Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Sustaining reservoir use through sediment trapping in NW Ethiopia
    Getahun, Mulatie Mekonnen - \ 2016
    Wageningen University. Promotor(en): Leo Stroosnijder, co-promotor(en): Saskia Keesstra; Jantiene Baartman. - Wageningen : Wageningen University - ISBN 9789462579101 - 132
    sediment - soil conservation - reservoirs - dams - models - ethiopia - sediment - bodembescherming - reservoirs - dammen - modellen - ethiopië

    To increase crop production and improve food self-sufficiency, rain-fed agriculture need to be supplemented with irrigated agriculture. To this end, a large number of reservoirs had been constructed in Ethiopia. However, reservoirs are suffering from sedimentation. This study was conducted in Minizr catchment, NW Ethiopia to (1) quantify the sediment entering Koga reservoir, (2) to assess the functioning and effectiveness of the existing man-made sediment trapping (ST) measures and natural sediment sinks, and (3) to design a possible solution to tackle the problem. Results of three years (2013-2015) field data show that 38% of the transported sediment was trapped within the Minizr catchment. Although considerable efforts were made to trap the sediment within the catchment through implementing various ST measures, lack of an integrated ST approach causes the remaining 62% of the sediment load still entering Koga reservoir.

    De invloed van vegetatie op de verdroging van kleikades
    Zee, F.F. van der; Frissel, J.Y. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2590) - 51
    dammen - bodemtypen - bodem-plant relaties - bodemwater - verdroging - dams - soil types - soil plant relationships - soil water - desiccation
    In 2003 braken bij Wilnis en Terbregge de (veen)dijken door als gevolg van extreme droogte. Sinds die tijd is veel zorg en aandacht besteed aan deze nieuwe vorm van bezwijkende dijken. Naast de grondsoort (klei, veen) als belangrijkste factor is ook de vegetatie mogelijk van invloed op het ontstaan van scheuren in de kade.
    The impact of erosion protection by Stone Dams on Salt-Marsh vegetation on Two Wadden Sea Barrier Islands
    Loon-Steensma, J.M. van; Slim, P.A. - \ 2013
    Journal of Coastal Research 29 (2013)4. - ISSN 0749-0208 - p. 783 - 796.
    dammen - zoutmoerassen - habitats - erosiebestrijding - vegetatie - sedimentatie - biodiversiteit - nederlandse waddeneilanden - dams - salt marshes - habitats - erosion control - vegetation - sedimentation - biodiversity - dutch wadden islands - level rise - defense
    This paper describes and quantifies the effect of low stone dams on the extent and composition of salt-marsh habitats on two Dutch Wadden islands: Terschelling and Ameland. The stone dams were built to prevent erosion of the salt-marsh edge. Analyses of a series of aerial photographs taken between 1949 and 2010 show a strong reduction in retreat of the marsh edge on the island of Terschelling, from an average rate of 1.3 m per year before construction of the dam to 0.2 m per year after dam construction. Within 20 years of construction of the dam, sedimentation raised the mudflats between the dam and the former cliff, creating a broader foreshore and new marsh area with typical salt-marsh vegetation cover. The dam on the island of Ameland was built on the remnants of a previous low coastal defense. This reinforcement stopped cliff retreat and led to restoration of the eroded salt-marsh strip. Vegetation surveys along transects perpendicular to the coastline revealed that at both sites, typical pioneer salt-marsh vegetation had developed in the raised area between the erosion protection works and the former marsh edge. These habitats were not found in the reference transects without erosion protection. Based on these findings, we conclude that under favorable conditions for sedimentation, erosion protection by low stone dams may bring about a strong reduction in retreat of the salt-marsh edge while helping to restore an ecological attractive foreshore zone.
    Onderzoek naar de affecten van de aanleg van damwanden en grondverdichting op tandwalvissen in het Dolfinarium Harderwijk
    Haan, D. de - \ 2013
    IJmuiden : IMARES (Report / IMARES Wageningen UR C020/13) - 62
    dammen - uitrusting - zeezoogdieren - dierentuindieren - simulatie - diergedrag - dierenwelzijn - geluiden - veluwe - walvissen - oscillatie - dams - equipment - marine mammals - zoo animals - simulation - animal behaviour - animal welfare - sounds - veluwe - whales - oscillation
    Voor het vaststellen van de effecten van de aanleg van damwandinstallaties en grondverdichting als onderdelen van het grootschalig bouwplan Waterfront Harderwijk van de gemeente Harderwijk werden op vijf verschillende locaties van het bouwplan installaties gesimuleerd en de geluidseffecten daarvan in vier verschillende bassins op het terrein van het dolfinarium simultaan gemeten. Het onderzoek naar de effecten van het trilgeluid was beperkt tot de bassins waar bruinvissen en tuimelaars werden gehouden. Omdat er tijdens de proeven sterke reacties van haaien en roggen in het roggenbasin werden waargenomen, zijn in dit rapport enkele mitigerende maatregelen voor deze diersoorten opgenomen.
    Impact of farm dams on river flows; A case study in the Limpopo River basin, Southern Africa
    Meijer, E. ; Querner, E.P. ; Boesveld, H. - \ 2013
    Wageningen : Alterra (Alterra-rapport 2394) - 62
    dammen - landbouw - rivieren - regenwateropvang - irrigatiebehoeften - zuidelijk afrika - dams - agriculture - rivers - water harvesting - irrigation requirements - southern africa
