It appears there is an assumption of forest land cover (until harvesting) providing water quality benefits in water sheds owing to less contaminant migration (i.e. leaching and runoff) and shading of streams minimising algal blooms. Forestry is also well known as a carbon sink in the context of climate change mitigation. However, the same forest cover imparts negative effects on water availability, aquifer recharge and stream flows owing to substantial rainfall water interception and transpiration by well established forest cover. The above fact is critical in discussing forestry ecosystem services and disservices.

Unsure if this may help - but here are a few thoughts.

From my logic training, and depending on the circumstances, some of these subjects can intersect, partially overlap, be unique or the same, as all can adjust in scale, and the circumstance changes with scale as to which, if any, may be a dominant factor for discussion. At its largest extent, the hydrologic cycle covers the earth and all ecosystems. The earth itself at its largest extent with atmosphere may also be considered an ecosystem, and contains the associated hydrology, lands, seas, surface and subsurface waters, watersheds of various sizes and scales, etc. Yet, the earth is but a speck in this or all universes. Scale could Affect which system or service you might want to discuss as dominant. if your water source is pristine forest catchment, its unique hydrologic cycle, ecosystem, forest and watershed overlap closely. But if your source water is karst spring, upwelling from a defined location, the scale and boundaries of watershed, forest or other land use, ecosystem and hydrology would not be as clear, may Directly, indirectly, cumulatively, intentionally or accidentally, man and other biologic contributors can influence and affect various ecological, hydrologic, watershed and land use circumstances and functions.

But concering each specific water supply, the hydrologic cycles and ecosystems contributing can be fairly defined, or fuzzy. Storms may be generated in distant locations, biotic life as trees and plants fairly static, but humans and animals both static and mobile, activities of varying intensities. As source water experts, we are challenged in perfectly and exactly defining the limits of and contributions to many source waters. The surface hydrology may be fairly well defined, subsurface not as fell defined, outside influences may be known or not, predictable or not. As scientists, we need to report as best as we can, try to clarify fuzziness, but also recognize that exacting hierarchy of cycles, systems, boundaries, land uses and activities will include some degree of uncertainty and fuzziness.

If I have a specific water supply, its surface watershed is definable. Subsurface contributing area approximated, forest or other ground covers definable, but also potentially rapidly changeable by man or severe event. Man, animals and/or extreme event can also alter hydrology, chemistry and function, and management or regulation can sometimes limit changes. But a new road may capture and move water into or out of defined catchment or watershed. Fuzziness is only clarified to the extent of our abilities to recognize and report these, yet some may remain, as water systems have some fairly static, but also dynamic elements. We must recognize that from a watershed, ecosystem, hydrologic and forest scientist perspective, we do not all have same perspective and must do best as we can to understand each other.

Well,

Return to the basic definition of Hydrology which obtains the followings;

HYDROMETEOROLOGY; (Atmospheric water- Precipitation and Evapotranspiration)

POTAMOLOGY (Streams and Rivers/ including forest hydrology)

LIMNOLOGY (Lakes and Wetlands)

CRYOLOGY (Glaciers and Glaciations)

OCEANOGRAPHY (Marines and Oceans)

HYDROGEOLOGY/Geo-hydrology, (Groundwater).

Each of the above categories is a part of the hydrological cycle. Therefore, the study can be described according to the conditions of the region and how it affects or is affected by the branches of hydrology.

Sincerely

Hi everyone,

Thanks for chiming in. From what I get from your contributions, it appears the answer to this question would be both dependent on the scale of study and the field of the study. Interesting.

Hi,

In my opinion, if your are studying on a watershed scale, it should be the watershed services since there is a certain border for watersheds, enabling us to measure the service of surface water supply. Also, watershed services can be varied depending on vegetation cover (forests, grassland, etc.) and/or climate, but with a known area (border), a watershed -with or without forest- can be studied better in respect to its provided services.

Good luck..

It is a Hydrologic Service.

It is a engineering hydrology which include the following:

Hydrology, surface hydrology, groundwater, hydrogeology, hydrograph, streamflow, calculation of discharge, recharge area and discharge area,........

In my view, surface water is an integral component of the larger eco-system in which it is found, and has an interconnected bearing on and affected by total vegetation management as well as judicious ground water use, health of glaciers feeding it, precipitation cycle that translates into inadequate (or otherwise) rainfall and snow accumulation. Belonging to South Asia as I do, where fresh water availability, though inadequate, should still not be a problem if better managed (which it is not), the commons (including surface waters like rivers that became trans-national overnight on 14th August 1947 became hostage to the "Partition Syndrome".

The mindset of fiercely nationalist possession/"ownership" over the commons has unfortunately sucked all the nations into a trap from which they cannot free themselves.

Please see my paper on "The looming Non-Traditional Challenges to Security in South Asia: Restoring Ecological Integrity and Security", Journal of Bangladesh studies, Volume 18, Number 1&2, 2016, ISSN 1529-0905

adding a file for your perusal

Hello Francois !

You have raised a very pertinent question, though the answers are difficult to have references. As per my education and experience, Watershed includes land use, hydrology and subsequent water use / supply. Nature doesn't differentiate or compartmentalizes human expertise of fields. Watershed is a unit where hydrologic cycle operates and land use pattern in the watershed influences the water supply. In my opinion the experts like you could understand have a better perspective of this integration of all three than the expert with single track mind.

Article Eco-Hydrological Footprint of a River Basin in Western Ghats

It is a hydrological process, evaporation, precipitation, infiltration, evapotranspiration, ......groundwater, surface hydrology, .....climatology,

Depends on which environment