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Öğe DETERMINATION OF THE WATER YIELDS FOR SMALL BASINS IN SEMI-ARID AREAS: APPLICATION OF THE MODIFIED TURC METHOD TO THE TURKEY'S CONDITIONS(Univ Zagreb, Fac Agriculture, 2005) Konukcu, F.; Istanbulluoglu, Ahmet; Kocaman, IsrafilThe Turc Method is used widely in Turkey to determine runoff depths therefore, water yield from a particular watershed and subsequently the reservoir's volume by Turkish General Directorate of Rural Services which is responsible for the investments on agricultural and rural infrastructures. However the method over predicts the water yield markedly when compared to the directly measured long-term water yields, which increases the total cost for the instruction of reservoirs and leads to environmental hazards due to disturbing more agricultural areas. In this research, the Turc Method was modified through replacing the new coefficients with the original coefficients of the 300 and 0.9 by fitting the calculated values to the directly measured long-term, a total of 223 years, in 22 sub-basin distributed throughout Turkey. Coefficients 566 and 0.68 were proposed as average values for Turkey in general instead 300 and 0.9, respectively, though the new coefficients for a particular watershed varied widely from 20 to 1135 and from 0.4 to 1.32, respectively. The country's sub-basins divided into three groups in terms of basin characteristics affective on these coefficients and new coefficients were also suggested for each group. Employing the modified Turc Method with these new coefficients for the research sub-basins can reduce the reservoir's volume by 45 % and this may decrease the total cost of the reservoirs by about 20-25 % through reducing occupied surface area, embankment and crest height.Öğe Development of Water Resources and Agricultural Practices under Irrigation in Thrace Region: Analysis of Existing Data for the Solution of Problems(Univ Namik Kemal, 2006) Istanbulluoglu, A.; Konukcu, F.; Kocaman, I.Although Turkiye, particularly Thrace Region, seems to be rich in soil and water resources in comparison to its location, population growth, pollution caused by industrialisation and possible global warming threaten the high potential cultivated lands and important water resources and shadows food security and economical development. Shortages in these resources are not only inevitable for all sectors but also affect profoundly irrigated agriculture which has an important place in the country's stability. In this research, soil and water resources potential of Thrace Region located in the European part of Turkiye were investigated, problems in relation to the use of water resources for irrigation in the regional base were evaluated, practical solution to the existing problems were suggested analysing the available data thoroughly. Problems and solution were categorised into three: problems related to the use of available resources wisely, problems encountered during the application of water, problems faced during operations. Initiating works to improve water resources before being late, producing scientific projects and supporting them with priority were particularly emphasised to overcome inevitable future water crisis in the region.Öğe Dry drainage: A sustainable solution to waterlogging and salinity problems in irrigation areas?(Elsevier, 2006) Konukcu, F.; Gowing, J. W.; Rose, D. A.Estimates of the global extent of irrigation-induced soil salinity vary, but there is widespread agreement that the twin menaces of waterlogging and salinisation represent serious threats to the sustainability of irrigated agriculture in many and and semi-arid regions. In certain circumstances, the conventional drainage solution may be questionable due to economic and/or environmental limitations and dry drainage has been postulated as an alternative. It involves the allocation of areas of fallow land, which operate as evaporative sinks drawing a stable flux of water and salt from irrigated areas. An evaluation of the merit of this approach requires answers to three key questions: (i) What is the limiting crop intensity? (ii) What is the limiting watertable depth? (iii) what is the long-term impact of salt accumulation in the drainage sink area? A simulation model was developed to investigate these questions for a dry-drainage system with a wheat-cotton cropping pattern using published data for the Lower Indus Basin in Pakistan, where shallow saline watertables, intensive irrigation, high evaporative demand and natural dry drainage exist. The simulation results showed that dry drainage could satisfy the necessary water and salt balance when the cropped area and sink area were approximately equal and watertable depth was around 1.5 m. The long-term impact of salt accumulation on the performance of the system was also considered. (c) 2005 Elsevier B.V. All rights reserved.