Dear Vivian and colleagues,

It is with deep sorrow that we learned of the tragic passing of Professor Yu Kongjian. His loss is profoundly felt across the global community of water, landscape, and urban resilience professionals.

Professor Yu was not only a visionary scholar but also a practitioner whose pioneering work on Sponge Cities has transformed how the world understands the relationship between nature and urbanization.

His ideas bridged science, design, and policy, inspiring countless researchers, planners, and students around the world to rethink how cities can live in harmony with water and ecology.

Beyond his remarkable intellect, he was a generous mentor and a courageous advocate for ecological civilization.

His legacy will continue to shape generations of scholars and practitioners striving for more sustainable and resilient futures.

We will remember him with great respect and gratitude—for his wisdom, his courage, and his enduring inspiration.

Our heartfelt condolences go out to his family, colleagues, and the entire Turenscape and Peking University community.

On behalf of  his 'Dutch' collaborators on Sponge Cities (Zihang Ding, William Veerbeek, Mila Montezuma, Frans van de Ven, Gerald Corzo, Dafang Fu, Yong Jiang and Chris Zevenbergen)

Chris Zevenbergen

译文：

致Vivian及同仁：

惊悉俞孔坚教授溘然长逝，全球水环境、景观规划与城市韧性领域的同仁同感哀恸。

俞教授不仅是开创性的学术巨匠，更是将"海绵城市"理念从理论推向实践的变革者。他重新定义了自然与城市共生的范式，其智慧已融入全球30余国的城市规划实践。

作为跨学科合作的典范，俞教授与荷兰代尔夫特理工大学的团队建立了深厚友谊。我们共同见证了他如何将东方"天人合一"的哲学，转化为可量化的水文模型与景观设计语言。2015年阿姆斯特丹海绵城市工作坊中，他坚持"让河流呼吸"的设计原则，至今仍是中欧生态合作的重要基石。

他更以师者胸怀培育了新一代规划师——无论是北京大学的课堂，还是威尼斯双年展的论坛，总能看到他手持草图，向年轻学者阐释"反规划"理念的身影。

谨代表荷兰合作团队（Zihang Ding, William Veerbeek, Mila Montezuma, Frans van de Ven, Gerald Corzo, Dafang Fu, Yong Jiang及本人），向俞教授的家人、土人设计团队及北京大学同仁致以最深切慰问。他的精神将如海绵般持续滋养未来城市。

Chris Zevenbergen

代尔夫特理工大学水文与气候适应教授

中欧海绵城市联合研究中心联席主任

2025年10月13日