Druppel 17-1 - Dispuut Watermanagement

DRUPPEL 1 - 2007Sponsor IndexArcadis Nederland Page 2 and 25Bam Civiel Page 2Duinwaterbedrijf Zuid-Holland Page 13HKV Lijn in water Page 2 and 4 TNO Page 13 WL Delft Hydraulics Page 2bam civiel2

DRUPPEL 1 - 2007ColofonVolume 17, Number 1, February 2007The ‘Druppel’ is a magazine of thestudent society of water management ofthe TU Delft. The magazine is publishedfour times a year.EditorsEvelyn Aparicio & Leon ValkenburgIn cooperation with:Cees Kamphuis, Harry de Brauw, Ruudvan der Ent, Maarten van Dieren, Prof.Kop, Prof. Brouwer, Prof. Brouwer,Thijs Dekker, Doris van Halem, JasperFlapper, Ivo Miltenburg, Marloes vanGinkel, Harry de Brauw, Joanne van derSpek, Roel Blesgraaf, Wouter Sottewes,Arthur Geilvoet, Carola van der Hout andMaarten SmoorenburgLay-outLeon ValkenburgPrintingThieme Media ServicesThe ‘Druppel’ is distributed toall members of theDispuut WatermanagementFaculty of Civil Engineeringand Geosciencesroom 4.74Stevingweg 1E-maildispuut.watermanagement@ct.tudelft.nlInternetwww.dispuutwatermanagement.nlFrom the EditorsHolas Reader!Currently the board and the editors of thedruppel are very busy with the januaryexams. This is also why this druppel is abit late. But this is obviously not the onlyreason...history that is pressed in A4 and (partly)in color. Of course this transition costs alot of time, but we think it is a succes! Thelay-out has also been improved, so maybewe can say the Druppel is coming of age!Of course, the stories in the magazine arestill the most important part of this Druppel.We have some very interesting storiesfor you. Our new board is presented andthe upcoming events of our Dispuut areannounced. You really should check thepages about our Elbe Study Tour and theSymposium about the millenium goals inApril.The interesting contributions of our membersof honour and the thesis summary ofDoris van Halem should not be missed aswell.Furthermore you can read about the adventuresof our water management studentsin Brasil, Senegal and Surinam. others to go abroad!!As always we are looking to entertain you,so really check our photo page !!!See you in our dispuutroom or somewhereelse.Ciao,Evelyn and Leon3

Bezoekadres:Botter 11 nr. 29LelystadPostbus 21208203 AC LelystadTelefoon: 0320 294242Telefax: 0320 253901E-mail: info@hkv.nlInternet: www.hkv.nlwww.hkv.nlHKV LIJN IN WATER is een onafhankelijk bureau voor adviesen onderzoek op het gebied van water en waterbeheer.Wij besteden10-15% van ons budget aan onderzoek enontwikkeling. Met deze insteek kunnen wij studentenvolop mogelijkheden bieden voor:afstudeerprojectenpromotiestudiesgrensverleggende onderzoekenInnovatieve ideeën worden door ons zeer op prijs gesteld.Wij horen graag van je!

DRUPPEL 1 - 2007Table of Contents- Page 9Elbe River Study Tour Company Case Witteveen + Bos- Page 15Project Suriname- Page 23Project CasamanceSponsor index 3From the Editors 4Watercolumn Prof. Brouwer 14Symposium 15Table of Contents 5 New Board Members 7Elbe River Study Tour 9CC Witteveen & Bos 10Project Suriname 19Project Casamance 22Photo Page 29Brasil, the ultimate experience 30Letter from Prof. Kop 135

