Druppel 16-3 - Dispuut Watermanagement
Transcription
Druppel 16-3 - Dispuut Watermanagement
From the editors Volume 16, Number 3, June 2006 The ‘Druppel’ is a magazine of the student society of water management of the TU Delft. The magazine is published four times a year. Editors L. Valkenburg and M. van Ginkel In cooperation with: Cees Kamphuis, Harry de Brauw, Ruud van der Ent, Caitlin Pilkington, Jair Smits, Benjamin Fischer, Erik Liefting, Sigrid Scherrenberg, Pieter Bol, WISST. Lay-out Jaïr Smits Printing Koopman & Kraaijenbrink The ‘Druppel’ is distributed to all members of the Dispuut Watermanagement Faculty of Civil Engineering and Geoscience room 4.74 Stevingweg 1 2628 CN Delft 7HOHSKRQH E-mail [email protected] Internet www.dispuutwatermanagement.nl The new board has been installed. Our new chairman Cees Kamphuis has written KLV¿UVWVWRU\IRUWKHGUXSSHORQSDJH This is followed by the introduction of the new board on pages 6 and 7. The succesful symposium last april is described on pages 8 and 9. Marloes van Ginkel gives an update of the situation on the educational front at pages 10. 7KH UHSRUWV RI WKH ¿HOG SUDFWLFDO LQ Luxembourg and the excursion urban watermanagement can be found on pages 11-14. Jair Smits tells about his fourthyears SURMHFWLQWKH3KLOOLSSLQHVRQSDJHV an 16. This is followed by the report of Benjamin Fischer from Tanzania on page 17. Druppel 3 - 2006 Colofon Hi all!! This is already the third druppel of the year 2006. This fresh new edition contains all the news and information about the activities of the student society of water management. The interesting master thesis of Erik Lieftink, an article written by Sigrid Scherrenberg on green roofs and Pieter Bol’s contribution ”Water for Benin” can be found on the pages 18-23. This druppel ends with a dramatic story about Suriname on page 26. Enjoy reading!!! Greetzz Marloes & Leon 3 Table of contents Table of contents Druppel 3 - 2006 From the editors Table of contents )URPWKHERDUG A fresh new board Symposium Urban Watermanagement Education Field Practical Luxembourg Excursion urban watermanagement )RXUWK\HDUVSURMHFWLQWKH3KLOOLSSLQHV Internship in Tanzania Master thesis Erik Liefting Green roofs Water for Benin Aid for Suriname Sponsors 3 4 6 8 10 11 13 17 18 20 23 26 27 Sponsor index KIWA HKV FLYGT WL Delft Hydraulics VEWIN Waterschap Rivierenland +RRJKHHPUDDGVFKDSYDQ'HOÀDQG 4 2, 27 27, 28 27 27 27 27 From the board From the board Cees Kamphuis This is not only the time for the barbeques and swimming in the ‘Delftsche hout’ but also for a lot of activity at the Dispuutshok. The symposium committee remembers with pleasure the interesting symposium about Urban Watermanagement, the GVR-committee is doing a good job in preparing the trip to Vietnam and lots of members are still busy with uitbuiken after the Watermanagement Barbeque. A group of 20, mostly watermanagement, students joined the Hydrological Fieldwork this year. In my opinion this was a week with lots of hard work, but also with lots of fun. I really think this was a tremendous week with a lot of integration between the Dutch and foreign students. It is a beautiful opportunity to perform hydrological measurements and research by yourself. So, when you’ve got the opSRUWXQLW\WDNHSDUWLQWRWKH¿HOGZRUN Druppel 3 - 2006 Meat, burnt meat…. I can’t stand it anymore… Normally the combination of lots of food and my stomach don’t make any trouble, but with this number of barbeques even the biggest carnivore has to surrender. This is actually quite good news, because it tells us something about the tremendous weather: it’s summer! Finally, I want to wish luck to all of you ZLWK \RXU ¿QDO H[DPV DQG HQMR\ \RXU holidays. A fresh new board A fresh new board Harry de Brauw As you probably know, the Water Management Board exists out of 6 members. Each half year three members are thanked and dismissed for their dedication for the Water Management Dispuut. I would like to thank Ronald Bothé, Marjolein van der Kraan and Jair Smits for their continuous effort during one year for the Dispuut. They are now replaced by: Druppel 3 - 2006 Floor van de Berg van Saparoea Treasurer Harry de Brauw – Commissioner of Companies Ruud van der Ent – Secretary Meanwhile, three of the old members have taken the following positions in the board: Maarten van Dieren – Commissioner of Students Marloes van Ginkel – Commissioner of Education Cees Kamphuis – Chairman As one of the new board members, I was assigned to write a contribution for “De Druppel”. “Introduce yourself” is the guideline for this text… As a small boy I was carried and pushed around through the great ranges of the Alps. My parents couldn’t know that these 6 weeks in summer and winter would be of JUHDWLQÀXHQFHRQWKHUHVWRIP\OLIHDW least until now). Everyone participating in water management has probably built dams in creeks and what used to look like enormous rivers with their rapids. So did , DQG , ORYHG LW $JLQJ FDPH WRJHWKHU with a slight shift of interest, maybe it’s better to say: “a widening of horizon”. The enormous peaks pointing in the sky around me started to attract me. Hiking and doing the water management game in rivers was no longer satisfactory. These