Applicability of modelling tools in watershed management for controlling diffuse pollution.

Diffuse pollution is hard to analyze, control and manage by its nature. Watershed models and Geographical Information Systems (GIS) are recently developed tools that aid analysis of diffuse sources of pollution. However, their applications are not always easy and straightforward. Turkey is a typical example of a mountainous country rich in rivers and streams. Due to the complex geomorphology, land-use and agricultural practices in most of the watersheds in Turkey, modelling, analyzing and managing diffuse pollution has been a challenge. The complex watershed structure forces the modellers to work with spatially high resolution data. Apart from the data, the models themselves may also cause operational problems. These issues and their probable solutions form the basis of the discussions in this paper. It acts as a guideline for modelling and analyzing diffuse pollution by emphasizing the referred problems and difficulties. Design of an Information Technology-based system tool for watershed and/or water quality modelling, which would be suitable for countries having watersheds with similar structure and problems to those of Turkey, is also outlined.

Analysis and modelling of land-based nutrient pollution by watershed models coupled with GIS: a case study from Turkey.

Diffuse pollution is usually temporally and spatially uncertain, and thus hard to analyze. In many cases, discretizing a diffuse source of pollution into individual point sources can ease diffuse pollution modelling and analysis, and therefore reduce high uncertainty especially in the spatial distribution of pollution loads. This is however a difficult task, since quite a number of sub-drainage areas, with complex structures and land-use properties, has to be delineated. Watershed models can be used to delineate the sub-drainage areas in a watershed with high accuracy and locate the related outlets which connect the sub-drainage areas to the main waterbody in a watershed. In this study, such an approach has been used on a case study to model the diffuse nutrient loads carried to streams that reach to a medium-sized lake in Turkey. The annual nutrient loads, which were calculated by using mathematical models, were then converted to a load-map with the help of a geographical information system.

Use of a geographic information system in an epidemiological study of measles in Istanbul.

A geographic information system was used in an epidemiological study of measles in Istanbul, Turkey. The aim was to obtain more reliable results and to increase the facilities for spatial monitoring in epidemiological studies. The Gaziosmanpasa district of Istanbul was selected as it experiences the highest level of migration, and currently has the highest population growth rate of the city's districts. The epidemic distribution of measles was investigated on the basis of examination of 320 children. The number, geographical distribution, complications and time of measles outbreaks were analysed and represented in thematic maps (a small selection is shown in this paper). The results were evaluated and, in view of these results, new vaccination plans were arranged.

Photogrammetric analysis of the articular surface of the distal radius.

Three-dimensional measurements made using photogrammetry have recently gained popularity with the development of real-time detection facilities and up-to-date equipment. The modelling of human bones presents a particular challenge as the measurements required are difficult to obtain, especially from uneven surfaces. In this study, the articular surfaces of 12 radius bones were evaluated using photogrammetry to obtain three-dimensional coordinates of certain points. Morphometric characteristics of the digital topography of the articular surface were analysed using three-dimensional data from more than 200 points for each specimen. The coronal plane curve, from the tip of the styloid process to the centre of the distal radioulnar articular notch, was found to be similar to the fourth degree polynomial function. A mathematical expression representing the sagittal curve passing through scapholunate border could not be found. Close-range photogrammetry is a safe and precise technique that can provide reliable, reproducible and accurate data for evaluating complex morphological surfaces.

Risk assessment of a dam-break using GIS technology.

Flood disasters cause massive loss of human lives and immense damage to the infrastructure and economic activities, not only in Turkey but also all over the world. Governments consider several long-term and short-term precautions for flood control. The numerical simulation of dam-break problems could be accomplished with geographic information systems and innovation maps. Spread of the flood wave after a dam break can be predicted using these enabling technologies. This kind of advanced modelling technology is becoming an inevitable tool for the decision-making process. Data produced by GIS are used as initial values for FLDWAV. ArcView GIS has been used to produce a Digital Elevation Model and visualization of dam-break effects and propagation of a possible flood wave. Using GIS techniques and hydrologic modelling software, possible effects and damage of a dam-break flood have been investigated and results were simulated to show significant dam break effects on the region.

Investigation of coastal morphological changes due to river basin characteristics by means of remote sensing and GIS techniques.

The Riva River is located on the Anatolian (Asian) side of Istanbul by the Black Sea coast, with a wonderful sandy beach and delta formation which has been selected as the study area. The Riva is the largest river in this region, which flows into the Black Sea and also gives its' name to the area. The river carries some amount of sediments to the Black Sea. These particles cause considerable changes not only in the bed bathymetry and coastal boundaries of the river but also along the coastline of the Black Sea. The aim of this study is to determine these variations by means of satellite data and GIS. In the study, satellite images dated 1975, 1984, 1992 and 2001 have been used. At the end of the study, the possibility of observing bathymetric changes in front of the coastline by means of satellite data has been investigated and results were evaluated and visualised by means of GIS.