DRUPPEL 1 - 2007From the BoardRuud van der EntBy the time you read this Druppel it’s JanuaryAfter enjoying all the delicious food andchampagne of a few weeks ago the studentswho read this Druppel startedlearning for their exams this January.On behalf of the board I’d like to wish allstudents good luck with their exams andI wish everyone a splendid 2007!Speaking of the board already the 40thboard had been installed last November.Another milestone reached for our board with a none Dutch speaker in it.As some of you know I’ve only been livingin Delft since June. The house I live in iscalled ‘Brackish Water’. When I told peoplethis name I noticed that a lot of peoplehad negative associations with this name.This is partly why I decided to write aboutbrackish water. My hope is that after readingthis article everyone will be more openminded towards brackish water.First of all I’ll start by convincing the religiouspeople amongst us. I quote from 2Kings 2, 19:22.Healing of the Water19 The men of the city of Jericho said toElisha, “Look, our lord, this town is wellsituated, as you can see, but the water isbad and the land is unproductive.”20 “Bring me a new bowl,” he said, “andput salt in it.” So they brought it to him.21 Then he went out to the spring andthrew the salt into it, saying, “This is whatthe LORD says: ‘I have healed this water.Never again will it cause death or makethe land unproductive.’ “22 And the waterhas remained wholesome to this day, accordingto the word Elisha had spoken.As can be read Elisha heals the water bymaking it brackish. For those of you whodo not believe in God I’ll give a more rationalexample. During last summer I wenton the study tour in Vietnam. In the Me-kong Delta the government is trying toprevent salinity intrusion, because therice agriculture needs fresh water. But wefound that in the Mekong Delta there wasa lot of shrimp farming. Shrimp farming incontradiction needs saline or brackish water.We also found that shrimp per hectarebrings up two to three times the moneythat rice does. So here we see a goodexample of the undervaluation of brackishwater by the government while mostfarmers do show the right appreciation.Unfortunately most of the areas in theNetherlands that used to be brackish haddissapeared. Such specialized biotopesare vital areas for the conservation of wild a valuable area is the Ouderkerkerplas.This is a former sand extraction pit to thesouth of Ouderkerk aan de Amstel, diggedfor the construction of the highway A9.It’s an important bird area with bird watchhuts around it. Because the lake is so deeplake. The water due to this is brackish, andthe lake doesn’t freeze up during winter.In winter the lake is very popular to waterbirds like the wigeon (smient), tufted duck(kuifeend) and various geese (ganzen).This is the end of my argument formore appreciation for brackish water.Enjoy reading the rest of this Druppel!6

DRUPPEL 1 - 2007New Board MembersEvelyn AparicioI thought it would have been easy to writea story about something, I consideredmany topics like: Being a foreigner? Somethingabout Bolivia? Why did I choose tostudy in the Netherlands? Why TU? WhyWater Resources Management? And thenI remembered that I wrote an essay answeringthose questions for being acceptedat TU, and that everybody has beena foreigner at some point of his life, so Idecided to write about how was to cooksomething for the lunch we had for theBoard Change and my feelings during day.Since I come from a different land ofcourse it was important for our boardchange lunch to have something typi-availability of ingredients and also askingfor advise I decided to cook “Rellenosde Papa” (Filled in Potatoes) very typicalfor an Andes Mountain range country.At that day I woke up at six approximatelyto chop the two kilos of onions needed, at(Edwin), at seven thirty my second back uparrived (Jaimito), we made a mess of mytinny kitchen (1x1.30 m). Between hugeboiling pans and heating oil we startedto make balls of potatoes, when we hadat that time was like 11 more or less.Then we thought how to take them to theUniversity? I live more or less 15 minuteswalking to the University, so if I would haveused the bike, instead of potato balls wecould have eaten smashed potatoes. WhenI arrived at the University I was sweatingbut fortunately it was not too late, everybodywas working already and there weremany nice things to share for lunch thateach board member made. I can not saythat the “Rellenos” were perfect but weremade with dedication, pleasure and fun.The three new members of the boardare Joanne van der Spek, Leon Valken- dentsI met and liked, our board changewas wonderful, the lunch was verycrowded and there was a nice “air” inthe room, it was a busy day and I enjoyedeverything we did and share.I am not sure exactly when the MasterProgramme started to be taught in English,but currently courses are entirelytaught in English; Professors, Studentsand Staff are very affable. To me overcom- consider the Dutch way: It is not possibleto live life inside of a bubble, open youreyes and discover that is not just a dream.7

DRUPPEL 1 - 2007Elbe River Study Tour any other place would not be so special,however for the excursion this year wewill go the Elbe River and we will spendsome days in the beautiful city of Prague.The committee for the Multi day Excursionstarted to organize the upcoming and had a meeting every week to analyzethe progress of the tour and de- Thanks to the contacts we got afterasking to our teachers, currently wehave the main projects we will visit: tionprojects and the Prague WaterworksMuseum which is locatedat one of the three waterworkssupplying Prague, with the collaborationof W&ET Team, Water & EnvironmentalTechnology Team in Czech Republic.Between Prague and Dresden wewill visit the mountains at the SachsischeSchweiz and camp over there.In Dresden among others we will visitThe Klingenberg reservoir, the TechnologiezentrumWasser Karlsruhe totalk about water quality change in thenetwork of Dresden, make a tour for Elbe River, with the collaboration of theDVGW Centre, Technique Universityof Dresden. And IOER Institute.The Trip is programmed for the last weekof April 2007, we will drive to Prague andmake the tour with vans we will rent, to-dentsand 2 supervisors.All of the students are welcome to join thetour; the enrollment will start on January15 by signing in outside the dispuut.Don´t miss it !!!!!!!9

