SAHRA is responding to this situation by developing integrated multidisciplinary understanding. Our original proposal noted the existence of a critical gap between the products of the conventional individual- and multiple-investigator research projects and the tools used by water resources practitioners, and also the lack of an "effective mechanism for rapidly moving the state of scientific knowledge into widespread usage by the public and private agencies responsible for managing our water resources." SAHRA's vision continues to be to "develop an integrated, multidisciplinary understanding of the hydrology of semi-arid regions, and to build partnerships with a broad spectrum of stakeholders (both public and private organizations) so this understanding is effectively and rapidly brought to bear on the management of water resources and rational implementation of public policy." The key question that we seek to address is How can SAHRA use science to help communities manage their water resources in a sustainable manner? We are therefore concerned with: a) advancing the understanding of fundamental principles in semi-arid hydrology through stakeholder-responsive multidisciplinary research; b) understanding the demand and supply aspects of water resources and their linkages; and c) developing strategies for implementing scientific understanding on a practical level through aggressive knowledge transfer and strong education initiatives (K-16, graduate, and public).

Considerable progress has been achieved. SAHRA's greatest challenge is to bring about a high level of coordination and integration across a broad range of scientific disciplines, and among scientists, policy and decision makers, and the general public. We have made considerable progress during our first three years. First and foremost, SAHRA has achieved an integrated, multidisciplinary and multi-institutional approach to research, from which a number of interesting scientific results have begun to emerge. Integration has taken four forms:

1. Extensive input from over 100 key water decision makers, researchers and various stakeholders has been integrated into the SAHRA research agenda, through numerous formal and informal meetings. This process is ongoing.
2. A multidisciplinary team drawn from institutions throughout the Southwest has been effectively integrated through frequent team meetings, co-location of full-time research associates, and development of research questions that cut across disciplinary boundaries.
3. A process for end-to-end (scenarios to research findings) integration has been implemented. Research activities are designed to provide the information needed to support the supply and demand aspects of decision-making in the context of plausible scenarios that link causes with impacts and responses.
4. Hydrologic processes are being studied in the context of their role in the hydrology of an entire basin. Research tasks are designed to fill gaps in existing knowledge, particularly at the interfaces between traditional scientific disciplines, in the areas of basin scale water balance, river systems, and regional hydrology. Multi-resolution integrated modeling is being used to help integrate individual local-scale research findings, and to facilitate overall understanding of the complex interactions that occur at various spatial and temporal scales. Given the large size of the team and the immense scope of the modeling endeavor, considerable dialogue has been required to arrive at a workable structure for coordinating model development. Through a series of workshops, a consensual framework has emerged. The process of arriving at a conceptual model structure has resulted in considerable cross-disciplinary education of all parties involved.

The research tasks currently being pursued are the outcome of a progressive and logical evolution in our science plan. The original research agenda involved five primarily science-focused thrust areas with a large variety of research tasks that were not explicitly geographically coordinated. Through a lengthy process, including a comprehensive evaluation of SAHRA activities conducted by SAHRA research staff and management, regular meetings of the Executive Committee, a very productive series of workshops, and a comprehensive internal review of all science tasks, we have concluded that a river basin focus can provide the necessary context and motivation to help identify knowledge gaps and drive both the inter-disciplinary and end-to-end integration processes. Most SAHRA research activities are therefore being conducted in the Rio Grande and San Pedro River basins, with supportive work in the Rio Conchos (Mexico) basin and at the scale of the regional SW U.S. Note that close connections have also been achieved between the science and educational/knowledge transfer activities.