Yıldız (Istranca) derelerinin hidrometeorolojik açıdan incelenmesi /
Yazar: SEVİNÇ SIRDAŞ
Danışman: PROF.DR. ZEKAİ ŞEN
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Meteoroloji Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 1996
Konu: Meteoroloji = Meteorology
Dizin: Hidrometeoroloji = Hydrometeorology ; Istranca dereleri = Istrance streams ; İstanbul = Istanbul

Özet:
ÖZET İstanbul'da giderek artan nüfus ve endüstrileşme hareketleri sonucunda bugün için şehrin var olan su sorununun gerekli ilave kaynakların getirilememesi durumunda daha da artacağı bilinmektedir. İstanbul'un her iki yakasındaki barajların bir anlık için toplam kapasiteleri 600 Mm3 kadardır. Halbuki bugün için bile şehire günde en azından 2.5 Mm3 suyun verilmesinin gerekli olduğu düşünülürse % 40'lara varan kaçaklarla kucak geçebilecek zamanlarda mevcut kaynakların İstanbul'un talebini karşılayamayacak durumlara düşmesi beklenir. Bu çalışmada da mevcut kaynaklardan olan Yıldız (Istranca) Derelerinin durumu incelenmiş ve burada kurulmuş olan tesislerin talep-risk, hacim-talep ve hacim-risk eğrileri elde edilmiştir. Bir bölgenin so kaynaklarının hesap ve planlanmasında ilk adım iklim ve özellikle yağış durumlanmn bilinmesidir. İncelenen bölge özellikle yaz aylarında Karadeniz ile Marmara danizlerinin etkisi altında başkalaşmış olan Akdeniz tipi bir iklimin tesiri altındadır. Bir bölgedeki meteorolojik değişkenlerin kendi aralarında nasıl değiştiğinin incelenerek o yerin iklim özellikleri hakkında bilgiler üretilmesi mümkündür. Bunun için orada yapılmış olan değişik meteorolojik değişkenlerin oldukça uzun yıllar (en az on yıl) olmak üzere yapılmış olan kayıtlarından ortalama değerler bulunur. İşte iki farklı değişkenin ortalama değerlerinin bir kartezyen koordinat sisteminde ortak aylar için bir noktayı gösterecek şekilde noktalanması ile elde edilen grafiklere İklim Çokgeni (İKÇOK) adı verilir. Aynca yağış ve akış verilerinden yararlanılarak YAKAÇ adı verilen çokgenlerde çizilmiştir. Herhangi bir akarsudansudan ihtiyaca eşit veya ondan daha fazla suyun bulunması halinde ihtiyacın karşılanarak fazlasının denize akışına müsade edilmesi, ihtiyaçtan az akışın bulunduğu zamanlarda ise mecrada bulunan kadar su talebin kısmen karşılanabilmesidir. Talep-Güven eğrileri yardımı ile t gibi bir talebin karşılanması veya karşılanmaması zaman yüzdeleri bulunur. 16 dere için hesaplanan debi gidiş çizgileri birbirine benzer ve eksponansiyel olarak azalan tiptedirler. Bir su biriktirme yapısının su temini açısından en önemli büyüklüğü hacminin belirlenmesidir. Verilen bir giriş akımının biriktirilmesi için gerekli olan hacim değerlerinin talep yani verim ile değişiminin bulunmasında hacim-talep (kapasite-verim) eğrileri yöntemi kullanılmıştır ve bu eğriler ikinci dereceden polinom olarak bulunmuştur. Talep-güven ve hacim-talep eğrileri kullanılarak yeni bir eğri elde edilmiştir ve buna hacim-güven eğrisi adı verilmiştir. Bu grafikler pratikte o yer için kabul edilebilecek güven seviyesine karar verildikten sonra hazne hacminin ne olacağına karar vermeyi sağlar. Bu çalışmada elde edilen eğrilerden görülmüştürki büyük güven değerlerinde hacim azalmaktadır. Hacim ile güven arasındaki denklem üstel olup : H = a.g"b şeklindedir. XVIII

Abstract:
SUMMARY Increase in the population and expansion in the industrialization continue steadily and if additional water resources are not transferred to Istanbul there might be water shortages in the future. Unfortunately, water intakes from assisting surface reservoirs within the city municipal borders are not different. Besides, ground water has already been exceedingly exploited and at planes due to pollution they are already last far water usage's for domestic or industrial purposes. Although sizes of surface water reservoirs such as Terkos, Büyükçekmece and Alibeyköy on the European side and Ömerli, Elmalı and Darlık dams on the Asian side have all together about 600 Mm3 existing total capacity of course, during the course of a year more than this amount is collected and distributed from these size reservoirs. Daily about 1.5 Mm3 of water is transferred to city by pipe line network. Unfortunately, for the time being it is known that almost 40% of this amount is lost either by leakage's from the pipes as by illegal usage. It is wisely decided that for the last 15 years various projects are proposed and most of them are actually completed or under constriction either for increasing the water supply from distant regions or to reduce the leakage. Such an initiate has been already started in Yıldız maintains region as the first stage including Duzdere, Kuzuludere, Büyükdere, Sultanbahçe, Erikli streams. Already the first three have been constructed and they started to function in 1995. The watershed areas are calculated by planimeter which represent the horizontal area which is drained by the whole system projected on an horizontal plane. Of course prior to the calculation of the drainage area it is necessary to delimit the watershed area. It is referred in the literature that this area is related to many different magnitudes of hydrometeorological events such as the peak discharges, the total aerial rainfall and runoff. The length of the main course is determined