DRUPPEL 1 - 2007transported to the sludge digestion chamber.The water is now cleaned for 30%. clean the water before it enters the new dry periods, to ensure the water quality,the dead end of the canal was connectedwith pipes to an external water source.After lunch we visited the water treatmentplant of Deventer, about 15.000 m3/s isbeing treated here during peak hours.After a brief introduction, we toured thefacility to get an idea about the process.The treatment process exists out of multiplesteps:1. Wastewater intake2. Main pump by jack-screws Filtered waste is dumped in a container,compressed and transported to a wastedeposal site.4. Primary settling tank: water is distributedover 2 settling tanks in which thecoarse material settles to the ground. A majorbroom sweeps the deposit to a cleanoutdrain in the middle of the tank from where are swept from the surface, collected and5. Biological reactor: Two biologicalreactors treat the water from the primarysettling tank by adding bacteria that breakup the waste materials. Some bacteria don’t. Therefore the process is divided in 5steps, starting in the middle of the reactor.5a. Anaerobic tank:Cultivates phosphate bacteria.5b. Contact tank: Water from the primarysettling tank mixes with the bacteriafrom the anaerobic tanks.5c. Anoxic tank: This tank contains nitratewhich disables nitrogen. Bacteria convertnitrate into nitrogen gas and oxygen.5d. Exchange tank: This tank can containoxygen rich or oxygen poor water, dependingon what is necessary to removethe leftover waste materials from the water.5e. oxygen tank: Contains oxygen richwater. Present ammonium in the waterwill be converted to nitrate by bacteria.Oxygen binding substances are removed. is lead to 7 large post settling tanks. Thebacteria settle to the bottom to form a siltlayer which is swept to a cleanout drainin the middle of the tanks. Large amountsof the silt are pumped to the oxygen tank(5e), it still contains useful bacteria. Thesilt surplus is directed to the sludge thick- pumpsto the river IJssel.11

DRUPPEL 1 - 2007 removes as much water as possible; thesludge settles to the bottom and is thanpumped to the sludge digestion chamber.The leftover wastewater is reverse pumpedto the wastewater intake (1) to go throughthe process again.9. Sludge digestion chamber: Bacteriaenable fermentation in the digestionchambers. This process releases methanegas which is used to produce electricity forthe plant.10. Sludge lagoon: The concentratedsludge from the digestion chamber isstored in the lagoon from where it is trans- installation (11). - 75% of the sludge which is pumped to thewastewater intake (1). The heavy sludgeis transported to a sludge processor whichcomposts it.The case we had to solve for the afternoonwas: design an additional treatmentstep for advanced removal of nitrogen ditionalinformation was given about dif- pectsof the new treatment step had to be-The same groups tackled the problemsand presented their solutions at the endof the day. They mainly agreed about theteveen+ Bos then presented their solutionand decided what team presented thebest designs. Overall, the group Muriel,Johan, Floor, Marloes, Leon and Harry didbest. They now enjoy the practice of cookingaccording to the “hanzekookboek”.Finally we were invited by Witteveen +taurants.The return by train wasn’t as badas the way in. Though we did encountersome delays, the beers made up for it.12

DRUPPEL 1 - 2007What is the relevance of Honorary Members?Prof. Ir. R. BrouwerOn 15 December 2005 the board ofthe Dispuut Water Management distinguishedme with the nominationof Honorary Member of the Dispuut.Nothing is for nothing in our world, so I wasnot surprised when a request was made tome at the occasion of the yearly banquetof the Board with the Honorary Members;the request: “to present my views on theDispuut and on the relevance of its HonorableMembers in a column for the Druppel”,I am happy hereby to comply with.During my active years as a professor inthe Department of Water Management,and especially during the years I servedas Chairman of the Dispuut Department,I begun to appreciate the Dispuut moreand more. The primary goal of the Dispuutis of course to facilitate the contactsbetween students, with a similarstudy interests and to improve their understandingand their enjoyment of thechosen study subjects by organising discussions,excursions and study tours.In addition the Dispuut is a source of inspirationfor the staff of the Departmentbecause the activities of the Dispuutraise many questions and ideas that willbe discussed also between students andstaff, formally and informally. In this waythe staff gets the opportunity to understandthe views of the students, and toreact on suggestions students may haveon their understanding of the study subjects.In the later years of the study thismay even become the form of a discussionbetween an experienced professional anda starting young colleague. These discussionscan be very effective to make theyoung future Engineer realises that onlythrough thorough understanding of theoreticaland practical principles, a validand applicable engineering result can beachieved; and that a mere passing a seriesof examinations will not be good enough.For these reasons I have supported the Dispuutwhenever was possible, and also listenedcarefully to suggestions made by theDispuut. But - of course - in this process notall suggestions from the Dispuut would necessarilyhave to be accepted by the seniorand experienced staff of the department!So what do we need Honorable Members for?For the Honorable Member himself is ofcourse very pleasant that his or hers effortsto make the Dispuut blossom out, arenoted and appreciated. And the Dispuutof experienced Honorable Members. Theseare not necessarily active at the Universityany more. But the fact that these memberslook from the outside world with specialinterest into the ongoing activities inthe Department, and particularly in theDispuut, does make them a useful sounding-boardfor the developments in theDispuut. Also they can function as thelong-term memory for the Board of theDispuut, and that can be necessary becausethe period that the students andthe board members are active in the Dispuutis – hopefully – limited in time. Thisway the Honorable Members can give auseful perspective, from a different pointof view, on the activities of the Dispuut.All these done, in order to the Dispu- and be fruitful in many years to come.14

