Süleyman Özhan

Sediment and nutrient discharge through streamflow from two experimental watersheds in mature oak-beech forest ecosystems near Istanbul, Turkey

Abstract Initial results concerning the seventeen months of the calibration phase of a paired watershed experiment are summarized. The water discharge from watershed IV is usually higher during the rainy season than that from watershed I, but this trend reverses during the dry season. Annual suspended sediment loads are low, of the order of 60–80 kg ha−1 yr−1. Mg, and particularly Ca and HCO3 concentrations vary inversely with the rate of streamflow. Average monthly loss of nutrients has significant correlations with streamflow. Regression equations for these relations are presented. Annual losses of Ca, Mg, Cl, HCO3 and Na are substantially higher than for K, N and P. The losses of N are 3—4 kg ha−1 yr−1 and those for P around 0.4 kg ha−1 yr−1.

Comparison of Rainfall-Runoff Relationship Modeling using Different Methods in a Forested Watershed

The daily rainfall-runoff relationship in an experimental watershed was modeled using a statistical method and an artificial neural network method. The estimations were examined and a performance evaluation was done. It was seen that the ANN method, FFBP (Feed Forward Back Propagation), provided closer flow estimations reproducing the shape of the observed hydrograph more realistic. The superiority of FFBP was reflected in the performance evaluation criteria. The extreme flows, i.e., high and low flows, were relatively better approximated by FFBP indicating its promise as a useful tool for hydrologic studies such as flood modeling. The Rational Method was also used, as a conventional tool, to predict the maximum discharge for selected return periods. It was found to be realistic for the forested watershed under consideration when the C coefficient was taken as 0.20 for the 10-year period.

Effects of recreational activities on the soil and water components of a deciduous forest ecosystem in Turkey

Impacts of recreational activities on some hydrological properties of a deciduous forest ecosystem related to water production have been evaluated with an inclusive soil study, coupled with a two‐year water quality monitoring program. Spatial variations of water quality parameters did not indicate a statistically significant deterioration caused by the recreational activities in the stream water, but the effects of trampling on physical soil properties were clear. The bulk density of the soils increased with the intensity of recreation from 1.18 to 1.29 g cm−3, while the percentage of clay fraction decreased, as an indicator of erosion. The soils of the stream banks in the recreation area had reasonable saturated hydraulic conductivity values, and were affected sharply by the intensity of recreational use. The low inclination (0.5%) and the coarse texture of the soils were possibly the main factors diminishing or concealing the trampling effects not observed on the water quality of the stream passing through the recreation area.

Results of a paired catchment analysis of forest thinning in Turkey in relation to forest management options

Adaptation to climate change has become a more serious concern as IPCC assessment reports estimate a rise of up to 2°C in average global temperatures by the end of the century. Several recently published studies have underlined the importance of forest management in mitigating the impacts of climate change and in supporting the adaptation capacity of the ecosystem. This study focuses on the role of water-related forest services in this adaptation process. The effects of forestry practices on streamflow can best be determined by paired watershed analysis. The impact of two cutting treatments on runoff was analyzed by a paired experimental watershed study in the Belgrade Forest and the results were evaluated in relation to similar experiments conducted around the world. Forest thinning treatments at 11% and 18% were carried out in a mature oak-beech forest ecosystem over different time periods. Although the thinning increased the runoff statistically, the amount of surplus water remained <5% of the annual water yield. Evidently, the hydrologic response of the watersheds was low due to the reduced intensity of the timber harvest. Finally, the results were combined with those of global studies on thinning, clearcutting and species conversion with the aim of formulating management options for adaptation.

Curriculum Vitae of Prof. Dr. Ahmet Hızal

Abstract Prof. Dr. Ahmet Hizal was born in Duzce on first of January 1, 1946 and died in a car accident on June 8, 2010. He was the Department head of Forest Engineering, Faculty of Forestry, Istanbul University. He served as an academician more than 30 years in the Department of Watershed Management. He published many research papers in the international and national scientific journals. Keywords: Professor Dr. Ahmet Hizal, watershed management, car accident Summary Prof. Dr. Ahmet Hizal, Head of the Department of Forest Engineering, Faculty of Forestry began his academic profession in 1979 and has carried out valuable studies during his academic life. He was a hard working, humble, honest, helpful and very kind person. He was role model for young scientist in terms of personality and ethics in science. Name: Ahmet Hizal, Professor of Watershed management, Date and Place of Birth: January 1, 1946 Duzce, Turkey Marital Status: Married, father of one Education: B.S. Forest Engineering University of Istanbul D. F. SC Watershed Management, Istanbul University Special Training: Soil survey and photo interpretation Netherland Languages: English - Good Awards Honors: The scientist of the year of 2010 by S.O.S (NGO) Experiences Teaching: Professor, Watershed Management, 1993-2010 Faculty of Forestry, Istanbul University. Associate Professor, Watershed Management Faculty of Forestry, Istanbul University, 1986-1993. Assistant Professor, Watershed Management, Faculty of Forestry, Istanbul University, 1982-1986. Instructor Watershed Management, Faculty of Forestry, Istanbul University, 1979-1992. Resources Management: Forest Engineer General Directorate of Forestry, Turkey 1969-1973. (Research assistant at Watershed Management) and Poplar and Fast Growing Forest Trees Research Institute 1973-1979. Publications: More than 70 scientific articles, papers on observations and experimental research published International and Turkish Journals. Administrative Activities: Head of the Department of Forest Engineering, Faculty of Forestry, 2005-2010. Editor-in-Chief for Review of the Faculty of Forestry, University of Istanbul, 2006-2007. Member of Faculty Board for the Faculty of Forestry: 2000-2003. Editor in Chief for editorial board of faculty of forestry: 2006-2007.