments are deposited. A period of high temperature, particularly the one from 8000 to 4000 B.P. (before the present era), which was apparently warmer in summers, as compared with the present, and with the precipitation zones shifted poleward. Also called the hypsithermal period. The condition under which one or more of the hydraulic properties of an aquifer vary according to the direction of flow. The soil moisture present before a particular precipitation event. farming of organisms that live in water, such as fish, shellfish, and algae. Water used for farming of organisms that live in water, such as fish, excluding fish hatcheries (commercial water use), shrimp, and other shellfish. Activities included in SIC code 0273. Subset of animal specialties water use. growing in, living in, or frequenting water. A unit of low permeability but is located so that it forms an upper or lower boundary to a groundwater flow system, now also called confining layer or leaky confining

托福阅读TPO28-1 Groundwater

TPO-28GroundwaterMost of the world’s potable water----freshwater suitable for drinking----is accounted for by groundwater, which is stored in the pores and fractures in rocks. There is more than 50 times as much freshwater stored underground than in all the freshwater rivers and lakes at the surface. Nearly 50 percent of all groundwater is stored in the upper 1,000 meters of Earth. At greater depths within Earth, the pressure of the overlying rock causes pores and cracks to close, reducing the space that pore water can occupy, and almost complete closure occurs at a depth of about 10 kilometers. The greatest water storage, therefore, lies near the surface.Aquifers, Porosity and PermeabilityGroundwater is stored in a variety of rock types. A groundwater reservoir from which water can be extracted is called an aquifer. We can effectively think of an aquifer as a deposit of water. Extraction of water depends on two properties of the aquifer: porosity and permeability. Between sediment grains are spaces that can be filled with water. This pore space is known as porosity and is expressed as a percentage of the total rock volume. Porosity is important for water-storage capacity, but for water to flow through rocks, the pore spaces must be connected. The ability of water, or other fluids, to flow through the interconnected pore spaces in rocks is termed permeability. In the intergranular spaces of rocks, however, fluid must flow around and between grains in a tortuous path; this winding path causes a resistance to flow. The rate at which the flowing water overcomes this resistance is related to the permeability of rock.Sediment sorting and compaction influence permeability and porosity. The more poorly sorted or the more tightly compacted a sediment is ,the lower its porosity and permeability. Sedimentary rocks----the most common rock type near the surface----are also the most common reservoirs for water because they contain the most space that can be filled with water. Sandstones generally make good aquifers, while finer-grained mudstones are typically impermeable. Impermeable rocks are referred to as aquicludes. Igneous and metamorphic rocks are more compact, commonly crystalline, and rarely contain spaces between grains. However, even igneous and metamorphic rocks may act as groundwater reservoirs if extensive fracturing occurs in such rocks and if the fracture system is interconnected.The Water TableThe water table is the underground boundary below which all the cracks and pores are filled with water. In some cases, the wate r table reaches Earth’s surface, where it is expressed as rivers, lakes and marshes. Typically, though, the water table may be tens or hundreds of meters below the surface. The water table is not flat but usually follows the contours of the topography. Above the water table is the vadose zone, through which rainwater percolates. Water in the vadose zone drains down to the water table, leaving behind a thin coating of water on mineral grains. The vadose zone supplies plant roots near the surface with water.Because the surface of the water table is not flat but instead rises and falls with topography, groundwater is affected by gravity in the same fashion as surface water. Groundwater flows downhill to topographic lows. If the water table intersect the land surface, groundwater will flow out onto the surface at springs, weather to be collected there or to subsequently flow farther along a drainage. Groundwater commonly collects in stream drainages but may remain entirely beneath the surface of dry stream-beds in arid regions. In particularly wet years, short stretches of an otherwise dry stream-bed may have flowing water because the water table rises to intersect the land surface.[Glossary]Sediment: materials (such as sand or small rocks) that are deposited by water, wind, or glacial ice.Topography: the shape of a surface such as Earth’s, including the rise and fall of such features as mountains and valleys.Paragraph 1: Most of the world’s potable water----freshwater suitable for drinking----is accounted for by groundwater, which is stored in the pores and fractures in rocks. There is more than 50 times as much freshwater stored underground than in all the freshwater rivers and lakes at the surface. Nearly 50 percent of all groundwater is stored in the upper 1,000 meters of Earth. At greater depths within Earth, the pressure of the overlying rock causes pores and cracks to close, reducing the space that pore water can occupy, and almost complete closure occurs at a depth of about 10 kilometers. The greatest water storage, therefore, lies near the surface.1.In paragraph 1, why does the author mention “the pressure of the overlying rock”?O To show how water can be forced deep under Earth’s surfaceO To show why groundwater is more plentiful than surface freshwaterO To correct a commonly made error about the location of groundwaterO To explain why most groundwater lies near Earth’s surface2.According to paragraph 1, groundwater differs from the water in rivers and lakes in terms of itsO portabilityO usefulnessO abundanceO costParagraph 2: Groundwater is stored in a variety of rock types. A groundwater reservoir from whichwater can is called an aquifer. We can effectively think of an aquifer as a deposit of water. Extraction of water depends on two properties of the aquifer: porosity and permeability. Between sediment grains are spaces that can be filled with