WATERMANAGEMENT SYMPOSIUM 2007MILLENIUM DEVELOPMENT GOALS: OUR RESPONSIBILITY?The Dutch approach in achieving safe drinking water and sanitationSUBJECT: This year’s symposium organized by the Dispuut Watermanagement concernswater management in relation to the Millennium Development Goals. As a lot of the MDG’s arelinked to water management the focus will be on “reducing the proportion of people withoutsustainable access to safe drinking water and sanitation by half, by 2015”. (MDG target 7)During the symposium the following subjects will be discussed:prospects for 2015?ENROLLMENT: To participate please send an e-mail to the addressbelow specifying your name, company name, address, telephonenumber and type of participant. Lunch and drinks are included. symposium.dispuut.wmg@citg.tudelft.nlMore information will be available shortly at: http://www.dispuutwatermanagement.nl/

DRUPPEL 1 - 2007High-tech vs. Low-tech: CERAMIC FILTRATIONDoris van HalemThroughout my studies at the Faculty ofCivil Engineering, I have been interestedin techniques that might contribute to thedevelopment of the third world. Choosingfor the specialisation of drinking watertreatment was a logical choice, since itis currently one of the ‘hot’ topics worldwide.Furthermore, I found the processesto treat water diverse and the combinationof physics and chemistry caught myattention. During courses and colloquiathe worldwide need for safe water wasfrequently addressed: the World HealthOrganization/UNICEF assessed in 2000that 1.1 billion people do not have accessto ‘improved drinking-water sources’. Thisnumber made me wonder, how can thisbe possible? There is so much knowledgeon the treatment of raw water, especiallyin The Netherlands. Of course, there isno clear-cut solution; many western techniquesare not suitable in the tropics, not toforget the social and cultural complications.For my MSc thesis I have chosen to investigatea household drinking water treatmentsystem; ceramic silver impregnatednitelylow-tech, but does that mean thatthe system should not meet high-tech demands?During this research study I haveasked myself this question frequently. Forexample, a technique that removes largerpathogenic micro organisms, such as bacteriaand protozoa, could result in a largereduction in diarrhoea cases. However,perhaps we must pursue a treatment systemthat has the ability to remove smallerorganisms also, such as viruses, and notto forget: heavy metals? It is not to be expectedthat viruses and heavy metals are-contribution to reach the ambitious targetestablished in the ‘Millennium DevelopmentGoal’ (MDG # 7):“halving the proportionof people without sustainable access tosafe water and basic sanitation by 2015”.Figure 1: Ceramic silver impregnated pot (CSF) is a system developed by the Non-Governmental Organisation named Pottersfor Peace. After installing a production facilityin Nicaragua, Potters for Peace hasother countries. This is done by involvinglocal entrepreneurs to start their ownCSF factories. Furthermore CSF (Figure2) is implemented by emergency relieforganisations including the InternationalRed Cross and Doctors without Borders.CSF is manufactured with local materialsand skills, and is therefore an inexpensiveproduct ranging from US$5 to US$12.A mixture of clay, sawdust and wateris pressed into a pot shape with press natedwith a layer of colloidal silver. Pot-I divided my research study into three sections;material characterisation, removalof pathogenic micro organisms and retention/releaseof (heavy) metals. To provide-16

