Watershed inventions should be targeted to ensure sustainability in terms of water and environment. For example, water recharging (combined - natural and artificial) has to counterbalance the lowering of water table because of over-exploitation. Other examples could be to optimize conjunctive use of surface and groundwater to sustain its annual variations within the desirable limits, to optimize waste load allocation to river system to sustain its flows with the desired quality and discharge, etc. These views are from technical point of view, and are required to be taken in policy formulations and planning watershed programs for the sustainability.
as the integrated approach integrates and unify all sectors,an overall strategy in watershed management can be done through strategic plan with all sectors involvement as well as to avoid overlapping and redundant jurisdiction. normally,there will be a strategic implementation plan developed for a specific area. also,the state gov plays the role in integrating between the development and management players.
No Govt-funded project works well unless people cooperate. So, your last point is the most important parameter, i.e., attitude changes at local/political level. Political will is certainly necessary, but then the user groups must participate actively for success of the project. In watershed management, public participation is the most important aspect.
The implementing agency needs to generate data in micro-scale in collaboration with the entities working in the field; this will help in the watershed management, but then community capacity building has to be emphasized more for larger public participation. Demystification of Science is the essence of the success. The people must understand the science of watershed management. Until the time they don't understand its meaning, no IWRM programme shall be successful, whatever money the Govt. invests. .
In addition to all mentioned above, do not forget public participation and ownership of the project. Once stakeholders feel that they have a say in project implementation and ownership and realize the benefits to them, it will succeed.