water. This pore space is known as porosity and is expressed as a percentage of the total rock volume. Porosity is important for water-storage capacity, but for water to flow through rocks, the pore spaces must be connected. The ability of water, or other fluids, to flow through thefluid must flow around and between grains in a tortuous path; this winding path causes a resistance to flow. The rate at which the flowing water overcomes this resistance is related to the permeability of rock.e is closest in meaning toO usedO pouredO removedO kept outO consideredO calledO limited toO caused by5.According to paragraph 2, what does porosity determine?O The rate at which the aquifer’s water overcomes resistance to flowO The amount of water that the aquifer can holdO The likelihood that fractures and joints will occur in the aquiferO The depth underground at which the aquifer lies6.According to paragraph 2, what is the relationship between permeability and porosity?O The more pores a rock has, the higher its porosity but the lower its permeability.O Rocks with many internal spaces that are not connected with each other will have high porosity but low permeability.O If water flows through a rock easily, it has high permeability but low porosity.O Rocks that have high permeability have high porosity and vice versa.Paragraph 3: Sediment sorting and compaction influence permeability and porosity. The more poorlysorted or the more a sediment is ,the lower its porosity and permeability. Sedimentary rocks----the most common rock type near the surface----are also the most common reservoirs for water because they contain the most space that can be filled with water. Sandstones generally make good aquifers, while finer-grained mudstones are typically impermeable. Impermeable rocks are referred to as aquicludes. Igneous and metamorphic rocks are more compact, commonly crystalline, and rarely contain spaces between grains. However, even igneous and metamorphic rocks may act as groundwater reservoirs if extensive fracturing occurs in such rocks and if the fracture system is interconnected.O hardO compressedO heavyO deeply buried8.According to paragraph 3, when can igneous rock serve as an aquifer?O When it has many connected fracturesO When it lies next to metamorphic rockO When it lies relatively near the surfaceO When it is crystallineParagraph 4: The water table is the underground boundary below which all the cracks and pores are filled with water. In some cases, the water table reaches Earth’s surface, where it is expressed as rivers, lakes and marshes. Typically, though, the water table may be tens or hundreds of meters below the surface. The water table is not flat but usually follows the contours of the topography. Above the water table is theleaving behind a of water on mineral grains. The vadose zone supplies plant roots near the surface with water.O streamO barrierO amountO layer10.Paragraph 4 implies which of the following about the roots of plants?O They prevent water from reaching the vadose zone.O They mark the boundary between the vadose zone and the water tableO They do not typically get their water from the water table.O They help keep the water table from dropping farther.Paragraph 5: Because the surface of the water table is not flat but instead rises and falls withGroundwater commonly collects in stream drainages but may remain entirely beneath the surface of dry stream-beds in arid regions. In particularly wet years, short stretches of an otherwise dry stream-bed may have flowing water because the water table rises to intersect the land surface.11. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.O Groundwater only flows out of the ground if the water table intersects the land surface.O If the land surface and the water table intersect, groundwater can flow underground.O Groundwater may be drained if springs occur where the water table intersects the land surface.O Where the water table meets the land surface, groundwater flows out through surface springs.12.Paragraph 5 implies which of the following about the level of the waterO It may rise or fall from year to year, depending on annual rainfall.O It does not vary in arid regions.O It rarely intersects the land surface of most regions.O It is unrelated to the rate at which groundwater flows.Paragraph 4: The water table is the underground boundary below which all the cracks and pores are filled with water. In some cases, the water table reaches Earth’s surface, where it is expressed as rivers, lakes and marshes. ■Typically, though, the water table may be tens or hundreds of meters below the surface. ■The water table is not flat but usually follows the contours of the topography. ■Above the water table is the vadose zone, through which rainwater percolates. ■Water in the vadose zone drains down to the water table, leaving behind a thin coating of water on mineral grains. The vadose zone supplies plant roots near the surface with water.13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.This is a consequence of the slow rate of movement of the groundwater, which often prevents the water table from attaining a flat (horizontal) level.Where would the sentence best fit?14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.Most of the world’s potable water is stored as groundwater in the pores and fractur es of underground rock, much of it at depths of less than 1,000 meters.●●●Answer ChoicesO Sedimentary rock may make poor aquifers because of tightly compacted sediment, which reduces porosity and permeability.O Porosity is a measure of the empty space within rock while permeability measures the degree to which water can flow freely through rock.O In arid regions, the water tables remain at a constant level far below the surface, preventing stream-beds from filling up even during wet years.O Groundwater reservoirs are characterized by the porosity and permeability of the rock in which theylie, and these factors vary according to the type of rock.O The vadose zone is typically dry because water does not stay in it, but instead percolates down to aquifers below or drains out through springs and streams.O Although the water table usually follows the contours of the land surface, its level may vary from year to year and may intersect to the surface in places.参考答案1.○42.○33.○34.○25.○26.○27.○18.○29.○410.○311.○412.○113.○314. Porosity is a measure of the…In arid regions, the water …Although the water table usually …。