ridges, faces and snow covered summits had to be climbed! This started with a course into mountaineering at the age of 16 and became an increasing time consuming hobby during the years to come. After high school, I left to study for one year at the University of Colorado LQ%RXOGHU&RORUDGR7KLVVWD\FRQ¿UPHG my interest in climbing which I tried to combine with my study civil engineering, the last sometimes suffering from the ¿UVW%DFNLQ+ROODQG,VLJQHGXSIRUFLYLO engineering at the TU Delft and became a member of the “Delftsch Studenten Corps”. Civil engineering couldn’t cause me to be very enthusiastic for this subject in the beginning. I preferred to travel and climb as much as possible. Nowadays things changed, sometimes I VWLOO¿QGP\VHOIZDNLQJXSLQDVQRZVWRUP on a tiny ledge at an altitude of over PHWHUV EXW ZDWHU PDQDJHPHQW has caught my attention. My climbing partners are complaining: “You do not join us anymore on all the trips abroad”. :DWHU PDQDJHPHQW LV JDLQLQJ ¿HOG EXW summer is still holy for me, the perfect time to climb the Alps….. I won’t make it A fresh new board Ruud van der Ent, our new secretary, is the youngest of the team. He managed to go through his study within the nominal time period. He is moving to Delft this week. Floor van den Berg van Saparoea, our new treasurer, is also known at the mechanical side of the faculty, you can sometimes ¿QG KHU OHFWXULQJ &7 0HFKDQLFV RI Systems. She is an active member of the “Delftsch Studenten Corps”. Druppel 3 - 2006 to Vietnam this summer. 7 Symposium Symposium “Urban Water management“ Pascal Kregting. This article should be completely obsolete, because everybody from the section was there. For the folks who were not there and maybe are feeling a bit of guilt this article will give you a short summary of the day. Druppel 3 - 2006 8 Nowadays water quantity and water quality are both important to the European water household. The aim of the symposium was, and still is, to give an innovative view on the current research WKDW LV GRQH LQ WKH ¿HOG RI XUEDQ ZDWHU management. With loads of coffee being served in the early morning, every participant had the chance to be completely awake for the ¿UVWSUHVHQWDWLRQ The chairman Frans van de Ven started the day with an introduction and made VXUHWKDWHYHU\RQHZDVDZDNHLQFOXGLQJ the people from the board who had a party the day before). Rutger de Graaf from the TU Delft started the sequence of presentations with one about innovative concepts for urban design. With a nice smile and keywords like vulnerability and the principle “Closed City” he moved the audience. After his presentation it was the turn to Aad Oomens from Grontmij. While, unfortunately, I was not present at his presentation I heard the “ooeeeesss” and “aaaaahhhs” from far away. I think this means that it was very interesting, because the topic was about sewerage. Mrs. Katheleen Poels from DHV was next in line. She could not wait to start the presentation and she was completely right. The topic about groundwater problems was well chosen and she made the audience hers, especially during the questions session. Because of chances to get a brain RYHUORDG WKH FDEDUHW ZLWK WKH ¿WWLQJ name “Abracadabaret” started halfway during the day. With a satiric, dry Dutch humor they made sure that the minds of the participants where on the subject, but not in a serious way. Because people were tired of laughing all the time, it was the right time for the lunch break. With the information from all the presentations and the cabaret people had enough to talk about while WKH\ZHUHQRW¿OOLQJWKHLUVWRPDFKVZLWK the excellent lunch. Then our guest from the United Kingdom, David Butler from the University of Exeter, gave a presentation with the title “water sustainability: a journey into the unknown”. My compliments for the perfect English and of course for the nice presentation. Now I will think twice EHIRUH,ÀXVKWKHWRLOHW After a small break and some discussion it was the turn to Rob Nieuwkamer from Witteveen+Bos to make the audience his. With a short but interesting presentation, he emphasized the working together with non-technical people like architects and he made an introduction for the case about the water management plan Dordrecht. Should we built our cities for twenty years or for centuries? There were some good discussions, and in the end, both visions turned out to have pros and cons. The day was coming to an end for all the participants and after some drinks all the participants had to leave. The day for all the speakers and the organization ended with a glass of beer in the hand and some nice conversations about everything and nothing. Druppel 3 - 2006 Symposium 9 Education Education Marloes van Ginkel Maarten doesn’t want to waste one of his opening sentences to me; so I’ll start my article about education in a less interesting way. Druppel 3 - 2006 10 The educational system of our master has changed. We are working with ‘blokvakken’ nowadays. This means: a change from lectures to integrated OHVVRQV ZLWK PRUH SUDFWLFDOV ¿HOGZRUN and information from company experts. The idea is that this will improve the educational system and prepare the students better for their future work. The change was sometimes