Acronyms
Acronyms
See the acronyms list
| Acronym | Description |
|---|---|
| APN | Allende Piedras Negras |
| BCM | Basin Characterization Model |
| CHIRPS | Climate Hazards Group InfraRed Precipitation with Station data |
| CILA | Comisión Internacional Límites y Agua |
| CONAGUA | Comisión Nacional del Agua |
| DAYMET | Daily Surface Weather and Climatological Summaries |
| DEM | Digital Elevation Model |
| EALCO | Ecological Assimilation of Land and Climate Observations |
| GRACE | Gravity Recovery and Climate Experiment twin satellites |
| GW | Groundwater |
| IBWC | International Boundary Water Commission |
| INEGI | Instituto Nacional de estadísticas y Geografía |
| MODIS | Moderate Resolution Imaging Spectroradiometer |
| PFBW | Permanent Forum of Binational Waters |
| REDPA | Registro Público de Derechos de Agua |
| SINA | Sistema Nacional de Información del Agua |
| SW | Surface water |
| SWB Model | Soil Water Balance Model |
| TBA | Transboundary Aquifer |
| TWDB | Texas Water Development Board |
| USGS | United States Geological Survey |
Definitions
Transboundary groundwater and aquifers
A transboundary aquifer, or “transboundary aquifer system”, is a relatively new concept, coined from the need to share an aquifer that has been divided artificially by two or more jurisdictions. The common definition of aquifer in hydrogeology applies in this case too, but in the transboundary aquifer case, jurisdictional boundaries are added to the natural boundaries of the aquifer. Groundwater that crosses a jurisdictional boundary under natural conditions dictated by recharge, discharge, and hydraulic gradient is a transboundary groundwater flux. A groundwater flux may become transboundary under anthropogenic conditions too.
Transboundariness
This term refers to a new approach that identifies and prioritizes transboundary aquifers using socio-economic and political criteria, improving their characterization by using other variables in addition to their mere physical boundaries.
Groundwater (GW) stocks and GW fluxes
GW stocks (or pools) are the volume of GW stored in aquifers, other than the yearly recharge; GW fluxes are the volumes of GW movement as a function of time and space. Stocks are generally estimated in cubic kilometers, while fluxes are estimated in cubic kilometers per year.
Groundwater depletion
Pumping water out of the ground at a faster rate than it is replenished over the long-term. GW depletion is primarily caused by sustained groundwater pumping having negative effects.
Water security
Water security is a relative term; its meaning depends on the specific situation you are dealing with. Water security should be linked to the scale you deal with: a wells field scale, the aquifer scale, the watershed scale, the national scale, or the transboundary scale. With these in mind, water security can be described as a situation where water governance over all scalar levels ensures an interaction with the flow of groundwater. Ideally, this would be consensually considered equitable across all social groups, while also ensuring the long-term sustainability of the environment.
Hydrogeological Unit (HGU)
A hydrogeological unit is defined as any soil or rock unit or zone that by virtue of its hydraulic properties has a distinct influence on the storage or movement of groundwater. HGUs may exist at various scales: regional, contextual, unit, or as a single aquifer. One HGU may contain more than one aquifer. Thus, when delineating transboundary aquifers, HGUs should be clearly identified as a TBA, or as a hydrogeological unit, or a framework, where a transboundary aquifer or aquifer systems are present.
Hydrostratigraphic Unit (HSU)
Body of sediment and/or rock characterized by groundwater flow that can be demonstrated to be distinct under both unstressed (natural) and stressed (pumping) conditions, and is distinguishable from flow in other HSUs. An HSU is distinguished and characterized by its porosity and permeability. Delineation of these units subdivides the geologic framework into relatively more or less permeable portions and thus aids in definition of the groundwater flow systems. Hydrostratigraphic units may include aquitards, which should be included in the groundwater water flow system as they may pose significant barriers to the vertical flow of groundwater. This is an important aspect to consider when dealing with transboundary aquifer systems, which may significantly affect the regional flow of groundwater at the scale of the jurisdictional boundary.
Groundwater Flow Systems (GWFS)
Dynamics of Groundwater Flow Systems: A groundwater system comprises the subsurface water, the geologic media containing the water, flow boundaries, and sources (such as recharge) and sinks (such as springs, inter-aquifer flow, or wells). Water flows through and is stored within that system.
GFS are based on Toth’s conceptual model framework for investigation of unconfined groundwater systems. Groundwater flow systems do not only occur in aquifers, groundwater moves through all the saturated materials between a recharge and discharge area. This can include multiple aquifers (unconfined, and confined) as well as aquitards as illustrated schematically in the figure below. Confined aquifers are recharged at outcrop sites or by downward leakage of water from overlying aquifers. In down gradient areas they may discharge in the form of upward leakage of water into overlying aquifers.