    The study analysed the impact of a farm dam on the river flow in the Limpopo River basin. Two methods are used to calculate the water inflow: one uses the runoff component from the catchment water balance; the other uses the drainage output of the SIMFLOW model. The impact on the flow in a sub-catchment with and without the presence of a farm dam, has been analysed. Different farm dam storage capacities and infiltration rates of the soil were considered. In general, the change in natural flow is decreasing when the farm dam capacity becomes higher. On the other hand, the Remaining Natural Flow is increasing when the catchment area becomes larger. The Crop Water Availability was expressed as the relative difference between the crop water requirements and the amount of water supplied by precipitation and irrigation from the farm dam. For a given storage capacity of the farm dam the change in natural flow is calculated when the farm dam covers 90% of the potential evapotranspiration of maize.
    Inventarisatie van mogelijke effecten van kribverlaging in de Waal op de beroepsvisserij
    Winter, H.V. - \ 2011
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR nr.: C189/11) - 21
    dammen - rivieren - hoogwaterbeheersing - waal - nadelige gevolgen - visserij - dams - rivers - flood control - river waal - adverse effects - fisheries
    Om de hoogwaterveiligheid van het rivierengebied te vergroten is het doel van Rijkswaterstaat om eind 2015 ca. 500 kribben in de Waal verlaagd te hebben en daarnaast langsdammen aangelegd te hebben tussen Wamel en Ophemert. In deze korte deskstudie wordt een inventarisatie gemaakt van mogelijke effecten van kribverlaging in de Waal op de vangsten van beroepsvissers, de kennis en gegevens die nodig zijn om deze effecten in te schatten en welke andere autonome ontwikkelingen op gebied van visserij en visecologie in de Waal plaatsvinden.
    Passende Beoordeling van een getijdencentrale in de Oosterscheldekering
    Smit, C.J. ; Dankers, N.M.J.A. - \ 2010
    Texel : IMARES (Rapport / IMARES Wageningen UR C042/10) - 56
    waterkracht - getijden - duurzaamheid (sustainability) - kustgebieden - natura 2000 - oosterschelde - dammen - stormvloedkeringen - deltawerken - water power - tides - sustainability - coastal areas - natura 2000 - eastern scheldt - dams - storm surge barriers - delta works
    De Nederlandse overheid streeft naar diversificatie van de energieopwekking. Een nauwelijks geëxploiteerd onderdeel is getijdenenergie. Reden waarom deze vorm van energieopwekking tot dusver weinig aandacht heeft gekregen is dat in het Nederlandse kustgebied de stroomsnelheden vaak te laag zijn om met de huidige technieken en energieprijzen rendabele installaties te ontwikkelen. Op enkele plaatsen treden wel relatief hoge snelheden op. Voorbeelden zijn grote stroomgeulen zoals zeegaten tussen de eilanden, de spuisluizen in de Afsluitdijk en Haringvliet en in de stormvloedkering van de Oosterschelde. In de toekomst zijn er wellicht ook mogelijkheden bij openingen in afsluitdammen zoals in de Grevelingen. Door de firma’s Tocardo en Ecofys wordt voorgesteld in twee (van de 62) openingen in de Oosterscheldekering een proefinstallatie voor getijdenenergie te installeren. Omdat het gaat om een nieuwe ontwikkeling waarvan de (mogelijke) effecten nog nooit goed zijn bestudeerd en omdat het project gepland wordt in een Natura2000-gebied, wordt in eerste instantie een proef uitgevoerd met een “centrale” in twee van de 62 doorstroom-openingen.
    Evaluatie van de effectschatting waterkwaliteit Terra Nova Zuid na aanbrengen damwand
    Kosten, S. ; Faassen, E.J. ; Lürling, M.F.L.L.W. - \ 2009
    Wageningen : Wageningen UR - 6
    watersystemen - waterkwaliteit - waterstroming - dammen - aquatische ecologie - water systems - water quality - water flow - dams - aquatic ecology
    Waternet is van plan om in het gebied Terra Nova een damwand aan te brengen tussen de delen Terra Nova Noord en Terra Nova Zuid om daarmee de overlast van blauwalgen in Terra Nova Noord tegen te gaan. Een groep bewoners van Terra Nova Zuid vreest echter voor negatieve gevolgen van deze maatregel op de waterkwaliteit van Terra Nova Zuid. Deze bewonersgroep heeft Wageningen UR gevraagd te beoordelen of de effecten van het aanbrengen van een dam op het watersysteem van Terra Nova Zuid goed zijn onderbouwd.
    Voorkomen en gedrag van trekvissen nabij kunstwerken en consequenties voor de vangkans met vistuigen
    Winter, H.V. - \ 2009
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR no. C076/09) - 57
    waterbouwkunde - dammen - sluizen - barrières - vismigratie - diergedrag - natuurbescherming - hydraulic engineering - dams - sluices - barriers - fish migration - animal behaviour - nature conservation
    Het Ministerie van Landbouw, Natuur en Voedselkwaliteit heeft IMARES opdracht verleend te onderzoeken of “het instellen van een visserijvrije zone rond kunstwerken (inclusief zoet/zout overgangen) kan bijdragen aan de bescherming van zalm, zeeforel en andere trekvissen zoals paling”. Hiertoe heeft IMARES literatuuronderzoek verricht en een analyse uitgevoerd van reeds beschikbare gegevens.
    Application of (economic) water valuation for devising a multiple uses operational strategy for Hoa Binh Dam. Hoa Binh hydropower dam and command area (Hoa Binh Province).
    Wageningen International, - \ 2008
    Hanoi, Vietnam : Hanoi Water resources university (HWRU) (Main case study 3) - 129
    waterbeheer - waterverdeling - watervoorziening - waterbeschikbaarheid - dammen - hydraulische systemen - reservoirs - vietnam - integraal waterbeheer - water management - water distribution - water supply - water availability - dams - hydraulic structures - reservoirs - vietnam - integrated water management