successful and sometimes less successful. A lot of feedback from students and teachers is used to evaluate the courses and to think about improvements for next year. Thank you for your help. The results from the questionnaires and the agreements I made with the teachers for next years courses will be put on Blackboard. The courses that are evaluated last year are: Water Quality Management, Drinking Water Treatment, Civil Engineering in Developing Countries, Operational Watermanagement, Wastewater Treatment, Ecology, Irrigation and Drainage, Biogeomorphology, Polders and Flood Control and Hydrological Measurements. I want to emphasize that feedback from students is very important, without your help we cannot improve the courses. Fill in the questionnaires and hand them in at room 4.74. And, when you want to say something about a course, please come to me. Field Practical Luxembourg Field Practical Luxembourg Caitlyn Pilkington The week consisted of a typical day of rise at 7:30 to arrive at the table with the aim of consuming as much bread as possible to ensure adequate fuelling for the mornings work. Make another VDQGZLFKHV GHSHQGLQJ RQ VL]H RI student/supervisor, gender and general Dutch-ness), pick up some equipment WKDW ORRNV LQWHUHVWLQJ DQG ¿QG D FDU WR climb into. (DFKGD\WKH¿YHJURXSVZHUHRXWZRUNLQJ at different locations in streams in the Wark river catchment. We all enjoyed the YDULRXV VWUHDPÀRZ PHDVXULQJ JXPERRW wearing, rainfall catching, weir measuring, tracer seeking, dam observing, theodolite posing and of course, macrofauna hunting activities throughout the eventful week of experiments. Not to mention the treeclimbing, dancing, swimming, singing, poetry writing and grass tumbling. Upon completion of the above activities then it must be time for an outdoor lunch, after which we daily enjoyed the uitbuikmoment, followed by the inkak-moment, by which time there were no excuses left and no dishes to clean anyway so back to work. Druppel 3 - 2006 On the morning of Friday 12th May, 20 eager young hydrology students arrived bright and early at the TU to commence WKHLU ZHHNORQJ K\GURORJLFDO ¿HOGZRUN course to Luxembourg. It was to be their most well-rested moment in the next seven days – even for Marloes who had arrived directly from a party. 11 Field Practical Luxembourg Druppel 3 - 2006 Finally back to camp in the afternoon to do DQ\WKLQJIURPGRQDÀDWWHULQJZKLWHFRDW DOPRVWDVÀDWWHULQJDVWKHJLDQWUDLQERRW SDQWVDQGHQWHUWKHODERUDWRU\¿JKWIRU a laptop to enter data onto, sieve some sand, take a siesta, drink beers, or plan the evenings menu with the impressive per-tent ‘survival kit’ bestowed by the organised Gerda. Work, eat, consume another beer or four in the name of hydrological research, perhaps some ODQJXDJH OHVVRQV WKH PRVW SUDFWLFDO RI my Dutch was learnt in these later hours) and eventually, sleep. We enjoyed some impressively close thunderstorms from our thin tents on some of those nights, though it didn’t rain in the daytime, much to the dismay of our very own team of Rainiacs. A trip to Luxembourg city on Saturday night ended in disaster as Martin put too much faith in his onboard GPS system and arrived in Luxembourg city…. 40 minutes after he had left it. Well, by the third day on a diet consisting predominantly of sandwiches, the Chinese had had enough and demanded the right to eat cake for lunch from that day forward. This opened up the door for experimentation from all cultural sides and by the next morning, even the Dutch 12 were happily pouring olive oil and salt onto their bread. On the last day, each group presented WKHLU ¿QGLQJV VR IDU DQG RQFH WKDW ZDV over, presentations followed. Notable achievements included the ‘relax’ DZDUGIRU;DYL&HHV¶LQÀDWDEOHVZLPPLQJ ring, Ana’s very own Olive oil trophy, Raheena’s roll of packing tape to prevent KHU RZQ VSHHFK DQG 0DUWLQV VRFNV with-sandals look. One particular prize was to be shared amongst almost every member of the trip during the barbeque that followed. The week was topped off by a soccer game and by a BBQ with a vast array of delicious foods, beginning at 6pm and lasting until the last sausage was cooked at around 1. The entire group bonded through the old Australian tradition of donning outrageously bright makeup while sharing food around a BBQ. I must say that Mr Luxembourg and Mr Baptist looked particularly fetching with their cheeks highlighted, and that purple shadow for the eyes is really their colour. So a big thankyou to everyone involved in organising and running the week, it was thoroughly enjoyable, and great to get RXWRIWKHFODVVURRPDQGLQWRWKH¿HOG Excursion Urban Watermanagement Excursion Urban Watermanagement Marloes van Ginkel 2XU ¿UVW YLVLW ZDV WR 5RWWHUGDP ZKHUH we visited Gemeentewerken Rotterdam. They have developed a very sophisticated solution for their rain water problem; a storage reservoir of 10.000 m3 under D YHU\ ODUJH SDUNLQJ JDUDJH &RVWV million euro. Our last excursion of this day was to IJburg near Amsterdam. They constructed an island in the IJmeer; a small scale example of Dubai. We spent the night in a castle in Heemskerk, where we had a good diner and drinks. 