The effects of non-integrated basin planning and improper land use on flooding: The case of Ürgüp (Nevşehir)

Abstract

This study aims to quantitatively reveal the combined effects of non-integrated basin planning and improper land use on flood risk, focusing on the Ürgüp-Damsa Stream basin. Flood management plans often disregard basin integrity by adhering to administrative boundaries, thereby neglecting the cumulative impact of tributaries that affect a settlement. This methodological flaw, combined with increased surface runoff from uncontrolled land-use change, elevates the risk to dangerous levels. In this study, the 120 km² basin area considered in the official plan was compared to the actual 383 km² basin area calculated with an integrated approach. Analysis of CORINE data from 1990 and 2018 showed that land-use change increased the runoff coefficient by 18.75%. Scenario analyses concluded that while the official 100-year design discharge (Q100) is 155 m³/s , the potential discharge reaches 393 m³/s when the basin's integrated and current conditions are considered. This discrepancy, where the actual potential risk is over 2.5 times the planned risk, explains the inadequacy of existing infrastructure and proves the predictability of floods, highlighting the urgent necessity of shifting to a holistic basin management paradigm.

Keywords

• Flood
• Integrated Basin Management
• Land Use Change

Bütüncül olmayan havza planlaması ve hatalı arazi kullanımının taşkın üzerindeki etkileri: Ürgüp (Nevşehir) örneği

Abstract

Bu çalışma, bütüncül olmayan havza planlaması ve hatalı arazi kullanımının sel/taşkın riski üzerindeki birleşik etkilerini Damsa Çayı havzası (Ürgüp-Nevşehir) özelinde nicel olarak ortaya koymayı amaçlamaktadır. Taşkın yönetimi planları, genellikle idari sınırlar esas alınarak havzanın bütünlüğünü göz ardı etmekte ve bir yerleşimi etkileyebilecek yan kolların kümülatif etkisini ihmal etmektedir. Bu metodolojik zafiyet, kontrolsüz arazi kullanım değişimlerinin yüzeysel akışı artırmasıyla birleşerek riski tehlikeli boyutlara taşımaktadır. Çalışmada, resmi planda ele alınan 120 km²'lik havza alanı, bütüncül yaklaşımla hesaplanan 383 km²'lik gerçek havza alanıyla karşılaştırılmıştır. 1990 ve 2018 CORINE verileriyle yapılan analiz, arazi kullanım değişiminin akış katsayısını %18,75 artırdığını göstermiştir. Senaryo analizleri sonucunda, 100 yıllık tasarım debisinin (Q100) resmi plandaki 155 m³/s değerine karşın havzanın bütüncül ve güncel durumu dikkate alındığında potansiyel olarak 393 m³/s'ye ulaştığı hesaplanmıştır. Planlanan risk ile gerçek potansiyel risk arasındaki bu 2.5 katı aşan fark, sahadaki altyapı yetersizliğini ve taşkınların öngörülebilirliğini kanıtlamakta, bütüncül havza yönetimi paradigmasına acil geçişin zorunluluğunu vurgulamaktadır.

Keywords

• Taşkın
• Bütünleşik Havza Yönetimi
• Arazi Kullanımı Değişimi

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