    Vietnam is located in typical monsoon climate region and therefore river are very abundant water. However, about 2/3 of water resources is originated from neighboring countries. Moreover, uneven spatial distribution and huge seasonal change are additional reasons that make Vietnam ranked low compared to other South East Asian countries in term of water resource availability (the index of water availability per capital in Vietnam is 4,170m3/s compared to 4,900 m3/s in South East Asian region). In Vietnam, there is dense network of river systems, out of which about 2,360 river have length of 10km or more with total volume of 835 billion m3. However, the flow during 6 or 7 months of dry season is counted for only 15-30% of total annual flow. As a result, every yeas, drought and water shortage have always occurred in many areas of different basins. To cope with this situation and also to meet increasing water demand, number of reservoirs has been built for water resource regulation. After many years of development, many large exploitation work systems have been constructed and operated in all the basins thought the country, such as dams, reservoirs, weirs, embankments and so on. Those systems are to supply water for all kinds of use, including: irrigation, drainage, and hydropower generation, households, industry and flood control. Those works have been played an important role in water supply for major social-economic development sectors of the country, such as irrigation, hydropower generation, domestic and industrial used.
    People and dams: environmental and socio-economic changes induced by a reservoir in Fincha'a watershed, western Ethiopia
    Bezuayehu, T.O. - \ 2006
    Wageningen University. Promotor(en): Leo Stroosnijder; Geert Sterk. - [S.l. ] : S.n. - ISBN 9789085044499 - 138
    dammen - stroomgebieden - plaatselijke bevolking - milieueffect - sociale economie - waterbescherming - bodembescherming - erosie - waterbeheer - reservoirs - ethiopië - integraal waterbeheer - dams - watersheds - local population - environmental impact - socioeconomics - water conservation - soil conservation - erosion - water management - reservoirs - ethiopia - integrated water management
    Dams that store water for electricity, irrigation, domestic water supply or flood control have been constructed for thousands of years worldwide. In too many cases, an unacceptable and often unnecessary price has been paid by watershed inhabitants to secure dam benefits, especially in social and environmental terms. The Fincha'a multipurpose dam in western Ethiopia has caused major land use changes, relocated people against their will and induced excessive population pressure in the upper watershed. Following the creation of this dam crop and livestock production have been shifted to steep and fragile parts of the watershed. Lack of agricultural intensification and soil and water conservation (SWC), poor family planning and land tenure insecurity are pressing socio-economic problems leading to impoverishment of the watershed inhabitants. Increased erosion rates and sediment yields reduce the economic life of the dam.Farmers are well aware of erosion problems but theylack confidence in the positive effect on crop yield of recommended SWC measures.The high labour requirement, loss of cropland, land tenure insecurity and the lack of immediate benefits has negatively affected SWC adoption.Integrated watershed management (IWM) has emerged as alternative to the centrally and sectorial approaches in planning dams. The focal point of any dam development programme, using IWM, is the combination of improving the livelihood of the watershed inhabitants and the sustenance of the resource base. For subsistence farmers it is mainly the production in the current season that guarantees the mere survival of their families. Therefore, IWM should be accompanied by creation of multi-stakeholders platforms and integration of soft and hard system methodologies forcreating an environment where science and knowledge help people to develop a diversity of locally appropriate resource management solutions.IWM can effectively address the social, environmental and economic problems during the planning of new dams in Ethiopia.
    Development and management of irrigated lands in Tigray, Ethiopia
    Eyasu, Y.H. - \ 2005
    Wageningen University. Promotor(en): E. Schultz, co-promotor(en): M. Haile. - s.l. : Balkema - ISBN 9780415384858 - 265
    geïrrigeerde terreinen - ethiopië - irrigatie - dammen - reservoirs - waterbeheer - bodembeheer - bodembescherming - hydrologie van stroomgebieden - erosie - irrigated sites - ethiopia - irrigation - dams - reservoirs - water management - soil management - soil conservation - catchment hydrology - erosion
    Ethiopia is one of the poorest countries in the world. It is characterised by famine as a result of high population pressure, resource base degradation, and insufficient rainfall for rainfed agriculture. On the other hand, it is endowed with a huge annual water resource potential of about 110 billion m 3 , a potentially irrigable land of 3.6 million ha and productive manpower of about 48% of the total population. In view of these facts, the Agricultural Development-Led Industrialization (ADLI) development strategy adopted in August 1992 has set irrigation as a major pillar to increase food production and to achieve food self-sufficiency. The earthen dam irrigation development program in the regional state of Tigray is part of this initiative.

