he high scientific standards maintained by Hydrology Research in its papers owe much to the continuing dedication of the journal's reviewers, who give freely of their time and expertise. IWA Publishing is pleased to pay tribute to this contribution by recognizing those who have participated in the review process. Thus, the Editors of Hydrology Research acknowledge with particular gratitude the following reviewers who have reviewed papers during the period January 2019–December 2019.
| Ali A. Assani | Giuseppe Del Giudice | Ozgur Kisi | Diana Mohanraj | Virginia Stovin |
| Aminuddin Ab Ghani | Jörg Dietrich | Nils-Otto Kitterød | Rangaswamy Mohsenipour | Fubao Sun |
| Yisak Sultan Abdella | Ling-Yun Ding | Michael Kizza | Morteza Moore | Qiaohong Sun |
| Mahyar Aboutalebi | Wenfeng Ding | Thomas Kjeldsen | Paul A. Moore | Xun Sun |
| Eyad Abushandi | Andre Diniz | Bjørn Kløve | Dan Morbidelli | Muh Taufik |
| Ismail Abustan | HF Duan | Ian Knack | Renato Muhammad | Søren Thorndahl |
| Bachir Achour | Andreas Efstratiadis | Harri Koivusalo | Ameer Musselman | Ye Tian |
| Abebe Girmay Adera | Kolbjørn Engeland | Teemu Kokkonen | Keith Muthanna | Mustafa Tombul |
| Ana Adeva Bustos | Keramaris Evagelos | Sjur Kolberg | Tone Nardi | Ali Torabi Haghighi |
| Sajal Adhikary | Fernando Fan | Tatjana Kolcova | Fernando Nazeri Tahroudi | Slavisa Trajkovic |
| Arash Adib | Duncan Faulkner | Marina Kolpakova | Mohammad Ngongondo | Hristos Tyralis |
| Ebrahim Ahmadisharaf | Ennio Ferrari | Akinola Adesuji Komolafe | Cosmo Nie | Tatsuhiko Uchida |
| Kamal Ahmed | Giuseppe Formetta | Nektarios Kourgialas | W. Ning | Fisaha Unduche |
| Pertti Ala-aho | Hayley Fowler | Valentina Krysanova | Like Novák | Andrew Wade |
| Moutaz Al-Dabbas | Felix Francés | Bimlesh Kumar | Viliam O'Donoghue | Andrzej Walega |
| Knut Alfredsen | Bjørn Frengstad | Hyun-Han Kwon | Thomas Okkonen | Long Wan |
| Nino Amvrosiadi | Guangtao Fu | Michele La Rocca | Jarkko Orr | Dingbao Wang |
| Gholamreza Andalib | Yavuz Selim Güçlü | Changwei Lü | Harriett Oshima | Chunying Wang |
| Joaquín Andreu | Tamer Gado | Matthieu Lafaysse | Kazuhiro Pang | Guoqiang Wang |
| Keyvan Asghari | Sigurdur Gardarsson | Luca Lanza | Bo Park | Shuo Wang |
| Pedram Attarod | Mohammad Ali Ghorbani | Karl Lapo | Youn Shik Parsaie | Xiaocui Wang |
| Hazi Azamathulla | Constantin Gogu | Deborah Lawrence | Abbas Peel | Xiaodong Wang |
| Junhong Bai | Yicheng Gong | Henning Lebrenz | Murray Pena-Haro | Xiekang Wang |
| James Ball | Simon Gosling | Jae-Kyoung Lee | Salvador Peng | Thomas Way |
| Reza Barati | Ashenafi Gragne | Guoyong Leng | Yong Persiano | Paul Webster |
| Stein Beldring | Francesco Granata | Matti Leppäranta | Simone Pollock | Wang Weiguang |