6HFRQGO\ ZH YLVLWHG WKH FLW\ RI¿FH RI Culemborg and talked about their urban ‘waterplan’. Investment costs: 8 million euro in 10 years. They designed the city quarter Lanxmeer, with a lot of attention to water, nature, ecology and good atmosphere. It was a very nice place. Druppel 3 - 2006 On the 1st and 2nd of June we have had a very nice excursion for the course Urban Water Management. )ULGD\PRUQLQJZHYLVLWHGWKHFLW\RI¿FHRI Haarlem and talked about their integrated urban ‘waterplan’. They have a progressive policy in Haarlem towards ground water management. It was interesting to talk about their experiences. We also visited two building sites. 13 Excursion Urban Watermanagement them, they were still in the building preparation phase. For our last visit we headed back to Delft. We visited the municipality and also met the waterboard there. They told us about their waterplan and we visited the city. They are going to disconnect the city canals from the Schie. Total costs are 12 million euro. A lot of attention is given to the communication with the citizens. Druppel 3 - 2006 After that we visited a Vinex location in Voorschoten, Krimwijk II, and we had an excellent lunch there. They are constructing a city quarter of 23 ha, with 660 houses, in the peat. When we visited 14 We concluded these two days in restaurant The Casserole in Delft and all went to bed early I guess. It had been two very interesting days. Fourth years project in the Phillippines Fourth years project in the Phillippines Joost van den Berg, Matthijs Lemans, Paul Roeleveld and I did a 2 month master project in Angeles City, in the Philippines. The project was about solving the water problems in Angeles City. I will not describe our project much further as we discovered there are only a few problems in the area. In a way this was sadly for us, but off course this is good for them. We have worked on river modeling, groundwater modeling and sanitary systems. For this particular piece in the Druppel, I think it is more interesting to write about the Philippines and our experience of working in this country. The Philippines is a third world country. About 40% of the citizens in Angeles City live below the poverty line. We saw many people live in self made houses. These houses were no bigger than 20 square PHWHUVDQGKRXVHVDERXWSHRSOHRQ average. The Philippines has a tropical climate, meaning an average temperature of 32 degrees and a humidity of 60-80%. During our stay it was the dry season, so luckily we did not experience too many monsoon rains. In the past, the Philippines was colonized by the Spanish and Americans. The Filipino people value their names a lot, so there are a lot of different names, ranging from Spanish names to Chinese to American names. Sometimes these names can be really funny, most funny of all was Fuk Jou IDPRXV)LOLSLQRER[HU:HZHUHPRVWO\ called “Joe” or “Hey Joe!”. ,QWKH¿UVWZHHNRIRXUDUULYDOLWZDV³+RO\ Week”. By coincidence, in our region they KDYHDKDELWRIGRLQJFUXFL¿[LRQVGXULQJ this week. We just had to see it. The people do not get to see the part where WKH\ SXW WKH QDLOV WKURXJK WKH FUXFL¿HG persons hands and feet. So actually, LW ORRNHG OHVV WHUULI\LQJ WKDQ ZH ¿UVW DQWLFLSDWHGZHRQO\JRWWRVHHWKH¿QDO UHVXOW D FUXFL¿HG PDQ 1HYHUWKHOHVV LW was quite impressive to see them nailed WRDFURVVKDQJLQJXQFRQVFLRXVLQWKH burning sun, with thousands of people watching them, taking pictures, praying for them and eating ice cream. Ice cream vans are all over the Philippines. If you didn’t see one, you could hear one. Druppel 3 - 2006 Jair Smits Fourth years project in the Phillippines Druppel 3 - 2006 We worked most of the time at the University of the Philippines in Quezon &LW\ 0DQLOD :H VKDUHG WKH URRP with the technical staff, consisting of at least 3 people, and the secretary of the department. During our stay, the WHFKQLFDO VWDII KDYH ¿[HG D ODPS DQG checked whether the TV was working every day. In the beginning we had the KDELWRIZRUNLQJXQWLODERXWSP2XU SURIHVVRU DVNHG XV WR VWRS EHIRUH SP because else the university had to pay the technical staff extra for overwork, since they are also in charge of closing the place. Transportation was just crazy. The horns went off non stop, the cars were changing lanes all the time, there is a near crash 16 event at least once every 3 or 4 minutes and one of our taxi drivers actually hit a dog that crossed the street and was ODXJKLQJ LV DVV RII IRU GRLQJ LW WKH GRJ was killed). There are so called Jeepneys all over the place. These are jeeps that the Americans left behind, which the people transformed into some Jamaican looking YHKLFOHV0RUHWKDQSHRSOHFRXOG¿WLQ A ride costs up to 10 euro cents. In our weekends we went out exploring the Philippines and in the evenings of the week days we sometimes used to go out, buy some DVD’s, buy some DVD’s and meet some Filipino people and buy some DVD’s. Internship in Tanzania Internship in Tanzania This is a short message from Dares Salam, Tanzania. They write the measurements every day at nine o’clock. Tanzania is a great country, everyone is very friendly. The last two weeks actually were one big jeep safari in a big Land Rover. You just can’t drive with any other car on the “roads” of Tanzania. We’ve been in Dares Salaam for three days now. We visited a workshop of the Sokoine University there. Yesterday we were at the campus of the Dares University to collect some knowledge there. So far I’ve done the following things: I’ve tried to learn all new names, I’ve tried to learn Swahili and I’ve fought the rain gauges and the dust. We have also made some astonishing walks to collect water samples and to place new rain gauges. 