(Zhizheng) Hefangji (至正)河防記 "Records on River Conservancy" is a book on river conservancy written by Ouyang Xuan 歐陽玄 (1283-1357), courtesy name Yuangong 原功, from Liuyang 瀏陽 (today in Hunan), during the Zhizheng reign-period 至正 (1341-1368/1370) of the Yuan dynasty 元 (1279-1368).
Ouyang was Director of Education (guozijian cheng 國子監丞). In 1328 he was appointed edict attendant (daizhi 待制) of the Hanlin Academy 翰林院 and was concurrently junior compiler (bianxiuguan 編修官) of the Historiography Institute (guoshiguan 國史院). He participated in the compilation of the official dynastic histories Liaoshi 遼史, Jinshi 金史 and Songshi 宋史.
In 1342 the dams of the Yellow River burst at Suiyang 睢陽 near Guide 歸德, three years later at Baomaokou 白茅口, the at Caozhou 曹州, Baimaoti 白茅堤 and Jinti 金堤. The court therefore issued an edict to reorganise the management of waterworks and entrusted Ouyang Xuan with this task. He first consulted ancient texts about river conservancy and found that the most famous histories recorded virtually nothing about the practical implementation of water control. Only local gazetteers, reports of local officials and interviews with persons in the afflicted regions led to satisfying results that he brought into the shape of a short text, with the intention to create a handbook for further generations of local officals.
The edition of the Hefangji in the series Xuehai leibian 學海類編 is one-juan long, but not divided into chapters, and has no preface. The first part of the book describes how Ouyang Xun and Counsellor-in-chief Toqtoγa (Ch. Tuotuo 脫脫, 1314-1355) deliberated about the problem, the second describes how dams and dykes have to be constructed, and the last part which and how much materials must be used to repair brakeages.