地下水资源论证解析

DOI：10.16616/ki.10-1326/TV.2016.03.005地下水资源论证解析池春广（辽宁省水利水电勘测设计研究院，辽宁沈阳110006）【摘要】本文以金新造纸厂水源地为实例，根据论证区内水文地质条件概况，按地下水动态径流补给条件，综合计算论证区内地下水资源量，同时根据区内地下水利用现状和区内未来规划，预测地下水利用量，进行地下水供需平衡预测，考虑到地下水的可持续利用，分析特枯年地下水位降低所动用的地下水净储量所占总储量的比例，及河流激发补给量，最终评价水源地可否满足用水要求。

通过论证，论证区内地下水资源量可满足建设项目用水需求。

【关键词】地下水资源；地下水补给；供需平衡；地下水净储量；激发补给量中图分类号：TV211.1+2文献标志码：A文章编号：2096-0131（2016）03-0015-05 Augment and parsing on groundwater resourcesCHI Chunguang（Liaoning WaterＲesources and Hydropower Survey＆Design Institute，Shenyang110006，China）Abstract：In the paper，water source pool of Jinxin Papermaking Mill is adopted as an example．Groundwater resources inthe argument zone is calculated comprehensively according to hydrogeology condition overview in the argument zone on the basis of groundwater dynamic runoff supply conditions．Meanwhile，groundwater utilization quantity is predicted accordingto ground water utilization situation and future plan in the zone．Groundwater supply-demand balance is predicted．Sustainable utilization of groundwater is considered．The proportion of net groundwater reserve in total reserve due to groundwater level reduction in especially dry year，and river included recharge of groundwater are analyzed，thereby evaluating whether water source can meet water consumption demand or not finally．Argument shows that the groundwater resources in the argument zone can meet the water consumption demand in the construction project．Key words：groundwater resources；groundwater recharge；balance between supply and demand；net groundwater reserves；included recharge of groundwater改革开放以来，随着工业发展蒸蒸日上，超量开采地下水引发了新的环境地质问题，为保证论证区水资源优化配置和可持续利用，需采用科学的方法对拟建项目水源区进行地下水资源论证分析，分析调整建设项目投产后的合理用水需求。

Spring Water A Symbol of Purity and Clarity

Spring Water A Symbol of Purity and Clarity Spring water is a symbol of purity and clarity. It is often associated with the pristine beauty of nature and the idea of unspoiled, untainted water sources. The image of a crystal-clear spring bubbling up from the earth is a powerful one, evoking feelings of freshness, vitality, and health. In this essay, we will explore the various ways in which spring water is seen as a symbol of purity and clarity, and examine the different perspectives on this concept.From a scientific perspective, spring water is indeed a pure and natural source of hydration. Unlike tap water, which can be contaminated with chemicals and pollutants, spring water is naturally filtered through layers of rock and soil, which remove impurities and minerals. This means that spring water is often considered to be of higher quality than other sources of drinking water, and is frequently used in bottled water products.However, the symbolic meaning of spring water goes beyond its chemical composition. For many people, spring water represents a connection to the natural world and a sense of harmony with the environment. The idea of drinking water that has been untouched by human hands is a powerful one, and it speaks to our desire for simplicity and purity in an increasingly complex and polluted world.From a cultural perspective, spring water has been revered for centuries as a symbol of purity and spiritual renewal. In many religions and belief systems, water is seen as a sacred element that has the power to cleanse and purify the soul. In ancient Greece, for example, the god Apollo was said to have created a spring that had the power to heal and purify those who drank from it. Similarly, in Hinduism, the river Ganges is considered to be a holy source of water that can wash away sins and grant spiritual enlightenment.In addition to its spiritual significance, spring water has also played an important role in human history as a source of sustenance and survival. For many ancient civilizations, access to clean water was a matter of life and death, and springs were often considered to be sacred sites. The ancient Maya, for example, built their cities around natural springs, which they believed were inhabited by gods and spirits.Today, the symbolic meaning of spring water continues to resonate with many people, particularly those who are concerned about environmental issues and the impact of human activity on the planet. The idea of drinking water that has been sourced from a natural spring, rather than from a factory or a treatment plant, is seen as a way to reduce our carbon footprint and minimize our impact on the environment.However, not everyone sees spring water as a symbol of purity and clarity. Some critics argue that the bottled water industry, which relies heavily on the marketing of spring water products, is actually contributing to environmental degradation and pollution. They point out that the production and transportation of bottled water requires large amounts of energy and generates significant amounts of waste, including plastic bottles that can take hundreds of years to decompose.Furthermore, some people argue that the symbolic meaning of spring water is based on a romanticized and idealized view of nature that is unrealistic and unsustainable. They point out that even natural springs can be contaminated by human activity, and that the idea of drinking water that is completely pure and untouched by human hands is an impossible ideal.In conclusion, spring water is a powerful symbol of purity and clarity that has resonated with people for centuries. Whether viewed from a scientific, cultural, or environmental perspective, the idea of drinking water that is sourced from a natural spring speaks to our desire for simplicity, health, and harmony with the environment. However, it is important to recognize that the symbolic meaning of spring water is not without its critics, and that the idealized view of nature that it represents may not always be realistic or sustainable. Ultimately, the symbolism of spring water is a reminder of the importance of clean water and the need to protect our natural resources for future generations.。

