IWRM is a general concept developed to improve the management of water resources based on four key principles adopted at the 1992 Dublin and Rio statements Conference on Water.
Watershed management could be considered as part (or as tool) directed to achieve IWRM.
holistic approach to wateshedr management is essenti and integrated Water Resources Management (IWRM) approach that has now been accepted internationally as the way forward for efficient, equitable and sustainable development and management of the world's limited water resources and for coping with conflicting demandsí8g
When you talk about IWRM, it's more of an integrated effort. In my understanding it is a resource management process that not only considers the natural resources, but also takes into account of the other sectoral development possibilities (say, socio-economic growth). For example, you want to construct an embankment structure, but you cannot disregard the sectoral needs for fisheries, socio-economic development etc. For reference:
In my view, watershed management is more eccentric towards the natural resources management. Like Ahmed said, watershed management can be a tool within IWRM.
'IWRM is a process which promotes the coordinated development and management of water, land and related resources, in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems.'
Watershed management is a term used to describe the process of implementing land use practices and water management practices to protect and improve the quality of the water and other natural resources within a watershed by managing the use of those land and water resources in a comprehensive manner.
Agarwal, A., delos Angeles, M. S., Bhatia, R., Chéret, I., Davila-Poblete, S., Falkenmark, M., ... & Rees, J. (2000). Integrated water resources management. Global water partnership.
'Watershed' is the unit for implementing "management" of natural resources like water, land, soil, forest, agriculture, etc. IWRM is a process / methodology which promotes the coordinated development and management of water, land and related resources, in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems.
Watershed is comparatively small unit for scientific development and management of land and water resources in an optimal manner for its socio-economic and environmental needs with participation of all the stakeholders.
This methodology itself is IWRM. However, IWRM concept is still evolving ....for instance....the optimal development indicators for socio--economic,environmental and ecological parameters are still grey.... while implementing IWRM on large river basins.
IWRM is broader spectrum/umbrella and while Watershed Management is specifically related to watershed. In IWRM about all the users (stakeholders) of the water and resources lies. On the other hand, watershed management referred to specific objectives/problems of watershed under study e.g. soil erosion, LUCC, Water Balance, CC impacts of runoff etc.
Water originated from watersheds, thus watershed management covers a broader range of water-related issues along with other influencing factors on water cycle. The watershed scale also contains all of water resources according to "ridge to reef" concept from the spatial point of view. All stakeholders live in watersheds (and large watersheds).
IWRM is a systematic process for the sustainable development, allocation and monitoring of WATER resource use in the context of social, economic and environmental objectives"
IWM: an adaptive, integrated, and multidisciplinary systems approach to management of watershed RESOURCES that aims to preserve productivity and ecosystem integrity regarding the water, soil, plants, and animals within a watershed, thereby protecting and restoring ecosystem services for environmental, social, and economic benefit"