This document discusses the complex interactions between groundwater and surface water systems. It notes that groundwater flows are influenced by surface water bodies through processes like seasonal water levels and evaporation. It also provides examples of gaining and losing streams based on interactions with groundwater. Additionally, it emphasizes the importance of accounting for stream-aquifer exchanges in water resource models and outlines some challenges around shared water resources in places like the Middle East.

1. Science View
Importance of Groundwater and
Surface-Subsurface Interactions
Miguel A. Medina, Jr.
Professor, Duke University
miguel.medina@duke.edu
First GEF Biennial International Waters
Conference,
October 14 – 18, 2000
Budapest, Hungary

2. 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.”

3. Complex Interactions

4. Overland - Channel Flow
Component
Net
Rainfall
Overland flow
Stream - Aquifer
Interactions
Channel flow
Free surface evaporation
Infiltration

5. Saturated Flow Component
Nearly horizontal flow
Stream-Aquifer
Interaction
Impervious bed
Unsaturated /
saturated zone
interaction
Phreatic
surface
Pumping
Reference datum
z0
h
H
qp
qr qi
qe

6. Unsaturated Flow
Component
Infiltration
Percolation /
Capillary rise
Phreatic surface
Rainfall
Unsaturated / saturated zone
Interactions
Soil
Evaporation
Root zone

7. evaporation
phreatic surface
leakagerecharge
root zone
transpiration precipitation /
evaporation
runoff
Surface
water body
vadose zone
Schematic of an example of surface-groundwater interactions. In this
example, the surface water body is losing water to the groundwater
zone.

8. Stream-Aquifer Systems
Gaining stream
Losing stream
Losing stream
induced by
pumping well

9. 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

10. Accounting for Stream-Aquifer Interaction --
Lateral Exchange (Hyporheic Process)
(After Harvey, et al., 1996)

11. Stream-groundwater exchange involving vertical and lateral interactions
( ) ( ) ε±∆∆+∆∆−+∆∆−= yxqzyqqyxqq up
gw
out
hor
in
hor
up
ver
dwn
ver0
( ) ( ) ε±∆∆+∆∆−−∆∆−=∆∆∆
∆
∆
yxqCyxqCqCyxqCqCzyx
t
C up
gwgw
out
horhyp
in
horrg
up
verhyp
dwn
versw
Steady state mass balance of water in the streambed:
Mass balance of solute in the streambed:
(After Battin, 1999)

12. 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

13. 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)

14. 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

15. 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.

16. Israeli-Palestinian Shared Groundwater Resources
(Kliot and Shmueli, 1998)
• Mountain Aquifer – 3 sub-aquifer systems: Western (300-
335 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.

17. 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 cross-
boundary 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.

18. 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

19. 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