7KH 0DNDQ\D FDWFKPHQW LV DOPRVW ¿OOHG with these things. So I’ve also started to read the measurements of the stations and collect the data. One rain gauge usually costs us around an hour. This is because we need to get there and collect the data from the farmers. Today Marloes went away again. So I’m alone now, let’s see if I can safely head back to Makanya tomorrow. I hope everthing is readable. This was the supershort story. I fear I need to organise a slideshow in Delft some day. This was it, the boy of the internet café wants to close. By the way, thanks for all the emails. See you in around 2 weeks. Regards, Ben Druppel 3 - 2006 Benjamin Fischer 17 Master thesis Erik Liefting Master thesis Erik Liefting Erik Liefting Within the framework of the project ‘Interactions in wastewater systems II’ an extensive monitoring campaign is being set up in the wastewater system of Eindhoven. Druppel 3 - 2006 The aim of the measuring program is to get insight in the water quality processes in the system. A future goal is to make SROOXWLRQEDVHGUHDOWLPHFRQWURO3%57& possible. In total more than 60 sensors will be used in the Eindhoven wastewater system, most of which are water quality sensors and others are water quantity sensors. Parameters that will be measured are turbidity, temperature, chemical R[\JHQ GHPDQG &2' DPPRQLXP DQG conductivity. The combination of the large size of the wastewater system, the amount of parameters and sensors and the high PHDVXULQJ IUHTXHQF\ RQFH SHU PLQXWH makes it an ambitious project. It will probably yield millions of data items. The next challenge is to process those data. Problems in acquiring data from sewer systems are many. Often the quality of the collected data is bad due to failing sensors or failing data storage. Also human faults may be a cause of faulty data. To be able to handle the concept of data quality better, we make a distinction EHWZHHQ¿YHDVSHFWVUHOLDELOLW\DFFXUDF\ FRPSOHWHQHVV DFWXDOLW\ DQG YHUL¿DELOLW\ of the data. 18 1. The reliability of the data is their physical soundness. The reliability can be affected by non-physical information, artefacts. 2. The accuracy of the data depends on the accuracy of the measuring instruments. However, it is useless to improve the accuracy when the data are not reliable. 3. A dataset has to be complete; missing data decrease the quality level. 4. The data are called actual if no changes of the conditions since the measuring period have made them obsolete. 7KH YHUL¿DELOLW\ RI WKH GDWD GHSHQGV on extra information, for example information from logbooks and data from ZHDWKHU VWDWLRQV DQG IURP RWKHU NLQGV of) sensors. 7KH¿YHDVSHFWVFDQEHDIIHFWHGE\DORW of possible different failing mechanisms, ranging from installation faults to fouling, physical breakdown or disordered data storage. For my graduation I am checking data quality on the basis of the abovementioned criteria; in other words, I am validating data. Being halfway through my thesis work, I have developed some tools to research the data quality, especially their reliability. I mainly use statistical methods, but also physical information and models: ordinary linear regression models and the more powerful neural networks. Master thesis Erik Liefting The next step is to integrate these tools into one computer program that can execute all tests on the datasets. With this program it will be possible to identify small as well as large data sections with bad quality. Even single measurements FDQEH¿OWHUHGRXW The datasets will be examined separately as well as combined with other sensor data; the models are used to identify a possible correlation between them. Incidental deviations from that correlation may indicate artefacts in one ore more datasets. All data will be labelled as probably good, doubtful or probably faulty. The original datasets will be preserved, but when you know that the quality of some sections is probably bad, it is possible to make new datasets where faulty data are substituted by interpolated good quality data. Such datasets can be used to model the processes in the system better. Druppel 3 - 2006 The amount of data coming from this project requires automation of the tests, so I have written them in Matlab-scripts. 