as the distance from the outlet of the drainage divide to the source of water along the overlandflow. The length of the main channel is also referred to as the basin length. Hence the division of the main channel length to the drainage area is defined as the drainage density. These parameters are calculated for whole the drainage basins considered in this study. The meteorological parameters are used in order to define the climate of the region. The records of the climatic variables were available for rainfall, temperature, relative humidity and to a certain extent evaporation amounts. As a result it is not very hot in the summer and not cold in the winter. In addition to this, the weather which is especially effective in mountainous regions and sea-water XIXmass has a considerable influence in the climate. For example, because of topographic height differences, beginning from the Black sea cost towards south, at a certain rate, rain fall increases. As a result of this, the streams on the hills facing Black Sea take surgical rungs to the sea. Especially, ranging of the heights through costs lessens the connection with costs. That is why as a result of rising of the clouds which are full of damp, air rainfall occurrences take place very often along the south heights. Average temperature is about 14 °C. It is very rare when it is below zero daily. Average monthly temperatures that rises after March decrease after August. Change of dampness differs between %50 at the bottom limit and %85 as a top limit Average dampness in different seasons is about %75. Mainly wind in west sides is from north-northeast. However, between November and April winds from south increase. Mainly wind blows are all year long from southwest. Period of having sunshine for this region in summer season is longer than that of the other seasons. In July and August average period of having sunshine is about 11-12 hours. So evaporation is more than the other times. But in winter it is rarely more than 3-4 hours On a Cartesian coordinate system the plot of any two different monthly meteorological variables shows a scatter diagram with twelve points. The connection of these points successively by straight lines provide the general appearance of the change between these two meteorological variables. Such scatter diagrams are referred to as the "Plimate Polygons" (CM). These provide valuable means in order to make further interpretations about the climate conditions in an area. In general these CM's are random in appearance but at places they provide rather regular shapes. Such graphics obtained by rising the average values of two variables in a Cartesian coordinate system to indicate a point for common months, are called "Climate Polygon". They are called polygon, because polygons are at random are obtained, when such points will be bound successively by a straight line to follow the months in a year. In this study, the statistical parameters about rain fall and surface flow are obtained following the aforesaid faints studies. Furthermore, demand-risk, volume-demand end volume-risk curves, are obtained which constitute the basis of this study. These graphics requireq the study of water deficiency or surplus, resulting from water supply from the flows through brooks, creeks, river and streams of a river basin, which due to rain overflow fall and surface the flow reach the sea or lake. If there is no construction of regulator, dike or dam along the stream coarse. The most important point here is that no accumulation or regulation reservoir is built on abovementioned watercourses. In other words, if water is equal or more than demand, the surplus shall be let to flow to the sea, after meeting the demand, and if water is less than demand, then the existing amount of water shall meet the demand partially. In this manner, after truncating the discharge sequences level there will appear water surpluses or shortage. If the flow rate amount is shown as xxDj ( i =l,2,3,.~..,n ) intervals; and demand is equal to T, then we get a bivarrate variable as I <0 then the demand is not met Dr T = { { >0 then there is a demand surplus The fact that in how many time intervals the demand is met throughout the whole time axis will be counted and found out be nIs then the number of the cases when the demand is not met shall be stated as n2 = n-n1. Thus, the time percentages for fulfilling or not fulfilling demand as will be obtained as p=100ni /n and q = 100n2/n. As to perceive from these definitions that p + q = 1.0. One should remember that for every demand different pair of will be obtained. Furthermore, at high demand values p fulfillment value will be low and at low demand values it will be high. It is concluded that with the increase of demand p will decrease as inversely proportional. The change of fulfillment (percentage) with demand is called Flow Rate Continuality Line. The flow rate lines, calculated at 16 flow measurement points are similar to each other and they all decrease exponentially. For instance, at Balkan Dam site The time percentage of demand met and the flow rate continually line, representing the variation, has an exponential shape and is expressed as follow: t = 23.53e4WM,6r (1) t = 100-23.53e-