HİDROLİK KONDAKTİVİTE TAYİN METOTLARININ ERZURUM OVASI DRENAJ PROBLEM SAHA TOPRAKLARINDA KULLANILABİLME İMKANLARI ÜZERİNDE BİR ARAŞTIRMA

Authors : Ersan GEMALMAZ

Pages : 0-0

View : 32 | Download : 11

Publication Date : 2010-12-11

Article Type : Other Papers

Abstract :ÖZET Erzurum ovasının Yeşilyayla, Muratgeldi, Yolgeçit, Güzelova, çayırtepe, Soğucak köyleri arazilerindeki drenaj problemlerinin çözümü için toprakların hidrolik kondakitiviteleriııi tayin etmede mevcut hidrolik kondaktivite tayin _metotlarının kullanılabilme imkanlarım tespit etmek amacıyle yapılmış olan bu araştırmada, araştırma sahasında toprakların hidrolik kondaktiviteleriııin tayini için piezometre, well point, bozulmamış numune, hava girışli permeametre VSDA - ses tarafından önerilen tekstür+strüktür kore- , i lasyonu, Hom tarafindan önerilen ortalama tane çapı - permeabilite korelasyonu metotlarının elveirışli olacakları sonul!Una varılmıştır. ARESEARCH ON THE PRACTIBILITIES OF HYDRAULIC CONDUCTIVITY DETERMINATION METHODS IN THE SOILS OF THE DRAINAGE PROBLEM AREAS OF ERZURUM VALLEY One of the most influeneing factors related drainage planning is hydraulic conductivity. Success of a drainage project depends on the determinatian of hydrauJic conductivity which will be the measure of the rea! hydr~ulic conductivity of the soils with which the project is dealing. Even though selection of the method for the deternlination of the hydraulic conductivity among those developed methods to satisfy our needs best depends on the conditions of the soils in the drainage problem area; it also depends on the technical personal and the availability of necessary equipments. Taking into consideration these peculiarities mentioned in the above paragraph, this reseaıch has been done to find the most suitable methods for determining the soil permeabilities in the lands of Yeşilyayla, Muratgeldi, Yolgeçit, Güzelova, Kösemehmet, Çayırtepe and Soğucak viııages which are heavy drainage problem areas of Erzurum valIey. Twenty-five places having dissimilar profile characteristics were chosen for experiments and soil permeabilities were determined for different depths in these places below the water table by piezometer method. Undisturbed soil cores were taken from the soil 'layer above the water table for the same places to determine soil permeability in the laboratory. Disturbed samples to represent the soil layers as perfectly as possible were alsa taken fıom these places, which a piezometer was driven and undisturbed soİI cores picked, an,d the water used in piezometer tests wcre obtained to analyze later in the laboratory. Structuml and textural anaIyses were made and va]ues of "soiI pH measured İn water" were deteı:mined, chemical analyses were made to determine organic matter and carbonate in the soil samples; Na+, ca++ + Mg++, pH and electricaI conductivities of the water samples were measured in the laboratory. Undisturbed soiI samples wete saturated under vacuum and then permeabilities were measured by using 'constant or falIing head permeameters, however permeability values of disturbed soiI samples were determined by using constant head penncameters. Laboratory results indicated that soils have textures changing from sandy lo!im to elay and medium-high-very high organic matter, however the carbonate content of samples vaıied within large limits. Surveyed soiI strata have granuIarı black, sirıgIe and massiye soil structures. A1though usually massiye structure is observed in lower and granular structure in upper layers, Lhere are some exceptions. Chemical analyses of the water samples obtained from the places having extreme drainage pı oblem indicated saline and saline-alkali conditions. The results of the soil permeabi1ity tests show that research area soils consist of layers having very different hydraulic conductivities and in addition soil surveys indicate big differences in the thickness and depth of the soillayers. All of the determined soil properties clearly point out the heterogeneous character of research area soils. The (ollowing conclusions are reached, for the potentilal use of the present hydraulic conductivity determination methods in the research area soils, in the light of the knowledge gained through field, laboratory and offiçe work: Piezo~eter and Pomana wel1-point methods which are used for measuring the hydraulie conductivity in situ have the possibİ!ity of potential use in layered research area soils. Use of auger-hole methods could faıse results because soils are layered and the sensitiye deliniation of the soil strata with auger is very difricult. Tube method is not advisable far reseaı ch area soijs because of high water table requirements and survey difficiulties when water table is high; and also conduetivity measnremenb with this method is limited to relatively shallow ,,depths. Childs'two-well, Kirkha:qı's tourweII and well discharging methods require same conditions that are ditricult to obtain or to find in the research area; therefore use of these methods are very limited. Air entry permeameter method for the measurement of penneability ahove water table was found advantageous to determine hydraulic conductivity of the upper soil strata in the research area. The other methods used to measure permeability above a water table require excessive' amount .of material and time. Hence they were not found praetical to use. Determinatio~ of soil permeability with undisturbed soil co" res need more repIicates than the other advised methods because of the size and heterogeruty of this area;therefore it is not suggested as a proper method for the drainage surveys. Results of the soil permeability tests conducted on djsturbed soil samples did not give any carrelation with results obtained from undisturbed cores and measurements in place, therefore use' of disturbed soil samples for deterınining hydraulic conductivity is not suitable for research area soils. There are some advisable methods as mentioned above for direct measurement of permeability in the research area, however exceptionally heterogeneous character of the soils and the size of the drainage problem area whi-ch hydraulic conductivity measurements have to be conducted on is LO 000 hectares, therefore use of these methods will require too much time and effoıt. Those methods requiring less time, in other words indirect permea bjlity determinatian; simp1e texture-permeability correlation did not seem appropriate to use because soil structure has more influenee than soil texture on the permeability of the research area soils. USDA-SCS proposed textur+ estructurecorrela tİon method may be used with great confidenee in this area. In order to employ the method proposed by Ham which uses the mean 61 parcticle size estimated from texstural analysis, some soil texture-permeability curves to represent .the local conditions much better ôhould be obtained for these parts that the reseaıch area should alr~ady have been- divided into, considering siınilar soil properties. A~ a. consequence, hydraulic conductivities could be determined by in situ measurements to plandraİnage faciIitief> for sma1J areas; generalization of these results obtained from a fewactual measurement (no matter how carefuUy this permeability methods chosen for Iocal conditions and applied with great care) for val1ey soil&, however, could cost to unneeesessary investment or failure draİnage facilities which wiU cost a lot of spending.
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