19 Green Roofs Green Roofs Sigrid Scherrenberg This article was written as an assignment for the course Urban Watermanagement and selected as one of the best articles handed in to the teacher. Druppel 3 - 2006 20 Introduction This essay about green roofs is not about roofs which are painted green. It is about roofs which have a soil layer with vegetation as a roof, see also Figure 1. The vegetation has the capacity to reduce stormwater runoff volumes, to reduce SHDN ÀRZV DQG WR FRRO EXLOGLQJV GXULQJ VXPPHUPRQWKV(PLOVVRQDQG5ROI Köhler et al., 2002). A distinction can be made between extensive and intensive JUHHQURRIV0HQWHQVHWDO Extensive green roofs have a very thin soil layer which can be down to a few FHQWLPHWUHV %HQJWVVRQ HW DO WKH VORSH DQJOH RI WKH URRI FDQ EH 0HQWHQV HW DO 7KHVH URRIV require almost no maintenance. The soil can dry out easily, as a result of the thin layer, when there are long periods without precipitation. Because of this special plants, like Sedum album and Sedum acre, that can survive long dry SHULRGV DUH XVHG (PLOVVRQ DQG 5ROI ,QWHQVLYHJUHHQURRIVKDYHDWKLFN soil layer, this layer can be more than FHQWLPHWUHV %HQJWVVRQ WKH VORSH RIWKHURRILVOHVVWKDQ0HQWHQVHW DO'XHWRWKLVWKLFNOD\HUWKHURRI can look like an ordinary garden, even trees can grow on it. Intensive green roofs need more maintenance and need a special roof construction because of the KHDY\ORDGV(PLOVVRQDQG5ROI Construction Building a green roof is not putting some ground on the roof en letting plants grow on it. A green roof is an extension of the H[LVWLQJ URRI )LJXUH PDGH RI D KLJK TXDOLW\ ZDWHU SURR¿QJ D URRW UHSHOOHQW V\VWHPDGUDLQDJHV\VWHPD¿OWHUFORWK a light weight growing medium and plants *UHHQ5RRIV Figure: Construction of a green roof *UHHQ5RRIV The light weighted growing medium, or substrate, mainly contains inorganic material with a high water-holding capacity and a low density, such as lava, pumice or H[SDQGHGFOD\(PLOVVRQDQG5ROI Green roofs can be established on-site or by bringing prefabricated vegetation to WKHURRI(PLOOVRQDQG5ROI:KHQ a green roof is established on-site the substrate needs to be good and the roof needs to be covered with plants rapidly to prevent erosion during rain events (PLOVVRQDQG5ROI Green Roofs Figure: Relationship between the annual runoff and the annual rainfall for various URRIV0HQWHQVHWDO %HQJWVVRQ HW DO IRXQG WKDW WKH annual runoff from a 3 cm sedum-moss green roof in Southern Sweden was about half of the precipitation. Mentens et al. IRXQGDUHODWLRQVKLSEHWZHHQWKH annual runoff and the annual rainfall for YDULRXVURRIV)LJXUH,WLVFOHDUIURP WKLV ¿JXUH WKDW WKH DQQXDO UXQRII IURP green roofs is lower compared to the runoff of a traditional roof. The rainfall relationship is quadratic for green roofs, this is due to higher annual precipitations interfere with a higher amount of extreme events, for which retentions are lower 0HQWHQVHWDO Druppel 3 - 2006 Effect on stormwater runoff Green roofs have the potential of retaining and delaying rain water during storms 0HQWHQV HW DO $ ODUJH SDUW RI the rain water gets soaked up in the soil, a part is used by the plants and a part evaporates. When the soil on a green roof gets saturated the excess water will drain RII *UHHQ URRI (YHQ ZKHQ WKH UXQRII of these roofs is considerable it may be delayed relative to the intensive rain and to the runoff from other surfaces so that smaller stormwater pipes can be used compared to an area where no green URRIVDUH%HQJWVVRQHWDORUWKH number CSO events can be decreased 9LOODUUHDOHWDO.|KOHUHWDO Brendtsson et al., 2006). The maximum stormwater reduction takes place when the soil is near wilting point and it starts raining. The soil will VWRUHZDWHUXQWLOLWUHDFKHV¿HOGFDSDFLW\ The available storage of an extensive roof FDQ EH DURXQG PP %HQJWVVRQ HW DO 9LOODUUHDO DQG %HQJWVVRQ found that the retention depended for a great extent on rainfall intensity and the slope of the green roof. For horizontal green roofs, under exceptional dry initial FRQGLWLRQV GXULQJ VXPPHUWLPH XS WR PP RI UDLQ FRXOG EH VWRUHG WKH maximum retention of a sloped roof is 10mm. During winter and spring the roof always contains moist hence the green roofs are more effective in summertime WKDQLQZLQWHUWLPH9LOODUUHDOHWDO When the soil is saturated by stormwater and another storm follows, no stormwater reduction will take place, but there will be a delay because the required time for rain to travel horizontal and vertical through the soil will take longer than the time UHTXLUHGIRUWKHUDLQWRÀRZRIDKDUGURRI %HQJWVVRQHWDO Effect on the stormwater quality Green roofs ensure better surface water quality as it reduces the pollution caused by rainwater runoff or by combined sewer RYHUÀRZV .|KOHU HW DO *UHHQ roofs also contribute to the reduction of pollution of roof runoff by absorbing the pollutants. The runoff quality of green roofs is expected to be depended of the thickness of the soil layer, the soil composition, the type of drainage, the age of the roof and the type of plants %HUQGWVVRQHWDO 21 Green Roofs Care should be taken because green roofs can also contribute to the pollution when pollutants are released, for example when the pH changes heavy metals can EH UHOHDVHG %HUQGWVVRQ HW DO Another interesting thing is that intensive green roofs are often fertilized when they are built and in springtime. Fertilizer consist of nitrogen and phosphorous compounds which can also be released during a storm event. Druppel 3 - 2006 Figure: Retention of the pollution in SHUFHQWDJH RI WKH LQSXW .|KOHU HW DO 2002) ,Q.|KOHUHWDO)LJXUHLVVKRZQ which gives the retention of heavy metals and nutrients by green roofs. In Sweden research is done at several locations by %HUQGWVVRQ HW DO ZKLFK VKRZHG that extensive roofs did not contribute to rain water treatment. Conclusion Green roofs have the potential of retaining and delaying rain water during storm events. Little research has been done XQWLO QRZ WR LQYHVWLJDWH WKH LQÀXHQFH RI green roofs on the runoff quality. The research which has been done does not all agree with each other. 