| Maria Bermudez | Claire Griffin | Binquan Li | Michael Prosdocimi | Harry West |
| Keith Beven | Salvatore Grimaldi | Chuanqi Li | Ilaria Pu | Howard Wheater |
| Rabin Bhattarai | Jorge A Guzman | Chunlin Li | Jaan Qin | Mark Wilkinson |
| Marcella Bidoccu | Erin Haacker | Hong Li | Xiaosheng qin | Keith D. Willett |
| Katrin Bieger | Anthony Hammond | Jianzhu Li | youwei Quinn | Kraig B. Winters |
| Daniela Biondi | Jianqiao Han | Lu Li | Nevil Rød | Daniel Wright |
| Basudev Biswal | Heechan Han | Peiyue Li | Jan Rahman | Xianhong Xie |
| Andrew Black | Masaki Hayashi | Xiaoyu Li | Mohammed Rahmati | Zhongbao Xin |
| Martijn Booij | Bin He | Wei Liang | Omid Rajagopal | Bin Xu |
| David Boorman | Hans Jørgen Henriksen | Ian Littlewood | Seshadri Raphael | Chong-Yu Xu |
| Péter Borsányi | Hidayat Hidayat | Bingjun Liu | Benny Ravindranath | Mengzhen Xu |
| Alistair Borthwick | Makoto Higashino | Dedi Liu | Arun Reihan | Xingya Xu |
| Morten Borup | Reinhard Hinkelmann | Heping Liu | Alvina Rhoades | Yunqing Xuan |
| Etienne Bresciani | Jaroslav Hofierka | Pan Liu | Alan Rientjes | Pingheng Yang |
| Oddbjørn Bruland | Ian Holman | Yaping Liu | Tom Romano | Zaher Yaseen |
| Tommaso Caloiero | Aida Hosseini Baghanam | Fan Lu | Emanuele Romanowicz | Xuchun Ye |
| Enrica Caporali | Jingming Hou | Jianzhong Lu | Renata Roohollah | Hsin-Fu Yeh |
| Ana Casado | Guoru Huang | XiXi Lu | Noori Sörensen | Dongqin Yin |
| Markus Casper | Shengzhi Huang | Lian Lundy | Johanna Sachindra | Yixin Yin |
| Artemi Cerdà | Denis Hughes | Lifeng Luo | D.A Sen | Fei Yuan |
| Kwok Wing Chau | Vito Iacobellis | Pingping Luo | Sumit Shao | Feifei Yuan |
| K.W. Chau | Eun Soon Im | Wei Luo | Songdong Shen | Antonio Zarlenga |
| Jie Chen | Seiichiro Ioka | Yandong Ma | Jian Shiri | Martina Zeleňaková |
| Qinbo Cheng | Hadi Jafari | Dmitrii Magritskii | Jalal Shrestha | Menberu Teshome Zeleke |
| Delson Chikobvu | Reza Jahanshahi | Rabin Malla | Rajesh Sihag | Guanghui Zhang |
| Ana Cingolani | Cong Jiang | Sukhmani Mantel | Parveen Skaugen | Jin Zhang |
| Declan Conway | Dong Jiang | Feng Mao | Thomas Solín | Jun Zhang |
| Rui Cortes | Collin G. Joseph | Hero Marhaento | Ľubomír Song | Qi Zhang |
| Barry Croke | Akbar Karimi | F Martínez-Capel | Jiyun Songhao | Yinsheng Zhang |
| Christophe Cudennec | Sepideh Karimi | Mario Martina | Shang Sordo-Ward | Yueguan Zhang |
| Ningbo Cui | Mahsa Kashani | Christpher Martinez | Alvaro Sortberg | Zengxin Zhang |
| Maria Cunha | Giri Kattel | Hannu Marttila | Asgeir Soulis | Guangju Zhao |
| Hammouda Dakhlaoui | Rijan Kayastha | Mohamed Mattar | Konstantinos Spencer | Jianshi Zhao |
| Vaclav David | Amin Kiaghadi | Saeid Mehdizadeh | Peter Stewart | Abdel-Razik Zidan |
| Richard Davis | Sungwon Kim | Rajeshwar Mehrotra | Elizabeth Stovin | Qiting Zuo |