234
R. Orthofer and W. Loibl
3 Risks for Groundwater Pollution
We have analyzed risks for nitrate pollution of the (1) deep mountain aquifers in
the west side of the valley, and (2) of the shallow groundwater in the overall
valley floor (on both sides of the River Jordan). Our work is based on the spatial
analysis of pollution sources that affect aquifers, and subsurface flows along wadis
or rivers.
The deep mountain aquifers in the western study area are the primary local
freshwater sources in the western part of the Lower Jordan Valley. Although they
have been studied thoroughly during the past 50 years, little information is
publicly available. Some characteristics of the recharge and flow dynamics have
been reported by Isaac and Shuval (1994). On the western side of the river, there
are Cenomanian and Pleistocene aquifers. The Upper and Lower Cenomanian
aquifers are located in the Mesozoical layers of the highlands, the Pleistocene
aquifer is embedded in the younger Quartenary layers above the Cenomanian
aquifers. The recharge area of the Cenomanian aquifers is located in the highlands
west of the Lower Jordan Valley. The recharge area of the Pleistocene aquifer is in
the valley and in the adjacent slopes. On the eastern side, the major aquifers are
located in the Jurassic layers, which are recharged in the eastern highlands.
The layered aquifer structure and the complex interconnections between the
recharge areas and the aquifer layers are a result of the tectonic folding and
faulting processes that occurred during the rift formation. The geological structure
shows Mesozoic layers that are directed from the highlands downward to the east
and reach the rift fault far below the valley floor.
Figure 1 gives an overview of the location and extent of the major aquifers and
the known Cenomanian recharge areas.
3.1 Pollution Sources and Risk Factors
The risk of nitrate pollution depends on the nitrogen input into the soils, part of
which can then move into the groundwater. Elevated levels of nitrate in water are
considered a major risk for human health and as disturbing the ecosystems. Figure
2 summarizes the spatial distribution of the nitrogen input into the T A and WRA
from precipitation, fertilizer use, irrigation with groundwater and wastewater, fish
pond seepage, waste dumps, and from domestic wastewater disposal. The nitrogen
inputs have been calculated by applying appropriate emission factors (Table 3),
taking into account the different local features and factors that affect the nitrogen
inputs.
The risk of nitrogen pollution for groundwater comes from the leakage of
nitrogen compounds through soils and rock into the aquifers. The rate of nitrogen
leakage depends on the soil types and on the pulse for the downward transport of
these compounds through water. The spatial distribution of the calculated nitrogen
leakage is shown in Fig. 3.
There are two major risk elements for groundwater pollution: the risk for deep
mountain aquifers (that supply most of the freshwater), and the risk for shallow
R. Orthofer and W. Loibl
3 Risks for Groundwater Pollution
We have analyzed risks for nitrate pollution of the (1) deep mountain aquifers in
the west side of the valley, and (2) of the shallow groundwater in the overall
valley floor (on both sides of the River Jordan). Our work is based on the spatial
analysis of pollution sources that affect aquifers, and subsurface flows along wadis
or rivers.
The deep mountain aquifers in the western study area are the primary local
freshwater sources in the western part of the Lower Jordan Valley. Although they
have been studied thoroughly during the past 50 years, little information is
publicly available. Some characteristics of the recharge and flow dynamics have
been reported by Isaac and Shuval (1994). On the western side of the river, there
are Cenomanian and Pleistocene aquifers. The Upper and Lower Cenomanian
aquifers are located in the Mesozoical layers of the highlands, the Pleistocene
aquifer is embedded in the younger Quartenary layers above the Cenomanian
aquifers. The recharge area of the Cenomanian aquifers is located in the highlands
west of the Lower Jordan Valley. The recharge area of the Pleistocene aquifer is in
the valley and in the adjacent slopes. On the eastern side, the major aquifers are
located in the Jurassic layers, which are recharged in the eastern highlands.
The layered aquifer structure and the complex interconnections between the
recharge areas and the aquifer layers are a result of the tectonic folding and
faulting processes that occurred during the rift formation. The geological structure
shows Mesozoic layers that are directed from the highlands downward to the east
and reach the rift fault far below the valley floor.
Figure 1 gives an overview of the location and extent of the major aquifers and
the known Cenomanian recharge areas.
3.1 Pollution Sources and Risk Factors
The risk of nitrate pollution depends on the nitrogen input into the soils, part of
which can then move into the groundwater. Elevated levels of nitrate in water are
considered a major risk for human health and as disturbing the ecosystems. Figure
2 summarizes the spatial distribution of the nitrogen input into the T A and WRA
from precipitation, fertilizer use, irrigation with groundwater and wastewater, fish
pond seepage, waste dumps, and from domestic wastewater disposal. The nitrogen
inputs have been calculated by applying appropriate emission factors (Table 3),
taking into account the different local features and factors that affect the nitrogen
inputs.
The risk of nitrogen pollution for groundwater comes from the leakage of
nitrogen compounds through soils and rock into the aquifers. The rate of nitrogen
leakage depends on the soil types and on the pulse for the downward transport of
these compounds through water. The spatial distribution of the calculated nitrogen
leakage is shown in Fig. 3.
There are two major risk elements for groundwater pollution: the risk for deep
mountain aquifers (that supply most of the freshwater), and the risk for shallow