Integrated urban water management and land use planning relationship: The case of Edremit bay

The water cycle is a system that includes different processes that express the behavior of water in the atmosphere. These processes can be summarized as water evaporating into water vapor, condensing to form clouds, and returning to the earth through precipitation. Throughout the cycle, water infiltrates into the soil through surface runoff and supplies groundwater. In addition to providing a buffer against rainfall variability, groundwater supports wetlands and biodiversity, provides water supply and base flow to rivers, provides recreational services and helps control floods. While steady rainfall benefits soils, biodiversity and groundwater, sudden and excessive rainfall over a short period of time can cause localized flooding and intense runoff. Such runoff exacerbates drought due to low soil absorption, especially in cities with highly impermeable areas. Since the 1950s, extreme heat has become more frequent and intense, while extreme cold has become less frequent and less severe, and the main reason for this has been observed to be anthropogenic climate change. Climate change caused by human activities causes many extreme weather and climate events such as heat waves, heavy rainfall, droughts. The most important of these activities is land use decisions. Today, the relationship between soil structure and land use has almost completely disappeared. The decrease in soil infiltration rate due to the increase in impervious surfaces negatively affects the urban water cycle, changes energy needs and usage habits, and also affects biodiversity by creating pressure on the surrounding permeable areas. Short-term measures such as the introduction of land use decisions disconnected from water and soil structure, piping water from other basins or sources to increase water supply instead of water conservation and reuse in urban basins are the result of traditional water management approaches. Coastal areas, which are among the most important parts of the world, are facing changes due to the interaction of local economic, social, political, climate and environmental factors. This situation increases the sensitivity of the coast. In addition to coastal sensitivity, factors such as weather events and sea level rise due to global warming and climate change cause multiple interdependent variables that lead to the formation of sediments along the coastline and affect the flow of rivers. Integrated Urban Water Management (IUWM), whose primary objective is to produce basin based planning approaches, integrates land use decisions with the urban water system to mitigate such negative impacts in urban areas, especially on the coasts, and contributes to the understanding of the relationship between groundwater and surface water and precipitation regime. It also helps access water and sanitation infrastructure, manage wastewater, stormwater, drainage and runoff pollution, control water-borne diseases, and reduce the risk of water-related risks such as floods, droughts and landslides. The concept of green infrastructure, one of the tools of IUWM, which emerged with the trend of uncontrolled urban sprawl, refers to interconnected links of all types of green spaces that "support native species, sustain natural ecological processes, protect air and water resources, and contribute to health and quality of life". The objective of green infrastructure is to provide clean water, moderate runoff, improve water quality xiii and control erosion. Low Impact Development, a green infrastructure strategy, refers to systems and practices that mimic nature to protect water quality and aquatic habitat. It is a hydrological and alternative land use approach and design that includes pollution prevention and mitigation measures to compensate for urbanization impacts on hydrology and water quality. In this study, firstly, demographic characteristics, natural structure, technical infrastructure, environmental problems and hazardous areas of the districts in the Edremit Basin were analyzed. After determining the current situation of the region, land use changes and trends from past to present are analyzed. With the Analytic Hierarchy Process method, which is one of the Multi-Criteria Decision Making Methods, suitable areas were determined according to the parameters selected for IUWM for artificial areas, agricultural areas, forest and semi-natural areas according to Corine land use classification. This study, which reveals how a land use model that converges the urban water cycle to the natural water cycle with the land use determined according to this method, targets to contribute to the studies to be carried out to reduce the effects of climate change on the urban water cycle and to integrate land use planning with water management plans.