Öğe Effects of Decreasing Soil Water Content on Evaporation under Saline and Non-Saline Conditions(Univ Namik Kemal, 2006) Coskun, Z.; Konukcu, F.Evaporation changes in mechanism and magnitude as the soil dries. Evaporation are closely related to the soil moisture. Penman's method is used most widely to define the upper boundary condition in computing evaporation from a relatively wet bare soil surface. It assumes saturated vapour pressure at the soil surface and calculates potential evaporation independent of the soil water content. It was modified by Staple (1974) including in it the soil's relative humidity of partially dried surface to predict evaporation from drying soils. The objective of this study was to investigate the rate of evaporation under aerodynamic (in door) and aerodynamic + radiation (out door) conditions for saline and non saline drying soil surface using Staple modified Penman equation seeking for further improvements. Soil samples (clayey) were first saturated with fresh and saline (16 dS/m) water and then exposed to evaporation. Generally, the agreements between simulated and measured rates for out/indoor conditions were good (R-2 = 0.90). However more deviation occurred at the beginning and the final stage, attributable to the difference in soil surface and air temperature. While the model calculated roughly the same rates for saline and non-saline conditions, the effect of soil texture is accounted by defining matric potential-water content and soil relative humidity-water content relationships.Öğe Impact of Shallow and Saline Water Tables on the Soil's Water and Salt Balance of Konya-Cumra District under Irrigation(Univ Namik Kemal, 2006) Konukcu, F.; Akbuga, R.Most of the irrigated areas are faced with waterlogging and salinity problem, whose irrigation schedules differ from a normal irrigation program. Capillary rise and subsequent salinity should be considered in these problematic areas. In this research, scheduling a new sustainable irrigation program was simulated for Konya-Cumra Irrigation District with shallow and saline water table conditions. The order of capillary losses from soils in magnitude from larger to smaller was loamy, sandy and clayey soils. Critical water table depths in terms of salinisation risks due to capillary rise were 1.0, 2.5 and 3.0, respectively for the sandy, loamy and clayey textures. For the chosen crop pattern, cereal-cereal, a considerable amount of salt accumulation was simulated during a three-month fallow period. With new irrigation scheduling, taking the capillary rise into account, not only a sustainable scheduling program is suggested but also a 10 % irrigation water is saved. The suggested program assumes the existence of a drainage system.Öğe Optimum Time Ratio for Maximum Application Efficiency in Furrow Irrigation(Univ Namik Kemal, 2006) Konukcu, F.; Delibas, L.Time ratio, which is defined as the ratio of the time required for infiltration of net amount of water needed for the rootzone to the time when the water front reaches the end of the run, plays a key role in determining optimum furrow length to achieve maximum irrigation efficiency. In this study, a model was developed to determine optimum time ratio for maximum application efficiency in furrow irrigation. The model was then tested on potatoes grown furrows, 0.75 m wide and 120 m long, with three different slopes 0.5, 1.0 and 1.5% and each slope had three different inflow rates (0.75, 1.0, 1.25 l/s; 0.4, 0.5, 0.6 l/s; 0.3, 0.4, 0.5 l/s, respectively). Stations with 10 m intervals were marked along the furrows to investigate the advance and recession speed of each rate. The attained application efficiency was 64 % for an average soil. It was concluded that when the intake rate was slow the maximum application efficiency could be attained providing that a relatively longer furrow length was chosen or vice versa.Öğe Research on the sedimentation and erosion problem of the Ergene River Basin in Western Turkey and precautions to control it(Maik Nauka/Interperiodica/Springer, 2007) Kocaman, I.; Konukcu, F.; Istanbulluoglu, A.The objective of this study was to asses the rainfall-runoff-sedimentation relationship from directly measured data since 1972, to find out the effect of the present land use and soil cultivation techniques on the sediment yield, and to offer practical solutions to the problems in the Ergene River Basins located in the European Part of Turkey. The suspended sediment yield was calculated by multiplying the daily average discharged water by the average sediment concentration, while the eroded coarse sediment yield was computed using a regression equation developed by the Japanese Ministry of Construction. The relationship between the runoff and suspended sediment rates was explained exponentially as S = 1.99 Q(A)(1.62) (P > 0.01 and R(2) = 0.846) (S is the suspended sediment rate in t d(-1), and Q(A) is the average daily runoff rate in m(3) s(-1)). The suspended sediment rates of the Ergene Basin can then be predicted from the flow rate at any time of the year using this produced regression equation. According to the results, 70% of the basin's soil (9534 km(2) and occupying 81.76% of the total area of the region) is under erosion hazard varying in intensity, namely, 25.3% light, 34.6% moderate, 8.6% strong, and 1.5% very strong. 47.09% of the average 604 mm precipitation falls in the critical period of October-January in terms of the sedimentation. The coarse and suspended sediment yield was 74.040 t km(-2) per year, which was well below the average for Turkey. However, it was 2 and 2.5 times larger than the average for Europe and Africa, respectively. Because 76.93% of the eroded land is in the 1rst, 2nd, and 3rd class, the severity of the sedimentation situation is proved. The causes of the high sediment yield were identified, and a series of precautions were suggested to minimize them.