DRUPPEL 1 - 2007long-term study of 12 weeks in the laboratoryof Sanitary Engineering. Ceramic silveredfrom 3 production locations; Cambodia,Ghana and Nicaragua. From Nicaragua verwere included in the experiment. Allto simulate the demand of a small family.measured weekly for: (i) pH, temperatureand conductivity; (ii) turbidity; (iii) totalcoliforms and E.coli; (iv) relevant metals.The situation of highly contaminated watersin rural areas of developing countrieswas translated to the laboratory by dosinghigh concentrations of indicator organisms:sulphite reducing Clostridium sporesas indicators for protozoa oocysts, E.coliK12 as indicators for pathogenic bacteriaand MS2 bacteriophages as indicators forviruses. The situation of highly contaminatedwaters in rural areas of developingcountries was translated to the laboratoryby dosing high concentrations of indicatororganisms: sulphite reducing Clostridiumspores as indicators for protozoa oocysts,E.coli K12 as indicators for pathogenicbacteria and MS2 bacteriophages as indicatorsfor viruses. The situation of highlycontaminated waters in rural areas ofdeveloping countries was translated tothe laboratory by dosing high concentrationsof indicator organisms: sulphite reducingClostridium spores as indicatorsfor protozoa oocysts, E.coli K12 as indicatorsfor pathogenic bacteria and MS2bacteriophages as indicators for viruses.are: (i) in 93% of the 144 taken 300mLsamples no total coliforms were detected;(ii) log10 reduction values between 4 and7 were reached for spikes with E.coli K12;(iii) sulphite reducing Clostridium spores(103-105 n/100mL) are successfully re-loidalsilver; (iv) MS2 bacteriophages arepartially removed by CSF (LRV 0.5-3.0).Figure 2: Diagram of the ceramic silver im- tersfor Peace)of interest to completely understand the intrusion porosimetry was used to meas-material and to calculate parameters suchas porosity, total pore area, permeabilityand tortuosity. The effective pores in theterminingthe particle sizes that can theoreticallypass the material; these weremeasured with bubble-point tests. A remarkableoutcome of these experiments is-pores are larger than the maximum of 1However, the effect of these pores on theorganisms much smaller than these pores17

DRUPPEL 1 - 2007are retained. It can therefore be concludedthat the indicator organisms are removedby other mechanisms than screening only,namely mechanism of sedimentation, diffusion,inertia, turbulence and adsorptionI have done the past months. If you areinterested to read more detailed information,you can ask Mieke (room 4.55) for myreport. It has surprised me, and others,that investigating such a low-tech systemwas possible with a high-tech approach.I hope this MSc thesis will lead to moreresearch on basic drinking water techniquesto stimulate the implementationof these systems in developing countries.l18

DRUPPEL 1 - 2007Ivo Miltenburg & Marloes van Ginkelerthis was a major catastrophy. Houses,schools and arable land were destroyed.The villagers were totally unprepared andmuch damage was done when the waterin the river kept rising.In the two previous editions of The Druppelyou might have read about the experiencesof our project team. This team isa multidisciplinary group of students (hydrology,sanitary engineering, technicalmanagement and building engineering)from the TU Delft, who went to the inlandsof Surinam to undertake a project to helpthe inhabitants coping better with futureHigh water is a certainty of nature andcan’t really be prevented. The area whereit’s all about is huge, and lies far away fromParamaribo. Logistically and economicallyworks or something like that. It is howeverpossible to prevent the damage of futureucationfor the local people. This is whatProject Team Surinam had in mind whenthey started the project. Our main goalswere: the institution of a simple hydrologicalwarning system between the villagesalong the Gran Rio, doing research on thedrinking water supply (in the normal andodto set up an evacuation plan.Our results are all published in the reportlywarning system in the inlands of Surinam.If you are interested in this subject,I recommend you read this report. A lot ofwork still has to be done, so if you wantto do a similar project in Surinam as well,come to one of the team members andwe can assist you achieving this. There isstill a lot of work in the continuity of thisproject and it’s really worthwhile doing it!What I would like to do now, is to give animpression of things you may encounterwhen you’re working on a project like thisin an area far, far away from ‘western civilization’.Below is an overview of the journeyand work of the ‘hydrology-group’ ofProject Team Surinam:Once we arrived in Surinam, it was importantto make contact with all the peoplewho were going to help us. Fortunately,the other part of the project team, of whichsome have Surinam roots, were alreadyin Paramaribo. We had two meetings witha hydrology professor of the ADEK Univer-19

