I am guessing you want something more than how to map surface hydrologic boundaries, which any hydrologist should be able to show how to do with topographic map or in GIS with digital elevation model, and flow accumulation modeling from raster data.  The suggestion with saline lakes, is there may be no outlet, but that should be no problem in following the surrounding ridge and connecting saddles on the topographic map elevation in following the high points as you digitize around the lake.  Defining a hydrogeologicsl boundary suggests a much greater level of sophistication and perhaps data to support this level of accomplishment, as there may be unseen groundwater circulation issues that are difficult to assess without geological mapping, interpretation, etc.  If the lake is surrounded by relative flat country, the groundwater circulation pattern (Toth theory 1962) should be local, however if surrounded by major elevation difference, groundwater circulation patterns may be well beyond local conditions.  I would suggest to do your question justice, you pull in collaborators if you are trying to address this on a complex scale.  If intended for one lake or circumstance, alot depends on the available geology and groundwater information as to potential sudsurface flow patterns or groundwater circulation patterns.  I will get into competer and add a paper that discusses use of water quality indicators to suggest what part groundwater plays in surface flow hydrograph, perhaps an idea like this might help you assess if the lake and area wells suggest outside groundwater influence.

Here is the Toth theory paper and the Garrett et all paper using the end member analysis of water quality difference between rainfall, interflow and groundwater quality that you might find interesting.  Our paper on springs quality of Missouri also supports the water quality change in karst terrain associated with more flow during storm periods. 

From question, my guess is you are not a student, but if your question is more basic than I perceived, you can probably obtain guidance in US Geologic Survey papers or hydrology book.  I don't remember what level of detail is within the 2005 paper in SC where we evaluated the hydrologic units in South Carolina.  I also failed to mention, that a lake with an outlet, the outlet becomes the lower part of the hydrologic unit, in a lake basin description, it has no outlet and then you follow the highest elevations as you go around the hydrologic unit boundary.

Surface hydrology is one of logic and gravity, water flows down hill, from higher to lower.  In groundwater hydrology, how it moves is more uncertain, complex and depends on various theories like Darcy's, Laplace, Toth and others.

Here is the Toth theory paper and the Garrett et all paper using the end member analysis of water quality difference between rainfall, interflow and groundwater quality that you might find interesting.  Our paper on springs quality of Missouri also supports the water quality change in karst terrain associated with more flow during storm periods. 

From question, my guess is you are not a student, but if your question is more basic than I perceived, you can probably obtain guidance in US Geologic Survey papers or hydrology book.  I don't remember what level of detail is within the 2005 paper in SC where we evaluated the hydrologic units in South Carolina.  I also failed to mention, that a lake with an outlet, the outlet becomes the lower part of the hydrologic unit, in a lake basin description, it has no outlet and then you follow the highest elevations as you go around the hydrologic unit boundary.

Surface hydrology is one of logic and gravity, water flows down hill, from higher to lower.  In groundwater hydrology, how it moves is more uncertain, complex and depends on various theories like Darcy's, Laplace, Toth and others.

Here is the Toth theory paper and the Garrett et all paper using the end member analysis of water quality difference between rainfall, interflow and groundwater quality that you might find interesting.  Our paper on springs quality of Missouri also supports the water quality change in karst terrain associated with more flow during storm periods. 

From question, my guess is you are not a student, but if your question is more basic than I perceived, you can probably obtain guidance in US Geologic Survey papers or hydrology book.  I don't remember what level of detail is within the 2005 paper in SC where we evaluated the hydrologic units in South Carolina.  I also failed to mention, that a lake with an outlet, the outlet becomes the lower part of the hydrologic unit, in a lake basin description, it has no outlet and then you follow the highest elevations as you go around the hydrologic unit boundary.

Surface hydrology is one of logic and gravity, water flows down hill, from higher to lower.  In groundwater hydrology, how it moves is more uncertain, complex and depends on various theories like Darcy's, Laplace, Toth and others.

Saline soils around lakes are normally either bar of vegetation or the vegetation consists of a specialized group of plant species adapted to the saline conditions.  However, there are many different salts that can cause salinity, and plants react differently to each chemical.  The salinity usually involves a mixture of salts in most semihumid areas, where they originate from the chemical weathering of primary minerals in the rocks from which the drainage originates.  Along temperate coasts, sodium chloride is usually the problem and there is an abundant literature on the species of native plants and their tolerances of this chemical.  However in desert environments and especially in basins, there is often one dominant salt, and these can be important sources of borates (Lake Chaka, Tibetan Plateau), potash (Saskatchewan), etc..

The contrast between the nonsaline vegetation and the bare , usually white salt deposits is the first, obvious clue.  Then you have to sample the soils along a transect across the changes in vegetation, determining the salts present and their concentration.  However this must be done at all seasons since the salts move with the flows of water from precipitation and groundwater in response to seasonal changes in hydrology,

Stuart.