    The effective and sustainable utilization of the limited water resource is very crucial in arid and semi-arid areas like Tigray. The results of the study carried out at two earthen dam irrigation schemes indicated that the schemes are playing a very important role in improving the livelihood of the poor farmers. However, the research has also identified problems that may affect the sustainability and ultimately the food security effort of the regional Government. These are related to sedimentation in the reservoirs, reservoir operation schedule, water management, salinity, policy, institutional and socio-economics issues. The major lesson learnt from the study was that the success and sustainability of the irrigation schemes depend on the level of integrated approach in the development and management. The integrated approach need to take the whole irrigation scheme as one entity, including the catchment, the reservoir and dam, the command area, the beneficiaries and downstream impacts. Failure or weakness in one of the links may affect the entire system.

    De effecten van bodemverhoging op het beekecosysteem van de Springendalse beek
    Verdonschot, P.F.M. ; Hoek, T.H. van den; Hoorn, M.W. van den - \ 2004
    Wageningen : Alterra (Alterra-rapport 1075) - 119
    natuurbescherming - waterdieren - dammen - geologische sedimentatie - herstel - waterlopen - hydrologie - nederland - aquatische ecosystemen - waterbodems - macrofauna - overijssel - twente - nature conservation - aquatic animals - dams - geological sedimentation - rehabilitation - streams - hydrology - netherlands - aquatic ecosystems - water bottoms - macrofauna - overijssel - twente
    Het natuurreservaat `Het Springendal¿ heeft jarenlang te kampen gehad met verdroging, verzuring en vermesting. Vanaf de midden negentiger jaren is gewerkt aan herstel van het gebied. Een experiment is uitgevoerd om met behulp open bodemdrempels, geconstrueerd als keiendammetjes, de beekbodem geleidelijk te verhogen. Dit geleidelijk herstelproces is gedurende ruim 2 jaar gevolgd. De beekbodem bleek binnen enkele weken te zijn opgehoogd. Het beekhabitat in het dammetjestraject vertoonde tijdens de eerste twee jaren een iets dynamischer karakter dan het bovenstroomse, niet heringerichte referentietraject. De ontwikkeling van beekmacrofauna in het dammetjestraject bleef enigszins achter ten opzichte van het referentietraject, dit was echter `ondergeschikt¿ aan de natuurlijke veranderingen die plaatsvonden in het gehele beeksysteem. De beekbodemverhoging had geen nadelige invloed op de beeklevensgemeenschap.
    Beheer kwelderwerken; verslag monitoring kwelderwerken Waddenkust Friesland en Groningen nov. 1999 - nov. 2000
    Dijkema, K.S. ; Bossinade, J.H. ; Nicolai, A. ; Frankes, J. ; Haan, K. ; Jongerius, H. ; Leusink, P. ; Venema, H. - \ 2000
    Rijkswaterstaat, Directie Noord-Nederland - 43
    bouwconstructie - dammen - engineering - constructie - bedrijfsvoering - natuurbescherming - ontgonnen land - nederland - friesland - groningen - waddenzee - kust - kwelder - natuur - vegetatie - Waddengebied - building construction - dams - engineering - construction - management - nature conservation - reclaimed land - netherlands - friesland - groningen - wadden sea
    Multiunit water resource systems management by decomposition, optimization and emulated evolution : a case study of seven water supply reservoirs in Tunisia
    Milutin, D. - \ 1998
    Agricultural University. Promotor(en): J.J. Bogardi. - S.l. : Milutin - ISBN 9789054858829 - 182
    dammen - meren - wateropslag - reservoirs - operationeel onderzoek - tunesië - water - dams - lakes - water storage - reservoirs - operations research - tunisia - water - cum laude