DRUPPEL 1 - 2007sity of Surinam, we met with the local nongovernmentalorganization (NGO) who haduseful contacts, and we planned our tripto the inlands. Furthermore we found outthat our insect repellent, which we boughtin large quantities in the Netherlands, wasvirtually useless for the local mosquitoes.Another feature which attracted our attentionand triggered our cautiousness wasthe amount of dogs populating the streetsand the fact that Surinam people nevertake the bones out of the meat when theymake dinner (watch the teeth in both situations).in the inlands, but this was highly discouragedby everyone who we talked to: inthe inlands, as we were about to learncourse there is no electricity (if there isdiesel, in some villages a generator couldlight up some bulbs in the evening hours).Everything you need, besides axes andkorjalen (scooped out tree trunks a.k.a.boats), you have to take with you. With aI repeat, a lot of water. Water isn’t verylight, not to mention the cans of sardines,beans, etc. and you pay your plane by thekilogram.most upstream village of the Gran Rio.There we started our work and believe itor not, we experienced that in the middleobtain wooden beams. We learned prettyfast that when you adapt to the local(Surinam) pace, things were achieved thequickest. In Kayana we worked very hard,which meant we won half a day in ourplanning, which we could use to do funstuff. We used this time to go swimmingand sunbathing in the beautiful and veryThen we took a boat to the next cluster ofvillages, which was 30-40 km furthermoredownstream. Again we had to take everythingwith us, including bags of cement(42 kg’s each) and the marble tiles forthe monuments we were building. Fortu-brought with us to the inlands, so that waskind of an advantage in the weight-department.Because the huge soela Grandamlied halfway, we had to carry all our stuffforewe could continue our journey overthe river.In Djoemoe we continued our project work.Every day we woke up as early as possible,because the temperature was only 30 degreesCelcius in the morning. We started20

DRUPPEL 1 - 2007with a bath in the river. Not only to diminishthe smell (we had to work hard,so yes, you sweat), but also to clean ourclothes and get our core temperaturesdown. Wherever we were bathing, littlefact they were reeling in piranha’s, someof them bigger then 30 cm. It’s worth tomention here that in this village our laptopbroke down, which meant we had to workin a different way and for some measurements(which had to be done using devicessteered by a computer) we had tofall back to plan B: pencil, paper, rope andduct-tape.In Asindohopo, a village in the vicinity ofDjoemoe, we met with the Granman, theleader of the Saramacan tribe. The Saramacantribe lives along the Gran Rio, sowe needed his permission to work there.It is very impressive to meet with a man ofsuch high importance. We weren’t allowedto speak directly to him, but we had to talkto a Captain, who was sitting next to himand translated everything. We broughthim a bottle of Palm liquor (90% alcohol)as a gift, which he could appreciate a lotfortunately.the village board was enormous. The Captainof the village (sort of mayor) built themonument himself and made a true pieceof art of it. We bought the leg of a woodhare, which was just shot by one of the villagers.This animal was a strange crossingbetween a pig and mouse, but the freshmeat was really nice.The last village we visited was Laduani.By now we were really experienced so wecould work quite effective. Finally, afterParamaribo in an absurdly small plane, butnevertheless we reached our destination.In Paramaribo we started processing ourmeasurements and tried to retrieve moreinformation from different ministries. Aftersome weeks, having had a great time overall,we headed back to the Netherlands.had a very well attended presentation. In an informal reception at PSOR with Surinamsnacks…a great end of a beautifulproject.By then we had drunk all our water, whichmeant we had to switch to an alternativesystem: a portable drinking water devicewe brought with us. By pumping creekorrainwater through this device we couldremove the pathogene organisms whichwere certainly going to make us sick. Unfortunatelyone team member did get sick,but after some miserable days, local medicationand some antibiotics, fortunatelythings got better quickly.And so we continued our work. We visitedthe village of Botopasi next, where the cooperationfrom the villagers and especially21

DRUPPEL 1 - 2007Frogs, birds and saltRoel Blesgraaf, Arthur Geilvoet, Carola van der Hout, Maarten Smoorenburg & Wouter SotthewesIn September and October we went withegal.This was within the framework of our we shared an immense villa with numerouscockroaches and frogs, outside thecity between mangroves and rice paddies.The Headquarter of our research. Whatbrought us to the idea to go to Senegal?About 25 years ago the Casamance estuarybecame hypersaline during the Saheliandrought. The extensive drought in-far upstream, not to be removed by sea-accumulation in the upstream part of theestuary, which is still present today. Salt concentration, around 170 kg/m3 PSU,have been measured. As a consequencethe whole ecosystem changed, mangroveareas have been destructed because nothingsurvives salinity concentrations likethese, except some algae. The change ofthe estuary into a hypersaline area hadmany social, economical en ecological in-In a guest lecture of Civil engineering inhypersalinity problems in the Casamanceregion. Via Professor Van de Giesen wecame in contact with IDEE Casamance, founded more than twenty years ago inSouthern Senegal by John Eichelsheim.This organization helps the local peoplewith all kinds of development projects.Professor Savenije build a Fortran computersimulation model for estuary salt intrusionas part of his PhD-thesis during thelate eighties. We improved the model withrecent data on bathymetry, precipitation,evaporation and tidal parameters. Withhelp of the model we wanted to answerour research questions: Why did the estuarybecome hypersaline? And is the hypersalinestate of the estuary reversible?Those were the questions to be answeredwhen we went to Senegal at the end ofAugust.Besides modeling, we made an inventoryof the water related problems in the region,to see where how and if these problemsare related and what the consequences ofthe hypersalinity are for the water management.Since the estuary became hypersaline,many anti salt dams have beenbuilt in the catchment, to avoid salt waterto intrude into the rice paddies. The impactof these dams was largely unknownand the management and organisationrequired to operate the bigger structureswas not available either. Besides that wesaw a lot of problems with urban erosionand sedimentation in Ziguinchor, the capitalof region where we lived. Urban erosionproblems clearly require an integrated approach.Because the rainy season was fully goingon when we entered Senegal, it was22

