Transcript Science View Importance of Groundwater and Surface-Subsurface Interactions Miguel A. Medina, Jr. Professor, Duke University [email protected] First GEF Biennial International Waters Conference, October 14 – 18, 2000 Budapest, Hungary.

Science View
Importance of Groundwater and
Surface-Subsurface Interactions
Miguel A. Medina, Jr.
Professor, Duke University
[email protected]
First GEF Biennial International Waters
Conference,
October 14 – 18, 2000
Budapest, Hungary
Relation of streams, lakes, and
wetlands to groundwater flow systems
(Winter, Hydrogeology Journal, 1999)
“Surface-water bodies are integral parts of groundwater flow systems.
Groundwater interacts with surface water in nearly all landscapes, ranging
from small streams, lakes, and wetlands in headwater areas to major river
valleys and seacoasts.”
“Hydrologic processes associated with the surface-water bodies themselves,
such as seasonally high surface-water levels and evaporation and transpiration
of groundwater from around the perimeter of surface-water bodies, are a
major cause of the complex and seasonally dynamic groundwater flow
fields associated with surface water.”
Complex Interactions
Overland - Channel Flow
Component
Net
Rainfall
Free surface evaporation
Overland flow
Channel flow
Infiltration
Stream - Aquifer
Interactions
Saturated Flow Component
Pumping
qp
qe
qr
qi
H
Unsaturated /
saturated zone
interaction
Phreatic
surface
h
Stream-Aquifer
Interaction
Nearly horizontal flow
Impervious bed
z0
Reference datum
Unsaturated Flow
Component
Rainfall
Soil
Evaporation
Infiltration
Root zone
Percolation /
Capillary rise
Phreatic surface
Unsaturated / saturated zone
Interactions
transpiration
precipitation /
evaporation
evaporation
runoff
root zone
vadose zone
recharge
leakage
Surface
water body
phreatic surface
Schematic of an example of surface-groundwater interactions. In this
example, the surface water body is losing water to the groundwater
zone.
Stream-Aquifer Systems
Gaining stream
Losing stream
Losing stream
induced by
pumping well
Vital Elements for a Conjunctive
Stream-Aquifer Model
• Element to calculate groundwater flow
• Element to calculate solute transport in aquifer
• Element to calculate stream flow
• Element to calculate solute transport in stream
• Element to account for stream-aquifer
interaction
Accounting for Stream-Aquifer Interaction -Lateral Exchange (Hyporheic Process)
(After Harvey, et al., 1996)
Stream-groundwater exchange involving vertical and lateral interactions
(After Battin, 1999)
Steady state mass balance of water in the streambed:




dwn
up
in
out
up
0  qver
 qver
x y  qhor
 qhor
y z  qgw
x y  
Mass balance of solute in the streambed:
C
dwn
up
in
out
up
x y z  Csw qver
 Chyp qver
x y  Crg qhor
 Chyp qhor
x y  C gw q gw
x y  
t




Conjunctive Use Water Supply Schemes
• Take advantage of the most favorable characteristics of
surface and subsurface storage of water
• Enhance long-term availability through use of large storage
volume in most aquifers to store surplus surface water
• During droughts, when surface supplies dwindle, recover
stored aquifer water by pumping (ASR – Aquifer Storage
Recovery)
• Low quality surface water may be filtered by porous media
percolation
Transport of water from one storage facility to
another – unique to conjunctive use
• Stream channels, pipelines, tunnels, open
channels
• Storage reservoirs (high evaporative loss)
• Artificial recharge – permeable beds of
rivers, surface spreading basins (losses due
to evaporation, absorption), injection wells
(pre-treatment required for high quality)
Common Arab-Israeli Surface and Groundwater
Resources (Kliot and Shmueli, 1998)
• Lebanon, Syria, Israel, Jordan and the Palestinian
Authority share the Jordan River and its tributary, the
Yarmuk
• The Upper Jordan (Lake Kinneret) has three sources: the
Hasbani (Lebanon), the Banias (since 1967 controlled by
Israel, and the Dan (Israel)
• Syria, Israel and Lebanon share the Upper Jordan
• Syria, Israel, Jordan and Palestinians share the Lower
Jordan
• Israel and Palestinians share groundwater
Over-Utilization of Jordan-Yarmuk system
(Kliot and Shmueli, 1998)
• The Yarmuk River – the most important tributary of the
Jordan River, has a discharge of 400-500 Mm3/year.
• Over-utilization of the Jordan-Yarmuk system has resulted
in a decline of the total discharge of the Jordan into the
Dead Sea to 250-300 Mm3/year, accelerating the decline of
the Dead Sea.
• Most of this discharge is actually irrigation return flow,
inter-catchment runoff, saline spring discharges and
sewage dumped by Israel to the Lower Jordan.
Israeli-Palestinian Shared Groundwater Resources
(Kliot and Shmueli, 1998)
• Mountain Aquifer – 3 sub-aquifer systems: Western (300335 Mm3/year); the Northeastern (130-150 Mm3/year); the
Eastern (150-250 Mm3/year). Total annual recharge is
about 680 Mm3/year.
• Israel uses about 480 Mm3/year and the estimate for the
Palestinians is 110-180 Mm3/year.
• Coastal Aquifer (in the Gaza Strip) yields 60 Mm3/year but
is overexploited by 30-50 Mm3/year, with total pumping of
90-110 Mm3/year.
• Issue of water quality perceived as important as water
quantity in peace treaties and agreements.
Joint Management Structures for Cross-Boundary
Aquifers (Feitelson and Haddad, 1998)
• Need is likely to become acute in near future, as reliance
on aquifers grows, and water stress increases
• Yet, there is scant experience in management of crossboundary GW resources
• Gradual simple positive steps, such as joint monitoring and
data sharing, should be taken first.
• At the same time, these steps should be part of a more
comprehensive institutional development path.
Transboundary Freshwater Dispute Database
(http://terra.geo.orst.edu/users/tfdd)
• 150 water-related treaties, 39 U.S. interstate
compacts, catalogued by basin, countries, date
signed, conflict resolution mechanisms, etc. (Wolf,
1999)
• Digital map of 261 international watersheds
• Full text of each treaty and compact
Water Conflict Chronology
Pacific Institute for Studies in Development,
Environment, and Security (2000)
http://www.worldwater.org/conflictIntro.htm
Covers water conflicts from 1503-2000