    Being one of the essential elements of almost any water resource system, reservoirs are indispensable in our struggle to harness, utilize and manage natural water resources. Consequently, the derivation of appropriate reservoir operating strategies draws significant attention in water resources planning and management. These operational issues become even more important with the ever increasing scale and complexity of water resource systems.

    In this respect, the primary obstacle in the analysis of a multiple-reservoir-multiple-user water supply system operation is the dimensionality of the problem. Namely, being a sequential decision making process, the operation of a complex reservoir system over a certain period of time can adequately be described only if all the relevant variables and parameters related to possible system state and decision realizations are taken into account. Clearly, this requirement tends to grow rapidly with the size of the system considered. The computational burden expands even more drastically if the processes involved bear unavoidable stochastic characteristics which are, in this study, assumed to be attributed only to reservoir inflows.

    With regard to the problem in hand, the methods proposed and analyzed in the study can be divided into three major groups. The first group of methods falls into the family of system decomposition approaches within the optimization and/or simulation of the operation of complex systems. The second one involves the assessment of the impact various simulation alternatives may have on the performance of the adopted iterative decomposition algorithms. Finally, the third part includes the application of genetic algorithms for the derivation of the best water allocation patterns within a multiple-reservoir-multiple-user water supply system.

    The decomposition models proposed and analyzed in this study are known as sequential decomposition methods. Essentially, to reduce the dimensionality of an optimization problem, they split up a complex system into its elementary units (i.e. reservoirs). Subsequently, the operating strategy of the system is derived in an iterative fashion by applying successive optimization, simulation and release allocation analyses to individual system elements.

    The optimization method employed within all the decomposition models is stochastic dynamic programming (SDP). Due to the inherent discrete nature of SDP operating policies, the iterative, decomposition-based optimization models have a certain "inaccuracy threshold" which directly affects the performance of the system. Therefore, three different simulation alternatives have been employed to assess the possibility of reducing this negative impact of discretization. It is shown that, by allowing limited policy violations within simulation, the system performance can improve significantly relative to the case when the operating policies are strictly followed.

    Ultimately, a method based on the theory of genetic algorithms (GA) has been employed to derive the most favourable water allocation patterns within a multiple-reservoir-multiple-user water supply system. Since GAs make use of simulation to guide their search for promising solutions, two distinct GA models have been tested: i) the first one assumes that individual reservoirs are to be operated according to the standard reservoir operating rule; and ii) the second model simulates the operation of the system according to the policies derived by a prior application of an iterative decomposition/SDP-based optimization of the system's operation.