DRUPPEL 1 - 2007cope with. We started with the collectionof data for the model, by measuring andwith a run around the city to all kinds oforganizations. We measured several tidalcycles on diverse locations. These measurementswere very plain; the only toolswe brought from Holland were a GPS andan analog conductivity meter. But togetherwith a bottle on a rope with buttons it wasenough to determine several cross-sectionsand salt concentrations. Many organizationswork rather slowly in Senegal,but we had a lot of support of IDEE Casamanceand the engineering post of the region.We often went there to discuss ourprogress, and when our French improved,these visits became very useful. However alanguage sometimes turned out to be unnecessaryin an engineer’s conversation: apencil, a piece of paper and some patience(always available in Senegal) turned out tobe enough.drologicalmaps, results and to-do lists. Theand books, and when there was electricity,it was good working. Three days per weekwe had a cook, on the other days we didit ourselves, which often meant that wepeeled one kilo of fresh shrimps.Of course we made some excursions in theweekends to discover the beautiful Casamanceregion. During these small trips wereckoned the typical way of traveling bythe Senegalese. Old European Mercedesbusses, those only leave the bus stationwhen they are full with people. Often thestart engine didn’t work, so other peoplehad to push the bus before we drove. Niceto mention is the maximum amount ofpeople in such a bus we counted, was 35people and a living chicken. This was includingthe boys at the roof and standingat the back. Imagine that on a road thatis so bad, one drives with two wheels ona roadside, except for when there is morespace, then you drive completely next toroad, also the main road to Ziguinchor wasextremely salt water didn’t stop the rustywrecks from transporting.An interesting note was that we were thereduring the Ramadan, the Islamic month offasting, which meant that religious peopledidn’t eat or drink during daylight. Thatmade the whole life different, because anextra break was inserted in daily life forthem. Especially because the temperaturenormally reaches 35 degrees, the Ramadanin this region isn’t very easy. But, theharder the fasting, the better the feast afterwards.We were invited to have dinnerwith the family of one of the employees ofIDEE. For this special occasion the familybought twenty chickens, which were keptin a storage room in the house we lived. Inspite of the smell for a week, we enjoyedthe meal. The chickens were roasted andserved with macaroni, which formed anexceptional meal in Senegal.At the end of our time in Ziguinchor the23

DRUPPEL 1 - 2007model gave us several interesting conclusions.First thing was that the salinity distributionin the estuary reacted faster ondry years than on wet years. The estuaryis more sensitive for dry years then for wetyears. The second thing was that morethan two successive wet years do not contributeto a less saline estuary. A new, lesssaline, equilibrium will establish but thereis no consecutive overall reduction. Thelast and most interesting conclusion wasthat only with twice as much rainfall in oneyear the hypersalinity might be reversible.Since this is quite unlikely to happen, thelocal people have to make use of the saltyestuary. Especially in the upstream partof the estuary (200 km from the AtlanticOcean) one has to cope with high salinityconcentrations.Beside the salinity distribution that can beexpected, we also looked at the consequencesand possible solutions. We investigatedthe anti salt dams and drew a mapwith the locations we knew on it, sincethere wasn’t one available. It seemedthat the dams are built on very differentscales, sometimes a small branch is cut offother cases a complete valley is dammed.It is not possible to draw hard conclusionsabout the effects of a dam, as all dams aredifferent in size and location. We advisedextra research on these dams, in particu- the upstream part of the valley. Anotherrecommendation is a central organizationof the dams. The Senegalese governmenthas to organize the building of these dams,for example with setting up a control organizationwhich have to give admissionto each NGO that wants to build an antisalt dam. At this moment, each organizationis doing its own project, without anycommunication with the government oreach other and without much technicalexperience.sedimentation demand an integrated approach.The problem is very severe, becausein several quarters in Ziguinchor wesaw ‘erosion gutters’ with a depth of morethan three meters, just between the hous-because they got silted up with city sediments.In a few quarters drainage chan-with sediment because of missing drainageupstream and lack of maintenance.One therefore has to build roads withstones and pavements, instead of onlysand. In combination with a complete systemof drainage channels and a good divisionof it, this will give a better and safersituation in the urban areas. means of a presentation in French at ourhouse. Especially the conclusions on antisalt dams and the irreversibility of thehypersalinity in the Casamance estuarycaused much discussion. Luckily the Dutch‘hutspot’ and pancakes we made for alunch afterwards tasted very good. EventuallyMaarten and Roel had an interviewwith a journalist of the Senegalese nationalradio. This was a nice thing to do, andknow that the results of our research werealso interesting for the local people andnot only for the TU Delft. If you are thinkingof doing a MSc project in Senegal, wecan really recommend it!Finally the reduction of urban erosion and24