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1. Introduction
chastic models. The "curse" refers to the fact that the
For many years, resourceeconomists and engineers have recognized the importanceof stochasticprocesses in the optimalallocation of resources like groundwater, yet in applied work these processes are often assumed away, by setting stochasticsurfacewater suppliesat their means,for instance, in order to fashiona tractableallocation problem. Reducing the sizeof a dynamicproblemin thismannerraises thepossibilitythat a resourceis seriouslymisallocated over time.In regardto the conjunctive use of groundwater and surface water, Burt [1976,p. 76] remarked,
Theinherently random natureof surface watersupplies andthe naturalrechargeto an aquifer give ground water stocks an important role as a contingent supply for timeswhenthe flow
the state variables. To the extent the state variables are
Tsurand Graham-Tomasi [1991]arguethat ignoring the the applicationof •this method stochastic nature of surface watersupplies maysignificantly Saad et al. [1992]discuss when state variables are likely to reach lower and upper bias estimates of the valueof a groundwater resource. In bounds. theirpaper,simulation exercises indicatethat underfairly In this paper we present two methods to estimate the reasonable parameterspecifications, well over half of the optimal pumpingpolicy for a multiaquifer groundwaterrer value of a groundwater resource is due to its role asa buffer source in a stochasticsetting. The first method we call the against surface waterdrought. Overthe years,numerous attempts havebeenmadeto approximatepolicy iteration approach, becauseinstead of circumvent the "curseof dimensionality" associated with directly calculatingthe value of the resourcefor a particular as choosing theoptimal allocation of waterin large-scale sto- pumpingpolicy and all statesof nature simultaneously,
components of supply are below average. Optimal intertempo-
conventional methodsof stochastic dynamicprogramming, namely, value iteration and policy iteration, are computationallyinfeasible whenthe statespaceis large, as is usually
Abstract. Thispaper presents twomethods for approximating theoptimal groundwater pumping policy for several interrelated aquifers in a stochastic setting that also involves conjunctive useof surface water. Thefirstmethod employs a policy
iteration dynamicprogramming (DP) algorithmwhere the value functionis estimated
byMonteCarlosimulation combined withcurve-fitting techniques. The second method uses a Taylor seriesapproximation to the functional equation of DP whichreduces the problem, for a givenobserved state,to solving a system of equations equal in number totheaquifers. The methods are compared usinga four-state variable, stochastic dynamic programming model of MaderaCounty, California. The two methods yield nearly identical estimates of the optimal pumping policy,aswell asthe steady state pumping depth,suggesting thateithermethod canbeused in similar applications.
occursin the standardpoe is
estimated via simulations. We refer to the second method as
largely independent, the approach proves unrewarding.
onlydifference beingextra pumping costsif the underground reservoir has adequate capacityand recharge to build backup
within a reasonable time.
three. Saad and Turgeon[1988]discussthe attemptsin the water resourcesliterature to overcome the dimensionality problem and add to the literature a particularly promising methodto reducedimensionality basedon principalcomponent analysis. In this method, m sequencesof disturbances are drawn from the probability spaceof the random variables of the problem at hand. Each sequencegeneratesa deterministic problem which may be solved for an optimal state variable path. The m optimalpaths are then usedin principal componentanalysisto determine whether linear combinations of a few of the state variables account for a large percentageof the variation in the optimal paths. If so, the origimil stochastic problemis appropriatelytransformedto one involving only these relatively few state variables and then solvedusingconventionalstochasticdynamicprogramming (DP). As the authorsemphasize, the usefulnessof this approachdependson the degree of interdependenceamong
Copyright 1994 bytheAmerican Geophysical Union.
Paper number93WR02683.
0043-1397/94/93 WR-02683 $05.00