Early Southern Mesopotamia shows a complex history of expansion of (irrigated) farming in relation to urban developments and changing landscapes. As a first step to study expanding irrigated farming system, an irrigation-related agent-based model was developed to explore farm(land)s and irrigation systems in relation to decision-making processes, both of farms and their farmlands (an agriculture unit) and collective decision-making processes for irrigation system management—especially sharing water between farms. The decision-making processes include options to move farms, expand the system, or start a new system, as these would be options available for Mesopotamian farmers as well. In this text, we report how model parameters contribute to the generation of various patterns of yields and expansion of farms and system. Additionally, the Gini coefficient (based on yields) is applied to estimate levels of inequality among farmers. Our results show how (1) human decision-making determines the level of influence of and benefits for farms, as well as the overall irrigation system; (2) Gini values effectively capture the degree of inequality in yields among farms based on water availability; and (3) our model is a suitable base for further study, by incorporating additional agents into the irrigation system and expanding the spatial–temporal scales of the irrigated landscapes, to reach a more comprehensive understanding of the evolutionary dynamics of irrigation systems in Southern Mesopotamia.

早期的美索不达米亚南部展示了与城市发展和景观变化相关的（灌溉）农业扩张的复杂历史。作为研究扩大灌溉农业系统的第一步，开发了一个基于灌溉相关代理的模型，以探索农场（土地）和灌溉系统与农场及其农田（农业单位）决策过程的关系。灌溉系统管理的集体决策过程——尤其是农场之间的共享水。决策过程包括迁移农场、扩展系统或启动新系统的选项，因为这些选项也适用于美索不达米亚农民。在本文中，我们报告了模型参数如何有助于生成各种产量模式以及农场和系统的扩展。此外，基尼系数（基于产量）用于估计农民之间的不平等程度。我们的结果表明：（1）人类决策如何决定农场以及整个灌溉系统的影响和效益水平； (2) 基尼值有效地反映了基于水资源可用性的农场间产量的不平等程度； （3）我们的模型是进一步研究的合适基础，通过将额外的药剂纳入灌溉系统并扩大灌溉景观的时空尺度，以更全面地了解美索不达米亚南部灌溉系统的演化动态。