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DRUPPEL 1 - 2007Brazil, the ultimate experience!Tijs DekkerFor my MSc Thesis I went to Brazil in Octoberand November. In the eight weeksI spent there, I did measurements for myfurther research. But of course I also sawa lot of interesting new things, met heapsof new, kind people and learned manythings not related to water.I am doing my research within the frameworkof the Small Reservoirs Project. Thisproject aims to develop planning and managementtools for small reservoirs, usedby small-scale farmers for irrigation, lifestockand domestic water. The last variableto be researched in the water balanceof these reservoirs is the seepage to thesubsoil. And that is what I am focusing onin my thesis. International Airport in the center of Brazil.in the 1950s and has since then been thecapital of the vast country. It took the Bra-which now has 2 million inhabitants. Thecity was planned by the visionary president,Juscelino Kubitschek, to stimulatethe economy in the centre of the country,Until then all activity concentrated in thecoastal regions, but the agricultural potentialof the central plane, on which the capitalis built, was already recognized.‘Cerrados’: a country that is very dry fromApril to September and wet in the othermonths. The Cerrados has its own peculiarvegetation consisting of small windingtrees in wide plains full of dry grass.This Cerrados is the landscape where thereservoir is located, where I did my measurements.The reservoir is approximatelyhalf a hectare big and the greater part isDuring my stay my place of work wasat Embrapa. This is a huge governmentalresearch institute, with around 2.000researchers, that focuses on agriculture.There are departments of Embrapathroughout Brazil, the one I was workingfor does research on agriculture in the Cerradossolely and has about 300 researchersworking there. to build my own measuring devices, calledseepage tanks. After some stops at thehardware store I bought six meters of largediameter PVC piping and got busy with siliconekit. From the Netherlands I broughtsome infuse bags and together with theseI made my seepage tanks. To do reliablemeasurements with these tanks, you pressthe tanks in the bottom of the reservoir to30

DRUPPEL 1 - 2007isolate an area of a known size. Then youconnect them to the seepage tanks. Aftersome time you disconnect the bags andweigh them again. Now you know the differencein volume over time and hence theseepage rate.Of course I also wanted to install somepiezometers to know the groundwaterheads in the surrounding of the reservoir.But before you can install a piezometer, the subsoil and its layering. For that I hadto drill a lot of holes around the reservoir.That was easier said than done, becauseat Embrapa they didn’t have proper drillsfor this work. But after some inventivenessand a lot of sweat I got the information Ineeded.So I was off to the hardware store to buyPVC tubes again, this time with a somewhatsmaller diameter, to use as piezometercasing. I sawed slots in the lowest 50centimeters of the tube to make a screenthrough which water can enter. In sandyor lightly silty soils piezometers made likethis will function very well, but unfortunatelythe ground near this reservoir consistsof clay. And I found out that this clayclogged the slots immediately. After somedeliberation with my supervisors I decidedto saw holes instead of slots in the lowest50 centimeters of the tube and use panty-I could measure the groundwater heads.Now the piezometers were installed andfunctioning correctly, I could also usethem to estimate the transmissivity of theaquifers. If you raise or lower the waterlevel inside a piezometer instantaneouslyand then record the recovery of the headover time, you can calculate the transmissivityin the surroundings of the well. Thisway of measuring is called a slug test andcan be seen as a small scale pumping test.The transmissivity that comes from thismethod is only valid very locally, but becauseof the small scale of my research, itcan be used very well.My experience with research in Brazil isthat you really have to get used to thetropical way of doing things; Almost all theequipment you are going to use, has to beborrowed somewhere. And it is very dif-equipment available. And when somethingis promised to you, it doesn’t really meanit will happen. But people will always besmiling and trying to help you as good asthey can.Besides all this research I also had a lotof fun in Brazil of course. One of the moststriking things I noticed about the countryis that the people are really open and kind.Once they decide you are their friend, theyreally make time for you and want to showyou their country. And that country is reallyworth it.31

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