22 Literature Bengtsson, L., Grahn, L., Olsson, J., +\GURORJLFDO IXQFWLRQ RI D WKLQ extensive green roof in southern Sweden, 1RUGLF+\GURORJ\9RO1RSS 268 Berndtsson, J.C., Emilsson, T., Bengtsson, / 7KH LQÀXHQFH RI H[WHQVLYH vegetated roofs un runoff water quality, Science of the Total Environment, Vol. SS (PLOVVRQ 7 DQG 5ROI . Comparison of establishment methods for extensive green roofs in southern Sweden, Urban Forestry & Urban Greening, Vol. 3, pp. 103-111 Köhler M., Schmidt, M., Grimme, F.W., Laar, M., de Assunção Paiva, V.L., Tavares, 6 *UHHQ URRIV LQ WHPSHUDWH climates and in the hot-humid tropicsfar beyond the aesthetics, Environmental Management and Health, Vol. 13, No. 4, pp. 382-391 Mentens, J., Raes, D. and Hermy, M., *UHHQURRIVDVDWRROIRUVROYLQJ the rainwater runoff problem in the urbanized 21st century?, Landscape and Urban Planning, Article in Press, accepted )HEUXDU\ Villarreal, E.L. and Bengtsson, L., 5HVSRQVH RI D 6HGXP JUHHQ roof to individual rain events, Ecological (QJLQHHULQJ9ROSS Villarreal, E.L. Semadeni-Davies, A. DQG %HQJWVVRQ / ,QQHU FLW\ stormwater control using a combination of best management practices, Ecological Engineering, Vol. 22, pp. 279-298 Websites Green Roof: www.greengroof.se Green Roofs: www.greenroofs.net Water for Benin Water for Benin Dr. P. Bol Figure: A girl in Benin Benin is an African country about four times the size of the Netherlands. Nigeria and Ghana are well known neighbouring FRXQWULHV 0$3 ,WV RI¿FLDO ODQJXDJH LV French. The country has known a period of communism and was for some time even a free haven for political extremists. Those times are long gone and at the moment Benin is a democracy and has a rather stable government. It is however poor, with a yearly income of 1100 dollar per capita and with a third of its population living below the poverty line. As in most developing countries, the availability of clean water is essential for health improvement but this commodity is not within reach of everyone. Urban 6FDUFLW\RIHQHUJ\ZRRGNHURVHQHDQG lack of education and information prevent proper water treatment and the result is water-related disease. Particularly gastroLQWHVWLQDO GLVRUGHUV RIWHQ GLDUUKRHDO diseases) are frequent and also a prominent cause of death, especially in FKLOGUHQ XQGHU ¿YH $PRQJ WKHVH DUH typhoid, bacillary dysentery, amoebic dysentery, bilharzias, dracontiasis and hepatitis A. Druppel 3 - 2006 areas are often served by a water distribution network organized by the State Water Company, but most rural areas are not. Women and girls have to walk far to fetch water from rivers, pools and ponds and sometimes from wells. Invariably the quality of the water is low, and sometimes it is heavily polluted, chemically and microbiologically. Figure: The well works! The aim of the Dutch-Beninese RUJDQL]DWLRQ µ/H 3RQW¶ 7KH %ULGJH LV D VXI¿FLHQW DPRXQW RI FOHDQ ZDWHU IRU villages that are unlikely to be connected to the main water supply in the foreseeable future. 23 Water for Benin At the moment the foundation is busy setting up wells in 10 villages in the South-West of Benin, where slow sand ¿OWUDWLRQ V\VWHPV WUHDW DERXW WLOO m3 of pumped up water a day. This is VXI¿FLHQWGULQNLQJDQGFRRNLQJZDWHUIRU the communities. At a later stage Le Pont would like to realize 7 more wells in the South-East of Benin. Druppel 3 - 2006 Normally there is a gap between plans and the situation after realization, and this is also the case with our projects. 'RULV YDQ +DOHP KDV VSHQW WKUHH months in Benin at the beginning of this year. She encountered a lot of problems, but failures provide a chance to learn and Le Pont is doing its best to improve the future works. Figure: Doris van Halem in Benin Unique (QJLQHHUV DQG DOVR GRFWRUV DUH TXLWH often focused on technical solutions. But the problems they want to solve are part of the intrinsic tissue of society. This implies that sometimes the most wonderful technical devices will not work and that very simple non-technical interventions may work wonders. 24 This is also the case when one changes the way that water is supplied to people who for centuries have collected their water from pools and shallow surfaces. /HW¶VORRNDWWKHSRVVLEOHGLI¿FXOWLHV Figure: Putawakou &OHDQ ZDWHU FRVWV VRPH PRQH\ Though the price is kept low, surface water is free, although it is at a large walking distance. 2. Can the population appreciate the QRQWDVWHRIWDSSHGZDWHU"2XUJUHDW grandmothers often kept taking water IURP FDQDOV DQG ULYHUV DIWHU WKH 'HOIW engineers had supplied their towns with water networks in the second half of the 19th century. At least the water of one ¿OWHURI/H3RQWLQ%HQLQLVQRWDFFHSWHG because of its cement taste. 3. Are the people able to understand the ¿OWUDWLRQSURFHVVDQGFDQWKH\KDQGOHWKH pump and the tap properly? There are H[DPSOHVRILQWHUYHQWLRQZLWKWKH¿OWUDWLRQ V\VWHPµFOHDQLQJ¶DQGWKDWHYHQVLPSOH technical devices are handled wrongly. Also, ignorance and lack of insight can cause spillage. 