Integrated water resources management $($IWRM$)$ is a holistic approach to managing water sustainably, considering the interconnectedness of water resources, ecosystems, and human activities. Investigate the theoretical foundations of IWRM, including principles such as stakeholder participation, adaptive management, and ecosystem$-$based approaches. How do water managers and policymakers apply theoretical models of IWRM to promote water security, equity, and sustainability through coordinated planning, allocation, and management of water resources at the basin scale?