    Throughout this study, particular emphasis is given to the appraisal of the system performance derived by different methods. Since all of the employed optimization and search models are essentially single-objective optimization techniques, and given the fact that the operation of a reservoir system cannot adequately be appraised on the basis of a single criterion, this study makes use of simulation to evaluate the performance of the system over a number of criteria, and thereby broaden the basis for the comparison of different models. Ultimately, it is believed that the presented results clearly exemplify the fact that performance indicators like reliability of meeting the targeted demand, resilience with regard to the system escaping from failure mode, vulnerability as a measure of the most severe failure and the likes play an essential role in comprehensive assessment of the operation of a complex reservoir system.

    The analyses performed in this study showed that a complex water resource system decomposition, combined with the appropriate choice of optimization and simulation approaches could provide a sound basis for a transparent, yet efficient and effective operational analysis of very large reservoir systems. In addition, the application of genetic algorithms to solve a rather large resource allocation problem of a multiple-reservoir-multiple-user water supply system proved to be both relatively uncomplicated and remarkably efficient. Furthermore, it is believed that the coupling of a genetic algorithm resource allocation model with a decomposition-based optimization model represents a potentially powerful approach for solving highly complex operational problems related to multiple-reservoir water resource systems.

    Dijken in de Hoeksche Waard: ecologische schakels in wording? Mogelijkhden voor inrichting en beheer van de dijken in de Hoekschge Waard.
    Laan, P. van der; Dekker, M. ; Liebrand, C.I.J.M. - \ 1996
    Wageningen : Wetenschapswinkel (Rapport / Wetenschapswinkel 114) - 60
    dijken - dammen - constructie - landschap - nationale parken - landschapsbescherming - bescherming - landschapsecologie - natuurbescherming - beleid - bedrijfsvoering - biocenose - herstel - Nederland - aquatische ecosystemen - natuur - natuurtechniek - zuid-holland - zuidhollandse eilanden - dykes - dams - construction - landscape - national parks - landscape conservation - protection - landscape ecology - nature conservation - policy - management - biocoenosis - rehabilitation - Netherlands - aquatic ecosystems - nature - ecological engineering - zuid-holland - zuidhollandse eilanden
    Reservoir management under consideration of stratification and hydraulic phenomena
    Nandalal, K.D.W. - \ 1995
    Agricultural University. Promotor(en): J.J. Bogardi. - S.l. : Nandalal - ISBN 9789054853718 - 173
    dammen - meren - wateropslag - reservoirs - waterbeheer - watervoorraden - computersimulatie - simulatie - simulatiemodellen - hydrologie - water - dams - lakes - water storage - reservoirs - water management - water resources - computer simulation - simulation - simulation models - hydrology - water

    Reservoirs are the most important components in a water resources system. They are used to store water to extend its temporal availability. The physical, chemical and biological characteristics of water change when impounded in reservoirs. This implies the possibility of using reservoirs for the control of the quality of water besides merely satisfying the quantity requirement. This study presents several techniques formulated to manage a reservoir when both quantity and quality of water are of interest. In this study salinity is selected to characterize the water quality status. The approaches are demonstrated using data from the Jarreh Reservoir on the Shapur river in Iran.

    Water in a reservoir is stratified for most of a year due to difference in density caused by temperature, dissolved and suspended solids. Therefore, in a stratified reservoir the quality of water that is interrelated to density varies with depth. Consequently, this feature could be used in the process of reservoir operational policy determination to improve the quality of water supply. The aim of this research is to analyze different approaches regarding the incorporation of this phenomenon into reservoir operational policies and to propose those which require the least increase in mathematical and computational complexity.

    Initially, two techniques that rely on the natural process of stratification occurring in a reservoir are presented. The first methodology proceeds stepwise in time alternating optimization and simulation of reservoir operation at each time step. A one-dimensional reservoir dynamics simulation model is employed to simulate the stratification of the reservoir. A constrained nonlinear optimization model is used to identify optimum releases. In the optimization step the reservoir is assumed to be equivalent to the parallel configuration of several smaller hypothetical reservoirs, the number of which being equal to the number of outlets. There is no communication among these hypothetical reservoirs. The applicability of the technique is tested for three hydrologically different years and for a continuous period of five years. Incorporation of inflow stochasticity into the methodology is devised through the integration of an optimization model based on Stochastic Dynamic Programming technique.

