Solving the Water conflict and optimal allocation of common water resources are the most important service of cooperative game theory to water economics. Zayandehrud basin is the most important disputed basin in several neighboring provinces in the first class basin of Iran's central plateau. The purpose of this research is to use the game theory with application of Bankruptcy approach (conflicting claims) in order to optimally allocate surface and underground water resources in the Zayandehrud basin, with regard to Zayandehrud need(tourism sector demand), water transfer to Yazd and Kashan, Gavkhoni wetland water use and demand of three sectors: drinking, mining, and agriculture. In order to estimate the river natural water right (tourism sector demand), the Montana method (tenant) was used under three different scenarios: weak, acceptable and optimal tenant during the period 1963-2017, which was 77.7, 130.5, and 466.5 m3 respectively yearly estimated. The conflicting claims theory in various scenarios for the river water right (tourism sector) showed that in all three proposed scenarios based on five different bankruptcy theory rules, Proportional, Constrained Equal Wards, Constrained Equal Losses, Talmud, Random Arrival, CEA rule was the most desirable method for 5 sectors (except agriculture). In order to choose a more equitable method, the Gini coefficient and the Lorenz curve were used which indicated that CEA rule has less inequality than other rules. Thus, regard to the increasing demand gap in the Zayandehrud Basin, water allocation based on the criteria of bankruptcy theory is proposed.