4. Can people grasp the ultimate goal of WKHVDFUL¿FHVWKH\PDNHIRUFOHDQZDWHU ODERXU PRQH\" 7KDW JRDO LV RI FRXUVH public and individual health. Water for Benin Figure: Women in Benin Le Pont has taken up an education and information program to introduce the ¿OWHUV WR WKH ORFDO SRSXODWLRQ $QG WR VDIHJXDUG WKH ¿OWUDWLRQ DQG GLVWULEXWLRQ every water point will have a water vendor who charges the water per jerry can taken. But since the price of the water is kept very low, she cannot make a living from this. Therefore the proposal is that she will have a small vending stall at the water point. Everyday commodities such as matches, batteries, snacks, cool drinks and the like can be obtained there. Most villages don’t have a shop and the inhabitants have to travel far to a market town to get their supplies. The stalls are therefore serving a need, apart from providing the vendor with a reasonable income. This concept reminds one of the so-called ‘komenijswinkels’ in the 19th century Netherlands. Here, apart from drugstore and ‘colonial’ articles, one could buy clean drinking water by the bucket, hot FRDOVIRUVWDUWLQJWKHVWRYHRU¿UHSODFH DQGLFHIRUWKHVLFN Call for support The Le Pont foundation does not pretend to have the ultimate knowledge and insight for solving Benin’s water problems. If there are any readers who have alternative views on technological and organizational aspects, and who would like to share these with us, we will be thankful to learn from them. In our department of Water Management there are three people who can be contacted: Dr. ir. Bas Heijman: [email protected] Doris van Dalem: [email protected] Dr. Pieter Bol: [email protected] Chairman of Le Pont: Ing. Kees Berkman: [email protected] ZZZOHSRQWQOWHO Dr. Pieter Bol is medical epidemiologist and teaches ‘Public hygiene and HSLGHPLRORJ\¶&7+HLVDGYLVHURI the foundation Le Pont. Druppel 3 - 2006 But even in Holland, after one and half a century of sanitation, only a small minority of the population understands the enormous importance of safe drinking ZDWHU,KRSHDOOUHDGHUVRIµ'UXSSHO¶DUH among it!). Aid for Suriname 7KHÀRRGVZHUHWKHZRUVWLQPHPRU\ Action Committee WiSST Druppel 3 - 2006 Several parts of the interior of Suriname were declared disaster areas after being KLWE\PDVVLYHÀRRGLQJLQWKHEHJLQQLQJ RI0D\7RUUHQWLDOUDLQVKDYHÀRRGHGWKH entire south and parts of the central Amazonian Lowlands of Suriname. Up WR WKDWFKHGKXW YLOODJHV KDYH EHHQ submerged under as much as two metres of muddy water and some are so badly ÀRRGHG WKDW RQO\ WKH KXW URRIV FDQ EH seen from the air. The affected districts include Sipaliwini and Brokopondo, where most of the inhabitants are descendants of West African slaves known as Maroons. 7KHVH YLOODJHUV VWDUWHG WR ÀHH WR KLJKHU grounds when the rains started at the EHJLQQLQJ RI 0D\ 6RPH SHRSOH have been directly affected. In the disaster area the most urgent food, water and shelter needs have met. While distribution of food packages is improving, water and sanitation currently remain the major concerns. Chlorine tablets are distributed throughout the area, but improving access to clean drinking water remains a major challenge. Several FDVHVRIGLDUUKRHDKDYHEHHQFRQ¿UPHG An outbreak of malaria has also been detected. The lack of proper sanitation systems and clean drinking water threatens the health of the population in WKH DUHD 7KH ÀRRGV ZHUH WKH ZRUVW LQ the memory of the Surinamese people. Especially for the ones living on the small islands in Suriname’s Eastern Rivers, there was literally no place to go. Responding to the effects of the PDVVLYH ÀRRGV WKDW KDYH ODVKHG WKH QDWLRQ RI 6XULQDPH :,667 :HUNJURHS 26 Inzamelingsactie voor Suriname door Studenten TUDelft- Action Committee for Surinam Aid ) has expressed their concern and solidarity. The action committee contains TUDelft students from different educational background and is established to provide help. Providing help is done in 2 stages. The ¿UVW VWDJH LV UDLVLQJ PRQH\ IRU ¿UVW DLG 7KLV LV GRQH E\ RUJDQL]LQJ D %HQH¿W party, collecting around Delft and writing donation letters to Civil-Engineering corporations. Secondly, projectgroups will be formed with the help of prof. H.H.G.Savenije of Hydrology. prof. T.Olsthoorn from geohydrology and Prof J.C.Van Dijk from drinkwater technology. These project groups will be working RQ D VWXG\ RI WKH SRVVLELOLWLHV RI ÀRRG management in the disaster area. 3RVVLELOLWLHV RI ÀRRG FRQWURO DV ZHOO as safe havens, forecasting, warning and evacuation will also be taken into account. Students who are interested in participating in the project part can contact Prof.Savenije. Weather forecasts predict more torrential rains in the affected areas. This is not unusual for this period of the year, since the long wet season in Suriname runs until the end of July, but it certainly will have some effects on the water levels. One night of rainfall could cause a river to rise again and recovery operations will have to start all over again. Donations are still welcome at giro 8978720 ovv WISST. The money will be doubled by Gemeente Delft. Indien onbestelbaar retourneren naar: Dispuut watermanagement - Faculteit Civiele Techniek en Geowetenschappen - TU Delft Stevinweg 1, kamer 4.74 2628CN Delft