    Next, an iterative technique, in which an optimization model and a reservoir stratification simulation model operate interactively, is presented. One iteration cycle comprises the run of the optimization model and the simulation model: i) Reservoir operation is optimized over the entire time period (year); ii) Simulation of stratification is applied over the entire time period. The optimization model is based on Incremental Dynamic Programming technique. In the optimization model, the hypothetical reservoir concept used in the above model is adopted. However, communication between any two adjoining hypothetical reservoirs is allowed in the model. The one-dimensional reservoir dynamics simulation model simulates the stratification of the reservoir. The applicability of the technique is examined for three hydrologically different years.

    Reservoirs could also be modelled by assuming that complete mixing of water is occurring throughout its entire volume during a year. It is a simplification as compared with the real behaviour of stratification occurring in reservoirs. Two models are developed based on this assumption to improve the quality of water supply. In one model only the releases are controlled. In the other, both inflows and releases are controlled. Optimization is based on Incremental Dynamic Programming technique. The results from both models show improvements in the quality of water supplied from the reservoir. However, the improvements obtained by manipulating both inflows and releases are more profound.

    Improving the quality of water supplied from a reservoir by diverting poor quality inflows and satisfying downstream quantity demands are two conflicting objectives. This problem is studied under the multiobjective analysis framework. The reservoir is assumed to be completely mixed throughout its volume during the whole annual cycle. The results show that a cautious balance between the quantity of water supplied for downstream and the volume of inflows diverted would lead to marked reduction in the supply salinity.

    The study reveals that the quality of reservoir releases could be improved by withdrawals from different elevations in a stratified reservoir. However, the benefits obtained in this way are marginal for the case study reservoir. Similar improvements are observed under the assumption that the reservoir is completely mixed throughout a year. On the other hand, by manipulating the inflows to the Jarreh reservoir these improvements could be enhanced significantly. That is, by-passing of poor quality inflows seems to be a very promising management alternative for improving the quality of water supplied from the reservoir. The assumption of reservoir's complete mixing is warranted for the stratified reservoir by the obtained results. Hence, a relatively simple and straightforward methodology based on the non-stratification assumption proves to be suitable in managing a density stratified reservoir.

    Duurzaam rijshout voor de kwelderwerken : onderzoek naar een goedkoper onderhoud van de rijshoutendammen in de Waddenzee
    Hekhuis, H.J. ; Vries, S.M.G. de - \ 1994
    Wageningen : IBN (IBN - rapport 056) - 49
    ontginning - ontgonnen land - polders - dammen - constructie - rijshout - kweldergronden - waddenzee - reclamation - reclaimed land - polders - dykes - dams - forestry - salt marsh soils - wadden sea
    Botanische en civieltechnische kwaliteiten van vegetatie op Nederlandse zeedijken.
    Sprangers, J.T.C.M. ; Sykora, K.V. ; Fliervoet, L.M. - \ 1991
    Landinrichting 31 (1991). - ISSN 0922-6419 - p. 2 - 10.
    kanaaloevers - kanaaloeverbeplantingen - constructie - dammen - dijken - onderhoud - Nederland - plantengemeenschappen - plantenecologie - bescherming - onderzoek - vegetatie - canal banks - canal plantations - construction - dams - dykes - maintenance - Netherlands - plant communities - plant ecology - protection - research - vegetation
    Dammen van riet, heide of boomschors als perceelverbinding in veenweidegebieden
    Wilde, J.G.S. de - \ 1984
    Wageningen : ICW (Rapport / Instituut voor Cultuurtechniek en Waterhuishouding ) - 46
    moerasgronden - hoogveengronden - veengronden - dammen - constructie - kostenanalyse - veenweiden - swamp soils - bog soils - peat soils - dykes - dams - construction - peat grasslands
    Ter verbetering van de bedrijfsvoering dient in een aantal veenweidegebieden de perceelontsluiting verbeterd te worden. Om na te gaan hoe en van welk materiaal de perceelverbindingen moeten worden gemaakt werd een werkgroep ingesteld die de aanleg van proefdammen adviseerde. De volgende factoren zijn in dit verband behandeld: uitgangspunten en werkplan; materiaal en materieel; metingen; uitvoering; directe meetresultaten; kosten; afweging inzet kleinere dieplepel; conclusies.
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