Water Resources Role in Sassanid Settlements Placement in the Sistan Plain

For a long time the Sistan Plain has been one of the important areas for men’s settlement due to abundant water resources. Following the preparation of the archaeological map of Iran and in methodical surveys of the Sistan plain, settlements of the era were identified and their geographical location was recorded. So far no comprehensive study on relation between water resources and settlements has been conducted. The present survey aims for studying reciprocal relation between Sassanid settlements and natural environment in areas based on water component. This research has been carried out through the descriptive -analytical and historical method using GIS software. To reach the research goals after environmental conditions had been studied, six variables including water resources types, distance from water resources, land slope, soil type, Geology and settlements area were studied and results indicate surface water resources effective role in settlements placement and settlements area. Locating on delta fans would lead to change of direction branching canals of rivers, which causes numerous relocations of settlements. The Water resources existence, gentle land slope and consequently ease of water flow down to different areas of plain, branching canals creation capacity to keep the suitable distance to river and also, placement on the alluvial terrace to avoid flood hazards are among the factors turned the area to population absorbing one despite shortage of aquifers and people’s heavy reliance on surface water resources.